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1
Lo, Xin Yin. "Analysis and reproduction of geopolymer concrete." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127289.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, May, 2020<br>Cataloged from the official PDF of thesis.<br>Includes bibliographical references (page 36).<br>Geopolymers are inorganic polymers based on aluminosilicates that are produced from synthesizing pozzolanic compounds or aluminosilicate source materials with highly alkaline solutions. Geopolymer concrete is a stronger, more durable and more environmentally friendly alternative to ordinary Portland cement (OPC) concrete. Based on Joseph Davidovits' recipe for geopolymer concrete, we varied the ratios of the materials in an attempt to produce the ideal formula for the concrete that withstands maximum compressive strength. Through our iterations, we found the optimum texture was produced when the amount of sodium carbonate and lime are proportionally increased relative to the rest of the materials.<br>by Xin Yin Lo.<br>M. Eng.<br>M.Eng. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
2
Matenda, Amanda Zaina. "GEOPOLYMER CONCRETE PRODUCTION USING COAL ASH." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1654.
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Coal powered power plants account for more than 40 percent of the electricity production of the United States. The combustion of coal results in a large number of solid waste materials, or coal combustion byproducts (CCBs). These waste materials are stored in landfill or ponds. The construction industry is heavily reliant on concrete which is used to make the building blocks for any type of structures, bricks. Concrete is a composite material made of a binder and coarse and fine aggregate. The most widely used binder in concrete production is Ordinary Portland Cement (OPC). Since cement manufacture is costly and environmentally damaging, research has increased in recent years to find a more readily available binder. This study aims at investigating the properties of Illinois fly ash as a binder in the production of geopolymer concrete. Geopolymer concrete is an innovative material made by using Alumina and Silica rich materials of geological origins as a binder as well as an alkali activated solution. Sodium Silicate and Sodium Hydroxide were used to make the activator solution of two different ratios. Geopolymer Concrete with a ratio of 1:1 of Sodium Silicate to Sodium Hydroxide reached a compressive strength above 6000 psi while samples made with a ratio of 1:2 reached a compressive strength above 4000 psi. This environmentally-friendly, green concrete was also found to have a cost comparable to conventional concrete.
3
Hardjito, Djwantoro. "Studies of fly ash-based geopolymer concrete." Thesis, Curtin University, 2005. http://hdl.handle.net/20.500.11937/634.
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The use of Portland cement in concrete construction is under critical review due to high amount of carbon dioxide gas released to the atmosphere during the production of cement. In recent years, attempts to increase the utilization of fly ash to partially replace the use of Portland cement in concrete are gathering momentum. Most of this by-product material is currently dumped in landfills, creating a threat to the environment. Geopolymer concrete is a ‘new’ material that does not need the presence of Portland cement as a binder. Instead, the source of materials such as fly ash, that are rich in Silicon (Si) and Aluminium (Al), are activated by alkaline liquids to produce the binder. Hence concrete with no Portland cement. This thesis reports the details of development of the process of making fly ash-based geopolymer concrete. Due to the lack of knowledge and know-how of making of fly ashbased geopolymer concrete in the published literature, this study adopted a rigorous trial and error process to develop the technology of making, and to identify the salient parameters affecting the properties of fresh and hardened concrete. As far as possible, the technology that is currently in use to manufacture and testing of ordinary Portland cement concrete were used. Fly ash was chosen as the basic material to be activated by the geopolimerization process to be the concrete binder, to totally replace the use of Portland cement. The binder is the only difference to the ordinary Portland cement concrete. To activate the Silicon and Aluminium content in fly ash, a combination of sodium hydroxide solution and sodium silicate solution was used. Manufacturing process comprising material preparation, mixing, placing, compaction and curing is reported in the thesis.Napthalene-based superplasticiser was found to be ii useful to improve the workability of fresh fly ash-based geopolymer concrete, as well as the addition of extra water. The main parameters affecting the compressive strength of hardened fly ash-based geopolymer concrete are the curing temperature and curing time, the molar H2O-to-Na2O ratio, and mixing time. Fresh fly ash-based geopolymer concrete has been able to remain workable up to at least 120 minutes without any sign of setting and without any degradation in the compressive strength. Providing a rest period for fresh concrete after casting before the start of curing up to five days increased the compressive strength of hardened concrete. The elastic properties of hardened fly ash-based geopolymer concrete, i,e. the modulus of elasticity, the Poisson’s ratio, and the indirect tensile strength, are similar to those of ordinary Portland cement concrete. The stress-strain relations of fly ash-based geopolymer concrete fit well with the expression developed for ordinary Portland cement concrete.
4
Hardjito, Djwantoro. "Studies of fly ash-based geopolymer concrete." Curtin University of Technology, Dept. of Civil Engineering, 2005. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=18580.
Full textAbstract:
The use of Portland cement in concrete construction is under critical review due to high amount of carbon dioxide gas released to the atmosphere during the production of cement. In recent years, attempts to increase the utilization of fly ash to partially replace the use of Portland cement in concrete are gathering momentum. Most of this by-product material is currently dumped in landfills, creating a threat to the environment. Geopolymer concrete is a ‘new’ material that does not need the presence of Portland cement as a binder. Instead, the source of materials such as fly ash, that are rich in Silicon (Si) and Aluminium (Al), are activated by alkaline liquids to produce the binder. Hence concrete with no Portland cement. This thesis reports the details of development of the process of making fly ash-based geopolymer concrete. Due to the lack of knowledge and know-how of making of fly ashbased geopolymer concrete in the published literature, this study adopted a rigorous trial and error process to develop the technology of making, and to identify the salient parameters affecting the properties of fresh and hardened concrete. As far as possible, the technology that is currently in use to manufacture and testing of ordinary Portland cement concrete were used. Fly ash was chosen as the basic material to be activated by the geopolimerization process to be the concrete binder, to totally replace the use of Portland cement. The binder is the only difference to the ordinary Portland cement concrete. To activate the Silicon and Aluminium content in fly ash, a combination of sodium hydroxide solution and sodium silicate solution was used. Manufacturing process comprising material preparation, mixing, placing, compaction and curing is reported in the thesis.<br>Napthalene-based superplasticiser was found to be ii useful to improve the workability of fresh fly ash-based geopolymer concrete, as well as the addition of extra water. The main parameters affecting the compressive strength of hardened fly ash-based geopolymer concrete are the curing temperature and curing time, the molar H2O-to-Na2O ratio, and mixing time. Fresh fly ash-based geopolymer concrete has been able to remain workable up to at least 120 minutes without any sign of setting and without any degradation in the compressive strength. Providing a rest period for fresh concrete after casting before the start of curing up to five days increased the compressive strength of hardened concrete. The elastic properties of hardened fly ash-based geopolymer concrete, i,e. the modulus of elasticity, the Poisson’s ratio, and the indirect tensile strength, are similar to those of ordinary Portland cement concrete. The stress-strain relations of fly ash-based geopolymer concrete fit well with the expression developed for ordinary Portland cement concrete.
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Deb, Partha Sarathi. "Durability of fly ash based geopolymer concrete." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/2126.
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Inclusion of ground granulated blast furnace slag (GGBFS) together with fly-ash can have significant effects on the development of mechanical and durability properties of geopolymer concrete when cured at normal temperature. The slag blended geopolymer concretes showed durability properties comparable to those of the control OPC concrete. In general, the results show that it is possible to design fly ash and slag blended geopolymer concrete suitable for ambient curing with similar or better durability properties of conventional OPC concrete.
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Neupane, Kamal. "Investigation of Structural Behaviour of Geopolymer Prestressed Concrete Beam." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/24951.
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Production of ordinary Portland cement (OPC) is a carbon-intensive process that generates significant amounts of carbon dioxide (CO2) gas from the combustion of fossil fuels and thermal decomposition of limestone. Overall, cement industries are responsible for around 7% of global CO2 emissions which poses a considerable threat to global climate change because of its greenhouse effects. Geopolymer is an inorganic polymer material having similar binding properties to OPC which can be produced from aluminosilicate compounds, such as fly ash when activated by alkaline solution. The recent advent of geopolymer technology shows great potential to reduce carbon footprints by utilising industrial by-products, such as fly ash and ground granulated blast furnace slag (GGBS), and convert into effective binding material.
The setting and hardening process of geopolymer binder is different from hydration of OPC, called “geopolymerisation” which is the condensation process of aluminate and silicate monomers to form a polymer chain. Generally, fly ash-based geopolymer concrete attains relatively lower early-age strength at ambient temperature due to the slow rate of reaction. However, geopolymer concrete based on GGBS or a combination of fly ash and GGBS can set and harden in ambient temperature with comparable early age strength to OPC concrete of same grade. In the recent past, several studies were carried out to investigate mechanical, serviceability, durability and microstructural properties of geopolymer concrete using different aluminosilicate materials. However, limited research has been carried out on applications of geopolymer binder in structural concrete, such as reinforced concrete beam, column and prestressed concrete beam.
Prestressed concrete is a construction technique in which flexural tensile stress generated in the concrete member due to imposed load is counteracted by applying an initial prestressing compressive force. The use of prestressed concrete structures has been increasing in modern construction practices because they can withstand significantly higher flexural load with minimal deflection and cracks than conventional reinforced concrete (RC) members of similar cross-section. Generally, tensile strength of concrete is ignored in the design of conventional RC structures. However, tensile or flexural strengths of concrete are significant in the design of prestressed concrete structures where tensile strength of concrete limits the maximum permissible prestressing load according to ACI 318. Application of higher prestressing load can increase the load-carrying capacity of prestressed concrete structures and minimize their deflection under service load. Previous results showed that geopolymer concrete possesses higher indirect-tensile and flexural strength than OPC concrete for the same compressive strength. In addition, time-dependent losses of prestressing stress are the major serviceability problems of prestressed concrete structure which reduce the load-carrying capacity of structures and increase the deflection under service loads. The time-dependent losses of prestressing stress are directly proportional to the amount of shrinkage and creep strains of concrete. Having smaller drying shrinkage and creep strains, geopolymer concrete can result in better serviceability than OPC concrete in prestressed concrete structures. Thus, this study investigates the application of geopolymer concrete in the prestressed concrete beam which may be a worthwhile utilization of geopolymer concrete in concrete structures.
Despite having higher mechanical strengths and durability properties than conventional OPC concrete, geopolymer concrete has not been widely used in structural grade concrete, so far. The safety hazards in mixing and handling of concrete due to the use of liquid sodium hydroxide in geopolymer binder is one of the barriers to the adaptation of geopolymer in concrete industry. In this study, the mechanical and serviceability properties of grade 50 MPa geopolymer concrete from sodium hydroxide-free one-part geopolymer binder are investigated under ambient temperature curing and compared against same grade OPC concrete. Development of strengths at an early age under accelerated curing is investigated to study the suitability of geopolymer concrete in precast prestressed concrete structures. Finite element models of prestressed concrete beams of three different lengths and sizes are analysed to investigate their load-deflection behaviours under imposed load for short-term and long-term durations using the Abaqus program. The effects of tensile strength of concrete in load-deflection behaviours of prestressed concrete beams are studied by comparing the results between identical geopolymer and OPC prestressed concrete beams.
This study finds that geopolymer concrete has around 27% higher indirect-tensile and flexural strengths than OPC concrete of same strength grade which contributes to geopolymer prestressed concrete beams to withstand around 20% higher first-crack load than OPC concrete beams of same span. In addition, geopolymer prestressed concrete beams show a relatively smaller loss in prestressing stress which results in a smaller loss in flexural capacity of beams over the service life of the structure.
7
Chang, Ee Hui. "Shear and bond behaviour of reinforced fly ash-based geopolymer concrete beams." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/468.
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Concrete is by far the most widely used construction material worldwide in terms of volume, and so has a huge impact on the environment, with consequences for sustainable development. Portland cement is one of the most energy-intensive materials of construction, and is responsible for some emissions of carbon dioxide — the main greenhouse gas causing global warming. Efforts are being made in the construction industry to address these by utilising supplementary materials and developing alternative binders in concrete; the application of geopolymer technology is one such alternative. Indeed, geopolymers have emerged as novel engineering materials with considerable promise as binders in the manufacture of concrete. Apart from their known technical attributes, such as superior chemical and mechanical properties, geopolymers also have a smaller greenhouse footprint than Portland cement binders.Research on the development, manufacture, behaviour and applications of low calcium fly ash-based geopolymer concrete has been carried out at Curtin University of Technology since 2001. Past studies of the structural behaviour of reinforced fly ash-based geopolymer concrete members have covered the flexural behaviour of members. Further studies are needed to investigate other aspects of the structural behaviour of geopolymer concrete. Design for both shear and bond are important in reinforced concrete structures. Adequate shear resistance in reinforced concrete members is essential to prevent shear failures which are brittle in nature. The performance of reinforced concrete structures depends on sufficient bond between concrete and reinforcing steel. The present research therefore focuses on the shear and bond behaviour of reinforced low calcium fly ash-based geopolymer concrete beams.For the study of shear behaviour of geopolymer concrete beams, a total of nine beam specimens were cast. The beams were 200 mm x 300 mm in cross section with an effective length of 1680 mm. The longitudinal tensile reinforcement ratios were 1.74%, 2.32% and 3.14%. The behaviour of reinforced geopolymer concrete beams failing in shear, including the failure modes and crack patterns, were found to be similar to those observed in reinforced Portland cement concrete beams. Good correlation of test-to-prediction value was obtained using VecTor2 Program incorporating the Disturbed Stress Field Model proposed by Vecchio (2000). An average test-to-prediction ratio of 1.08 and a coefficient of variation of 8.3% were obtained using this model. It was also found that the methods of calculations, including code provisions, used in the case of reinforced Portland cement concrete beams are applicable for predicting the shear strength of reinforced geopolymer concrete beams.For the study of bond behaviour of geopolymer concrete beams, the experimental program included manufacturing and testing twelve tensile lap-spliced beam specimens. No transverse reinforcement was provided in the splice region. The beams were 200 mm wide, 300 mm deep and 2500 mm long. The effect of concrete cover, bar diameter, splice length and concrete compressive strength on bond strength were studied. The failure mode and crack patterns observed for reinforced geopolymer concrete beams were similar to those reported in the literature for reinforced Portland cement beams. The bond strength of geopolymer concrete was observed to be closely related to the tensile strength of geopolymer concrete. Good correlation of test bond strength with predictions from the analytical model proposed by Canbay and Frosch (2005) were obtained when using the actual tensile strength of geopolymer concrete. The average ratio of test bond strength to predicted bond strength was 1.0 with a coefficient of variation of 15.21%. It was found that the design provision and analytical models used for predicting bond strength of lapsplices in reinforced Portland cement concrete are applicable to reinforced geopolymer concrete beams.
8
Alanazi, Hani Mohammed. "Explore Accelerated PCC Pavement Repairs Using Metakaolin-Based Geopolymer Concrete." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27633.
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In order to adopt geopolymer concrete as a pavement repair material due to its better durability, splitting and slant shear tests are performed. Effect of curing time, degradation of the pavement concrete under different acid conditions on the bond strength of geopolymer with conventional concrete, and comparison of the metakaolin geopolymer with other pavement repair materials are analyzed. It was found curing time affects the interface bond strength greatly and the interface bond strength degrades quickly in an acid environment. Effect of molar ratio of SiO2/Na2O, calcium aluminate cement, and slag on early strength of the geopolymer have been studied. It was found molar ratio of SiO2/Na2O of 1.0 gave the highest early strength in 24 hours. Also, freeze-thaw durability of geopolymer concrete are investigated by exposing the specimens to rapid freeze-thaw cycles. Based on these research results, adopting metakaolin geopolymer in accelerated PCC pavement repairs is a feasible option.
9
Paija, Navin. "FEASIBILITY STUDY OF USING GROUND BOTTOM ASH IN GEOPOLYMER CONCRETE." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2134.
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AN ABSTRACT OF THE THESIS OF NAVIN PAIJA, for the Master of Science degree in CIVIL ENGINEERING, presented on 04/06/2017, at Southern Illinois University Carbondale. FEASIBILITY STUDY OF USING GROUND BOTTOM ASH IN GEOPOLYMER CONCRETE MAJOR PROFESSOR: Dr. Sanjeev Kumar Dr. Manoj K. Mohanty United States alone has about three quarters of the accessible worldwide reserve of coal. There are about 511 coal-powered electric plants and generates about 33% of the nation’s electricity. The combustion of coal results in a large number of solid waste materials known as coal combustion byproducts (CCBs) that are stored in landfill or ponds. These are easily accessible and with proper research it can be put into beneficial use. Today concrete is the second most consumed substance after water. Concrete, a composite material made of a binder in combination with coarse and fine aggregate, is used in foundations and structures of buildings, bridges, roads, dams. Cement is the most widely used binder for concrete, however, research has shown that a single cement industry produces approximately 5% of global CO2 emissions, and one ton of Portland cement emits approximately one ton of CO2. This emission of CO2 is one of the main reasons for global warming and has detrimental impacts on environment. The possibility of using fly ash and bottom ash as an alternative to cement as a binder to produce sustainable concrete is investigated in this study. The process of geopolymerization includes the reaction of ash and an alkali activated solution made of diluted sodium silicate and sodium hydroxide. The initial objective of this study was to produce fly ash geopolymer concrete which has a strength comparable to that of cement concrete. However, later the possibility of bottom ash as a binder material for geopolymer production was also studied. During this study, the strength of conventional mortar with 10%, 20%, and 30% cement replacement with fly ash and bottom ash was experimented and compared with strength of cement mortar. The test results showed that with increase in the fly ash and bottom ash replacement the strength of the mortars decreased, moreover, the mortars that was replaced by bottom ash produced better results than that of the fly ash replacement. Also, the effect of increase in the ratio of sodium silicate to sodium hydroxide ratio on the strength of geopolymer mortar is studied. Sodium silicate to sodium hydroxide ratio of 1.5, 2.5, and 3 is used in this ratio, and the test results showed that with the increase in this ratio the compressive strength of geopolymer mortar also increased. Similarly, different combinations of fly ash and bottom ash is used to produce geopolymer mortars. The results showed that geopolymer mortar with higher bottom ash content produced better results. The effect of ground fly ash and bottom ash on the compressive strength of geopolymer mortar is also studied. The test result showed that with increase in fineness of fly ash and bottom ash, there was slight improvement in the strength.
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Rahman, Muhammad Motiur. "Geopolymer concrete columns subjected to axial load and biaxial bending." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/1410.
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This thesis focuses on the behaviour of fly ash based geopolymer concrete columns under axial load and biaxial bending. Tests showed that failure load of columns increased with the increase of concrete compressive strength and longitudinal reinforcement ratio, and decreased with the increase of load eccentricity. Use of the Bresler’s reciprocal load formula with an iterative procedure for slender columns in uniaxial bending conservatively predicted the strength of the test columns.
11
Deb, Partha Sarathi. "Properties of Geopolymer Concrete Using Ultrafine Fly Ash and Nanosilica." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75529.
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This study investigated the effects of ultrafine fly ash and nanosilica in geopolymers cured at room temperature. It was found that the optimum percentages of ultrafine fly ash and nanosilica with fly ash alone or that blended with 15% GGBFS or 10% OPC significantly improved strength and durability of geopolymers. The properties of geopolymer improved by enhancement of the hydrated phases and microstructure that reduced porosity.
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Karmokar, Trijon R. "Tensile performance of cast-in headed anchors in geopolymer concrete." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2023. https://ro.ecu.edu.au/theses/2657.
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Geopolymer concrete is an ecofriendly alternative to normal concrete and its use in construction industry is growing due to the increased awareness of global warming. The relationships between the mechanical properties, such as the compressive strength, elastic modulus and mode I fracture energy of geopolymer concrete are not similar to those of normal concrete; these are specifically important for the prediction of the tensile capacity of structural anchors in a concrete substrate. As there are limited studies on the fracture energy of ambient-temperature cured geopolymer concrete, experiments are conducted to study the fracture energy and compressive strength of geopolymer concrete and compare the results with the respective properties of normal concrete. The results show that the ambient-temperature cured geopolymer concrete provides approximately 85% lower fracture energy than normal concretes of comparable compressive strengths. Based on the experimental results, a new fracture energy prediction equation is proposed for ambient-temperature cured geopolymer concrete.
In the current research study, the tensile behaviour of cast-in headed anchors in ambient-temperature cured geopolymer concrete is studied using the results of over 100 experimental tests and over 90 numerical simulations. There are 3 sets of experiments on anchors, which are differentiated based on the mix design of concrete. In each set of experiments, cast-in headed anchors of sizes 1.3T, 2.5T and 5T are embedded at effective embedment depths of 40 mm, 70 mm and 90 mm. In addition to the above sets, anchors of 2.5T and 5T sizes at embedment depths of 40 mm and 70 mm are also installed in normal concrete for comparison purposes. The difference in the capacity of anchors due to the variations in fracture energy of geopolymer concretes of the same compressive strength as well as the influence of anchor head size ratio is investigated using experimental tests.
Numerical simulations are used to complement and expand the results from the experimental study. Nonlinear Finite-Element analyses are conducted to study the influence of surface cracking of the substrate material and the effect of anchor head profile on the tensile capacity of anchors.
The experimental and numerical results are compared with two of the currently available prediction models namely: Concrete Capacity Design (CCD) and Linear Fracture Mechanics (LFM) models. It is shown that on average, the CCD model overestimated the tensile capacities by 10% to 40%, depending on the anchor embedment depth, and the LFM model accurately predicted the capacity of anchors at 40 mm embedment depth, and underestimated the results by 40% at 90 mm embedment depth.
In comparison to similar anchors embedded in a normal concrete of a comparable compressive strength, the capacity of anchors in geopolymer concrete is on average 35% lower. Hence, new modification factors are proposed to extend the application of CCD and LFM models to anchors installed in geopolymer concrete. The modification factors are validated using 60 numerical simulations whereby the effective embedment depth ranges between 40 mm and 180 mm.
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Chang, Ee Hui. "Shear and bond behaviour of reinforced fly ash-based geopolymer concrete beams." Curtin University of Technology, Department of Civil Engineering, 2009. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=120482.
Full textAbstract:
Concrete is by far the most widely used construction material worldwide in terms of volume, and so has a huge impact on the environment, with consequences for sustainable development. Portland cement is one of the most energy-intensive materials of construction, and is responsible for some emissions of carbon dioxide — the main greenhouse gas causing global warming. Efforts are being made in the construction industry to address these by utilising supplementary materials and developing alternative binders in concrete; the application of geopolymer technology is one such alternative. Indeed, geopolymers have emerged as novel engineering materials with considerable promise as binders in the manufacture of concrete. Apart from their known technical attributes, such as superior chemical and mechanical properties, geopolymers also have a smaller greenhouse footprint than Portland cement binders.<br>Research on the development, manufacture, behaviour and applications of low calcium fly ash-based geopolymer concrete has been carried out at Curtin University of Technology since 2001. Past studies of the structural behaviour of reinforced fly ash-based geopolymer concrete members have covered the flexural behaviour of members. Further studies are needed to investigate other aspects of the structural behaviour of geopolymer concrete. Design for both shear and bond are important in reinforced concrete structures. Adequate shear resistance in reinforced concrete members is essential to prevent shear failures which are brittle in nature. The performance of reinforced concrete structures depends on sufficient bond between concrete and reinforcing steel. The present research therefore focuses on the shear and bond behaviour of reinforced low calcium fly ash-based geopolymer concrete beams.<br>For the study of shear behaviour of geopolymer concrete beams, a total of nine beam specimens were cast. The beams were 200 mm x 300 mm in cross section with an effective length of 1680 mm. The longitudinal tensile reinforcement ratios were 1.74%, 2.32% and 3.14%. The behaviour of reinforced geopolymer concrete beams failing in shear, including the failure modes and crack patterns, were found to be similar to those observed in reinforced Portland cement concrete beams. Good correlation of test-to-prediction value was obtained using VecTor2 Program incorporating the Disturbed Stress Field Model proposed by Vecchio (2000). An average test-to-prediction ratio of 1.08 and a coefficient of variation of 8.3% were obtained using this model. It was also found that the methods of calculations, including code provisions, used in the case of reinforced Portland cement concrete beams are applicable for predicting the shear strength of reinforced geopolymer concrete beams.<br>For the study of bond behaviour of geopolymer concrete beams, the experimental program included manufacturing and testing twelve tensile lap-spliced beam specimens. No transverse reinforcement was provided in the splice region. The beams were 200 mm wide, 300 mm deep and 2500 mm long. The effect of concrete cover, bar diameter, splice length and concrete compressive strength on bond strength were studied. The failure mode and crack patterns observed for reinforced geopolymer concrete beams were similar to those reported in the literature for reinforced Portland cement beams. The bond strength of geopolymer concrete was observed to be closely related to the tensile strength of geopolymer concrete. Good correlation of test bond strength with predictions from the analytical model proposed by Canbay and Frosch (2005) were obtained when using the actual tensile strength of geopolymer concrete. The average ratio of test bond strength to predicted bond strength was 1.0 with a coefficient of variation of 15.21%. It was found that the design provision and analytical models used for predicting bond strength of lapsplices in reinforced Portland cement concrete are applicable to reinforced geopolymer concrete beams.
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Suwan, Teewara. "Development of self-cured geopolymer cement." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12975.
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To support the concept of environmentally friendly materials and sustainable development, the low-carbon cementitious materials have been extensively studied to reduce amount of CO2 emission to the atmosphere. One of the efforts is to promote alternative cementitious binders by utilizing abundant alumina-silicate wastes from the industrial sectors (e.g. fly ash or furnace slag), among which “Geopolymer (GP) cement” has received most attention as it can perform a wide variety of behaviours, in addition to cost reduction and less environmental impacts. The most common geopolymer production, fly ash-based, gained some strength with very slow rate at ambient temperature, while the strength is evidently improved when cured in high (above room) temperature, e.g. over 40°C. The major challenge is to step over the limitation of heat curing process and inconvenience in practice. In this study, the testing schemes of (i) GP manufacturing in various processes, (ii) inclusion of ordinary Portland cement (OPC) in GP mixture, called GeoPC and (iii) GeoPC manufactured with dry-mixing method, have been intensively investigated through mechanical testing (Setting time, Compressive strength and Internal heat measurement) and mechanism analysis (XRD, FTIR, SEM and EDXA) in order to develop the geopolymers, achieving reasonable strength without external sources of heat curing. It is found that the proposed (dry) mixing process could have generated intensive heat liberation which was observed as a comparable factor to heat curing from any other external sources, enhancing the curing regime of the mixture. The additional calcium content in the developed GeoPC system not only resulted in an improvement of an early strength by the extra precipitation of calcium compounds (C,N-A-S-H), but also provided a latent heat from the reaction of its high potential energy compounds (e.g. OPC or alkaline activators). The developments from these approaches could lead to geopolymer production to achieve reasonable strength in ambient curing temperature known as “Self-cured geopolymer cement”, without external heat, and hence provide construction industry viable technologies of applying geopolymers in on-site and off-site construction.
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Shadnia, Rasoul, and Rasoul Shadnia. "Green Geopolymer with Incorporated PCM for Energy Saving in Buildings." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/622931.
Full textAbstract:
This research studies the green geopolymer incorporated with phase change material (PCM) for energy saving in buildings. First class F fly ash (FA) based-geopolymer binder was studied. In order to improve the mechanical properties, low calcium slag (SG) was added to the FA to produce geopolymer. The effect of different factors including SG content (at different relative amounts FA/SG = 0/100, 25/75, 50/50, 75/25 and 100/0), NaOH solution at different concentrations (7.5, 10 and 15 M), various curing times (1, 2, 4, 7, 14 and 28 days) and curing temperatures (25 (ambient), 45, 60, 75 and 90°C) was investigated. The unit weight and uniaxial compressive strength (UCS) of the geopolymer specimens were measured. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD) were also performed to characterize the microstructure and phase composition of the geopolymer specimens. The results show that the incorporation of SG not only improves the strength of the geopolymer specimens but also decreases the initial water content and thus the NaOH consumption at the same NaOH concentration required for geopolymer production. In addition, the inclusion of SG increases the unit weight of the geopolymer specimens, simply because SG has a much greater specific gravity than FA. The results also show that the strength of the FA/SG-based geopolymer develops rapidly within only 2 days and no obvious gain of the strength after 7 days. The optimum curing temperature (the curing temperature at which the maximum UCS is obtained) at a FA/SG ratio of 50/50 is around 75°C. Second, FA-based geopolymer concrete was synthesized and the effect of different factors including sodium silicate to sodium hydroxide (SS/SH) ratio, aggregate shape, water to fly ash (W/FA) ratio, curing time, water exposure and PCM inclusion on the compressive strength of the geopolymer concrete specimens cured at different ambient temperatures was studied. The results show that the UCS of the specimens increases with higher SS/SH and W/FA ratios up to a certain level and then starts to decrease at higher ratios. The results also indicate that a major portion of the strength of the specimens cured at ambient temperatures develops within the first four weeks. In addition the strength of the FA-based geopolymer concrete is slightly decreased with water exposure and PCM incorporation. Third, the mechanical and thermal properties of geopolymer mortar synthesized with FA and different amount of PCM were studied and the effect of incorporated PCM on the unit weight and UCS of geopolymer mortar was evaluated. SEM imaging was performed to identify the change of micro structure of the geopolymer mortar after incorporation of PCM. The thermal properties of the geopolymer mortar containing different amount of PCM were also characterized using differential scanning calorimetry (DSC) analysis. In addition model tests were performed using small cubicles built with geopolymer mortar slabs containing different amount of PCM to evaluate the effectiveness of geopolymer mortar wall with incorporated PCM in controlling the heat flow and internal temperature. The results indicate that both the unit weight and UCS of the geopolymer mortar decrease slightly after PCM is incorporated, mainly due to the small unit weight and low strength and stiffness of the PCM, respectively. However, the compressive strength of geopolymer mortar containing up to 20% PCM is still sufficiently high for applications in buildings. The results also show that the incorporation of PCM leads to substantial increase of heat capacity and decrease of thermal conductivity of the geopolymer mortar and is very effective in decreasing the temperature inside the cubicles. Finally, a numerical study on the thermal performance of geopolymer with incorporated PCM was carried out. In order to simulate the heat transfer through geopolymer containing PCM, a simplified method was first presented. The influence of phase transition was linked to the energy balance equation through variable specific heat capacity of the PCM-geopolymer. The thermal properties of the geopolymer containing PCM for the numerical analysis were determined using DSC and guarded heat flow (GHF) tests. The simplified method was validated based on the good agreement between the numerical and experimental results. With the validated model, the effect of various factors including the specific heat capacity, thermal conductivity and wall thickness on the thermal performance of PCM-geopolymer walls was studied. Then a modified numerical method was proposed for simulating the whole thermal transfer processes and the simulation results were used to conduct the economic evaluation of PCM-geopolymer walls for energy savings in buildings.
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Soltaninaveh, Kaveh. "The properties of geopolymer concrete incorporating red sand as fine aggregate." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/2481.
Full textAbstract:
Concrete is the most common building material in the world and its use has been increasing during the last century as the need for construction projects has escalated. Traditionally, concrete uses Ordinary Portland Cement (OPC) as binder, water as the activator of cement and aggregate. Finding an appropriate replacement for traditional concrete is a desirable solution to obviate the environmental problems caused by cement production. The use of fly ash as a partial replacement for Portland cement is a method to maintain the properties of concrete and reduce the need for cement. Fly ash is a by-product from coal-fired power plants and is abundantly available. The percentage of cement replacement can be varied according to application and mix design. One of the potential materials to substitute for conventional concrete is geopolymer concrete (introduced by Davidovits in 1979). Geopolymer concrete is an inorganic alumino-silicate polymer synthesized from predominantly silicon, aluminum and byproduct materials such as fly ash. Geopolymer properties have been investigated for several years and it is still a major area of interest among researchers and industry partners as it does not contain cement and uses fly ash and alkali liquids as binders to produce a paste to consolidate aggregates. Furthermore, the aggregate comprises a substantial portion of concrete. Including coarse and fine aggregates it is normally obtained from natural sources. Fine aggregate in Australia is usually mined from sand quarries. As the demand for concrete production increases, more natural sand is needed. The need for fine aggregate should be addressed in an environmentally friendly manner, considering the diminishing sources of natural sand. Red sand is a by-product generated from the manufacture of alumina from bauxite by the Bayer process.Previous studies on properties of red sand have shown that it has the potential to be used in concrete as a fine aggregate. While the use of red sand in traditional concrete has been investigated by some researchers, no research has been reported regarding the use of this by-product in manufacturing geopolymer concrete. This research looks into the replacement of natural sand fine aggregates with red sand in geopolymer concrete. Initially, an extensive series of mixtures was prepared and tested. The objective of the research was to identify the salient parameters affecting the properties of geopolymer concrete when natural sand is replaced by red sand. At the next stage, attempts were made to enhance the mechanical and durability features of red sand geopolymer concrete. The final stage consisted of testing red sand geopolymer concrete to find out the various properties of this novel construction material.
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Ryno, Barnard. "Mechanical properties of fly ash/slag based geopolymer concrete with the addition of macro fibres." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95866.
Full textAbstract:
Thesis (MEng) -- Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: Geopolymer concrete is an alternative construction material that has comparable mechanical
properties to that of ordinary Portland cement concrete, consisting of an aluminosilicate and
an alkali solution. Fly ash based geopolymer concrete hardens through a process called
geopolymerisation. This hardening process requires heat activation of temperatures above
ambient. Thus, fly ash based geopolymer concrete will be an inadequate construction material
for in-situ casting, as heat curing will be uneconomical.
The study investigated fly ash/slag based geopolymer concrete. When slag is added to the
matrix, curing at ambient temperatures is possible due to calcium silicate hydrates that form
in conjunction with the geopolymeric gel.
The main goal of the study is to obtain a better understanding of the mechanical properties of
geopolymer concrete, cured at ambient temperatures. A significant number of mix variations
were carried out to investigate the influence that the various parameters, present in the matrix,
have on the compressive strength of fly ash/slag based geopolymer concrete. Promising
results were found, as strengths as high as 72 MPa were obtained. The sodium hydroxide
solution, the slag content and the amount of additional water in the matrix had the biggest
influence on the compressive strength of the fly ash/slag based geopolymer concrete.
The modulus of the elasticity of fly ash/slag based geopolymer concrete did not yield
promising results as the majority of the specimens, regardless of the compressive strength,
yielded a stiffness of less than 20 GPa. This is problematic from a structural point of view as
this will result in large deflections of elements. The sodium hydroxide solution had the most
significant influence on the elastic modulus of the geopolymer concrete. Steel and polypropylene fibres were added to a high- and low strength geopolymer concrete
matrix to investigate the ductility improvement. The limit of proportionality mainly depended
on the compressive strength of the geopolymer concrete, while the amount of fibres increased
the energy absorption of the concrete. A similar strength OPC concrete mix was compared to
the low strength geopolymer concrete and it was found that the OPC concrete specimen
yielded slightly better flexural behaviour. Fibre pull-out tests were also conducted to
investigate the fibre-matrix interface. From the knowledge gained during this study, it can be concluded that the use of fly ash/slag
based geopolymer concrete, as an alternative binder material, is still some time away as there
are many complications that need to be dealt with, especially the low modulus of elasticity.
However, fly ash/slag based geopolymer concrete does have potential if these complications
can be addressed.<br>AFRIKAANSE OPSOMMING: Geopolimeerbeton is ‘n alternatiewe konstruksiemateriaal wat vergelykbare meganiese eienskappe
met beton waar OPC die binder is, en wat bestaan uit ‘n aluminosilikaat en ‘n alkaliese oplossing.
Vliegas-gebaseerde geopolimeerbeton verhard tydens ‘n proses wat geopolimerisasie genoem word.
Hierdie verhardingsproses benodig hitte-aktivering van temperature hoër as dié van die onmiddellike
omgewing. Gevolglik sal vliegas-gebaseerde geopolimeerbeton ‘n ontoereikende konstruksiemateriaal
vir in situ gietvorming wees, aangesien hitte-nabehandeling onekonomies sal wees.
Die studie het vliegas/slagmentgebaseerde geopolimeerbeton ondersoek. Wanneer slagment by die
bindmiddel gevoeg word, is nabehandeling by omliggende temperature moontlik as gevolg van
kalsiumsilikaathidroksiede wat in verbinding met die geopolimeriese jel vorm.
Die hoofdoel van die studie was om ‘n beter begrip te kry van die meganiese eienskappe van
geopolimeerbeton, wat nabehandeling by omliggende temperature ontvang het. ‘n Aansienlike aantal
meng variasies is uitgevoer om die invloed te ondersoek wat die verskeie parameters, aanwesig in die
bindmiddel, op die druksterkte van die vliegas/slagmentgebaseerde geopolimeerbeton het. Belowende
resultate is verkry en sterktes van tot so hoog as 72 MPa is opgelewer. Daar is gevind dat die
sodiumhidroksiedoplossing, die slagmentinhoud en die hoeveelheid water in die bindmiddel die
grootste invloed op die druksterkte van die vliegas/slagmentgebaseerde geopolimeerbeton gehad het.
Die styfheid van die vliegas/slagmentgebaseerde geopolimeerbeton het nie belowende resultate
opgelewer nie. Die meeste van die monsters, ongeag die druksterkte, het ‘n styfheid van minder as 20
GPa opgelewer. Vanuit ‘n strukturele oogpunt is dit problematies, omdat groot defleksies in elemente
sal voorkom. Die sodiumhidroksiedoplossing het die grootste invloed op die styfheid van die
vliegas/slagmentgebaseerde geopolimeerbeton gehad. Staal en polipropileenvesels is by ‘n hoë en lae sterke geopolimeer beton gevoeg om die buigbaarheid
te ondersoek. Die die maksimum buigbaarheid het hoofsaaklik afgehang van die beton se druksterkte
terwyl die hoeveelheid vesels die beton se energie-opname verhoog het. ‘n OPC beton mengsel van
soortgelyke sterkte is vergelyk met die lae sterkte geopolimeerbeton en daar is gevind dat die OPC
beton ietwat beter buigbaarheid opgelewer het. Veseluittrektoetse is uitgevoer om die veselbindmiddel
se skeidingsvlak te ondersoek.
Daar kan tot die gevolgtrekking gekom word dat, alhoewel belowende resultate verkry is, daar steeds
sommige aspekte is wat ondersoek en verbeter moet word, in besonder die styfheid, voordat
geopolimeerbeton as ‘n alternatiewe bindmiddel kan optree. Volgens die kennis opgedoen tydens hierdie studie, kan dit afgelei word dat die gebruik van
vliegas/slagmentgebaseerde geopolimeerbeton, as 'n alternatiewe bindmiddel, nog 'n geruime tyd weg
is, as gevolg van baie komplikasies wat gehandel moet word, veral die lae elastisiteitsmodulus. Tog
het vliegas/slagmentgebaseerde geopolimeerbeton potensiaal as hierdie komplikasies verbeter kan
word.
18
Król, Maciej R. "Studies of concrete properties based on geopolymer binders : PhD thesis summary." Rozprawa doktorska, [s.n.], 2017. http://dlibra.tu.koszalin.pl/Content/1039.
Full text
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Nath, Pradip. "Study of fly ash based geopolymer concrete cured in ambient condition." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/190.
Full textAbstract:
This research studied the properties of concrete using fly ash geopolymer as a low-emission alternative of Portland cement. Inclusion of small quantity of additives enabled curing in normal ambience eliminating the need for elevated heat. Mixtures suitable for curing in ambient condition were found that provided the setting time, workability and strength comparable to those of traditional cement concrete. Blending of additives with fly ash resulted in enhanced engineering and durability properties of geopolymer concrete.
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Olivia, Monita. "Durability related properties of low calcium fly ash based geopolymer concrete." Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/506.
Full textAbstract:
Geopolymer material using by-products can lead to a significant reduction of the carbon footprint and have positive impact on the environment. Geopolymer is recognized as an alternative construction material for the Ordinary Portland Cement (OPC) concrete. The mechanical properties of geopolymer concrete are superior for normal exposure environments. In terms of durability in the seawater, a limited number of publications were available. The seawater environment contains chloride ions and microorganisms that are harmful for reinforced concrete structures. Hence, a study of the durability of fly ash geopolymer concrete is essential when this material is to be used in a real application. The present study aims to investigate the durability of fly ash geopolymer concrete mixture in a seawater environment such as seawater resistance and corrosion of steel reinforcement bars. The development of mixtures and their mechanical properties were also presented.The concrete mixtures were developed using the Taguchi optimization method. Three mixtures, labelled T4, T7, T10 and a control mix were investigated further. Mechanical properties such as compressive strength, tensile strength, flexural strength, Young’s Modulus of Elasticity were determined for each mix. In addition the water absorption/AVPV and drying shrinkage were also measured. The seawater resistance study comprises chloride ion penetration, change in strength, change in mass, change in Young’s Modulus of Elasticity, change in effective porosity and change in length. The corrosion performance of steel reinforcement bars in fly ash geopolymer concrete was determined by measuring the corrosion potential by half-cell potential, accelerated corrosion test by impressed voltage method and microbiologically influenced corrosion incorporating algae. The microstructure of the samples was also investigated using SEM and microscope.It can be summarized that the fly ash geopolymer concrete has an equivalent or higher strength than the OPC concrete. The seawater resistance revealed a high chloride ion penetration into the fly ash geopolymer concrete due to lack of a chloride binding ability and continuous hydration under aqueous medium. The geopolymer concrete had a higher strength and small expansion following exposure to wetting-drying cycles. There was a rapid depassivation of steel reinforcement bars in fly ash geopolymer concrete, although it has a smaller corrosion rate than the OPC concrete. This could delay the pressure in generating cracks in the concrete cover which is not favourable in the long term, due to a sudden loss of load carrying capacity. A novel study on the corrosion performance in algae medium demonstrated a risk of steel bar corrosion in fly ash geopolymer concrete due to the low alkalinity of this concrete. It can be concluded that the low calcium fly ash geopolymer offers some advantages in durability for reinforced concrete in seawater environments.
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Cheema, Didar Singh. "Low calcium fly ash based geopolymer concrete: Long term durability properties." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/2146.
Full textAbstract:
Alkaline activated low-calcium fly ash geopolymer (LCFG) was investigated for durability compared to conventional concrete. The investigation involved simulated laboratory testing mimicking the severe field environments and in-situ field observations of commercially produced culverts. Laboratory test data: pore structure, porosity, chloride diffusion, scaling, strength and electrochemical testing supported and explained the observed field data. Research investigated the impact of slag and reinforcing pre-treatment. Geopolymer binder being non-cement one using by-products, can be significantly sustainable.
22
Soltaninaveh, Kaveh. "The properties of geopolymer concrete incorporating red sand as fine aggregate." Curtin University of Technology, Curtin Engineering Faculty, Department of Civil Engineering, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=115093.
Full textAbstract:
Concrete is the most common building material in the world and its use has been increasing during the last century as the need for construction projects has escalated. Traditionally, concrete uses Ordinary Portland Cement (OPC) as binder, water as the activator of cement and aggregate. Finding an appropriate replacement for traditional concrete is a desirable solution to obviate the environmental problems caused by cement production. The use of fly ash as a partial replacement for Portland cement is a method to maintain the properties of concrete and reduce the need for cement. Fly ash is a by-product from coal-fired power plants and is abundantly available. The percentage of cement replacement can be varied according to application and mix design. One of the potential materials to substitute for conventional concrete is geopolymer concrete (introduced by Davidovits in 1979). Geopolymer concrete is an inorganic alumino-silicate polymer synthesized from predominantly silicon, aluminum and byproduct materials such as fly ash. Geopolymer properties have been investigated for several years and it is still a major area of interest among researchers and industry partners as it does not contain cement and uses fly ash and alkali liquids as binders to produce a paste to consolidate aggregates. Furthermore, the aggregate comprises a substantial portion of concrete. Including coarse and fine aggregates it is normally obtained from natural sources. Fine aggregate in Australia is usually mined from sand quarries. As the demand for concrete production increases, more natural sand is needed. The need for fine aggregate should be addressed in an environmentally friendly manner, considering the diminishing sources of natural sand. Red sand is a by-product generated from the manufacture of alumina from bauxite by the Bayer process.<br>Previous studies on properties of red sand have shown that it has the potential to be used in concrete as a fine aggregate. While the use of red sand in traditional concrete has been investigated by some researchers, no research has been reported regarding the use of this by-product in manufacturing geopolymer concrete. This research looks into the replacement of natural sand fine aggregates with red sand in geopolymer concrete. Initially, an extensive series of mixtures was prepared and tested. The objective of the research was to identify the salient parameters affecting the properties of geopolymer concrete when natural sand is replaced by red sand. At the next stage, attempts were made to enhance the mechanical and durability features of red sand geopolymer concrete. The final stage consisted of testing red sand geopolymer concrete to find out the various properties of this novel construction material.
23
Slabbert, Michael Charles. "Utilising waste products from Kwinana industries to manufacture low specification geopolymer concrete." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/606.
Full textAbstract:
One technology that makes concrete without cement and does not have the associated carbon footprint is geopolymer concrete. This technology utilizes waste fly ash from power stations and mixes it with activating chemicals to form a binder with similar or better properties than cement. Not only does this technology directly reduce carbon emissions by replacing cement it also utilizes the waste bi-product from power stations and prevents it from going to landfill. Concrete is composed of coarse aggregates, sand and cementitious paste. It seemed possible to make geopolymer concrete from 100% waste. The aggregates would come from recycled concrete and hard brittle bottom ash from power stations, the sand would come from foundries and the fly ash binder would also come from the same power station as the bottom ash. All of these materials are waste and would all be dumped in landfill. Where would one find all these waste materials in one place? The industrial suburb of Kwinana outside Perth is home to a large number of industries producing all these wastes. To find products that have a specification that these materials would suit was a material with a relatively low specification, one such specification is the concrete masonry units’ specification. For this to be adopted the mix design would then have to be altered to a drier type mix without any slump. As recycling facilities do not make a range of products it was decided to crush the aggregates in the laboratory specifically for this research and to blend all the waste materials. Numerous combinations were blended, analysed and assessed to establish which blends would best suit the aims and scope of this research. Eventually three blends were selected that encompassed all the waste products.To find the right mix design proved challenging as these masonry products generally require a mix to have zero slump. It was decided to test across all the known and analysed water to geopolymer solids ratios for each of the mixes and establish the best mix based on compressive strength, workability and slump A known mix design based on research into low calcium Class F geopolymer concrete, developed at Curtin University using natural aggregates, was applied to these selected recycled waste mix designs. The benefit was to be able to compare the results of this research to a known result. Flash setting, an unknown phenomenon in geopolymer concrete, did occur in the low water mixes, but in spite of this, geopolymer concrete was successfully manufactured. The compressive strengths were substantially lower than those of the design mix and more research is required in this regard, however an indirect relationship was observed between the amount of bottom ash and the compressive strength. The high degree of LOI (loss of ignition) in both ashes, porosity of recycled aggregates, angularity, degree of fineness of the fines and flash setting are all possible factors influencing the properties of the geopolymer concrete. More research is recommended in a number of these areas to be able to understand and develop this technology further in order to make this a practical and robust technology in the quest to find solutions to our warming planet and our changing climate.
24
Slabbert, Michael Charles. "Utilising waste products from Kwinana industries to manufacture low specification geopolymer concrete." Curtin University of Technology, Department of Civil Engineering, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=117996.
Full textAbstract:
One technology that makes concrete without cement and does not have the associated carbon footprint is geopolymer concrete. This technology utilizes waste fly ash from power stations and mixes it with activating chemicals to form a binder with similar or better properties than cement. Not only does this technology directly reduce carbon emissions by replacing cement it also utilizes the waste bi-product from power stations and prevents it from going to landfill. Concrete is composed of coarse aggregates, sand and cementitious paste. It seemed possible to make geopolymer concrete from 100% waste. The aggregates would come from recycled concrete and hard brittle bottom ash from power stations, the sand would come from foundries and the fly ash binder would also come from the same power station as the bottom ash. All of these materials are waste and would all be dumped in landfill. Where would one find all these waste materials in one place? The industrial suburb of Kwinana outside Perth is home to a large number of industries producing all these wastes. To find products that have a specification that these materials would suit was a material with a relatively low specification, one such specification is the concrete masonry units’ specification. For this to be adopted the mix design would then have to be altered to a drier type mix without any slump. As recycling facilities do not make a range of products it was decided to crush the aggregates in the laboratory specifically for this research and to blend all the waste materials. Numerous combinations were blended, analysed and assessed to establish which blends would best suit the aims and scope of this research. Eventually three blends were selected that encompassed all the waste products.<br>To find the right mix design proved challenging as these masonry products generally require a mix to have zero slump. It was decided to test across all the known and analysed water to geopolymer solids ratios for each of the mixes and establish the best mix based on compressive strength, workability and slump A known mix design based on research into low calcium Class F geopolymer concrete, developed at Curtin University using natural aggregates, was applied to these selected recycled waste mix designs. The benefit was to be able to compare the results of this research to a known result. Flash setting, an unknown phenomenon in geopolymer concrete, did occur in the low water mixes, but in spite of this, geopolymer concrete was successfully manufactured. The compressive strengths were substantially lower than those of the design mix and more research is required in this regard, however an indirect relationship was observed between the amount of bottom ash and the compressive strength. The high degree of LOI (loss of ignition) in both ashes, porosity of recycled aggregates, angularity, degree of fineness of the fines and flash setting are all possible factors influencing the properties of the geopolymer concrete. More research is recommended in a number of these areas to be able to understand and develop this technology further in order to make this a practical and robust technology in the quest to find solutions to our warming planet and our changing climate.
25
Williams, Franklin. "The formation of geopolymer concrete from bauxite-refining residue and fly ash: Application in sustainable concrete production." Thesis, Williams, Franklin (2021) The formation of geopolymer concrete from bauxite-refining residue and fly ash: Application in sustainable concrete production. Honours thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/63765/.
Full textAbstract:
Bauxite-refining residue is generated in the processing of bauxite into alumina using the Bayer process, and fly ash is a by-product of burning pulverized coal in an electricity generating. Bauxite-refining residue (red mud) and its’ concentrated sodium aluminate solution (Spent Liquor) are known to have properties of high alkalinity and fly ash consisting of fine powder are easily dispersed into the surrounding environment, such as aquatic, air and soil which may lead to ecological problems. This research synergistically incorporates red mud, fly ash, and the Spent Liquor from the Bayer process along with sodium-silicate solution to produce a geopolymer based material which can be used as building materials. This research focused on the sustainable use of red mud as an additive material with fly ash to form concrete. A series of three laboratory trials using of 10 – 30% dried and crushed red mud addition on the geopolymer formation reaction, and 70% red mud as combined with Spent Liquor was carried out.
An improvement in setting time and compressive strength was observed with red mud addition at all trial conditions for 7, 14, and 28 days. The structural characterization revealed that the rate of reaction of red mud was dependent on the caustic soda (NaOH) concentration. However, the development of mechanical properties was related to the collaborative effect of NaOH concentration, solubility of silicates and the iron oxides presence. Based on standards for concrete, the compressive strength achieved in all series is suitable for paving blocks, slabs, driveway, backfill, retaining blocks etc. The production of these concrete materials and compressive strength test meets the requirements of the Australian Standards’: AS 1012.1- 2014, AS 1012.3.1, AS 1012.8.1-2014, and AS 1012.9-2014 respectively. Leaching of toxic metals were within permissible limits, but further research should be carried out for the identification of ongoing reactions.
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Bondar, Dali. "Alkali activation of Iranian natural pozzolans for producing geopolymer cement and concrete." Thesis, University of Sheffield, 2009. http://etheses.whiterose.ac.uk/14553/.
Full textAbstract:
The challenge for the civil engineering community in the near future will be to realize the building of structures in harmony with the concept of sustainable development, through the use of high performance materials which have low environmental impact and can be produced at reasonable cost. Geopolymers are novel binder materials that could provide a route towards this objective. Although research on geopolymer has advanced, most of the previous research conducted on geopolymers has dealt with pastes and concentrated on the material's chemistry and microstructure. There is little information available concerning the engineering and durability properties of geopolymer concrete and none considering the use of natural pozzolans for production of geopolymer concrete. This investigation has studied the potential of using five natural pozzolans from Iran as geopolymer precursors. Most of the raw materials contain zeolites and clay minerals and have a high loss on ignition. Therefore, trials were made where samples were calcined at 700, 800 and 900°C. The solubility of both the raw and calcined materials in an alkaline solution was used as an indicator for pozzolanic activity. Improvements in pozzolanic properties due to heat treatment and elevated curing temperatures (20, 40, 60, and 80°C) were studied by using alkali solubility, XRD and compressive strength tests. It has been found that geopolymer binders can be synthesized by activating natural pozzolans and condensing them with sodium silicate in a highly alkaline environment. A new model is presented which allows the prediction of the alkali activated pozzolan strength from information on their crystallinity, chemical compositions and alkali solubility. Two types of Iranian natural pozzolans, namely Taftan which can be activated without calcination and Shahindej which was calcined were selected for further activation to study the effect of the alkaline medium on the strength of the alkali-activated natural pozzolan. The effect of the type, form, and concentration (molarities =2.5, 5.0, 7.5, 10.0 M) of the alkaline hydroxide, the modulus of sodium silicate (Si02INa20 ratio =2.1, 2.4, 3.1) and different curing conditions on the geopolymerisation of the above two natural pozzolans were studied. The optimum range and contributions for each factor is suggested based on their effect on compressive strength. An optimum paste formulation has been developed for concrete mixing together with the procedure of addition of the raw materials to the reaction mixture and suitable curing methods for producing the geopolymer concrete derived from them. The properties of this geopolymer concrete in both the fresh and hardened states have been investigated in terms of setting time, workability, air content, compressive strength, splitting tensile strength, static modulus of elasticity, ultrasonic pulse velocity, and drying shrinkage. Studies related to durability such as gas permeability, chloride ion penetration, and sulphate resistance have been undertaken and compared to these for typical OPC concretes. Some problems were encountered in applying the standard concrete durability tests. In this study attempts have been made to determine the relationships between the different properties of geopolymer concrete with its compressive strength and compared to results for ope concrete, to help to explain the differences between alkali-activated natural pozzolan concrete and ope concrete. In the countries which have large resources of natural pozzolan, geopolymer concrete based on alkali activation of these resources can help decrease the energy consumption and environmental impacts involved in using traditional cement pastes.
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Gildenhuys, Hendrik. "Pioneering a new approach to sustainable concrete in Western Australia: Geopolymer concrete from fly-ash with recycled aggregates." Thesis, Gildenhuys, Hendrik (2020) Pioneering a new approach to sustainable concrete in Western Australia: Geopolymer concrete from fly-ash with recycled aggregates. Honours thesis, Murdoch University, 2020. https://researchrepository.murdoch.edu.au/id/eprint/59791/.
Full textAbstract:
This study investigates the suitability of a closed-loop approach to the management of useful waste derived materials such as recycled aggregates from construction waste and fly-ash to manufacture recycled aggregate geopolymer concrete.
This investigation was carried out in two parts. Part 1 considered the particle size distribution, water absorption and particle densities for both recycled coarse and fine aggregates. These materials were used to create recycled aggregate concrete specimens used for part 2 – compressive strength and slump test for both conventional Portland cement concrete and fly-ash based geopolymer concrete.
The results demonstrate that the higher water absorption values obtained for the recycled aggregates can be attributed to the decreases in particle size fraction and particle density. Overall, the use of recycled aggregates in geopolymer concrete had better workability than in conventional concrete. The use of manufactured results in a very dry mix for both the conventional and geopolymer concrete mixes. The use of recycled sand results in a mix that had better workability than a mix with natural sand for types of concrete. The technical, sustainability and economic implications of these findings are further discussed.
Overall, the manufacturing of recycled aggregate geopolymer concrete is a two-fold solution, addressing both the problem of natural resource depletion and the large carbon footprint linked to cement manufacturing. It was determined that integrating FGRAC into the Western Australian concrete market requires specific focus on low value, fit-for-purpose pre-cast applications. For higher value applications of concrete, pre-treatment of the source materials is suggested to improve their attributes.
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Abu, Bakar Asif. "Effects of Nano Silica and Basalt Fibers on Fly Ash Based Geopolymer Concrete." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/31729.
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Emission of carbon dioxide gas has been a source of major concern for the construction industry. To curb this emission, geopolymer concrete has been deemed as a potential alternative in the recent studies. Previous research also indicates that silica and fibers provide strength benefits to ordinary Portland cement concrete OPC. This study was undertaken to recognize the benefits of adding silica and basalt fibers in Class F fly ash based geopolymer concrete and comparing it with OPC concrete. One OPC and four Geopolymer mixtures were prepared. The results show a tremendous potential of using geopolymer concrete in place of OPC concrete with Nano silica proving to be the most advantageous. Nano silica provided 28% increase in compressive strength, 8% increase in resistivity when compared with normal Fly ash based geopolymer concrete. The SEM analysis of geopolymer concrete indicates that nano silica improved the compactness of concrete providing a dense microstructure.
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Dlamini, Mandla. "Performance of geopolymer concrete subjected to mineral acid corrosion and related to microbially-induced corrosion (MIC) of concrete in sewers." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33644.
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worse than degradation at the crown of the sewer pipe. Furthermore, results from this study show that high resistance under the static acid corrosion exposure condition cannot be extended to mean high resistance under the erosion-corrosion exposure condition for some concrete mixes. In this study, the static HCl test and the dynamic HCl test were used to measure the resistance of concrete mixes under the static corrosion exposure condition and erosion-corrosion exposure condition respectively. However, concretes that exhibited high resistance to the erosion-corrosion exposure condition were consistent in exhibiting high resistance to the static corrosion exposure condition. This finding is consistent with the sequence of corrosion processes in MIC, wherein dissolution of the concrete components occurs before the precipitation of corrosion products. Therefore, it expected that high resistance in the dynamic acid test (i.e. resistance to dissolution) implies high resistance in the static test, which measures the combined resistance of dissolution and resistance emanating from corrosion products. Both static and dynamic acid corrosion tests revealed that the geopolymer concretes tested in this study outperformed PC and CAC concretes. Results from the static HCl test showed that GP-ferro-quartz concrete, the most durable concrete specimen, provided a 69-fold improvement in resistance when compared to PC-dolomite mixes (control #1) and a 4.72-fold improvement in resistance when compared to CAC-dolomite mixes (control #2). Results from the dynamic HCl test show that the GP-ferro-quartz mix provided a 180-fold increase in resistance when compared to the PC-dolomite mix and a 275-fold increase when compared to CAC-dolomite mix. The CACdolomite mix was found to have the lowest resistance to the erosive-corrosive exposure conditions of the dynamic HCl test. Thus, in terms of the concrete MIC resistance properties identified in this study, it is suggested that the CAC-dolomite mix had poor kinetic resistance to dissolution. However, under the static acid test (static corrosion exposure condition), the CAC-dolomite mix performed better than the PC-dolomite mix and GP-dolomite mix. CAC-dolomite concrete performed inferiorly only to the set of GP-siliceous-aggregate mixes in the static HCl test. The difference in the performance of CAC-dolomite concrete performance between the static and dynamic test is largely attributed to the formation of alumina gel, an acid corrosion product of CAC hardened paste, which envelopes the concrete specimen and reduces the rate of surface corrosion in the static HCl test. However, under v the dynamic HCl test, the gel layer is brushed off the surface of the concrete specimen rendering it ineffective in protecting the concrete specimen from corrosion. Previous research on the acid attack of concrete posits that the chemical make-up of concrete materials has a strong bearing on corrosion behaviour. To this end, various measures have been suggested such as the ratio of calcium to silicon (Ca/Si) in concrete. The approach utilised in this study was to calculate the “basicity value” which provides the ratio of major basic to acidic oxides found in the concrete. XRF analysis of the hardened cement pastes and the 5 aggregate types used in the experiments enabled the calculation of basicity values. The combined basicity value for concrete specimens was determined by proportionally summing (according to mass) the basicity values of the aggregate and hardened cement paste parts. A strongly correlated linear relationship between the basicity value of concrete and the corrosion rate from the dynamic HCl test was established. This empirical relationship warrants further investigation and verification, as it would, in principle provide a means to estimate the dissolution rate of concrete by calculating its basicity instead of undertaking laboratory acid tests. Basicity was also found to be useful in determining the corrosion compatibility of binder type and aggregate types. It was found that the difference between the basicity value of hardened cement paste and the basicity value of the aggregate was useful in determining the type and extent of preferential corrosion of a concrete specimen tested under the dynamic HCl test. For ease of reading, this difference was called the “basicity differential”. By visually assessing corroded concrete specimens from the dynamic HCl test, it is was possible to determine whether the hardened cement paste or aggregate component was preferentially corroded, and to gauge the extent of preferential corrosion visually. GP-ferro-quartz and GP-granite concretes had the lowest levels of preferential corrosion which corresponded to their low basicity differential values. In contrast, CAC-dolomite concrete had the highest basicity discrepancy which corresponded visually to a high preferential corrosion of the hardened cement paste. Mineralogical analysis via XRD, found that the hardened cement pastes of the three binder types consisted mainly of amorphous phases (>70%). The crystalline phase of the geopolymer hardened cement paste was mostly constituted by insoluble minerals such as mullite. This partially explains the higher corrosion resistance of geopolymer concretes. However, a more comprehensive explanation needs to include analysis of the amorphous phases, which fell outside the scope of this study. SEM analysis of HCl corroded geopolymer hardened cement paste found that fly ash spheres embedded within the geopolymer matrix were preferentially corroded. This indicates that fly ash content negatively affected the rate of corrosion of the geopolymer hardened cement paste. Furthermore, SEM analysis showed that the geopolymer matrix surrounding the fly ash spheres was relatively intact.
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Paudel, Shree Raj. "Pore Structure and Pore Solution in Alkali Activated Fly Ash Geopolymer Concrete and Its Effect on ASR of Aggregates with Wide Silicate Contents." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31687.
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Alkali silica reaction (ASR) is detrimental to concrete. It is a time-dependent phenomenon, which can lead to strength loss, cracking, volume expansion, and premature failure of concrete structures. In essence, it is a particular chemical reaction involving alkali hydroxides and reactive form of silica present within the concrete mix. Geopolymer is a type of alkaline activated binder synthesized through polycondensation reaction of geopolymeric precursor and alkali polysilicates. In this thesis, three types of reactive aggregates with different chemical compositions were used. Systematic laboratory experiments and microstructural analysis were carried out for the geopolymer concrete and the OPC concrete made with the same aggregates. The result suggests that the extent of ASR reaction due to the presence of three reactive aggregates in geopolymer concrete is substantially lower than that in OPC based concrete, which is explained by the pore solution change and verified through their microstructural variations and FTIR images.
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Hosan, Md Anwar. "Residual mechanical properties of steel fibre reinforced geopolymer concrete (SFRGC) after exposure to elevated temperatures." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/1341.
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This study presents the effects of two types of alkali activators (Na and K-based) on the residual mechanical properties of steel fibre reinforced geopolymer concretes (SFRGC) after exposed to various elevated temperatures and compared with those of steel fibre reinforced concrete (SFRC). Results show that the SFRGC containing Na- based activators exhibited much higher residual compressive and indirect tensile strength at all elevated temperatures including at ambient condition than its K-based counterpart and SFRC.
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Bosch, Giner Juan. "Chloride and Carbonation Induced Corrosion of Steel in Fly Ash Geopolymer Pore Solution." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627755030968028.
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Ren, Xin. "Complete Recycling and Utilization of Waste Concrete Through Geopolymerization." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/577187.
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This research investigates complete recycling and utilization of waste concrete to produce new structural concrete through geopolymerization. The investigation was conducted through both macro-and micro/nano-scale studies. First the geopolymer paste synthesized using a mixture of waste concrete fines (WCF) and class F fly ash (FA) as the source material and a mixture of NaOH solution (N) and Na2SiO3 solution (SS) as the alkaline activating agent was studied. Various NaOH concentrations, SS/N ratios, and WCF contents were used to produce geopolymer paste specimens in order to study their effect on the properties of the geopolymer paste. Uniaxial compression tests were conducted to measure the strength of the geopolymer paste specimens. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier transform infrared spectroscopy (FTIR) analyses were performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the geopolymer paste and the effect of calcium (Ca) on them. The results indicate that by using 10 M NaOH solution, SS/N of 2 and 50% WCF, the highest geopolymer paste strength can be obtained. Second, the interfacial transition zones (ITZs) between geopolymer (GP) and recycled aggregates (RA) were studied. Considering that RA consist of the stone particles and the attached paste/mortar from the original ordinary Portland cement (OPC) concrete, both the ITZs between GP and natural aggregate (NA) and those between GP and residual OPC paste/mortar (ROPM) were studied. For comparison, the ITZs between OPC paste and NA and those between OPC paste and ROPM were also investigated. 4-point bending tests were conducted to measure the bonding strength of the different types of ITZs at water to solid (W/S) ratio of 0.30, 0.35 and 0.40 for the geopolymer and OPC pastes after 7 and 14 days curing, respectively. SEM imaging was performed to investigate the microstructure of the ITZs. The results indicate that when NA is used, the bonding strength of both the GP-NA and OPC-NA ITZs decreases with higher water to solid (W/S) ratio. When ROPM is used, higher W/S ratio leads to smaller bonding strength for the GP-ROPM ITZ but greater bonding strength for the OPC-ROPM ITZ. Based on the measured bonding strength values for NA- and ROPM-based ITZs, the bonding strength of the GP-RA and OPC-RA ITZs was estimated by considering the average area coverage of ROPM on the RA surface. The GP-RA ITZ has the highest bonding strength among the different ITZs, implying the great potential for utilizing waste concrete (both the WCF and the RA) to produce geopolymer concrete. Third, based on the studies on geopolymer paste and ITZs, geopolymer concrete (GPC) was produced and studied using WCF and FA as the cementitious material and RA as the aggregate. For comparison, GPC using NA was also produced and studied at similar conditions. Various NaOH concentrations, SS/N ratios, and cement (WCF and FA) to aggregate (C/A) ratios were used to produce GPC specimens in order to study their effect on the behavior of GPC. The effect of water content and curing temperature on the initial setting time and 7-day unconfined compressive strength (UCS) of the GPC was also studied. The results show that the GPC produced from RA has higher UCS than the GPC from NA at both room curing temperature and 35°C curing temperature. Based on this study, it can be concluded that waste concrete can be completely recycled and used to produce new structural concrete based on the geopolymerization technology. Fourth, considering that the Si/Al and Na/Al ratios have great effect on the geopolymerization process and the properties of the final geopolymer product, a study was conducted on copper mine tailings (MT)-based geopolymer containing different amount of aluminum sludge (AS). The results indicate that by including AS and utilizing appropriate amount of NaOH, the UCS can be increased significantly. The main reason is because the addition of AS along with utilization of appropriate amount of NaOH makes both the Si/Al and Na/Al ratios reach the optimum values for geopolymerization, leading to higher degree of geopolymerization and more compact geopolymer microstructure. It is noted that although this study is not directly on waste concrete, it provides useful information for optimizing the design on complete recycling and utilization of waste concrete to produce new GPC. Finally, to better understand the effect of Ca on the geopolymerization process and the properties of geopolymer, molecular dynamics (MD) simulations were performed on geopolymer at different Ca contents. The molecular models at different Ca contents were constructed and uniaxial compression test was then performed on the numerical specimens. The results indicate that MD simulation is an effective tool for studying the effect of Ca on the properties of geopolymer at nano-scale.
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Tran, Thanh Tung. "Structural Analysis and Design of Fibre-reinforced Ambient-cured Geopolymer Concrete Beams under Static and Dynamic Loading." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/84212.
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This study through intensive static and impact tests demonstrated the possibility of replacing conventional Portland cement concrete beams with steel reinforcements by greener ambient-cured geopolymer concrete (GPC) beams reinforced with corrosion-resistant basalt fibre reinforced polymer (BFRP) bars. Analytical formulae were also derived by taking into consideration the unique material properties of GPC and BFRP, and verified against testing results for design analysis of this new type of sustainable and durable structures in construction.
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Al-Majidi, Mohammed Kadhim Haloob. "Development of Fibre Reinforced Geopolymer Concrete (FRGC) cured under ambient temperature for strengthening and repair of existing structures." Thesis, University of Brighton, 2017. https://research.brighton.ac.uk/en/studentTheses/13f703df-e33a-42d7-ad73-8511390fd582.
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Most of the previous research on plain and fibre reinforced geopolymer concrete (FRGC) has concerned on the properties of geopolymer mixtures hardened under heat curing conditions, which is a severe limitation for on-site, cast-in-place applications. This study focuses on the material and structural properties of novel fibre reinforced geopolymer concretes cured under ambient temperature. The overall aim of the study was to develop and test a more environmentally sustainable concrete material with improved structural characteristics, which utilises waste rather than primary mineral products, suitable for cast-in-place applications and for the structural strengthening of existing buildings. In the first part of this thesis, the material behaviour of FRGC cured under ambient temperature was examined. Initially, the work identified the role of various parameters which may affect material compressive strength, in order to enhance overall performance. In addition, the mechanical and microstructural properties of geopolymer mortar with different slag contents and variant silica fume types (densified, undensified and slurry) were assessed. Following this, the effect of slag content and silica fume particle size on the properties of steel fibre reinforced geopolymer composites (SFRGC) was examined. The optimum FRGC mixtures were further investigated in term of its durability characteristics and mechanical properties, in order to provide strain hardening characteristics. In the examined mixes, different fibre types, aspect ratios, and volume fractions, and its comparison with Portland cement based conventional concrete, have been assessed and appropriate mixtures have been identified with multiple fine cracks and strain hardening in tension. In the final part of the thesis, the structural behaviour of FRGC is examined at larger scale application. PVA and steel fibre reinforced geopolymer concrete mixtures were used as strengthening and repair materials for the protection of steel bars in a new material layer, and for subsequent improvement of the flexural strength of existing beams. Large scale beams strengthened with additional FRGC layers reinforced with steel bars have been examined. Also, an additional investigation was conducted in beams where part of the concrete cover at various depths was replaced by FRGC. In all the examined cases respective beams with conventional concrete were examined in order to evaluate the efficiency of the proposed technique. Accelerated corrosion tests were performed using the induced current technique by applying a nominal 300 mA constant anodic current. The results of this investigation showed significant improvements in the structural performance of the examined beams following strengthening or repair with FRGC. The outcomes of the experimental work indicate that FRGC considerably enhanced both the flexural strength capacity and the durability of strengthened and repaired reinforced concrete elements.
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Kothari, Ankit. "Effects of Fly Ash on the properties of Alkali Activated Slag Concrete." Thesis, Luleå tekniska universitet, Geoteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63534.
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This master thesis presents the effects of fly ash on the properties of alkali activated slag concrete, commonly referred as Geopolymer concrete (GPC). Cement manufacturer are major producers of CO2 which negatively affects the environment. Due to the increased construction activities and environmental concern, it is necessary to introduce alternative and eco-friendly binders for concrete. Slag and fly ash based concrete, which is by-product from industrial waste, is probably the best replacement for OPC concrete due to less or nil environmental issue. Most of the researchers have already concluded that slag and fly ash can be used as binders in concrete by activating them with alkali activator solution (e.g. by sodium silicate or sodium carbonate). In the present work concretes were produced by varying the proportion of slag to fly ash (40:60, 50:50, 60:40 & 80:20); amount of alkali activators (5, 10 & 14) and chemical modulus of sodium silicate (Ms) (0.25, 0.5 & 1). Setting times and compressive strength values were evaluated. Results showed that decrease in fly ash content irrespective of % of alkali activators and alkali modulus (Ms), the compressive strength was increasing and setting time was getting shorter. The produced concretes showed increasing compressive strength with increase in % of alkali activator for Ms 0.5 and 1, while for Ms=0.25 the strength was decreasing with increase in % of alkali activators. From this it can be concluded that, Ms=0.5 was the optimum point below which the reaction got slower. Based on the initial investigations, mix S8:F2-SS10(1) and S8:F2-SS10(0.5) showed most promising results in terms of fresh and hardened concrete properties and were easy to handle. Consequently, the above mentioned mixture was chosen to be studied in more detail. The experimental program for these mixes included determination of slump flow, compressive strength (7, 14, 28 days) and shrinkage (drying and autogenous). The results shows that, strength increased with time and comparatively mix with Ms=0.5 showed higher compressive strength than mix with Ms=1, due to higher alkalinity of the pore solution. Mix with Ms=1 showed higher drying shrinkage compared to mix with Ms=0.5, which was explained by higher alkalinity of the solutions (Ms=0.5) leading to rapid formation of aluminosilicate gel. Autogenous shrinkage appeared to be higher for mix with Ms=0.5. This was associated with lower modulus which leads to densification of concrete microstructure at early ages. Pore diameter decrease and the water trapped in the pores exerted increasing tensile stress resulting for higher autogenous shrinkage.
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Ahmari, Saeed. "Recycling and Reuse of Wastes as Construction Material through Geopolymerization." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/223338.
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Storage of mine tailings and waste concrete imposes economical and environmental impacts. Researchers have attempted to reuse wastes as construction material by utilizing ordinary Portland cement (OPC) to stabilize them. This method, however, has a number of limitations related to OPC. In this research, a recent technology called geopolymerization is used to stabilize mine tailings and concrete waste so that they can be completely recycled and reused. The research includes three main parts. The first part studies the effect of different factors on the mechanical properties, micro/nano structure, and elemental and phase composition of mine tailings-based geopolymer binder. The second part investigates the feasibility of producing geopolymer bricks using mine tailings. The physical and mechanical properties, micro/nano structure, durability, and environmental performance of the produced bricks are studied in a systematic way. Moreover, the enhancement of the mine tailings-based geopolymer bricks by adding cement kiln dust (CKD) is studied. The third part of the research investigates the recycling of the fines fraction of crushed waste concrete to produce binder through geopolymerization in order to completely recycle concrete waste. The results indicate the viability of geopolymerization of mine tailings by optimizing the synthesis conditions. By properly selecting these factors, mine tailings-based geopolymer bricks can be produced to meet the ASTM standard requirements and to be environmentally safe by effectively immobilizing the heavy metals in the mine tailings. The physical and mechanical properties and durability of the mine tailings-based geopolymer bricks can be further enhanced by adding a small amount of CKD. The results also show that the fines fraction of crushed waste concrete can be used together with fly ash to produce high performance geopolymer binder. Incorporation of calcium in the geopolymer structure and coexistence of the calcium products such as CSH gel and the geopolymer gel explains the enhancement of the mine tailings-based geopolymer bricks with CKD and the high performance of geopolymer binder from the waste concrete fines and fly ash. The research contributes to sustainable development by promoting complete recycling and utilization of mine tailings and concrete waste as construction material.
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Shearer, Christopher R. "The productive reuse of coal, biomass and co-fired fly ash." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52298.
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Stricter greenhouse gas emission limits and renewable energy requirements are expected to further increase the worldwide practices of firing biomass and co-firing biomass with coal, which are both considered more sustainable energy sources than coal-only combustion. Reuse options for the by-products of these processes -biomass ash and co-fired fly ash -remain limited. Therefore, this research examines their use as supplementary cementitious materials (SCMs) in concrete and as precursors for alkali-activated geopolymers.
Toward their potential use as an SCM, after characterizing these ashes assessing their compliance with ASTM C618 requirements, their impact on early-age hydration kinetics, rheology, setting time and permeability was assessed. Furthermore, the pozzolanic reactivity and the microstructural and hydrated phase development of the cement-ash samples were analyzed. The results show that a wood biomass ash sample was not satisfactory for use as an SCM. On the other hand, the findings demonstrate that co-fired fly ashes can significantly improve the strength and durability properties of concrete compared to ordinary portland cement, in part due to their pozzolanicity. Thus, it is recommended that the ASTM C618 standard be modified to permit co-fired fly ash sources that meet existing requirements and any additional requirements deemed necessary to ensure their satisfactory performance when used in concrete.
Toward their potential use in geopolymers, this study characterized the early-age reaction kinetics and rheological behavior of these materials, showing that their exothermic reactivity, plastic viscosity and yield stress are significantly influenced by the activator solution chemistry and other characteristics of the ash. Two co-fired fly ashes were successfully polymerized, with compressive strengths generally highest for ashes activated with solutions with a molar ratio of SiO₂/(Na₂O + K₂O) = 1. The results show that geopolymerization is a viable beneficial reuse for these emerging by-products. Further characterization of these materials by scanning transmission X-ray microscopy analysis revealed the heterogeneity of the aluminosilicate phase composition of the co-fired fly ash geopolymer gel at the nano- to micro-scale.
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Kuranchie, Francis Atta. "Characterisation and applications of iron ore tailings in building and construction projects." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1623.
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The mine tailings are generated as the wastes worldwide as a result of exploration, excavation, blasting, beneficiation and extraction of mineral ores. In Western Australia, due to the extensive mining activities and increasing low grade ores, there is generation of mine tailings in large quantities, which could lead to environmental and disposal problems. The common practice of handling the tailings are to store them in tailing dams or as stockpiles near mine sites. Limited quantities are sometimes used as backfills and other applications. The utilisation of tailings in building and construction projects, which may consume a large volume of wastes, have not been explored extensively so far. Additionally, the understanding of chemical composition-based utilisation of tailings has very limited investigation.
In the present research, a critical review of the literature was made focusing on the utilisation of mine tailings in large quantities. Experiments have been conducted by developing a methodology to characterise the tailings based on the relationship that exists between electrical resistivity and the relative density of the tailings in dry and wet conditions. The results show that the electrical resistivity of iron ore mine tailings produced in Western Australia in dry condition ranges from 11 kΩm in a more dense state to 19 kΩm in a very loose state, while that in fully saturated condition ranges from 20 Ωm for a very dense state to 31 Ωm in a very loose state.
The laboratory investigation has been conducted to utilise iron ore tailings to produce geopolymer bricks. The sized tailings were mixed with sodium silicate solution used as an activator to form a paste. The paste was moulded and cured for different durations. It was found that the geopolymer bricks produced from iron ore tailings could have a compressive strength as high as 50.35 MPa. This is either superior or similar to international standard specifications for conventional bricks. Additionally, the new bricks will be more economical than conventional bricks with potential cost reduction of 36.8%.
The research has also investigated the utilisation of iron ore mine tailings to replace conventional aggregates in concrete. 100% of both fine and coarse conventional aggregates were replaced with tailings in the mixed design. The concrete mix was casted into moulds and cured. It was found that the compressive strength of the concrete with tailings aggregates at 28 days was 36.95 MPa which shows an improvement of 11.56% over the concrete with conventional aggregates. Additionally, the new concrete met all other requirements for quality assessment of concrete.
Finally, the research has conducted investigation into load-settlement behaviour of iron ore tailings to be considered as a structural fill material. The experiment was conducted in a model test tank in the laboratory varying the relative density of the tailings. It was found that the load-bearing capacity is 22 times higher, and the stiffness is 13.5 times higher than their values for conventional fill materials.
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Fialová, Barbora. "Rehydratace alkalicky aktivované strusky po vysokoteplotním namáhání." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-239940.
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Ground granulated blast furnace slag is a by-product of the steel industry and is often used in combination with ordinary Portland cement as a binder in concrete. When concrete is exposed to high temperatures, physical and chemical transformations lead to significant loss of mechanical properties. This study aims to investigate the effect of high temperatures and rehydration on the mechanical properties, microstructure and phase composition of alkali activated slag. The results of the research could make an important contribution to decisions made concerning the reconstruction of structures affected by fire. In suitable cases it would be possible to regenerate parts of a structure instead of totally rebuilding it.
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Lee, William K. "Solid-gel interactions in geopolymers." Connect to thesis, 2002. http://repository.unimelb.edu.au/10187/1071.
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This is partly because the requirements for such an ultimate material change with people’s perception about its properties as well as its environmental impact. Thus, the once-believed ultimate Portland cement binder is now becoming unacceptable for a number of reasons including poor durability as well as severe environmental impact during production. Thus, an improved mineral binder is required by modern society to serve the same purposes as the existing Portland cement binder, as well as to reduce the current environmental impact caused by Portland cement production.<br>Geopolymerisation is such a ‘green’ technology capable of turning both natural ‘virginal’ aluminosilicates and industrial aluminosilicate wastes, such as fly ash and blast furnace slag, into mechanically strong and chemically durable construction materials. However, the source materials for geopolymer synthesis are less reactive than Portland cement clinkers and the chemical compositions of these source materials can vary significantly. Consequently, product quality control is a major engineering challenge for the commercialisation of geopolymers.<br>This thesis is therefore devoted to the mechanistic understanding of the interfacial chemical interactions between a number of natural and industrial aluminosilicates and the various activating solutions, which govern the reactivity of the aluminosilicate source materials. The effects of activating solution alkalinity, soluble silicate dosage and anionic contamination on the reactivity of the aluminosilicate source materials to produce geopolymeric binders, as well as their bonding properties to natural siliceous aggregates for concrete making, are examined. In particular, a new set of novel ‘realistic’ reaction models has been developed for such purposes. These reaction models have been further utilised to develop a novel analytical procedure, which is capable of studying geopolymerisation on ‘real’ geopolymers in situ and in real time. This novel procedure is invaluable for the total understanding of geopolymerisation, which is in turn vital for effective geopolymer mix designs.
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Hasnaoui, Abdelaziz. "Optimisation d'un géopolymère à base de laitier et de metakaolin pour la rélisation d'un béton de structure." Thesis, Cergy-Pontoise, 2019. http://www.theses.fr/2019CERG1019.
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Ce travail concerne le comportement des bétons géopolymères formulés à base de laitier et de métakaolin en utilisant une solution de silicate de sodium comme activateur. La première partie de l’étude s’attache à l’optimisation de la formulation du ciment géopolymère. Pour atteindre cet objectif, un mortier Portland de référence et vingt-quatre mortiers géopolymères ont été développés en faisant varier le rapport massique Laitier/Métakaolin (25/75, 50/50, 75/25) et le rapport molaire SiO2/Na2O, noté RM, des solutions alcalines (RM compris entre 1,0 et 2,0). Les mortiers ont été caractérisés à l’état frais (ouvrabilité et temps de prise) ainsi qu’à l’état durci en termes de résistances mécaniques à la flexion et à la compression, module d’élasticité dynamique et porosité. Les résultats ont montré que le liant géopolymère composé de 50/50 Laitier/Métakaolin avec un rapport molaire RM de 1,8 permet d’obtenir un mortier plus résistant que le mortier de référence tout en assurant une bonne ouvrabilité et une excellente stabilité à l’efflorescence. La deuxième partie du travail porte sur l’étude des performances des bétons géopolymères synthétisés avec le liant optimisé dans la première partie de la thèse. De plus, l’effet des conditions de cure ainsi que l’influence de l’incorporation des granulats recyclés sur les performances de ces bétons ont été évalués. En effet, trois modalités de cure ont été choisies, 20°C et 50% HR, 20°C et 90% HR ainsi qu’une immersion totale dans l’eau à 20°C. Quant à la valorisation des granulats recyclés, trois taux de substitution volumique ont été sélectionnés, à savoir 10, 30 et 50%. Pour tous les matériaux, les propriétés à l’état frais et les performances physiques et mécaniques à l’état durci ont été étudiées. Les résultats obtenus montrent que le durcissement dans un environnement de faible humidité relative conduit à l’obtention de faibles performances physiques et mécaniques en comparaison avec le durcissement à une humidité relative élevée et en immersion totale dans l’eau. En ce qui concerne la valorisation des granulats recyclés, il a été montré que leur introduction induit une diminution de la résistance à la compression et à la traction. En revanche, à des faibles taux de substitution (inférieure à 30%), des performances rhéologiques et mécaniques acceptables sont obtenues.Les résultats expérimentaux du présent travail ainsi qu’un nombre considérable des résultats rapportés dans la littérature ont permis d’évaluer la fiabilité des équations empiriques développées pour la prédiction des propriétés mécaniques des bétons Portland. Pour la prédiction de la résistance à la traction des bétons géopolymères, l’équation proposée pour les bétons Portland reste applicable. Par contre, une nouvelle équation a été proposée pour la prédiction du module d’élasticité<br>This work concerns the behavior of slag and metakaolin based geopolymer concrete formulated using a sodium silicate solution as activator. The first part of the study focuses on the optimization of the geopolymer cement. To achieve this objective, a reference Portland mortar and twenty-four geopolymer ones were developed by varying the Slag/Metakaolin weight ratio (25/75, 50/50, 75/25) and the molar ratio SiO2/Na2O, RM, of the alkaline solutions (RM between 1.0 and 2.0). The mortars were characterized in the fresh state (workability and setting time) as well as in the hardened state in terms of flexural and compressive strengths, modulus of elasticity and porosity. The results showed that the geopolymer binder composed of 50/50 Slag/Metakaolin with a molar ratio RM of 1.8 allows obtaining a more resistant mortar than the reference one while ensuring a good workability and an excellent stability against efflorescence.The second part of the work deals with the behavior of geopolymer concrete, synthesized with the binder optimized in the first part of the thesis. In addition, the effect of curing conditions and the influence of recycled aggregates incorporation on the performance of these concrete were evaluated. Indeed, three curing methods were chosen, 20°C and 50% RH, 20°C and 90% RH and a total immersion in water at 20°C. For recycled aggregates valorization, three volumetric substitution ratios were selected: 10, 30 and 50%. For all materials, the properties in the fresh state and the physical and mechanical properties in the hardened state were studied. As regards the influence of recycled aggregates, it has been shown that their introduction induces a decrease in compressive and tensile strengths. However, at low substitution ratios (less than 30%), acceptable rheological and mechanical performances are obtained.The obtained results show that curing in a low relative humidity leads to poor physical and mechanical performance compared to hardening at high relative humidity and total immersion in waterThe experimental results of this work as well as a considerable number of results reported in the literature allowed to evaluate the reliability of the empirical equations developed for the prediction of the mechanical properties of Portland concrete. For the prediction of the tensile strength of geopolymer concrete, the proposed equation for Portland concrete remains applicable. Nevertheless, a new equation has been proposed for the prediction of the elastic modulus
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Zheng, Yong Chu. "Shrinkage behaviour of geopolymers /." Connect to thesis, 2010. http://repository.unimelb.edu.au/10187/7157.
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Mohelská, Lucie. "Modifikace betonových prvků pro chladicí věže." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216998.
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This master´s thesis deals with the suppression of the growing of algae in cooling towers. Subject of the work is suggestion and testing surface modification of the existing mature concrete in order to suppress the growth of algae. In the frame surface modification, several commercially available and newly developed systems were tested. Testing systems are based on the basis of portland cement, geopolymers or formation of insoluble complex compounds containing metal elements (Zn, Cu). Experimental methods were applied in the real environment of cooling towers of Dukovany Nuclear power plant.
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Wasserbauer, Jaromír. "Mechanické vlastnosti mikrostrukturních komponent anorganických materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-233368.
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Disertační práce se zabývá studiem strukturních a mechanických vlastností anorganických materiálů. Cílem je nalezení jednotlivých fází ve zkoumaném materiálu a hlavně lokalizace (mechanicky) nejslabšího místa, jeho ovlivnění a následně výroba materiálu o lepších mechanických vlastnostech. Z důvodu velkého množství použitých metod je základní teorie vložena vždy na začátku příslušné kapitoly. Taktéž z důvodu značného množství výsledků jsou na konci kapitol uvedeny dílčí závěry. Práce je rozdělena na tři části, kdy první se zabývá seznámením s možnostmi modelování mikro-mechanických vlastností a provedením experimentů umožňujících posouzení rozsahu platnosti některého modelu. V druhé části je provedeno shrnutí současných možností indentačních zkoušek pro měření mechanických vlastností strukturních složek betonu a praktické zvládnutí metodiky vhodné k užití pro výzkum materiálů zkoumaných domovským pracovištěm. V třetí části je navržena metoda identifikace nejslabších článků struktury anorganických pojiv a její ověření na konkrétním materiálu zkoumaném na domovském pracovišti. V této dizertační práci jsou použity tyto metody: kalorimetrie, ultrazvukové testování, jednoosá pevnost v tlaku, nanoindentace, korelativní mikroskopie a rastrovací elektronová mikroskopie s energiově disperzním spektrometrem. Dílčími výsledky jsou kompletní charakterizace cementových materiálů, upřesnění stávajících poznatků a nalezení optimálního postupu pro charakterizaci. Hlavním výsledkem je inovativní přístup vedoucí k pozitivnímu ovlivnění materiálu.
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Muntingh, Yolandi. "Durability and diffusive behaviour evaluation of geopolymeric material." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2882.
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Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2006.<br>The study presented in this thesis symbolises one of the first ever efforts to better understand and describe the durability of geopolymers used in large scale commercial applications. In terms of the construction industry, geopolymers can be seen as a value-added approach to substitute the Ordinary Portland Cement (OPC) monopoly. It is particularly the fly ash-based geopolymers that are the main attraction, due to their economic and environmental advantages, over and above the large quantities of this material that are commonly available.
Despite the fact that geopolymers have been around for thousands of years, it is only now that the accumulation of research across the globe has pooled their knowledge to broadly define this material in terms of its physical and chemical composition. The development of geopolymers for construction applications remains quite new, therefore requiring insight into the durability that can be expected from these materials, consequently leading to this work.
Concrete technology and -science is one of many techniques which can offer considerable insight into effective durability studies, in addition to acting as a reference for firm material comparisons. Thus, this work is based on a collection of concrete durability studies and recommendations which resulted from a broad range of investigations. Principally, this work aims to confirm the superiority of geopolymers in terms of corrosion resistance.
Chloride induced corrosion has been identified as being the main cause for deterioration of OPC structures and subsequently the origin of very costly, and frequent, reconstructive requirements. Geopolymers now have the opportunity to be introduced into this monopoly due to its advanced, yet credible, chloride penetration resistance. This thesis reports the development of the experimental design, as well as the associated analyses to describe the diffusive properties exhibited by fly ash-based geopolymers. Ultimately, two independent methods showed that Chloride Diffusion Coefficients (CDC) for all of the geopolymeric formulations are significantly lower (typically 1.43 x 10-15 cm2/s) than for cement (typically 0.5 x 10-8 cm2/s) or any other concrete mixture.
Furthermore, the work presented here will consider the diffusive behaviour of the geopolymer formulations in an acidic sulphate environment, presenting this material’s superior resistance not only to the sulphate ion, but more so to the acid attack. Probable geopolymer applications are now further expanded to industrial applications, due to its acid resistance along with reduced Sulphate Diffusion Coefficients (SDC).
In addition, the development of a time-to-corrosion software-tool is discussed. This tool may prove to be a valuable instrument for future geopolymer durability research, as well as iv commercial users in which extended material comparisons can be made. It may even assist the formulation-tailoring process where the relevant CDC/SDC can be chosen for a specific life-expectancy, reaching far beyond the limited scope of recipes covered in this work.
Finally, this thesis provides the stepping-stone in proving geopolymer durability superiority. The formulations which proved to show the best results in terms of durability and acid resistance are highlighted and valuable recommendations are made towards the selection of suitable starting materials for optimum material robustness. The findings of this work, however, can be fortified by future research and exposure.
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Guimarães, Paulo Victor Campos. "Estudo da aderência de concretos ativados alcalinamente à base de cinza da casca de arroz e metacaulim /." Ilha Solteira, 2019. http://hdl.handle.net/11449/182264.
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Orientador: José Luiz Pinheiro Melges<br>Resumo: A indústria do cimento Portland é responsável direta por uma carga de poluentes de significativo dano ambiental. Os Concretos Ativados Alcalinamente (CAA) são matrizes compostas por um ativador alcalino e um aglomerante alternativo. O material comumente utilizado para a ativação alcalina é o silicato de sódio, cuja fabricação também se mostra como ambientalmente nociva. O silicato de sódio, junto ao cimento Portland, podem ser dispensados, uma vez que a produção do ativador pode se dar através de um composto rico em silício (materiais pozolânicos no geral), sendo a cinza da casca de arroz (CCA) o instrumento de estudo do trabalho apresentado, e a soda cáustica como fornecedora de sódio (meio alcalino). Os concretos CAA foram definidos conforme o parâmetro ξ (CAA-ξ), que representa a relação molar entre SiO2 e Na2O, com as variações ξ = 1,2, ξ = 1,6 e ξ = 2,0, esta última representando o concreto ativado alcalinamente com maior taxa de CCA. Este trabalho tem como intuito a avaliação das propriedades mecânicas dos concretos CAA, comparando-as, em seguida, com duas tipologias de concreto com cimento Portland CPV-ARI, com distintos fatores água cimento (0,45 e 0,55). A variação na relação a/c teve como intuito a análise de duas referências com valores diferentes de fck. Os resultados demonstram que a resistência à compressão axial e diametral (sete dias de cura) para os concretos CAA se encontraram na faixa de 25 a 30 MPa, e de 1,5 a 3,5 MPA, respectivamente. Não foram observados... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The Portland cement industry is directly responsible for a load of pollutants of significant environmental damage. Alkali-Activated Concrete (AAC) is a matrix with prior activation and alternative binder. The catalyst material commonly used for prior activation is the sodium silicate, the manufacture of which is also environmentally harmful. Sodium silicate, together with Portland cement, can also be dispensed with, since the activator can be produced through a silicon-rich compound (pozzolanic materials in general), with the rice husk ash (RHA) being the instrument of study of the work presented, and caustic soda as a supplier of sodium. The AAC concretes were defined according to the parameter ξ (AAC- ξ), which represents the molar ratio of SiO2 and Na2O, with the variations ξ = 1.2, ξ = 1.6 and ξ = 2.0, the latter representing the AAC with higher RHA rate. This work intends to evaluate the mechanical properties of AAC, comparing them to two types of concrete with ordinary Portland cement with high early resistance, with different water cement factors (0.44 and 0.55). The variation in the water/binder mass ratio was intended to analyze two references with different values of compressive strength class. The results demonstrate that the axial and diametric compression strength (seven days cure) for the AAC concretes were in the range of 25 to 30 MPa, and of 1.5 to 3.5 MPA, respectively. There were no significant gains in the transition between the ages of 7 and 28 days, and 2... (Complete abstract click electronic access below)<br>Mestre
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Citeroni, Chiara. "Alkali-activated expanded lightweight aggregates for the production of special asphalt concretes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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La presente tesi sperimentale si focalizza sulla produzione e successiva analisi, tramite test prescritti dalla normativa europea, di conglomerati bituminosi costituiti da aggregati leggeri che vadano a sostituire il 12% degli aggregati naturali, presenti in un tipico strato d’usura.
Questi aggregati leggeri sono stati originati partendo da due differenti polveri di scarto ad attivazione alcalina, quali polvere di basalto e bentonite esausta impiegati come principali precursori. Infatti, l’utilizzo di materiali di riciclo come prodotti sostenibili desta molto interesse nell’ambito ingegneristico, nello specifico in applicazioni su pavimentazioni stradali, in quanto essi possono rappresentare un modo per risparmiare energia e ridurre gli impatti ambientali.
Lo studio sperimentale si pone come ulteriore obiettivo la comparazione dei materiali leggeri sopracitati con l’argilla espansa, in modo da comprovare la loro efficacia e poterli considerare degli ottimi e più sostenibili sostituti.
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Chiu, Wei-Ting, and 邱緯婷. "Development of FA/GGBFS Geopolymer Concrete." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5e48n3.
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碩士<br>國立臺北科技大學<br>土木工程系土木與防災碩士班<br>106<br>Iron blast-furnace slag is a by-product produced by the steel plant during the iron making process, and fly ash is a major by-product of coal-fired power plants. Every year, a large amount of blast-furnace slag and fly ash produced. With great difficulty, if it is disposed of as waste, it will not only be environmentally unfriendly, but will also cost a lot of costs. If blast-furnace slag is water-quenched cooling, grinding into fine powder and adding to concrete can replace part of the cement, it is generally considered that the concrete can be made denser and the durability is increased. The same is true for fly ash, which saves cement consumption. However, in order to make fuller and more efficient use of waste resources, this study attempted to produce geopolymer based on fly ash and blast-furnace slag, it is expected to develop cement-free concrete. According to the experimental results, a slurry of fly ash and geopolymer material ratio of 1, the strength of it can be up to 253.9 kgf/cm2 in 28 days. A slurry of blast-furnace slag and geopolymer material ratio of 1 and the performance is better, the strength of it can be up to 578.2 kgf/cm2. However, when gravel was separately added to make fly ash and blast-furnace slag geopolymer concrete specimens, the 28-day strength was only 148.8 kgf/cm2 and 229.7 kgf/cm2, respectively. It is initially known that the key factors may be in the gradation of coarse aggregates and will be discussed in subsequent research.
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Chen, Jing-Len, and 陳敬仁. "Preparation of Geopolymer Green Concrete and Pervious concrete by using Marble." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/y8322w.
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碩士<br>國立臺北科技大學<br>資源工程研究所<br>106<br>In this study, by using the cement raw material –marble and slag as the main material, mix with the alkali solution to make the marble based geopolymer green cement, concrete and pervious concrete. This research can be divided into three parts, the first part uses the marble based geopolymer to make the geopolymer green cement paste, which the result shows the setting time of green cement paste can control more than 80 mins, and the compressive strength can reach more than 70MPa after 28 days curing time. By Comparing with traditional Portland cement, green cement paste not only emits much lower carbon dioxide but also provide good mechanical strength and working ability. The results showed that the geopolymeric concrete curing in the indoor and outdoor environment for 90days the compressive strength can achieve 44MPa and 31MPa. The durability of the geopolymer concrete also shows a good performance. The result shows the geopolymeric pervious concrete compressive strength can achieve more than 11MPa, the permeability coefficient can reach more than 1.51 cm/s. The testing results of the pervious concrete all confirm the construction standards. The final part is carbon emission and cost calculated. Comparing with the Portland cement product, the cost of marble based geopolymer 10% worth than Portland cement product, but the carbon emission can reduce more than 44%. The marble based geopolymer product can provide a good performance in many practices. In future, hope this material can use in the civil engineering and achieve the goal of the carbon reduction.