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Cement
About: Cement is a research topic. Over the lifetime, 68440 publications have been published within this topic receiving 829356 citations.
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TL;DR: In this article, a shrinking sphere model is proposed to explain the competitive kinetics of hydration processes with formation of inner and outer products which are shown to differ significantly in mineralogy.
Abstract: Calorimetry, X-ray diffraction, scanning electron microscopy, microprobe and porosimetry were used to investigate hydration processes occurring at 25°C, 55°C and 85°C for commercial calcium sulfoaluminate (CSA) cement during the first 24 h. CSA cement pastes harden through the formation of an initial ettringite skeleton and its subsequent infilling by mixtures of ettringite, AFm and C-S-H. At low water/cement ratios these yield a dense, rather featureless paste. The formation rate of ettringite is significantly increased at elevated temperatures. A ‘shrinking sphere’ model is proposed to explain the competitive kinetics of hydration processes with formation of inner and outer products which are shown to differ significantly in mineralogy.
160 citations
TL;DR: In this article, the effect of diatomite properties on physical and mechanical properties of block elements with different aggregate granulometries and cement contents were investigated and the results showed that materials with a ratio of 30% fine, 40% medium and 30% coarse size have the best compressive strength and thermal insulation in all series.
160 citations
TL;DR: In this article, the authors evaluated the effect of OMMT micro-particles on the improvements of strengths and permeability of cement mortars and found that the optimal dosage gave higher compressive and flexural strength and a lower coefficient of permeability.
160 citations
TL;DR: In this paper, the internal relative humidity in drying concrete specimens was measured at early ages, and the variation of relative humidity due to self-desiccation in sealed specimen was measured.
160 citations
TL;DR: In this paper, an experimental study described in this paper on three different binder systems including Ordinary Portland Cement, Portland Pozzolana Cement with 30% Type F Fly Ash (designated FA30), and Limestone Calcined Clay Cement (LC 3 ) pastes shows that the LC 3 system attains greater refinement of the pore structure as early as 3 days, as seen from mercury intrusion porosimetry.
Abstract: Use of limestone and calcined clay together for clinker substitution makes an effective low clinker cement blend, which shows promising mechanical properties at early ages. The performance of these cementitious systems strongly depends on the pore structure, which is a dominant factor governing the durability characteristics because of its direct influence on the transport properties. The experimental study described in this paper on three different binder systems including Ordinary Portland Cement, Portland Pozzolana Cement - with 30% Type F Fly Ash (designated FA30) - and Limestone Calcined Clay Cement (LC 3 ) pastes shows that the LC 3 system attains greater refinement of the pore structure as early as 3 days, as seen from mercury intrusion porosimetry. Electrical measurements also reveal lower conductivity in the system, which suggests better resistance to ionic transport in the binder phase. The results of hydrate phase assemblage studied by X-ray diffraction also indicate that greater amount of hydrates contribute in a major way to the reduction in the (water-filled) porosity in all the systems. This change occurs at varying rates for the different systems due to the difference in hydration characteristics. The estimated permeability suggests that the LC 3 binder system attains much lower permeability compared to the ordinary Portland cement and FA30. A comparison of the formation factor shows distinct differences in the microstructural development and suggests a more durable binder with LC 3 cementitious system.
159 citations