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Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Effects of kaolinite and montmorillonite calcined clays on the sulfate balance, early hydration and artificial pore solution of limestone calcined clay cements
Combining clinker with limestone and calcined clay has been one of the main strategies to reduce CO2 emissions in the cement production industry. Calcium sulfate is mainly used to control setting times. Compared to ordinary Portland cement, these blended cements exhibit accelerated sulfate depletion during hydration. This is highly influenced by the calcined clays' physical and chemical effects and methods for determining the appropriate sulfate content require further investigation. There is no unique or best method to ensure sulfate balancing, nor what effects different clay minerals (kaolinite vs. montmorillonite) have on this adjustment. Thus, this study aimed to assess methods for the optimum sulfate content determination, in terms of SO3total, of ternary cements composed of both calcined clays. In addition, their physical and chemical effects on the sulfate balance, early-age hydration, and artificial pore solution chemistry were evaluated. The impacts of the clays were compared with an inert material (quartz powder) in a reference cement. The experimental program was divided into two phases. In phase 1, sulfate optimization was carried out using isothermal calorimetry, compressive strength, thermogravimetric (TG) analysis, and chemical shrinkage (CS) analysis at different ages. In phase 2, the impact of fineness, dissolution, and possible adsorption capacity of the calcined clay minerals were evaluated by isothermal calorimetry, ICP-OES and zeta potential, respectively. Phase 1 demonstrated that there is no single best technique to predict sulfate optimization, especially for LC³s, but combining several techniques can assist in more coherent decision-making. A careful combination of calorimetry results with compressive strength can be useful at early ages. TG results do not relate well to the other techniques but are useful for comparative reactivity between cements. As well as CS, since it is not sensitive to detect changes between total SO3 contents but indicates the reactivity of cement pastes as a ...
Effects of kaolinite and montmorillonite calcined clays on the sulfate balance, early hydration and artificial pore solution of limestone calcined clay cements
Combining clinker with limestone and calcined clay has been one of the main strategies to reduce CO2 emissions in the cement production industry. Calcium sulfate is mainly used to control setting times. Compared to ordinary Portland cement, these blended cements exhibit accelerated sulfate depletion during hydration. This is highly influenced by the calcined clays' physical and chemical effects and methods for determining the appropriate sulfate content require further investigation. There is no unique or best method to ensure sulfate balancing, nor what effects different clay minerals (kaolinite vs. montmorillonite) have on this adjustment. Thus, this study aimed to assess methods for the optimum sulfate content determination, in terms of SO3total, of ternary cements composed of both calcined clays. In addition, their physical and chemical effects on the sulfate balance, early-age hydration, and artificial pore solution chemistry were evaluated. The impacts of the clays were compared with an inert material (quartz powder) in a reference cement. The experimental program was divided into two phases. In phase 1, sulfate optimization was carried out using isothermal calorimetry, compressive strength, thermogravimetric (TG) analysis, and chemical shrinkage (CS) analysis at different ages. In phase 2, the impact of fineness, dissolution, and possible adsorption capacity of the calcined clay minerals were evaluated by isothermal calorimetry, ICP-OES and zeta potential, respectively. Phase 1 demonstrated that there is no single best technique to predict sulfate optimization, especially for LC³s, but combining several techniques can assist in more coherent decision-making. A careful combination of calorimetry results with compressive strength can be useful at early ages. TG results do not relate well to the other techniques but are useful for comparative reactivity between cements. As well as CS, since it is not sensitive to detect changes between total SO3 contents but indicates the reactivity of cement pastes as a ...
Effects of kaolinite and montmorillonite calcined clays on the sulfate balance, early hydration and artificial pore solution of limestone calcined clay cements
Silva, Micael Rubens Cardoso da (Autor:in) / Kirchheim, Ana Paula / Walkley, Brant
01.01.2022
001213604
Hochschulschrift
Elektronische Ressource
Englisch
Kaolinite , Montmorillonite , Hydration , Sulfate balance , LC³ , Cimento , Sulfato , Argila
Sulfate resistance of calcined clay – Limestone – Portland cements
| Elsevier | 2018
Calcined clay limestone cements (LC3)
| British Library Online Contents | 2018