Journal articles: 'Pozzolanic Reactions'

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Merida, Ahcene, and Fattoum Kharchi. "Corrosion of the Pozzolan Concrete in Sulfates." Advanced Materials Research 911 (March 2014): 494–98. http://dx.doi.org/10.4028/www.scientific.net/amr.911.494.

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Sulfate attack and its effects are important from both scientific and industrial viewpoints. Itis perceived that cements containing pozzolan have better performance in sulfate solutions,since the pozzolanic reactions reduce the quantity of calcium hydroxide and increasecalcium silicate hydrate. This paper investigates the physical and mechanical properties ofconcretes made by blended cement containing Algerian natural pozzolan of volcanic origin, and Portland cement. in order to better determine the pozzolanic effect of the pozzolan addition in the concrete, the analysis of the experimental results of the effect of the partial replacement of the cement by the naturalpozzolana showed that it contributes positively to the improvement of its mechanical characteristics, its durability with respect to the permeability to the chlorine ions, the ultrasonic pulse velocity as well as the sulphate resistance. The present study confirms the pozzolanic reactivity of the natural pozzolans used.

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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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Juimo Tchamdjou, Willy Hermann, Sophie Grigoletto, Frédéric Michel, Luc Courard, Toufik Cherradi, and Moulay Larbi Abidi. "Effects of Various Amounts of Natural Pozzolans from Volcanic Scoria on Performance of Portland Cement Mortars." International Journal of Engineering Research in Africa 32 (September 2017): 36–52. http://dx.doi.org/10.4028/www.scientific.net/jera.32.36.

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The aim of this paper is to assess the possibility of using natural pozzolans (NPs) from Cameroonian volcanic scoria as supplementary cementitious materials (SCMs) in the production of Portland cement mortars. Four natural pozzolans (Black Natural Pozzolan: BNP, Dark-Red Natural Pozzolan: DRNP, Red Natural Pozzolan: RNP and Yellow Natural Pozzolan: YNP) with 3600, 4500, 4700 and 5200 cm2/g Blaine fineness respectively were produced from different colors (Black, Dark red, Red and Yellow) volcanic scoria in a laboratory mill. Natural pozzolans were characterized with regard to particle size distribution, particle shape, electrical conductivity, X-ray fluorescence (XRF) and X-ray diffraction (XRD). The calcium hydroxide consumption by NPs was assessed firstly by electrical conductivity measurements of calcium hydroxide/NPs suspensions with calcium hydroxide excess. Evidence of pozzolanic reactivity of NPs is revealed in hydrated lime pastes, and low reactivity was observed in aqueous suspensions. The effects of 15, 25, and 35 wt.% of NPs as cement substitution on the properties of Portland cement mortars were investigated. Different properties were studied such as setting time, consistency, mechanical strength, pozzolanic activity, absorption by capillarity and resistance to carbonation. The reactivity of NPs was also assessed by means of the mechanical strength development of mortars. The results obtained show that pozzolanic and hydraulic reactions take place in OPC systems. The correlation between mechanical strengths and physical properties of NPs has been established. The study concludes that using DRNP and RNP at 15 wt. % cement replacement can ameliorate globally the performance of mortar. Using all NPs at 35 wt. % has negative effect on the fundamental properties of cementitious mortars.

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Cizer, Özlem, Koen Van Balen, and Dionys Van Gemert. "Competition between Hydration and Carbonation in Hydraulic Lime and Lime-Pozzolana Mortars." Advanced Materials Research 133-134 (October 2010): 241–46. http://dx.doi.org/10.4028/www.scientific.net/amr.133-134.241.

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A combined reaction of hydration and carbonation takes place in hydraulic lime and lime-pozzolana mortars. Hydration reactions are the first reaction and carbonation of lime is the complementary reaction in the strength gain. Competition between these two reactions can occur in lime-pozzolana mortars if the pozzolanic material has low reactivity with lime, leading to the consumption of lime by carbonation reaction. The degree and the order of these reactions are strongly influenced by the moisture content. Hydration reactions are enhanced under moist conditions while carbonation is delayed. Curing under dry conditions does not sufficiently increase their strength because the hydration reactions are slowed down or even terminated by the full carbonation of lime in lime-pozzolana mortars. The consequence of this on the mechanical properties of the mortars is remarkable while the same impact is not observed in their porosity. Such mortars require moist conditions to ensure sufficient strength development.

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Ťažký, Martin, and Rudolf Hela. "Synergistic Effect of High Temperature Fly Ash with Fluidized Bed Combustion Fly Ash in Cement Composites." Key Engineering Materials 722 (December 2016): 113–18. http://dx.doi.org/10.4028/www.scientific.net/kem.722.113.

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Using high temperature fly ash for his pozzolan properties to cement composite production is known a few years ago. New ways combustion of fossil fuels also creates a new type of fly ash, named fluidized bed combustion fly ash. However, this fly ash has same pozzolan properties as has high temperature fly ash, this type is not using for production of cement composites. Fluidized bed combustion fly ash has highly variable chemical composition but usually it has a higher amount of free CaO together with sulphates. This higher amounts of free CaO after mixing of fluidized bed combustion fly ash with water to some extent becomes an activator for the beginning of the pozzolanic reaction, during which is consumed the extinguished CaO. If there is also present high temperature fly ash in cement composite, it could be accelerated his pozzolanic reaction in the same manner using a fluidized bed combustion fly ash. In this experiment was tested a synergy effect in the use of fluidized bed combustion fly ash with high temperature fly ash as an additive. The experiment was carried out on cement pastes that have been studied in particular the progress of hydration processes, pointing to a possible acceleration of pozzolanic reactions of both types of fly ash.

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Suttikul, Supaluk, Kanyarat Ano, and Kedsarin Pimraksa. "Effect of Calcium Hydroxide Content on Pozzolanic Reaction of Calcined Clays: Their Mechanical Properties and Microstructures." Materials Science Forum 1034 (June 15, 2021): 161–68. http://dx.doi.org/10.4028/www.scientific.net/msf.1034.161.

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The research aimed to investigate the effect of calcium hydroxide content on pozzolanic reaction of calcined clays. Pozzolanic reaction of calcined clay was determined in terms of its mechanical properties, phase development and microstructures. Three clay minerals (two kaolinitic clays and kaolinite-montmorillonite clay) were chosen to produce pozzolanic materials via calcination at temperature of 700 °C to allow dehydroxylation of clay minerals. Ratios of calcium hydroxide to calcined clays were varied from 0.1 to 0.5. Mixing water contents or liquid to solid ratios (0.62, 0.75 and 0.80) and curing times (7 and 28 days) were also studied. It was found that calcium aluminosilicate hydrate (stratlingite) could be formed after pozzolanic reactions of all clay minerals. The development of stratlingite agreed with the strength development showing the highest compressive strength at 26 MPa (28 days) when kaolinite-montmorillonite clay was used as pozzolanic material and the ratio of calcium hydroxide to calcined clay was 0.5.

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Wang, Xiao-Yong. "Analysis of Hydration and Optimal Strength Combinations of Cement-Limestone-Metakaolin Ternary Composite." Advances in Materials Science and Engineering 2019 (May 2, 2019): 1–13. http://dx.doi.org/10.1155/2019/8361810.

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Metakaolin (MK) is an aluminosilicate pozzolan material and can contribute to property development of concrete due to the pozzolanic reaction. Limestone (LS) powder presents the dilution effect, nucleation effect, and chemical effect on hydration of cement. When metakaolin and limestone are used together, due to the additional chemical reaction between the aluminum phase in MK and limestone, the synergetic benefit can be achieved. This study presents a hydration model for cement-limestone-metakaolin ternary blends. Individual reactions of cement, metakaolin, and limestone are simulated separately, and the interactions among cement hydration, limestone reaction, and metakaolin reaction are considered through the contents of calcium hydroxide and capillary water. The hydration model considers the pozzolanic reaction of metakaolin, chemical and physics effects of limestone, and synergetic effect between metakaolin and limestone. Furthermore, the gel-space ratio of hydrating concrete is calculated using reaction degrees of binders and concrete mixtures. The strength development of ternary blends is evaluated using the gel-space ratio. Based on parameter analysis, the synergetic effect on strength development is shown and the optimal combinations of cement-limestone-metakaolin ternary blends are determined.

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Lee, Nankyoung, Yeonung Jeong, Hyunuk Kang, and Juhyuk Moon. "Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification." Materials 13, no. 13 (July 1, 2020): 2950. http://dx.doi.org/10.3390/ma13132950.

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This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of silica fume in ultra-high performance concrete. By actively consuming a limited amount of water and outer-formed portlandite on the unreacted cement grains, it was confirmed that high-temperature curing greatly enhances the pozzolanic reaction when compared with cement hydration under the same environment. The rate of strength development from the dual reactions of cement hydration and pozzolanic reaction was increased. After the high-temperature curing, further strength development was negligible because of the limited space availability and preconsumption of water under a low water-to-cement environment. Since the pozzolanic reaction does not directly require the anhydrous cement, the reaction can be more easily accelerated under restrained conditions because it does not heavily rely on the diffusion of the limited amount of water. Therefore, it significantly increases the mean chain length of the C–S–H, the size of C–S–H globules with a higher surface fractal dimension. This finding will be helpful in understanding the complicated hydration mechanism of high-strength concrete or ultra-high performance concrete, which has a very low water-to-cement ratio.

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Ouypornprasert, Winai, Narong Traitruengtatsana, and Kong Kamollertvara. "Optimum Partial Replacement of Cement by Nanosilica, Microsilica and Rice Husk Ash for Mass Production of Concrete." Key Engineering Materials 751 (August 2017): 544–49. http://dx.doi.org/10.4028/www.scientific.net/kem.751.544.

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The objective of this technical paper was to propose the use of optimum partial replacement of cement by pozzolan of high-silica content i.e. nanosilica, silica fume and rice husk ash. Firstly cement hydration, pozzolanic reactions of pozzolan and stoichiometry were reviewed. Then the optimum fractional replacement of cement by pozzolan based on the complete consumption of calcium hydroxide and the strength activity index (SAI) were formulated and proposed. After that the results of a series of tests of cement mortars were shown to verify the proposed concepts. The applicability for the mass concrete production was demonstrated by prediction of mean values of nonnormal distributions from the corresponding specifications.

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Gadouri, Hamid, Khelifa Harichane, and Mohamed Ghrici. "Assessment of sulphates effect on pH and pozzolanic reactions of soil–lime–natural pozzolana mixtures." International Journal of Pavement Engineering 20, no. 7 (June 7, 2017): 761–74. http://dx.doi.org/10.1080/10298436.2017.1337119.

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Quan, Hong Zhu. "The Glass Phase Characterization of Coal Ash Slag." Advanced Materials Research 580 (October 2012): 473–76. http://dx.doi.org/10.4028/www.scientific.net/amr.580.473.

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In recent years, coal power generation are strongly desired lower environmental burden, emissions of SOx, NOx, and CO2 are reduced to the level. Since high efficiency of combustion or gasification systems are discharges coal ash component of complex ashes or glassy molten slag(what is CCP), and the other point of view these CCPs are expected to be effectively used for sustainable development as component for civil engineering etc. Using the CCPs for civil engineering work, Pozzolanic reactions are very important character with hydration materials, but to measure Pozzolanic reaction by mortar test is necessary to wait very long term, waiting the new method of determine the Pozzolanic reactions. So, chemical and mineralogical investigations were carried out on these inorganic materials. The glass phase which was formed by quenching is difficult to characterize by X-ray analysis by every CCP, and discussed only how percentage of glass phases, without not good explanation of CCP reactions in each steps. So in this study, we promote the new method by optical analysis and acid extraction tests etc. In this study, three phases are distinguished, such as glass I, glass II, and crystal phase. Glass I has low flux compositions, and glass II has high flux compositions which makes the basic character of Class C ash in ASTM and Chinese GB standards.

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Li, Qin, Xiao Jun Zhou, Zhuo Yin Jiang, and Ke Wei Sun. "Research on Mechanism of Architectural Wastes Solidified by Alkali-Activated Cement and Fly Ash." Advanced Materials Research 446-449 (January 2012): 2708–13. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2708.

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An comparison research on the effect of pozzolanic reactions of fly ashes in architectural wastes recycle is described in the paper. In the experiment, NaOH and Na2SO4-Ca(OH)2 were used to activate the pozzolanic activities in the fly ashes—cement system to solidify the architectural wastes. The macro and micro testing methods were used to test the compressive strength, phase and electronic micro morphology of the hydration of alkali-activated fly ashes—cement cementitious system. The testing result shows that proper alkali-activated fly ashes—cement cementitious architectural wastes can shorten the incubation time of the pozzolanic reactions of fly ashes, whi ch make the reactions of fly ashes more sufficient. So the hydration products of fly ashes —cement cementitious system with alkali additions were more than those of without alkali add itions, and the compressive strength of the alkali-activated fly ashes—cement cementitious system is higher than that of non alkali-activated fly ashes—cement cementitious system.

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Tamanna, Nafisa, Norsuzailina Mohamed Sutan, Rabin Tuladhar, Delsye Teo Ching Lee, and Ibrahim Yakub. "POZZOLANIC PROPERTIES OF GLASS POWDER IN CEMENT PASTE." Journal of Civil Engineering, Science and Technology 7, no. 2 (September 30, 2016): 75–81. http://dx.doi.org/10.33736/jcest.307.2016.

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This paper investigates the formation of Calcium Silicate Hydrate (C-S-H) as a product ofpozzolanic reactions in a cement paste with cement partially replaced with crushed recycled glass at therate of 10% and 20%. Three different particle sizes for crushed glass used in this study were in therange of 150-75μm, 75-38μm and lower than 38μm; and a water to cement ratio of 0.45 was used for allspecimens. This study showed that the formation of Calcium Hydroxide Ca(OH)2 is decreased while theformation of C-S-H is increased simultaneously at 90 days for 75-38μm and <38μm glass powder. Theuse of waste glass as a partial cement replacement improves the cement strength through the formationof C-S-H due to the pozzolanic reaction with Ca(OH)2 improving the strength of the mortar.

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Awad, Muwafaq, Ibrahim Al-Kiki, and Amina Khalil. "Permeability of Expansive Soils Modified/Stabilized with lime (Review Paper)." Diyala Journal of Engineering Sciences 14, no. 2 (June 16, 2021): 129–40. http://dx.doi.org/10.24237/djes.2021.14212.

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The aim of this paper was to review the mechanism of the expansive soil-lime reactions: short term and long-term reactions in both lime modification and lime stabilization. The focus of the study was the effect of curing time for a certain centigrade 25C curing temperature in both lime modification / stabilization-expansive soils on the coefficient of permeability. Peer reviewed articles published between 2000- and 2019 were collected and relevant data were extracted. Results of this review study showed that the coefficient of permeability of expansive soils modified with lime increased during the first 7 days of curing time at curing temperature 25C and it remains constant or slightly decreased for longer curing time periods. However, for expansive soils stabilized with lime, it was found that the coefficient of permeability increased during the first 7-day curing time at curing temperature 25C, then decreased during the longer curing time periods (pozzolanic reaction). It is also noted that even though the coefficient of permeability decreased during pozzolanic reaction, it remains higher than that of the untreated soils

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Raheem, Akeem Ayinde, Solomon I. Adedokun, E. A. Adeyinka, and B. V. Adewole. "Application of Corn Stalk Ash as Partial Replacement for Cement in the Production of Interlocking Paving Stones." International Journal of Engineering Research in Africa 30 (May 2017): 85–93. http://dx.doi.org/10.4028/www.scientific.net/jera.30.85.

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In an attempt to reuse and convert agro wastes into useful materials for the construction industry, this research considered the application of corn stalk ash (CSA) as partial replacement for ordinary Portland cement (OPC) in the production of interlocking paving stones. The study investigated the oxide composition of CSA to ascertain its suitability as a pozzolanic material. Some properties of paving stones with CSA as a replacement for OPC were examined. The results showed that CSA is a good pozzolana having satisfied the required standards. The compressive strength of the specimens with replacement levels ranging from 5 to 25% cured for periods of 3–56 days was lower at early curing time but improved significantly at later age. 10% replacement level showed increased strength compared to 0% CSA at 28 days curing period. Density decreased with increasing ash content, water absorption rate increased with increased CSA contents, while abrasion resistance increased with increasing amount of CSA substitutions. The test results revealed that CSA paving stones can attain higher strength than the conventional ones at longer curing periods, due to its pozzolanic reactions.

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Wong, John Kok Hee, Sien Ti Kok, and Soon Yee Wong. "Fibers, Geopolymers, Nano and Alkali-Activated Materials for Deep Soil Mix Binders." Civil Engineering Journal 6, no. 4 (April 1, 2020): 830–47. http://dx.doi.org/10.28991/cej-2020-03091511.

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Ordinary Portland Cement (OPC) and Lime (CaO) have traditionally been used as binder materials for Deep Soil Mix (DSM) ground improvement. Research has been conducted into possible alternatives such as pozzolans to reduce reliance on either cement or lime. However, pozzolans still undergo similar calcium-based reactions in the strengthening process. In this review, further alternative binder materials for soil strength development are explored. These recent developments include fiber reinforcement materials, alkali activation methods, nanomaterials and geopolymers, which can potentially achieve equal or improved performance. Research to date has shown that alkali-activated materials and geopolymers can be equivalent or superior alternatives to pozzolanic supplemented cement binders. The case is made for GP cements which potentially produces 80% less CO2 than conventional portland cement during manufacture. One-part AAM and GP cements are a promising substitute for portland cement in DSM. A combined approach which incorporates both Ca and alkali activated/geopolymer types of materials and hence reactions is proposed.

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Shi, Caijun. "An overview on the activation of reactivity of natural pozzolans." Canadian Journal of Civil Engineering 28, no. 5 (October 1, 2001): 778–86. http://dx.doi.org/10.1139/l01-041.

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Natural pozzolan is one of the oldest construction materials. Lime-pozzolan cements have been used for several thousands of years and have an excellent reputation for their durability. Pozzolans are being widely used as a cement replacement in Portland cement concrete. The use of pozzolans has the advantage of lower costs and better durability, but the disadvantage of a longer setting time and a slower early strength development. Different techniques have been tried to increase the reactivity of natural pozzolans to overcome these disadvantages. This paper has reviewed various methods used to activate the pozzolanic activity of natural pozzolans. All activation methods can be classified into three catalogues: thermal, mechanical, and chemical activation. A comparison based on strengthcost relationship indicates that the chemical activation method is the most effective and cheapest one.Key words: activation, reactivity, natural pozzolans, pozzolanic reaction, calcination, elevated temperature curing, chemical activators, strength, cost.

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Wedding, PA, and MSY Bhatty. "Mechanism of Pozzolanic Reactions and Control of Alkali-Aggregate Expansion." Cement, Concrete and Aggregates 7, no. 2 (1985): 69. http://dx.doi.org/10.1520/cca10372j.

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Tri Hatmoko, John, and Hendra Suryadharma. "Parametric study on the behaviour of bagasse ash-calcium carbide residue stabilized soil." MATEC Web of Conferences 195 (2018): 03015. http://dx.doi.org/10.1051/matecconf/201819503015.

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A series of experiments including unconfined compression tests, three-axial tests, compaction tests, and split tensile tests were undertaken to investigate the influence of compaction parameters on the behaviour of bagasse ash-calcium carbide residue stabilized soil. A preliminary study on soil with the addition of 4%, 6%, 8%, 10%, and 12% calcium carbide residue established that the lime fixation point (LFP) was 4%. Then 9% bagasse ash was added to soil with 4% calcium carbide residue, and the cation exchanges and pozzolanic reactions were investigated. The addition of calcium carbide residue to bagasse ash stabilized soil caused short-term changes due to cation exchange reactions, including an increase in the friction angle and cohesion in the stabilized soil. In addition, due to the short-term reaction, the maximum stiffness in three-axial tests occurred in the samples moulded with less than their optimum moisture content (OMC), whereas the peak strength occurred in the samples moulded at their OMC. After a 28-day curing period, pozzolanic reactions improved significantly the three-axial peak strength and stiffness of the stabilized soil, and the maximum three-axial shear strength and stiffness occurred in the samples prepared below their OMC.

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Bumrongjaroen, Walairat, Richard A. Livingston, Dan A. Neumann, and Andrew J. Allen. "Characterization of fly ash reactivity in hydrating cement by neutron scattering." Journal of Materials Research 24, no. 7 (July 2009): 2435–48. http://dx.doi.org/10.1557/jmr.2009.0267.

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Partial replacement of hydrating Portland cement by fly ash produces competing effects: it contributes calcium hydrate silicate (C-S-H) gel through the pozzolanic and alkali-activated reactions but dilutes the contribution of the main Portland cement reaction. To investigate this, two neutron-scattering methods were applied to density-fractionated lignite-type and bituminous-type fly ash/Portland cement pastes (20% by mass replacement). Small-angle neutron scattering (SANS) measured the effect of the fly ash on the fractal C-S-H microstructure, whereas inelastic neutron scattering (INS) measured the pozzolanic reaction in terms of calcium hydroxide (CH) consumption. The CH consumption increased with the effective density fraction, and the fractal microstructure evolved more slowly for all fly ash mixes compared with the pure cement control. However, gel volume measured by SANS showed no correlation with the CH consumption measured by INS. The implications of these results are discussed.

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de la Villa, R. Vigil, I. S. De Soto, R. García-Giménez, and M. Frías. "Thermodynamic Evaluation of Pozzolanic Reactions between Activated Pozzolan Mix of Clay Waste/Fly Ash and Calcium Hydroxide." Journal of Materials in Civil Engineering 29, no. 8 (August 2017): 04017065. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0001940.

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Doleželová, Magdaléna, and Alena Vimmrová. "Porosity of the Ternary Gypsum-Based Binders with Different Types of Pozzolan." Key Engineering Materials 677 (January 2016): 122–27. http://dx.doi.org/10.4028/www.scientific.net/kem.677.122.

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Ternary gypsum-binders with different types of pozzolan were stored in the water and in the air. Brick powder, microsilica and blast slag were used as a pozzolan admixture. The quantity of the pozzolan in the mixture was determined from the amount of the amorphous phase in the pozzolan. Mixtures with pozzolans do not lose strength when stored in the water. Porosimetry shows that the product of the pozzolanic reaction started to develop.

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Marsh, Bryan K., and Robert L. Day. "Pozzolanic and cementitious reactions of fly ash in blended cement pastes." Cement and Concrete Research 18, no. 2 (March 1988): 301–10. http://dx.doi.org/10.1016/0008-8846(88)90014-2.

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Joshi, R. C., J. P. A. Hettiaratchi, and Gopal Achari. "Properties of modified Alberta fly ash in relation to utilization in waste management applications." Canadian Journal of Civil Engineering 21, no. 3 (June 1, 1994): 419–26. http://dx.doi.org/10.1139/l94-046.

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This paper presents the results of a laboratory investigation on hydraulic conductivity (k, also known as coefficient of permeability), compressive strength, and contaminant leachability of self-cementitious fly ash produced by two different coal-fired thermal power plants in Alberta. Hydraulic conductivity data are presented for fly ash and lime-modified fly ash samples with tap water and brine as permeants. The tap water k values of fly ash samples are almost two orders of magnitude higher than 1 × 10−7 cm/s, the usually required k value for a landfill bottom liner material. Addition of lime to fly ash increased the unconfined compressive strength and decreased the k value. The effect was directly proportional to the curing time and the percentage of lime added to the ash. The pozzolanic reactions between lime, water, and alumino-siliceous glass in the fly ash give rise to insoluble cementitious calcium alumino silicate hydrates. These pozzolanic reaction products contribute to strength gain and decrease in k value. It is also quite possible that salt precipitation during brine permeation blocked pore spaces and resulted in decreased k value. Nonetheless, the permeabilities of lime-modified fly ash samples are significantly lower than those of fly ash samples.In general, the amount of trace elements leached from test samples during tap water permeation decreased with increasing curing time and percentage of lime in samples. Exception was lead (Pb). Leachability of Pb increased with increasing lime content and curing time. Leachate pH held constant with time, which indicates that the removal of Ca(OH)2 in pozzolanic reactions did not have a significant impact on the pore solution pH. Key words: fly ash, hydraulic conductivity, contaminants, lime, leachability, liners, waste management, compressive strength, heavy metals.

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Rao, Sudhakar M., and K. Asha. "Role of Fly Ash Pozzolanic Reactions in Controlling Fluoride Release from Phosphogypsum." Journal of Materials in Civil Engineering 25, no. 8 (August 2013): 999–1005. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0000649.

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Indraratna, B., P. Nutalaya, K. S. Koo, and N. Kuganenthira. "Engineering behaviour of a low carbon, pozzolanic fly ash and its potential as a construction fill." Canadian Geotechnical Journal 28, no. 4 (August 1, 1991): 542–55. http://dx.doi.org/10.1139/t91-070.

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Detailed laboratory investigations were conducted on Mae Moh fly ash from northern Thailand for the determination of its grain size distribution, mineralogy, pozzolanic activity, compaction and strength characteristics, and the collapse potential. On the basis of the experimental results, this fly ash is classified as ASTM class C, which is considered to be pozzolanic. It has good potential to be utilized as an effective fill for embankments (roads and dams), airfields, pavements, and building bricks, as well as for the stabilization of compressible or erodible foundations. Because of the fact that Mae Moh fly ash contains only a negligible amount of unburned carbon, its pozzolanic reactivity is accelerated, in comparison with the relatively inert, high-carbon fly ash produced elsewhere in Thailand and many other parts of Asia. It is also demonstrated that Mae Moh fly ash can be easily compacted to produce acceptable dry densities over a wide range of water contents. Curing with an adequate moisture supply in the presence of calcium oxide plays an important role in accelerating the pozzolanic reactions, hence improving the time-dependent-properties. This study further proposes that a curing period of 2–3 weeks is sufficient for this material to approach its maximum strength. Although the behaviour of one specific fly ash cannot generalize the wide array of other ashes, the test results obtained for Mae Moh fly ash may be applied to lignite ashes in the category of ASTM class C. Key words: fly ash, structural fill, compaction, compressive strength, shear strength, collapse potential, pozzolanic activity.

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Sumariuk, O. V., V. F. Romankevych, O. D. Halunka, O. V. Kutsyk, V. V. Polevetsky, S. M. Novikov, and I. M. Fodchuk. "Influence of polyfunctional nanomodificators on the microstructure of concrete composites of high strength and density." Фізика і хімія твердого тіла 21, no. 1 (March 28, 2020): 19–26. http://dx.doi.org/10.15330/pcss.21.1.19-26.

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The patterns of formation of highly functional concretes structure, which consist in formation of an ordered, low-porous, fine-crystalline microstructure of cementitious matrix, in particular due to pozzolanic reactions of the non-clinker part of the binder with formation of an additional amount of low-basic hydrocarbons, are investigated.

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Villar-Cociña, Ernesto, Moisés Frías, Holmer Savastano, Loic Rodier, María Isabel Sánchez de Rojas, Isabel Fuencisla Sáez del Bosque, and César Medina. "Quantitative Comparison of Binary Mix of Agro-Industrial Pozzolanic Additions for Elaborating Ternary Cements: Kinetic Parameters." Materials 14, no. 11 (May 29, 2021): 2944. http://dx.doi.org/10.3390/ma14112944.

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In this research work, the quantitative characterization of a binary blend comprised of two pozzolans (sugar cane straw (SCSA)–sugar cane bagasse ashes (SCBA), bamboo leaf ash (BLAsh)–SCBA and paper sludge (PS)–fly ash (FA)) taking into account the calculated values of the kinetic parameters of the reaction in the pozzolan/calcium hydroxide system is shown. The paper shows the most significant and important results obtained by the authors in the quantitative assessment (calculation of kinetic parameters) of the pozzolanic reaction of different mixtures of pozzolanic materials that are residues from agriculture or industrial processes. This allows a direct and rigorous comparison of the pozzolanic activity of the binary combinations of materials. The values of the kinetic parameters (reaction rate constant or activation free energy) constitute a very precise quantitative index of the pozzolanic activity of the binary combinations of materials, which is very useful for its employment in the elaboration of ternary cements. This paper shows that the binary blends 1SCBA60Blash40, 1SCBA50Blash50, 1SCBA70Blash30 have a very high pozzolanic reactivity followed by PSLSFA, 2SCBA50SCSA50, PSISFA and SCWI.

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Giménez-García, Rosario, Raquel Vigil de la Villa Mencía, Virginia Rubio, and Moisés Frías. "The Transformation of Coal-Mining Waste Minerals in the Pozzolanic Reactions of Cements." Minerals 6, no. 3 (June 30, 2016): 64. http://dx.doi.org/10.3390/min6030064.

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Philippot, Samuel, Sylvie Masse, Hélène Zanni, Pedro Nieto, Vincent Maret, and Marcel Cheyrezy. "29Si NMR study of hydration and pozzolanic reactions in reactive powder concrete (RPC)." Magnetic Resonance Imaging 14, no. 7-8 (January 1996): 891–93. http://dx.doi.org/10.1016/s0730-725x(96)00174-9.

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He, Changling, Bjarne Osbaeck, and Emil Makovicky. "Pozzolanic reactions of six principal clay minerals: Activation, reactivity assessments and technological effects." Cement and Concrete Research 25, no. 8 (December 1995): 1691–702. http://dx.doi.org/10.1016/0008-8846(95)00165-4.

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Mertens, G., R. Snellings, K. Van Balen, B. Bicer-Simsir, P. Verlooy, and J. Elsen. "Pozzolanic reactions of common natural zeolites with lime and parameters affecting their reactivity." Cement and Concrete Research 39, no. 3 (March 2009): 233–40. http://dx.doi.org/10.1016/j.cemconres.2008.11.008.

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Bessaim, Mohammed Mustapha, Aicha Bessaim, Hanifi Missoum, and Karim Bendani. "Effect of quick lime on physicochemical properties of clay soil." MATEC Web of Conferences 149 (2018): 02065. http://dx.doi.org/10.1051/matecconf/201814902065.

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Clay soils are known for their water sensitivity, which causes irreparable damage to any structure built on this type of soil. In order to avoid such problem, it is necessary to use various improvement and stabilization methods such as treatment with lime. This process has been used successfully in the field for decades. The addition of lime generates various physicochemical reactions within the soil such as cation exchange and pozzolanic reactions which are largely responsible for the improvement of the soil in question. This paper presents a study concerning the variation of physicochemical properties of clayey soil with the addition of quicklime at different percentages. Experiments were performed on two clayey soils (CL type) in order to investigate the influence of quicklime on Atterberg limits and pH. These tests were carried out in an attempt to study and follow the development and progression of various reactions occurred within the soil with various lime percentages. The results show that the addition of quicklime causes a significant improvement in soil properties by reducing plasticity and thereby improves the soil workability. It can also be found that the addition of lime increase pH of soil, which allow activating pozzolanic reactions who tend to stabilize the soil in question by formation of cementitious compounds. Finally, the pH can be considered as a relevant parameter who allows a better understanding of the reactions that occur in the soil matrix.

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Belfiore, Cristina Maria, Giusj Valentina Fichera, Gaetano Ortolano, Antonino Pezzino, Roberto Visalli, and Luigi Zappalà. "Image processing of the pozzolanic reactions in Roman mortars via X-Ray Map Analyser." Microchemical Journal 125 (March 2016): 242–53. http://dx.doi.org/10.1016/j.microc.2015.11.022.

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35

Kazemian, Sina, Bujang B. K. Huat, Thamer A. Mohammed, Farah N. A. Abdul Aziz, Hossein Moayedi, and Maassoumeh Barghchi. "Influence of Peat Characteristics on Cementation and Pozzolanic Reactions in the Dry Mixing Method." Arabian Journal for Science and Engineering 36, no. 7 (October 19, 2011): 1189–202. http://dx.doi.org/10.1007/s13369-011-0121-1.

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Joseph, Al-Bahar, Chakkamalayath, Al-Arbeed, and Rasheed. "Monitoring of Early and Late Age Hydration Products of Volcanic Ash Blended Cement Paste." Proceedings 34, no. 1 (November 18, 2019): 9. http://dx.doi.org/10.3390/proceedings2019034009.

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One of the major concerns of concrete industries is to develop materials that consume less natural virgin resources and energy to make sustainable construction practices. Efforts have been made and even implemented to use the waste/by product materials such as fly ash, slag, silica fume, and natural pozzolana as a partial or complete replacement for Portland cement in concrete mixtures. The deterioration of concrete structures in the existing hot and cold climates of Gulf Cooperation Council countries, along with chloride and sulphate attack, demands the use of pozzolanic materials for concrete construction. Volcanic ash incorporated cement based concretes are known for its better performance in terms of strength and durability in harsh marine environments. Understanding the cement hydration process and characterizing the hydration products in microstructural level is a complex and interdependent process that allows one to design complex mix proportions to produce sustainable concrete materials. In this paper, the early and late age hydration behavior along with micro- and pore structure of cement paste samples prepared with locally available ordinary Portland cement (OPC) and volcanic ash (VA) obtained from Saudi Arabia was monitored using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TGA) and N2-Adsorption analysis. The hydration progress of cement paste samples with different combinations of OPC and VA (0%, 15%, 25%, and 35%) at a w/c ratio of 0.45 after 14, 28, and 90 days were discussed. The qualitative XRD and SEM of cement paste samples showed no new phases were formed during the course of hydration. The disappearance of portlandite with increase in VA content was due to both pozzolanic effect and dilution effect. This was further confirmed quantitatively by the TGA observations that the samples with VA contain less Ca(OH)2 compared to the control specimens. N2 adsorption experiments after 90 days of curing showed larger hysteresis as the VA content increases. The studies show that the incorporation of volcanic ash certainly contributes to the generation of C-S-H and hence the cement hydration progress, especially in the later ages through pozzolanic reactions. A 15–25 % volcanic ash blended cement paste samples showed compact and denser morphological features, which will be highly detrimental for the durability performances.

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Onyelowe, Kennedy C., Michael E. Onyia, Duc Bui Van, Haci Baykara, and Hyginus U. Ugwu. "Pozzolanic Reaction in Clayey Soils for Stabilization Purposes: A Classical Overview of Sustainable Transport Geotechnics." Advances in Materials Science and Engineering 2021 (March 25, 2021): 1–7. http://dx.doi.org/10.1155/2021/6632171.

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Problematic soil stabilization processes involve the application of binders to improve the engineering properties of the soil. This is done to change the undesirable properties of these soils to meet basic design standards. However, very little attention has been given to the reactive phase of soil stabilization. This phase is the most important in every stabilization protocol because it embodies the reactions that lead to the bonding of the dispersed particles of clayey soil. Hence, this reactive phase is reviewed. When clayey soils which make up the greatest fraction of expansive soil come in contact with moisture, they experience volume changes due to adsorbed moisture that forms films of double diffused layer on the particles. When this happens, the clayey particles disperse and float, increasing the pore spaces or voids that exist in the soil mass. Stabilizations of these soils are conducted to close the gaps between the dispersed clayey soil particles. This is achieved by mixing additives that will release calcium, aluminum, silicon, etc., in the presence of adsorbed moisture, and a hydration reaction occurs. This is followed by the displacement reaction based on the metallic order in the electrochemical series. This causes a calcination reaction, a process whereby calcium displaces the hydrogen ions of the dipole adsorbed moisture and displaces the sodium ion responsible for the swelling potential of clayey soils. These whole processes lead to a pozzolanic reaction, which finally forms calcium alumina-silica hydrate. This formation is responsible for soil stabilization.

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Lilkov, V., O. Petrov, V. Petkova, N. Petrova, and Y. Tzvetanova. "Study of the pozzolanic activity and hydration products of cement pastes with addition of natural zeolites." Clay Minerals 46, no. 2 (June 2011): 241–50. http://dx.doi.org/10.1180/claymin.2011.046.2.241.

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AbstractThis paper presents results from comparative thermogravimetric, calorimetric and pozzolanic activity analyses of five natural zeolite samples from Bulgaria, Slovakia, Philippines, USA and North Korea. The zeolites actively participate in the hydration processes of cement. Their activity in the early stage of hydration is based mainly on the large surface area of the particles while, in the later stages of activation, chemical reactions occur between the products of the hydration of cement and the soluble SiO2 that is present in the bulk of the zeolites. It has been shown that in all cement pastes which contain zeolite additives, the quantity of portlandite is lower than that in pure cement paste or is even totally absent. The amounts of hydration products are greater when 30% zeolite is used than when 10% zeolite is added (excluding the sample with chabazite). The lowest pozzolanic activity is shown by chabazite, which possessed the lowest SiO2/Al2O2 ratio.

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Papatzani, Styliani, and Kevin Paine. "From Nanostructural Characterization of Nanoparticles to Performance Assessment of Low Clinker Fiber–Cement Nanohybrids." Applied Sciences 9, no. 9 (May 11, 2019): 1938. http://dx.doi.org/10.3390/app9091938.

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With the current paper three nano-Montmorillonites (nMt) are applied in cement nanohybrids: an organomodified nMt dispersion, nC2; an inorganic nMt dispersion, nC3; and an organomodified powder, nC4. nC4 is fully characterized in this paper (X-ray diffraction, scanning electron microscopy/X-ray energy dispersive spectroscopy and thermal gravimetric analysis/differential thermogravimetry. Consecutively a ternary non pozzolanic combination of fiber–cement nanohybrids (60% Portland cement (PC) and 40% limestone (LS)) was investigated in terms of flexural strength, thermal properties, density, porosity, and water impermeability. Flexural strength was improved after day 28, particularly with the addition of the inorganic nMt dispersion. There was no change in density or enhancement in pozzolanic reactions for the powder nMt. Mercury intrusion porosimetry showed that the pore related parameters were increased. This can be attributed to mixing effects and the presence of fibers. Water impermeability tests yielded ambiguous results. Clearly, novel manufacturing processes of cement nanohybrids must be developed to eliminate mixing issues recorded in this research.

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Prasetia, Irfan, and M. Fahmi Rizani. "Analysis of fly ash from PLTU Asam-Asam as a construction material in terms of its physical and mechanical properties." MATEC Web of Conferences 280 (2019): 04013. http://dx.doi.org/10.1051/matecconf/201928004013.

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Nowadays, PLTU Asam-Asam produced enormous amounts of combustion waste in the form of coal ash. On the contrary, only a little effort has been made to utilize coal ash from PLTU Asam-Asam, especially from the research side. In fact, due to its siliceous material, when reacting with CH in concrete, will form CSH hence improves concrete strength. In this study, in order to analyze the physical and mechanical properties of concrete using fly ash from PLTU Asam-Asam, 54 concrete samples were prepared according to SNI-03-2834-2000. The examination of concrete samples workability was conducted based on the slump test according to SNI 1972:2008. Moreover, the compressive tests were carried out in accordance with SNI 1974:2011. The slump test results show that the pozzolanic reaction of fly ash contributes to the improvement of concrete workability. Furthermore, the variation in w/b ratio was also affecting the results of the slump test. As for the compressive strength, in general speaking, the replacement ratio of 30% of cement with fly ash in concrete could produce concrete strength up to 30 Mpa. It is also important to note that due to the pozzolanic reactions tends to delayed, it is expected that at later ages (above 28 days) concrete with fly ash will gain much more strength compared to ordinary concrete.

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Gruyaert, Elke, Kim Van Tittelboom, Hubert Rahier, and Nele De Belie. "Activation of Pozzolanic and Latent-Hydraulic Reactions by Alkalis in Order to Repair Concrete Cracks." Journal of Materials in Civil Engineering 27, no. 7 (July 2015): 04014208. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0001162.

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42

Urhan, S. "Alkali silica and pozzolanic reactions in concrete. Part 2: Observations on expanded perlite aggregate concretes." Cement and Concrete Research 17, no. 3 (May 1987): 465–77. http://dx.doi.org/10.1016/0008-8846(87)90010-x.

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43

De Windt, Laurent, Dimitri Deneele, and Nicolas Maubec. "Kinetics of lime/bentonite pozzolanic reactions at 20 and 50°C: Batch tests and modeling." Cement and Concrete Research 59 (May 2014): 34–42. http://dx.doi.org/10.1016/j.cemconres.2014.01.024.

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Doneliene, Jolanta, Anatolijus Eisinas, Kestutis Baltakys, and Agne Bankauskaite. "The Effect of Synthetic Hydrated Calcium Aluminate Additive on the Hydration Properties of OPC." Advances in Materials Science and Engineering 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/3605845.

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The effect of synthetic CAH (130°C; 8 h; CaO/(SiO2+ Al2O3) = 0.55; Al2O3/(SiO2+ Al2O3) = 0.1, 0.15) with different crystallinity on the hydration kinetics of OPC at early stages of hydration was investigated. Also, the formation mechanism of compounds during OPC hydration was highlighted. It was determined that the synthetic CAH accelerated the initial reaction and shortened the induction period. Also, the second and third exothermic reactions begun earlier, and, during the latter reaction, the higher values of the heat flow were obtained in comparison with pure OPC samples. At later stages of hydration, synthetic CAH affect the OPC hydration as the usual pozzolanic additives; moreover, the larger values of cumulative heat were reached. It should be noted that the nature of synthetic CAH samples accelerated the dissolution of gypsum and stimulates the earliest C3S hydration.

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Bach, Quoc Si. "Quantitative Study of Hydration of C3S and C2S in the Reactive Powder Concrete together with its Strength Development." Applied Mechanics and Materials 889 (March 2019): 294–303. http://dx.doi.org/10.4028/www.scientific.net/amm.889.294.

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The compressive strength development always go along with the microstructure development in concrete through the process of cement hydration. In the hydrated products of cement, calcium silicate hydrate (C-S-H) forms a network of nanoparticles so C-S-H gel is the main compound giving compressive strength of concrete. As we know that C-S-H gel produced by the reactions with water of two main minerals in cement such as Tricalcium Silicate () and Dicalcium Silicate (). In addition, the increase of C-S-H content in concrete due to the pozzolanic reaction of the pozzolan with calcium hydroxide (CH). With the aim of this research is quantitative study of hydration of and in the Reactive Powder Concrete (RPC) together with its compressive strength development, three concrete formulas were estimated in this study which made from three different types of cement ownership different mineral compositions content were tested on compressive strength and on heat flux emitted from hydration process by isothermal calorimetry. The purpose of measuring heat flux emitted from chemical reaction process in concrete is to verify the hydration kinetic model for portland cement containing the silica fume. Basing on this simulation program, the amount of C-S-H gel in concrete is calculated. The research results showed that the the C-S-H content formed in binder paste of RPC is proportional to compressive strength development. The (Ordinary Portland Cement) OPC with higher content have compressive strength development earlier.

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Serpa, D., António Santos Silva, D. Soares, M. Barreto Santos, and J. de Brito. "Behaviour of Glass in Cement-Based Materials: Its Role on ASR." Materials Science Forum 730-732 (November 2012): 415–20. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.415.

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One of the most worrying degradation mechanisms in hardened concrete is the occurrence of chemical expansive reactions, namely due to alkali-silica reactions (ASR). This pathology involves the formation of expansive products inside the material. This situation is very difficult to deal with, because presently there is no efficient method to repair concrete structures affected by ASR. Hence, there is an urgent need to find preventive methods that may inhibit these reactions in new concrete structures. Nowadays, the use of pozzolanic mineral additions is recommended to mitigate this type of degradation. Moreover, their effect depends on their chemical and mineralogical composition and also on the cement content replacement ratio. Glass is a common material with some environmental problems regarding recycling and landfilling. Some studies exist about its use as fine powder, like a pozzolan, in cement-based materials. However, there are also some problems related to its use as coarse aggregate in cement–based materials due to ASR development. This paper presents the results obtained in mortars exposed to 1M NaOH solution prepared with crushed glass as aggregate and as addition in cement substitution. The results reveal that ASR is reduced with the incorporation of glass as aggregate or addition, and its efficiency depends on its replacement content. This study shows that an incorporation of glass aggregates up to 20% in mass will generate no significant expansion when compared with concrete made with natural aggregates.

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Vitale, Enza, Dimitri Deneele, and Giacomo Russo. "Microstructural Investigations on Plasticity of Lime-Treated Soils." Minerals 10, no. 5 (April 25, 2020): 386. http://dx.doi.org/10.3390/min10050386.

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The surface charge distribution of clay particles governs the interparticle forces and their arrangement in clay-water systems. The plasticity properties are the consequences of the interaction at the microscopic scale, even if they are traditionally linked to the mechanical properties of fine-grained soils. In the paper, the plasticity modifications induced by the addition of lime were experimentally investigated for two different clays (namely kaolinite and bentonite) in order to gain microstructural insights of the mechanisms affecting their plastic behavior as a function of the lime content and curing time. Zeta potential and dynamic light scattering measurements, as well as thermogravimetric analyses, highlighted the mechanisms responsible for the plastic changes at a small scale. The increase of the interparticle attraction forces due to the addition of lime increased the liquid and plastic limits of kaolinite in the short term, without significant changes in the long term due to the low reactivity of the clay in terms of pozzolanic reactions. The addition of lime to bentonite resulted in a decrease of interparticle repulsion double layer interactions. Rearrangement of the clay particles determined a reduction of the liquid limit and an increase of the plastic limit of the treated clays in the very short term. Precipitation of the bonding compounds due to pozzolanic reactions increased both the liquid and plastic limits over the time.

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Louafi, Bahia, Billal Hadef, and Ramdane Bahar. "Improvement of Geotechnical Characteristics of Clay Soils Using Lime." Advanced Materials Research 1105 (May 2015): 315–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1105.315.

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This study presents the results of an experimental work carried out to investigate the effects of treatment of fine bentonite clay using various contents of lime. Tests conducted verified substantial changes and significant improvement in physical and mechanical characteristics of the clay. Techniques including ultrasonic tests and unconfined compression were utilized for a series of lime content (0%,2%, 4% and 6%) for variable curing times. The studied clay soils revealed that lime treated clays get changed and improved with regard to particular geotechnical characteristics due to cation exchanges, particle rearrangements and pozzolanic reactions. The analysis of ultrasonic tests and compressive strength showed a process of gradual increase in strength and compactness of the reaction products over time. For an optimum dose and extended curing time, the stabilized soil acts as a rock.

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Wang, Shuangzhen. "Quantitative kinetics of pozzolanic reactions in coal/cofired biomass fly ashes and calcium hydroxide (CH) mortars." Construction and Building Materials 51 (January 2014): 364–71. http://dx.doi.org/10.1016/j.conbuildmat.2013.10.057.

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Cecconi, Manuela, Costanza Cambi, Stefano Carrisi, Dimitri Deneele, Enza Vitale, and Giacomo Russo. "Sustainable Improvement of Zeolitic Pyroclastic Soils for the Preservation of Historical Sites." Applied Sciences 10, no. 3 (January 30, 2020): 899. http://dx.doi.org/10.3390/app10030899.

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Climate changes are inducing a modification of environmental loads on historical sites, requiring new actions towards their conservation. In the paper, the results of an experimental work on sustainable improvement of a pyroclastic soil belonging to the Orvieto cliff (Central Italy) have been investigated in the perspective of its preservation from degradation. The slightly coherent facies of Orvieto Ignimbrite (pozzolana) was treated with hydrated lime and the subsequent chemo-physical evolution was investigated by means of a multi-scale analysis. The beneficial effects obtained from the improvement in terms of mechanical behaviour were interpreted and correlated to the chemo-physical evolution of the system. Microstructural analyses, X-ray diffractometry, thermo-gravimetric analyses (DTG), SEM observations, mercury intrusion porosimetry performed on raw and treated samples, showed that the pozzolanic reactions develop since the very beginning in the system and that the observed mechanical improvement of the treated soil is mainly due to the formation of calcium silicate hydrates (CSH) and calcium aluminate hydrates (CAH). In the paper, the mechanical improvement is put in evidence by comparing the results of oedometer tests performed on both raw and treated samples.

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Journal articles on the topic 'Pozzolanic Reactions'

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