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1
Golewski, Grzegorz Ludwik. "Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages." Materials 13, no. 22 (November 19, 2020): 5241. http://dx.doi.org/10.3390/ma13225241.
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This study investigated the influence of the curing time on the fracture toughness of concrete produced with different content of low calcium fly ash (LCFA). During the study, the amounts of 20% and 30% of pozzolanic additive were used. In order to observe the effect of the applied pozzolanic additive on the analyzed concrete properties, the obtained results were compared with the values obtained for the reference concrete. Compressive strength—fcm and fracture toughness, by using mode II loading—KIIc (shearing), were determined between the 3rd and 365th days of curing. In the course of experiments, changes in the development of cracks in individual series of concrete were also analyzed. In addition, the microstructures of all composites and the nature of macroscopic crack propagation in mature concretes were assessed. It was observed that the greatest increase in fracture toughness at shear was in the case of reference concrete during the first 28 days, whereas, in the case of concretes containing LCFA, in the period of time above 4 weeks. Furthermore, concrete without the LCFA additives were characterized by a brittle fracture. In contrast to it, concretes with LCFA additives are mainly characterized by a quasi-plastic process of failure. Moreover, most of the samples showed a typical pattern of the destruction that occurs as a result of shearing. The presented test results may be helpful in selecting the composition of concrete mixtures containing LCFA to be used in concrete and reinforced concrete structures subjected to shear loads.
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Justs, Janis, Genadij Shakhmenko, Diana Bajare, and Nikolajs Toropovs. "Comparison of Pozzolanic Additives for Normal and High Strength Concrete." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 2 (August 5, 2015): 79. http://dx.doi.org/10.17770/etr2011vol2.979.
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Microsilica is widely recognized as a “benchmark” for pozzolanic products. Although microsilica is an industrial byproduct, it has recently become very expensive. Four different pozzolanic additives were compared by the authors of this study. Two of the additives were commercially available products – microsilica by Elkem and Centrilit NC by MC Bauchemie. The other two additives were produced under laboratory conditions. Both of them were clay-based materials. Compressive strength was determined after 7, 28 and 155 days. The objective of this research was to determine alternatives to microsilica and evaluate pozzolanic additives performance in normal and high-strength concrete.
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Sētiņa, Janīna, Inna Juhņeviča, Jānis Baroniņš, and Liene Gulbe. "Minerālo saistvielu pētījumi Silikātu materiālu institūtā." Materials Science and Applied Chemistry 35 (November 1, 2018): 134–59. http://dx.doi.org/10.7250/msac-2018-0006.
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Parādīti pēdējās desmitgades pētījumi minerālo saistvielu jomā. Pētīta dažādu aktīvo ķīmisko piedevu ietekme uz betona struktūru, mehāniskajām un fizikālajām īpašībām. Novērtēta iegūto betonu korozijas izturība pret sulfātu sāļu šķīdumiem. Pētīta dažādu rūpniecisko blakus produktu – pelnu – kā pucolānu piedevas ietekme uz betona īpašībām.Investigation of Mineral Binders in the Institute of Silicate MaterialsThe influence of natural and artificial pozzolanic and micro-filler additives on the cement paste hydration process, structure, properties was studied. Different additives and chemical compositions were used: micro- and nano-silica, amorphous silicon dioxide synthesized by sol-gel method, glass powder, highly disperse sand, different types of ash. The pozzolanic activity of additives mainly depends on quantity and specific surface area, i. e., the dispersity of active SiO2 and Al2O3. Depending on the pozzolanic activity chemical additives can be used as concrete aggregates or as active additives.The influence of superplasticizer Semflow MC (SP) on microstructure and properties of concrete was investigated. The compressive strength of concrete with SP increased to 154 MPa, corresponding to HPC. The capillary absorption of water and solutions containing sulphate ions into HPC depends on amount of SP. The depth of penetration of solution in the samples decreases consistently by increasing the amount of SP. The formation of crystalline phase during maturation was analysed, and it was found that by increasing testing time the amount of portlandite decreased and calcium hydrosilicate formed. The concrete samples with low W/C ratio, pozzolanic additives and SP up to 2.5 % according mechanical and chemical properties conform to the characteristics of HPC. The investigated concrete has high chemical resistance to solutions containing sulphate ions.Keywords – binders, concrete, pozzolanic additives, ash, concrete corrosion
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Konkol, Janusz. "Fracture Toughness and Fracture Surface Morphology of Concretes Modified with Selected Additives of Pozzolanic Properties." Buildings 9, no. 8 (July 26, 2019): 174. http://dx.doi.org/10.3390/buildings9080174.
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Modern methods of designing and testing concrete must be extended to appropriate material engineering approaches. It is then crucial to link the properties of concrete with its structure described in a quantitative way. The aim of the article was to present the results of research on concretes modified with three additives: Silica fume (SF), activated fluidal ash (FA), and metakaolinite (MK). The concretes were tested for compressive strength, fracture toughness (determining critical stress intensity factor KIcS and elastic modulus E). Also, stereological and fractal tests were performed. The research program covered three separate experiment plans, adopting the water/binder ratio and the additive/binder mass ratio as the independent variables. The results of experiments and their analysis proved a statistically significant relationship between fracture morphology (fractal dimension D) and concrete composition and fracture toughness. A higher fractal dimension was found in concretes with a higher content of cement paste and a lower content of additive. No significant effect of the type of additive used in the above dependence was found. An original method enabling the determination of mechanical properties of concrete with no need for destructive testing has been developed.
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Setina, Janina, Alona Gabrene, Inna Juhnevica, and Ieva Ose. "Effect of Siliceous Pozzolanic Additives on the Hydration Process of Cement." Key Engineering Materials 604 (March 2014): 110–13. http://dx.doi.org/10.4028/www.scientific.net/kem.604.110.
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The given study investigates the influence of pozzolanic admixtures both micro- and nanosize silica and biomass ashes on microstructure and properties of hydration process of cement paste. The investigations were carried out by - XRD, SEM and FTIR. Pozzolanic activity of the concrete admixtures strongly depends on their chemical composition, content of reactive silica as well as the specific surface area. The micro- and nanosilica pozzolanic additives demonstrated the higher values of pozzolanic activity. Those activate the process of mineralization and are acting both as the cementitious admixture as well as the fine filler.
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Larsen, O., O. Aleksandrova, V. Naruts, A. Polozov, and A. Bakhrakh. "STUDY OF THE PROPERTIES OF ACTIVE MINERAL ADDITIVES FOR USE IN HYDRAULIC ENGINEERING CONSTRUCTION." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 5, no. 8 (August 4, 2020): 8–17. http://dx.doi.org/10.34031/2071-7318-2020-5-8-8-17.
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Improving the technology of construction production contributes to improving the quality of construc-tion of hydraulic structures and their reliability. In recent decades, rolled compacted concrete has be-come widespread in the construction of dams in our country and in world practice. The technology of rolled compacted concrete in hydraulic engineering projects has a number of advantages: it reduces labor costs and expenses, allows fully mechanization the concreting process with implement of high-performance equipment, and thereby increases the rate of construction of massive structures. The use of mineral fillers in rolled concrete will reduce heat generation, contribute to a reduced adiabatic rise in the temperature of concrete, improve its performance and increase durability. The test method for assessing pozzolanic activity of volcanic scoria, fly ash, crushed powder of basalt and volcanic tuff by degree of absorbed lime from a saturated calcium hydroxide solution with a simultaneous change in volume is described. The studies have shown that volcanic scoria and crushed powder of basalt are additives with the lowest volume increase at the age of 30 days, they show the high pozzolanic proper-ties and can be selected as initial pozzolanic materials for production rolled compacted concrete with significant economic and environmental advantages.
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Koťátková, Jaroslava, Dana Koňáková, Eva Vejmelková, Pavel Reiterman, and Jamal Akhter Siddique. "Mechanical and Water Transport Properties of HSC with Different SCMs." Materials Science Forum 824 (July 2015): 105–10. http://dx.doi.org/10.4028/www.scientific.net/msf.824.105.
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Pozzolanic materials and their usage in concrete production are nowadays widely spread. Their application as additives is inherent especially for the purpose of high strength concrete. This article deals with evaluation and comparison of the influence of two different supplementary cementitious materials on the properties of high strength concrete: natural pozzolana (NP) and finely crushed brick (FCB). The studied characteristics are basic physical properties with connection to mechanical parameters, and next to this, characterization of water transport. In the scope of this study results revealed better pertinence of finely crushed brick, as the appropriate replacement of cement was found out to be up to 30%, whilst for natural pozzolana only 10% of cement substitution is favourable. The open porosity as the first indicator of both mechanical and water transport properties appeared to be lower in all studied mixtures with FCB than in the case of NP. With increasing ratio of the additive to cement there is significant worsening of mechanical and water transport parameters when NP is involved. The behaviour of mixtures with FCB is better even when high amount of cement is substituted.
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Setina, Janina, Alona Gabrene, and Inna Juhnevica. "Effect of Pozzolanic Additives on Structure and Chemical Durability of Concrete." Procedia Engineering 57 (2013): 1005–12. http://dx.doi.org/10.1016/j.proeng.2013.04.127.
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Vitola, L., G. Sahmenko, D. Erdmane, G. Bumanis, and D. Bajare. "The effect of various pozzolanic additives on the concrete strength index." IOP Conference Series: Materials Science and Engineering 251 (October 2017): 012038. http://dx.doi.org/10.1088/1757-899x/251/1/012038.
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Yener, Engin. "The effect of pozzolanic mineral additives on the strength and durability properties of structural lightweight concrete." CEBEL Vol 2 Issue 2 April 2021 2, no. 2 (February 18, 2021): 35–40. http://dx.doi.org/10.36937/cebel.2021.002.005.
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Structural lightweight concretes have the potential to be used in road pavements and bridge decks due to their properties such as sufficient wear resistance, high impermeability, superior freeze-thaw resistance and ductile behavior. However, road pavements are directly exposed to nitric acid and sulfuric acid solutions created by the exhaust gases of transportation vehicles in humid environments. Therefore, the concrete to be used in road pavements must be resistant to these acid effects. In addition, sufficient strength must be guaranteed when used as pavement material. The aim of this study is to produce lightweight concrete suitable for road pavements and other structures exposed to acid effects. For this, the effect of silica fume (SF) and fly ash (FA) on acid resistance and strength development of lightweight concrete with perlite aggregates was investigated. Five different lightweight concrete mixtures were produced by substituting 0%, 5%SF, 10% SF, 10%FA, 20% FA instead of cement by weight. Natural perlite rock has been used as an aggregate source in order to provide high strength and lightness. The cylindrical samples produced were kept in lime saturated water cure for 120 days and their compressive strength was measured on the 28th, 56th, 90th and 120th days. In addition, in order to monitor the acid resistance, the strength changes of the samples exposed to 5% sulfuric acid and 5% nitric acid solution after 28 days of standard curing were followed until the 120th day. Results show that, SF and FA additives increase the compressive strength especially at older ages. In case of 10% SF, the 120-day strength value increased by 18.6% and reached 34.5 MPa. Also, lightweight perlite concrete is highly resistant to nitric acid and sulfuric acid effects. In the case of 92 days of nitric acid and sulfuric acid exposure, the strength losses are only 5.2% and 13.4%, respectively. In order to fully benefit from SF and FA, concretes must be adequately cured before acid attack. It has been concluded that it is possible to produce high-strength and acid-resistant lightweight concretes suitable for road pavements and many other structural elements by using natural perlite aggregate.
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Belbachir, B., A. S. Benosman, and H. Taïbi. "Mineral-Based Composite Materials for Energy Efficiency in Buildings." Key Engineering Materials 678 (February 2016): 123–34. http://dx.doi.org/10.4028/www.scientific.net/kem.678.123.
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Degradation of building materials is an important phenomenon influencing their design and utilization. Mineral-based polymer-mortar composites (PMC) are often used as inexpensive promising materials to prevent the deterioration of constructions or remedy various reinforced concrete structures and they are used as materials for energy efficiency in buildings. In repair applications, polymer addition allows improving the adhesion properties of materials used in coating. With the intention of improving the sustainability of these composites, the influence of latex polymer and supplementary cementitious materials (natural pozzolan and silica fume) additions on the characteristics of these composites was investigated in aggressive media, such as acids. Mortars made with local pozzolanic mineral admixtures, obtained by substituting cement by different proportions of polymer (0, 5, 7.5, 10, 12.5 and 15%) were conserved in acidic solutions for 56 days. The microstructural analysis of these mortars was performed, using the X-ray diffraction technique, after 56 days of exposure to acid attack. The obtained results enable to bring out the beneficial effect of adding a latex polymer and other pozzolanic additives into modified materials on resistance to acid attacks. So, these composite materials can be recommended as materials for energy efficiency in buildings.
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Dembovska, Laura, Diana Bajare, Ina Pundiene, and Laura Vitola. "Effect of Pozzolanic Additives on the Strength Development of High Performance Concrete." Procedia Engineering 172 (2017): 202–10. http://dx.doi.org/10.1016/j.proeng.2017.02.050.
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Damara, Bobby, and Zulkifli Lubis. "PENGARUH PENAMBAHAN LIMBAH B3 PADA KUAT BETON MUTU K-175." Jurnal CIVILA 3, no. 1 (May 15, 2018): 100. http://dx.doi.org/10.30736/cvl.v3i1.216.
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Innovations of concrete growing quite rapidly now from reuse and reduce. materials unused or addition of additives in order to increase the quality of concrete include the addition of waste carbide (B3) is an effort to increase the element calcium is required in the reaction pozzolanic when mixed with SiO2 in the fly ash, Pozzolanic reaction is a reaction between calcium, silica or aluminates with water to form a strong and rigid mass similar to the cement hydration process. The mixing process carbide waste as a concrete material is done by laboratory testing in accordance with data from literature Indonesian Standard SK SNI and foreign standards are ASTM with variation of composition dregs carbide 5% as a substitute for cement material with a target quality of concrete K-175. From this result the composition of dregs addition of a mixture of dregs carbide 5% with an average compressive strength of 249,69 kg/cm2. That value greater than 1,77% of the normal concrete 245,36 kg/cm2.
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Aras, A., M. Albayrak, M. Arikan, and K. Sobolev. "Evaluation of selected kaolins as raw materials for the Turkish cement and concrete industry." Clay Minerals 42, no. 2 (June 2007): 233–44. http://dx.doi.org/10.1180/claymin.2007.042.2.08.
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AbstractTurkey has a long tradition (starting with prehistoric civilizations) and experience in exploring for raw clay materials and processing them into ceramic products. Many of these products, such as tiles and sanitary ware, are manufactured for domestic and export markets. Kaolin is one of the raw materials of major importance for the ceramic and paper industry, as well as for a number of auxiliary applications. There is ongoing interest in applying kaolin in the construction industry as a raw material in the production of white cement clinker and as an artificial pozzolanic additive for concrete (in the form of metakaolin). This report presents results related to search, assessment and evaluation of available resources for advanced cement and concrete additives.
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Čáchová, Monika, Magdaléna Doleželová, and Martin Keppert. "Influence of Pozzolanic Additive on Pore Size Distribution of Lime Mortar." Materials Science Forum 908 (October 2017): 51–55. http://dx.doi.org/10.4028/www.scientific.net/msf.908.51.
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Pozzolanic additives are widely applied as components of cementitious composites as well as mortars based on white lime. They are generally recognized as components improving the durability of resulting material – concrete or mortar. The mechanism responsible for this favorable effect lies in physical and chemical modification of initial binding system. The present paper deals with influence of a pozzolanic additive – ceramic dust (CD) – on pore system of lime – based mortar. The CD was characterized by means of elementary and phase analysis. The range of mortars of varying CD/lime ratio was prepared; their pore size distribution, strength and rate of liquid water and water vapor were determined. The presence of CD caused change in the pore size distribution while the total porosity did not changed significantly. The volume of large pores was reduced and amount of fine pores was increased as consequence of growing CD content. It had positive effect on rate of liquid water transport. Diffusion resistance factor was influenced by the presence of CD towards the lower values; in opposite to the liquid sorptivity the diffusion resistance was controlled by the total porosity. The strength was improved by addition of pozzolanic additive as could be expected. It is in accordance with the reduced volume of capillary pores but obviously the presence of pozzolanic additive in lime converts the binding system to hydraulic and thus the effect of CD on strength cannot be explained just by its influence on pore size distribution.
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Roslan, Ahmad Farhan, Hanizam Awang, and Md Azree Othuman Mydin. "Effects of Various Additives on Drying Shrinkage, Compressive and Flexural Strength of Lightweight Foamed Concrete (LFC)." Advanced Materials Research 626 (December 2012): 594–604. http://dx.doi.org/10.4028/www.scientific.net/amr.626.594.
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This paper presents an investigation on lightweight foamed concrete (LFC) with different type of additives. LFC with 600, 1000 and 1400 kg/m3 density were cast and tested. Fly ash, lime and polypropylene fibre were used on each density with different percentages. All the additives effects were compared with normal LFC as control mix. Mechanical properties of LFC were evaluated with several tests up to 180 days. The results show that the drying shrinkage, compressive strength and flexural strength are affected by the hydration process of each additive in the harden LFC. Fly ash as pozzolanic material helps to strengthen the LFC, though it needs longer curing period to achieve ultimate strength. Lime gives slight contribution to strength as detail investigation on microstructure formation will give clear answer on how the mechanical properties were affected. The addition of polypropylene contributes to flexural strength and shrinkage of LFC. Polypropylene fibre only contributes to compressive strength at low LFC density.
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Pundienė, Ina, Modestas Kligys, and Jurga Šeputytė-Jucikė. "Portland Cement Based Lightweight Multifunctional Matrix with Different Kind of Additives Containing SiO2." Key Engineering Materials 604 (March 2014): 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.604.305.
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Additives containing SiO2 (ACS) and having pozzolanic properties such as metakaolin (MK), microsilica (MS) and milled autoclaved aerated concrete waste (MAACW) are promising materials for partially replacement of Portlandcement (PC) in matrix of lightweight building materials. Studies have shown that SA effects on the hydration process of PC matrix. The highest wetting heat release rate values were obtained using MS additive, and the lowest a mix of MS and MK additives. In a mix with both MS and MK additives, the maximal value of heat release rate was reached after 10 h and in a mix with MS additive after 13 h. MS additive extends while MK additive accelerates the hydration process of PC. The most effective plasticizer (P) was chosen according to the study of dynamic viscosity (DV) of PC matrix. It was fixed that surfactant (SU) in amount of 0.03 % (from PC) reduces the density of matrix about 30 % compared with the density of matrix without SU. Increased quantity of MAACW (from 5 to 15 % from PC) causes in increase of compressive strength of PC matrix (after 28 days curing) from 19 to 47 MPa.
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Jamellodin, Zalipah, Mohd Saman Hamidah, Suraya Hani Adnan, Noor Shuhada Mohammad, and Wan Yuslinda Wan Yusof. "Compressive and Flexural Strength of Fine Grained Mortar Containing Rice Husk Ash: A Review." Advanced Materials Research 1051 (October 2014): 757–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.757.
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Fine Grained Mortar (FGM) offers a new innovative technology binder system to strengthen or repair concrete structures. The innovative technique is achieved by using a small maximum grain size of 1 mm for the mortars. Therefore, less than 2 mm of mortar thickness would be fitted between the strengthened layers. FGM also has high binder contents, by adopting different pozzolanic additives and high performance of plasticizers. Recently, the utilisation of supplementary of cementing materials such as Fly Ash (FA) and Rice Husk Ash (RHA) has a become an important in concrete industry. It has demonstrated significant influence in improving the strength of mortar. Most of the previous studies have focused on the FA to be replaced in the FGM. There is still lacking of research of using other pozzolanas in making FGM. This paper presents an overview on the use of FA and RHA as partial replacement of cement in mortar and FGM as well as future research that will be conducted by the authors.
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Chyliński, Filip, Jan Bobrowicz, and Paweł Łukowski. "Undissolved Ilmenite Mud from TiO2 Production—Waste or a Valuable Addition to Portland Cement Composites?" Materials 13, no. 16 (August 12, 2020): 3555. http://dx.doi.org/10.3390/ma13163555.
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This paper presents a method of utilising ilmenite MUD created during the production of titanium dioxide (TiO2) according to the sulphate method as an additive for Portland cement composites. After the production process, undissolved MUD was additionally rinsed with water and filtrated in the factory to make it more useful (R-MUD) for implementation and also to turn back some of the by-products of the production of TiO2. R-MUD is less hazardous waste than MUD. It has a lower concentration of sulphuric acid and some heavy metals. The rinsing process raised the concentration of SiO2, which is a valuable part of R-MUD because of its potential pozzolanic activity. This means that the R-MUD might be a reactive substitute of part of Portland cement in building composites. The article presents the results of research on the pozzolanic activity of R-MUD and other materials with proved pozzolanic activity, such as silica fume, fly ash and natural pozzolana (trass). Tests were performed using thermal analysis techniques. The tests showed that the pozzolanic activity or R-MUD after three days is at the same level as silica fume and after 28 days it is twice as high as the activity of fly ash. Beyond the 180th day of curing, R-MUD had the same level of activity as fly ash. The summary is supplemented by calorimetric tests, which confirm the high reactivity of R-MUD compared to other commonly used concrete additives, already in the initial hydration period. In summary, heat of hydration after 72 h of Portland cement with R-MUD is at the same level as the heat of hydration of Portland cement with silica fume and also pure Portland cement grout. The results confirm that the process of formation of micro-silica contained in R-MUD react with calcium hydroxide to form the C-S-H phase, which is responsible for the microstructure of cement composites.
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Priya, C. Chandana, M. V. Seshagiri Rao, V. Srinivasa Reddy, and S. Shrihari. "High Volume Fly Ash Self Compacting Concrete with Lime and Silica Fume as Additives." E3S Web of Conferences 184 (2020): 01109. http://dx.doi.org/10.1051/e3sconf/202018401109.
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SCC is expensive when compared with normal conventional concrete. Hence, it is desired to produce low cost SCC by replacing cement with higher percentages of fly ash, which is a no cost material and available in abundance. At the same time to achieve higher grade HVFASCC, micro silica which is otherwise condensed silica fume can also be used along with fly ash to enhance the strength properties of HVFASCC. By replacing fly ash in high volumes in the mix, high amount of pozzolanic material becomes available, majorly reactive silica, for which more calcium hydroxide is necessary for further pozzolanic reaction. As we are reducing cement quantity, the amount of calcium hydroxide available is reduced thus demanding external addition of hydrated lime which can be supplied as additive to cater to the need of calcium hydroxide required for reactive silica in fly ash.The present investigation aims to achieve strength for high volume fly ash self-compacting concrete. The replacement of cement with fly ash is made in 45%, 50%, 55%, 60%, 65% and 70% with 20% hydrated lime and 10% silica fume in one trial. In another trial, 30% hydrated lime and 10% silica fume is added with replacement of fly ash to cement varying in same percentages. The design mix is tested for workability and flowability and cubes are casted for compression strength test and tested at 28 day,, 56 day, and 90 day,.
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Yunchao, Tang, Chen Zheng, Feng Wanhui, Nong Yumei, Li Cong, and Chen Jieming. "Combined effects of nano-silica and silica fume on the mechanical behavior of recycled aggregate concrete." Nanotechnology Reviews 10, no. 1 (January 1, 2021): 819–38. http://dx.doi.org/10.1515/ntrev-2021-0058.
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Abstract Recycled aggregate concrete (RAC) is an environmentally friendly material. However, owing to inherent characteristics of the recycled aggregate (RA), it is difficult to promote and apply it in structural engineering. Silica fume (SF) and nano-silica (NS) have different characteristics as additives for RAC. It has been proven that adding SF only enhances the strength of RAC at a later stage, and NS can improve the early strength of RAC owing to its high pozzolanic activity. In this study, to further improve the properties of RAC, two types of additives were combined into RAC, which was named SF-NS-modified RAC (SSRAC). Compression and split tensile tests were conducted to analyze the mechanical properties of SSRAC at different curing ages. The results indicated that the combined addition of NS and SF improved the performance of RAC at early and later curing ages. Scanning electron microscopy and X-ray diffraction analyses were performed to explore the NS and SF mechanism. The results indicated that SF and NS in SSRAC had a good pozzolanic effect and underwent a secondary hydration reaction with calcium hydroxide to increase the production of calcium silicate hydrate, resulting in an increase in the properties of the interface transition zone. Finally, 6% SF and 2 or 3% NS are recommended as supplementary cementitious materials for RAC.
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Pu, Xincheng. "Investigation on pozzolanic effect of mineral additives in cement and concrete by specific strength index." Cement and Concrete Research 29, no. 6 (June 1999): 951–55. http://dx.doi.org/10.1016/s0008-8846(99)00012-5.
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Witkowski, Hubert, and Marcin Koniorczyk. "The influence of pozzolanic additives on the carbonation rate and Life Cycle Inventory of concrete." Construction and Building Materials 254 (September 2020): 119301. http://dx.doi.org/10.1016/j.conbuildmat.2020.119301.
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Toghroli, Ali, Peyman Mehrabi, Mahdi Shariati, Nguyen Thoi Trung, Soheil Jahandari, and Haleh Rasekh. "Evaluating the use of recycled concrete aggregate and pozzolanic additives in fiber-reinforced pervious concrete with industrial and recycled fibers." Construction and Building Materials 252 (August 2020): 118997. http://dx.doi.org/10.1016/j.conbuildmat.2020.118997.
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SHEINICH, L., and М. MYKOLAIETS. "THE RESEARCH AND USE IN CONSTRUCTION OF THE BY-PRODUCTS FROM THE THERMAL POWER PLANT HYDRAULICALLY REMOVED ASH CLASSIFICATION." Наука та будівництво 27, no. 1 (April 8, 2021): 3–7. http://dx.doi.org/10.33644/scienceandconstruction.v27i1.1.
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Today the environment protection is one of the most important issues in the world. The utilization of accumulating industrial waste is an up-todate area of construction research. The paper suggests a method for processing an electricity production waste, namely an ash from the hydraulic removal in the thermal power plant (TPP). The special classification by fractions of ashes from the hydraulic removal allows to receive such products as iron-containing product, fine sand (coarse filler), aluminosilicate hollow microsphere, and product with pozzolanic activity (fine filler).The experts of the State Enterprise "The State Research Institute of Building Constructions" and "Engineering Company "Perspective"" have conducted a series of studies on the obtained products properties and chemical composition, as well as on determining the fractional composition of each product. The density and specific surface area were evaluated, and each product binding properties control was performed. It was found that the aluminosilicate hollow microsphere and the product with pozzolanic activity had binding properties, and hardened mortars based on these materials were insoluble in water. Chemical analysis showed that in each of the products, except for iron-containing one, oxides of silicon and aluminum predominated. The iron containing product had a high content of iron oxides and by its composition was close to magnetite.The carried-out studies show that the products obtained during the hydraulic ash removal at TPP have a wide range of applications, both in the construction industry and in the chemical, mining, and metallurgical industries. In construction, these materials can be widely used as active mineral additives in the grinding of cements, or as additives improving the concrete mixtures and concretes properties. The iron-containing product is applicable in the special ultraheavy concretes manufacture.
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Tee, Kong Fah, and Sayedali Mostofizadeh. "A Mini Review on Properties of Portland Cement Concrete with Geopolymer Materials as Partial or Entire Replacement." Infrastructures 6, no. 2 (February 9, 2021): 26. http://dx.doi.org/10.3390/infrastructures6020026.
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The main aim of this paper is to review recent studies over the past 10 years investigating the influencing factors for improving the mechanical properties of concrete. This focuses on concrete comprising of pozzolanic materials, partially or entirely replacing ordinary Portland cement, in the concrete mixture. Firstly, the effectiveness of main factors such as temperature, water to solid (W/S) ratio, and alkaline solution ratio was briefly discussed. Next, the effects of significant factors such as different superplasticizer and alkaline solutions and combinative materials on the improvement of concrete workability were reviewed and compared. Eventually, other concrete properties such as water absorption and durability were discussed in the last section. After reviewing all types of concrete additives, including mineral or chemical materials, the influence of these admixtures under different laboratory conditions were highlighted to objectively evaluate the benefits of each factor. As a whole, the significant reasons of such experimental tests arising from the usage of these materials, in accordance with the laboratory results obtained from these investigations, are discussed.
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Ngo Хuan Hung, Tang Van Lam, Boris I. Bulgakov, Olga V. Aleksandrova, and Oksana A. Larsen. "Effect of organo-mineral additives on physical-mechanical properties and corrosion resistance of sand-cement mortars." Stroitel stvo nauka i obrazovanie [Construction Science and Education], no. 1 (March 31, 2020): 5. http://dx.doi.org/10.22227/2305-5502.2020.1.5.
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Introduction. TConstruction of large-scale offshore structures in the coastal area of Vietnam requires new compositions of binders for hydraulic concretes, advanced concrete mixing technologies, and concrete transportation to depositing sites. Materials and methods. The binder, containing sulfate resistant Portland cement and finely dispersed mineral additives, including low calcium fly ash of TPP “Vung Ang” and silica fume SF-90 (SF-90), was added to the mortar mix, and the same about SR 5000F superplasticizer and quartz river sand. Powder particle shape and size were measured using laser granulometry; X-ray diffraction was employed to identify the mineral composition of sulfate-resistant cement; the effect of multi-component organo-mineral additives on the phase composition of the cement stone was studied using methods of thermogravimetric analysis; the absolute volume method was employed to analyze the composition of the mortar. Results. The co-authors have analyzed the application of new compositions of multi-component organic-mineral additives whose content, if taken as a percentage of the cement weight, reaches 1.1–1.45 % of SF 5000F superplasticizer, 10–15 % of SF-90, and 30 % of fly ash. New additives accelerate compressive and tensile strength development by 1.4–1.9 times, and that’s been confirmed by bending early-age and 28-day cement-sand mortar specimens, that have sulfate-resistant cement, and their benchmarking against control specimens. It’s been identified that SF-90 and fly ash, if added to the mix, reduce the Portlandite content in the cement stone by 1.27–3.29 % at the age of 28 days in comparison with the benchmark composition due to their high pozzolanic activity Conclusions. Testing results enable co-authors to recommend the application of multi-component organo-mineral additives to increase the resistance of cement-sand compositions to sulfate corrosion due to the denser structure and lower porosity of the cement stone, caused by the lower value of the water/binder ratio and the packing of pore spaces with active mineral fillers. Therefore, new additives are recommended for use in the production of corrosion resistant concretes suitable for construction of offshore hydraulic structures in Vietnam.
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Khalyushev, A., A. Mayilyan, Sergey Stelmakh, and Evgeniy Shcherban. "The Activation Technology for the Surface Modification High Voltage Electric Field Dispersed Mineral Additives for Concrete." Materials Science Forum 1011 (September 2020): 23–30. http://dx.doi.org/10.4028/www.scientific.net/msf.1011.23.
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The aim of the research was to study the activation technology of the materials for concrete by their surface modification in a high-voltage electric field. It is noted that the mineral additives modified in a high-voltage electric field are characterized by a higher activity of the calcium hydroxide absorption. It was established that, despite the presence of a large number of crystalline compounds in metakaolin, its pozzolanic activity in the absorption of calcium hydroxide from a saturated solution is quite high. The same value of the hydration activity coefficient is also determined for the ground slag. The authors found that a characteristic feature of the dispersed mineral additives, surface-modified in a high-voltage electric field in comparison with control samples, are the lower values of bulk density and repose angle. This is due to a change in the forces balance that occurs during the mutual contact of particles. The influence of the mineral additives’ surface modification in a high-voltage electric field on interparticle interactions in the “solid – liquid” system is evaluated. It is established that in the absence of a repulsion barrier, the particles form the aggregates that increase their sedimentation rate. During unipolar or bipolar charging of particles in an electric field, the sedimentation rate slows down or accelerates accordingly. These effects are used to modify the cement surface.
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Ahad, Muhammad, Muhammad Ashraf, Rabinder Kumar, and Mukhtar Ullah. "Thermal, Physico-Chemical, and Mechanical Behaviour of Mass Concrete with Hybrid Blends of Bentonite and Fly Ash." Materials 12, no. 1 (December 25, 2018): 60. http://dx.doi.org/10.3390/ma12010060.
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Mass concrete has been commonly known for its thermal stresses which arise due to the entrapment of hydration temperature susceptible to thermal cracking. The utilization of mineral additives is a promising and widely adopted technique to mitigate such effects. This paper presents the thermal, physico-chemical, mechanical, and morphological behaviour of mass concrete with blends of bentonite (BT) and fly ash (FA). Apart from the rise in temperature due to hydration, the compressive strength, ultrasonic pulse velocity (UPV), differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) analysis, and microstructure were studied. The results of this study revealed that the substitution of BT and FA significantly improved the compressive strength and development rate of UPV in the mass concrete samples. The FA concrete (FC) specimen presented the lowest temperature during the peak hours compared to all other concrete mixes studied in this research. Bentonite concrete (BC) was also found to be more effective in controlling the escalation of temperature in mass concrete. Scan electron microscopy (SEM) micrographs presented partially reacted FA particles in a mix. XRD and DTA analysis indicated that the concentration of calcium hydroxide (CH) declined by substituting FA and BT, specifically in ternary blends, which was due to the dilution effect and consumption of CH through the pozzolanic reaction.
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Potapova, Ekaterina, Tatiana Guseva, Kirill Shchelchkov, and Hans Bertram Fischer. "Mortar for 3D Printing Based on Gypsum Binders." Materials Science Forum 1037 (July 6, 2021): 26–31. http://dx.doi.org/10.4028/www.scientific.net/msf.1037.26.
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3D construction printer - is an innovative construction approach with which building elements can be constructed without the use of formwork and you to get products of various complex shapes with minimal time and material costs. Binder 3D printing technology results in a cheap and high-speed construction method that allows greater freedom in both architectural and structural design of concrete. The principle of operation of a 3D printer is based on the principle of gradual (layer-by-layer) creation of a solid model, which is, as it were, "grown" from a certain binding material. The working mixture must have thixotropic and adhesive properties, it must be workable by the printer and at the same time not spread under the influence of subsequent layers. Therefore, it is important to select the composition of the composition of the working mixture. This paper presents the results of a study on the development of the composition of a working mixture based on a gypsum-cement-pozzolanic binder. The developed composition of the gypsum-cement-pozzolanic binder with a complex of modifying additives is characterized by low spreadability, high viscosity and is easy to lay.
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Roshani, Mohammad Mehdi, Seyed Hamidreza Kargar, Visar Farhangi, and Moses Karakouzian. "Predicting the Effect of Fly Ash on Concrete’s Mechanical Properties by ANN." Sustainability 13, no. 3 (January 31, 2021): 1469. http://dx.doi.org/10.3390/su13031469.
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Fly ash, as a supplemental pozzolanic material, reduces concrete’s adverse environmental footprint by decreasing the emission of carbon dioxide (CO2) during the cement manufacturing process. Fly ash, which is a waste material, can enhance both the mechanical characteristics and durability of concrete, and has the capability to play an important role in sustainable design. Considering the widespread interest in applying Fly ash, and despite research studies, the level of replacement is still unclear. In this paper, a novel method using artificial neural networks (ANN) is presented to predict concrete’s mechanical characteristics by adding Fly ash. In this regard, a host of available experimental data, such as the properties of Fly ash, along with concrete additives, was fed into an ANN model. Concrete samples’ tensile and compressive strengths, in addition to their modulus of elasticity, were defined as outputs. It was observed that the predicted outcomes agreed well with the experimental results. To further enhance the research outcomes, simple but practical equations are presented to assess the effect of using Fly ash on concrete’s mechanical characteristics.
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Serdyuk, V., and D. Rudchenko. "ENSURING CARBONIZATION RESISTANCE OF AUTOCLAVE HARDENED CONCRETE CONCRETE." Modern technology, materials and design in construction 29, no. 2 (2021): 13–23. http://dx.doi.org/10.31649/2311-1429-2020-2-13-23.
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The analysis of tendencies of production of autoclaved aerated concrete is resulted. Given the price factor, energy and environmental status of the industry of construction wall and insulation materials, autoclaved aerated concrete has significant advantages over traditional wall materials and prospects for production. Studies of the durability of autoclaved aerated concrete are due to the increase in its production and use in the construction industry in recent years due to rising energy costs and the need to reduce greenhouse gas emissions. At the same time, the density of aerated concrete decreased almost 2 times. The transition to the production of low-density autoclaved aerated concrete D300, D150 on the one hand improves the thermophysical characteristics of aerated concrete, reduces material consumption, on the other - increases the specific cost of binder (cement) per unit mass of aerated concrete and increases its vapor and air permeability. High vapor permeability and adsorption properties of water vapor and gases from the air pose a potential threat due to possible carbonization of aerated concrete, "loosening" of the macrostructure of the material during wetting and drying, irreversible deformation during freezing and thawing of wet aerated concrete, which occur almost simultaneously. Under the conditions of soaking, capillary suction of water and adsorption of water vapor, the processes of carbonization of autoclaved aerated concrete are accelerated. The material can adsorb moisture and carbon dioxide from the air. The formation of carbon dioxide in aerated concrete reduces the alkaline environment, neutralizes free lime and the destruction of calcium hydrosilicates and corrosion of reinforced products. Carbonization can have both positive and negative effects on cement concrete. To ensure the carbonization stability of autoclaved aerated concrete should be achieved by implementing a number of technological solutions that increase the carbonization resistance of autoclaved aerated concrete while reducing the clinker component in the mineral binder. The results of the use of natural mineral additives of hydraulic and pozzolanic action in the composition of autoclaved aerated concrete are given.
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Pichór, Waldemar, Magdalena Barna, Ewa Kapeluszna, Artur Łagosz, and Łukasz Kotwica. "The Influence of Waste Expanded Perlite on Chemical Durability of Mortars." Solid State Phenomena 227 (January 2015): 194–98. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.194.
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Degradation of building materials is an important phenomena influencing its design and utilization. Corrosion of concrete, due to common use of this material is especially important. Chemical corrosion of cementitous materials may be mitigated using various methods. Among them introduction of properly chosen active supplementary cementitous materials to the mix is one of most commonly used. One of possible additives possessing pozzolanic properties is ground waste expanded perlite. No data on the influence of such perlite on chemical durability of cementitous materials can be found in literature. Present paper presents results of investigation on the influence of ground waste expanded perlite on chemical durability of cement mortars. Results obtained showed that there is an improvement of durability of mortars modified with ground waste expanded perlite in sodium sulfate enviroment.
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Vázquez-Rodríguez, Francisco Javier, Nora Elizondo-Villareal, Luz Hypatia Verástegui, Ana Maria Arato Tovar, Jesus Fernando López-Perales, José Eulalio Contreras de León, Cristian Gómez-Rodríguez, et al. "Effect of Mineral Aggregates and Chemical Admixtures as Internal Curing Agents on the Mechanical Properties and Durability of High-Performance Concrete." Materials 13, no. 9 (May 1, 2020): 2090. http://dx.doi.org/10.3390/ma13092090.
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In the present work, the effect of mineral aggregates (pumice stone and expanded clay aggregates) and chemical admixtures (superplasticizers and shrinkage reducing additives) as an alternative internal curing technique was investigated, to improve the properties of high-performance concrete. In the fresh and hardened state, concretes with partial replacements of Portland cement (CPC30R and OPC40C) by pulverized fly ash in combination with the addition of mineral aggregates and chemical admixtures were studied. The physical, mechanical, and durability properties in terms of slump, density, porosity, compressive strength, and permeability to chloride ions were respectively determined. The microstructural analysis was carried out by scanning electronic microscopy. The results highlight the effect of the addition of expanded clay aggregate on the internal curing of the concrete, which allowed developing the maximum compressive strength at 28 days (61 MPa). Meanwhile, the replacement of fine aggregate by 20% of pumice stone allowed developing the maximum compressive strength (52 MPa) in an OPC-based concrete at 180 days. The effectiveness of internal curing to develop higher strength is attributed to control in the porosity and a high water release at a later age. Finally, the lowest permeability value at 90 days (945 C) was found by the substitutions of fine aggregate by 20% of pumice stone saturated with shrinkage reducing admixture into pores and OPC40C by 15% of pulverized fly ash. It might be due to impeded diffusion of chloride ions into cement paste in the vicinity of pulverized fly ash, where the pozzolanic reaction has occurred. The proposed internal curing technology can be considered a real alternative to achieve the expected performance of a high-performance concrete since a concrete with a compressive strength range from 45 to 67 MPa, density range from 2130 to 2310 kg/m3, and exceptional durability (< 2000 C) was effectively developed.
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Belaribi, N. Belas, M. Semcha, and L. Laoufi. "Influence de la pouzzolane de Beni-saf sur les caractéristiques mécaniques des bétons." Canadian Journal of Civil Engineering 30, no. 3 (June 1, 2003): 580–84. http://dx.doi.org/10.1139/l03-029.
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Builders in our country are not familiar with the practice of using mineral additives, as cement substitutes, in cast-in-place and in ready-mix concretes. It thus seemed important to study and evaluate the impact of these additives, as cement substitutes, on the properties of set concrete. The mineral additive used is natural pozzolan found in large quantities in Western Algeria (Béni-Saf); however, it must be beneficiated. To do so, we designed three pozzolan-based concretes (20, 25, and 30%). We measured compressive strengths at various times and produced a reference control concrete for comparison purposes.Key words: pozzolan, dosage, concrete, composition, substitution, compressive strength.[Journal translation]
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Olofinnade, Oluwarotimi M., Anthony N. Ede, Julius M. Ndambuki, and Gideon O. Bamigboye. "Structural Properties of Concrete Containing Ground Waste Clay Brick Powder as Partial Substitute for Cement." Materials Science Forum 866 (August 2016): 63–67. http://dx.doi.org/10.4028/www.scientific.net/msf.866.63.
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With the increasing concerns on the impact of cement production on the environment and the need to protect the environment, the use of mineral additives as cementitious material to partially substitute cement is being considered as an effective option. One of such material is fired clay brick which can be sourced as generated waste from clay brick industry. This has an added advantage of reducing industrial waste and preserving the natural resources. The experimental objective of this study is to examine the possibility of utilizing clay brick waste as partial replacement for Portland cement in concrete. The clay brick was finely ground into powder size, and after grinding, the morphological characterization of the powder materials was carried out using scanning electron microscopy (SEM). Moreover, the chemical composition of the brick material was determined using X-ray fluorescence (XRF). Laboratory tests were carried out to determine the workability, split tensile and compressive strength properties of the concrete with 0%, 10%, 20%, 30% and 40% partial replacement of cement with ground clay brick (CB). From the test results, the chemical composition of the brick powder meets the standard requirements for pozzolanic material, with the SEM revealing an amorphous solid mass. The workability of the concrete reduces with increase in brick powder content. A significant improvement of the split tensile and compressive strength of the concrete was achieved at 10% cement replacement, after which a decrease in strength with increasing ground clay brick content was recorded. The use of ground clay brick of not more than 15% was recommended for concrete production.
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Rikmann, Ergo, Ivar Zekker, Tõnis Teppand, Vello Pallav, Merrit Shanskiy, Uno Mäeorg, Toomas Tenno, Juris Burlakovs, and Jüri Liiv. "Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive." Water 13, no. 7 (March 30, 2021): 942. http://dx.doi.org/10.3390/w13070942.
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Construction of road embankments in peatlands commonly involves replacement of the peat with a fill-up soil of an adequate load-bearing capacity. This usually requires a lowering of the water level, turning a peatland from a carbon sink to a source of greenhouse gases. Thus, alternatives are sought that are less costly in both economic and ecological terms. Mass-stabilization technology can provide a cheap substitute for Portland cement. Calcareous ashes (waste materials), supplemented with pozzolanic and alkali additives to facilitate and accelerate the setting and hardening processes, are attractive alternatives to soil excavation or replacement techniques. Silica fume and waterglass were used as pozzolanic agents and KOH as a soil-alkalizing agent. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses and stress–strain tests were performed for the hardened samples. Crystallization of alkali feldspars was observed in all test samples. Comparable hardening of peat soil was achieved for both ashes. It was shown that the ashes of Estonian kukersite (oil shale) from both pulverized firing and a circulating fluidized bed incineration process (produced in energy sector as quantitatively major solid waste in Estonia) can be used as binding agents for peat stabilization, even without the addition of Portland cement. Hardened peat soil samples behaved as a ductile material, and the cellulose fibers naturally present in peat gave the peat–ash composite plasticity, acting mechanically in the same way as the steel or glass fiber in ordinary reinforced concrete. The effect of peat fiber reinforcement was higher in cases of higher load and displacement of the composite, making the material usable in ecological constructions.
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Voronov, V. V., and E. S. Glagolev. "POLYMINERAL COMPOSITE BINDERS FOR FOAM CONCRETE: FEATURES OF HYDRATION AND HARDENING." Russian Automobile and Highway Industry Journal 17, no. 1 (March 5, 2020): 122–35. http://dx.doi.org/10.26518/2071-7296-2020-17-1-122-135.
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Introduction. The paper devotes to the features of hydration and hardening of polymineral composite binders. The authors carry out the complex research of the phase composition, hydration and structure formation processes of hardened composite binders with active mineral additives by X-ray phase analysis, differential scanning calorimetry and electron microscopy. The study using a Tescan MIRA 3 scanning electron microscope reveals differences in the microstructure of hardened binders and the authors confirm the results by microprobe studies. The authors study the hydration of the composite binder prepared on the basis of Portland cement and mineral components. Moreover, the paper demonstrates the dynamics of the system’s heat dissipation from the moment of mixing with water and hardening up to 24 hours and up to 72 hours by the expressed bond of dQ / dt = f (t) using a differential calorimeter.Methods and materials. The authors carried out experimental studies at Belgorod State Technological University named after V.G. Shukhov, at the Department of Building Materials, Products and Structures, at the High Technology Center and “BelGTASM-Certificate” Test Center. Therefore, the authors used the existing basic research methods, including modern physicochemical methods of analysis: X-ray phase, scanning electron microscopy, etc. The paper determined the main characteristics of raw materials, composite binders and foam concrete using standard methods and regulatory requirements.Results. The authors obtained the results that testified the peculiarities of hydration and hardening processes of polymineral composite binders on the basis of Portland cement and mineral additives: opoka marl and fly ash.Conclusion. The research establishes the hydration and hardening processes of polymineral composite binders. As a result, the authors demonstrate that the opoka marl introduced into the cement leads to the increased hydration in the induction and accelerated periods and also increases the hydration completeness of the main clinker minerals due to the manifestation of the pozzolanic reaction and the active binding of blocking Portlandite, as well as to the higher concentration of accumulated neoplasms, second generation calcium hydrosilicates.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.
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Vouk, D., D. Nakic, N. Štirmer, and A. Baricevic. "Effect of lime addition during sewage sludge treatment on characteristics of resulting SSA when it is used in cementitious materials." Water Science and Technology 75, no. 4 (December 8, 2016): 856–63. http://dx.doi.org/10.2166/wst.2016.554.
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Final disposal of sewage sludge is important not only in terms of satisfying the regulations, but the aspect of choosing the optimal wastewater treatment technology, including the sludge treatment. In most EU countries, significant amounts of stabilized and dewatered sludge are incinerated, and sewage sludge ash (SSA) is generated as a by product. At the same time, lime is one of the commonly used additives in the sewage sludge treatment primarily to stabilize the sludge. In doing so, the question arose how desirable is such addition of lime if the sludge is subsequently incinerated, and the generated ash is further used in the production of cementitious materials. A series of mortars were prepared where 10–20% of the cement fraction was replaced by SSA. Since all three types of analyzed SSA (without lime, with lime added during sludge stabilization and with extra lime added during sludge incineration) yielded nearly same results, it can be concluded that if sludge incineration is accepted solution, lime addition during sludge treatment is unnecessary even from the standpoint of preserving the pozzolanic properties of the resulting SSA. Results of the research carried out on cement mortars point to the great possibilities of using SSA in concrete industry.
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Małolepszy, Jan, and Ewelina Grabowska. "The influence of zeolites on hydration process of mineral binders." Budownictwo i Architektura 12, no. 3 (September 11, 2013): 185–92. http://dx.doi.org/10.35784/bud-arch.2031.
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This paper presents the results of physical and chemical properties of zeolite - clinoptilolite (Z), on the basis of which its usefulness in different terms and applications was assessed. Same pozzolan was also investigated and analyzed in term of the changes that it causes in the system pozzolan - cement – lime - sand - water with different content of ingredients. In order to identify the hydration products in the natural conditions, infusion (80ºC) and autoclaving (180°C) XRD, DTA / TG and SEM was used. The results indicate that clinoptilolite is characterized by moderate pozzolanic activity and can be successfully used as a pozzolanic additive for cement, and a binder in the production of aerated concrete.
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Čáchová, Monika, Lenka Scheinherrová, Libor Kobera, Martina Urbanová, Jiří Brus, and Martin Keppert. "Monitoring of Kinetics of Pozzolanic Reaction." Key Engineering Materials 722 (December 2016): 126–31. http://dx.doi.org/10.4028/www.scientific.net/kem.722.126.
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The pozzolanic additions are widely used as concrete component for numerous technical, economic and environmental reasons. Obviously the hydration process in a pozzolana containing system differs from hydration of Ordinary Portland Cement (OPC) what is indicated macroscopically by slower increase of strength and lower hydration heat. This paper aims to study pozzolanic reaction from perspective of chemical kinetics. From this point of view pozzolanic reaction and carbonation are two parallel reactions which are competing for portlandite (Ca (OH)2). The rate of each of these two reactions is characterized by rate constant and order of reaction. The system under study was 1:1 mixture lime – ceramic powder. The course of reaction was primarily studied by thermogravimetry which results were further subjected to kinetic analysis. MAS NMR spectroscopy was used for study of structural changes taking place in material in the course of pozzolanic reaction.
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Ermilova, Elizaveta, and Zagira Kamalova. "The influence of calcined mixture cooling method on hydration products composition of blended cement stone." E3S Web of Conferences 274 (2021): 04011. http://dx.doi.org/10.1051/e3sconf/202127404011.
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Complex additives based on combinations of calcined clays, including kaolinite with limestone, due to the synergetic effect play a major role in the creation of blended cements. Usually carbonate rocks contain clay impurities with adverse effects on the properties of the resultant cements and concretes. At the same time calcium carbonate contained in marl clays during calcination allows getting high-quality pozzolanic material. The effective complex additive based on the calcined mixture of clay and limestone was created. The aim of the study is to determine the effect of fast and slow cooling methods of the artificial mixture after calcination on the hydration products composition of blended cement stone with complex additives of calcined mixtures of clays and carbonates. Obtained results allow determining the conditions for obtaining effective complex additives based on calcined mixtures of ubiquitous clays and carbonate rocks for their application in blended Portland cement, and thus to expand the range of the latter. It is found that the preferred method is the fast cooling of the resulting mixture, which contributes to obtaining a complex additive with higher pozzolanic properties, compared with the additive obtained by the slow cooling method.
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Menéndez, Esperanza, Miguel Ángel Sanjuán, Ricardo García-Roves, Cristina Argiz, and Hairon Recino. "Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates." Applied Sciences 10, no. 24 (December 17, 2020): 9042. http://dx.doi.org/10.3390/app10249042.
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The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash.
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Klyuev, Sergey V., A. V. Klyuev, and E. S. Shorstova. "The Micro Silicon Additive Effects on the Fine-Grassed Concrete Properties for 3-D Additive Technologies." Materials Science Forum 974 (December 2019): 131–35. http://dx.doi.org/10.4028/www.scientific.net/msf.974.131.
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The effectiveness of silica fume for the fine-grained concrete used for 3-D technologies is proved in the give scientific paper. The advantages of silica fume using for concretes are presented. The mathematical modeling is used for the fine-grained concrete high-quality compositions’ development. The effectiveness of silica fume has been proved by the studies. The increase in the strength characteristics of concrete with the addition of silica fume is explained by the active pozzolan reaction, which starts when the concrete mix is mixed with water.
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Si Kiong, Lau, and Norsuzailina Mohamed Sutan. "Initial Surface Absorption of Pozzolan and Polymer Modified Mortar." Journal of Civil Engineering, Science and Technology 4, no. 1 (April 1, 2013): 8–12. http://dx.doi.org/10.33736/jcest.103.2013.
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This study involves the investigation of water absoption of mortar modified with combinations of polymer and pozzolan by using initial surface water absorption test (ISAT). Since surface of mortar or concrete serves as medium that will be most easily penetrated by moisture that can cause corrosion of reinforcement bars that leads to durability problem, it is imperative to make it durable.Polymer additive and pozzolanic cement replacement used in this study was Styrene Butadiene Rubber (SBR) and Fly Ash (FA) respectively. Mixes were prepared with two water to cement ratios (w/c) of 0.3 and 0.4 with different combinations of 5%, 7% & 10% SBR additive and 10%, 20% and 30% FA cement replacement. Results showed that modified mortar with combination of higher percentages of polymer additive and lower percentages of pozzolonic cement replacement have the lowest initial surface absorption rate compare to unmodified mortar. It can be concluded based on this study that high percentage of polymer addition and low percentage of pozzolanic cement replacement in mortar can enhance its resistance to water absorption.
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Saad, Siti Asmahani, Nasir Shafiq, Maisarah Ali, and Mariana Mohamed Osman. "Analysis by Means of Surface Response to Chemical Composition and Pozzolanic Reactivity of Ultrafine Treated Rice Husk Ash (UFTRHA) as Cementing Additive Material." International Journal of Engineering & Technology 7, no. 4.35 (November 30, 2018): 342. http://dx.doi.org/10.14419/ijet.v7i4.35.22759.
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Pozzolanic reactive material is considered as one of the most essential characteristic of cementing additive material in concrete technology application. Normally, the reactive material contains abundant silica that enhances concrete strength activity. Undeniably, it is proven that rice husk ash (RHA) possesses large quantity of silica that induces the pozzolanic reaction in concrete. Nevertheless, usage of conventional RHA is still widely accepted in concrete industry nowadays. One of the setback of conventional RHA incorporation is simply because of its properties inconsistency. Therefore, enhancement on the RHA properties by introduction of a specific pretreatment prior to incineration process is expected to provide an alternative way in order to produce highly reactive cementing additive material from locally available agricultural by-product, the rice husk. In this paper, a total number of 30 experimental set points was conducted. Statistical analysis was conducted for four independent variables and two responses using Response Surface Method (RSM). The analysis was completed using a commercial software set (Design-Expert) for experimental design and analysis. The independent variables were HCl concentration, soaking time, burning temperature and soaking temperature. Meanwhile, the responses investigated in this study were including cumulative pozzolan percentage and electric conductivity decrement from 0 to 2 minutes. As for the statistical analysis of the data for response 1, the cumulative pozzolan percentage calculated from the model was in-line with the experimental data, with R-squared value of 0.9565. Hence, the result validates the precision of the model. On the other hand, the R-squared value for response 2 which is the EC decrement from 0 - 2 Minutes, it shows that the model was in agreement to the experimental values at 0.9342. Thus, it is again justifies the model accuracy.
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Wang, Hai Long, Qi Wen Peng, and Xiao Yan Sun. "Mechanical Behaviors and Chloride Permeability of Rice Husk Ash Concrete." Applied Mechanics and Materials 238 (November 2012): 75–78. http://dx.doi.org/10.4028/www.scientific.net/amm.238.75.
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Rice husk ash (RHA) was used as a mineral additive in concrete and replaced the ordinary cement by 0-30% in this study. The fresh concrete properties, compressive strength, split tensile strength, and elastic modulus as well as the chloride permeability of concretes mixed with different RHA contents was tested. The experimental results reveal that the fluidity, the mechanical behaviors and the chloride ion resistance of rice husk ash concrete decrease with the increasing replacement rate of RHA. The particle size of RHA limits its pozzolanic activity, which indicates that the controlled burning temperature and the fineness of RHA have significant impact on the properties of rice husk ash concrete.
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Bertolini, Luca, Maddalena Carsana, Massimiliano Frassoni, and Massimo Gelli. "Pozzolanic additions for durability of concrete structures." Proceedings of the Institution of Civil Engineers - Construction Materials 164, no. 6 (December 2011): 283–91. http://dx.doi.org/10.1680/coma.1000041.
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Arroudj, Karima, Saida Dorbani, Mohamed Nadjib Oudjit, and Arezki Tagnit-Hamou. "Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials." International Journal of Engineering Research in Africa 34 (January 2018): 48–58. http://dx.doi.org/10.4028/www.scientific.net/jera.34.48.
Full textAbstract:
Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.
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Chyliński, Filip, Krzysztof Kuczyński, and Paweł Łukowski. "Application of Ilmenite Mud Waste as an Addition to Concrete." Materials 13, no. 4 (February 14, 2020): 866. http://dx.doi.org/10.3390/ma13040866.
Full textAbstract:
Storing waste in concrete instead of landfills is environmentally friendly and also might make concrete more sustainable if some part is replaced with cement. This article presents a new way of valorising hazardous waste, namely ilmenite MUD from the production of titanium dioxide, which is used as a reactive additive to concrete. In fact, there are currently no articles presenting the way of valorisation that is presented in this paper. The global annual production of MUD is estimated to be about 0.7 million tons. Valorisation is possible due to the additional rinsing and filtering in the factory, which also confirms the novelty of this article. In this operation, the most hazardous compounds are returned back to the factory process. Rinsed mud (RMUD) is a pozzolanic reactive material with the potential use as a substitute of a part of Portland cement in concrete and other cementitious binders, like siliceous fly ash (FA). The level of RMUD pozzolanic activity is as high as the activity of siliceous fly ash. Comparative tests of concretes containing RMUD and fly ash, such as compressive strength, bending strength and shrinkage, were conducted. The concrete containing RMUD reached almost 90% of compressive and 108% of bending strength after 28 days of curing, compared to FA concrete. The results presented in this article are very promising and might point to a new way of valorising ilmenite mud waste.