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Cement
Published in A. Bahurudeen, P.V.P. Moorthi, Testing of Construction Materials, 2020
Further, the reaction between activated silica and CaO forms belite (C2S). Belite is di-calcium silicate in its mixed form with 5% of oxides such as Al2O3, Fe2O3, MgO, SO3, Na2O, K2O, TiO2 and P2O5. This whole reaction takes place in the range of 900–1200ºC.
Life cycle cost analysis of runway reconstruction alternatives for commercial service airports
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
Calcium Sulfoaluminate Cement—The history of Calcium Sulfoaluminate (CSA) cement traces back to the 1960s (Rice, 2012). Over the years, CSA technology has evolved from being an additive to portland cement to becoming a single component cement in its own right. The cement is very low shrinkage, fast setting and contains as its major component dicalcium silicate (belite), a portland cement compound. Therefore, it behaves like ordinary portland cement in concrete placement. In the last 20 years, it has been used extensively as a pavement repair material because of its ultra or very fast setting properties. The manufacturer has documented the use of RapidSet CSA cement at over 40 airports worldwide, although mostly as a panel replacement or repair material.
Effects of sodium gluconate on hydration reaction, setting, workability, and strength development of calcium sulfoaluminate belite cement mixtures
Published in Journal of Sustainable Cement-Based Materials, 2022
Guangping Huang, Rajender Gupta, Wei Victor Liu
In addition to having low CO2 emissions, CSAB cement mixtures have high early-age strength and comparable long-term strength compared to PC mixtures. Once CSAB cement encounters water, ye’elimite reacts quickly with calcium sulfate and water to generate ettringite (AFt or ) and alumina hydroxide (AH3), or it hydrates rapidly to form monosulfate (AFm or ) and AH3 when calcium sulfate is not available, as shown in Equations (1) and (2) [3,12,13]. The rapid hydration reaction of ye’elimite allows fast strength development at very early ages. For example, our previous studies [14,15] showed that CSAB cement mortar gained a UCS of 17.0 MPa at 1 h, which was 4.2 MPa higher than the 1-day UCS of ordinary Portland cement (OPC) mortar with the same mixture proportion. At later ages, belite reacts with alumina hydroxide to form strätlingite (C2ASH8) following Equation (3) [4,16]. Strätlingite is unstable in the presence of belite since it can react with belite to form amorphous C-S-H and siliceous-hydrogarnet [17,18]. The hydration of belite contributes to the strength development of CSAB cement mixtures at later ages, ensuring a high long-term strength [5,19]. Ramseyer and Bescher [20] reported that the compressive strength of CSAB cement-based concrete was over 69 MPa at 28 days.
Geopolymer and ordinary Portland cement interface analyzed by micro-Raman and SEM
Published in Journal of Nuclear Science and Technology, 2022
Vincent Cantarel, Isao Yamagishi
Standard cement was characterized as received and 28 days after hydration by XRD (Figure 1). Before hydration, the cement is composed mainly of alite (C3S) and belite (C2S). Gypsum and calcium aluminoferrite (C4AF) are also present in small quantities.