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Clinker grinding and cement making
Published in Anjan Kumar Chatterjee, Cement Production Technology, 2018
Three of the polymorphs belong to the triclinic system (T), another three to the monoclinic system (M), and the seventh belongs to the trigonal rhombohedral system (R). However, industrial clinkers generally show the presence of M1 or M3 or their mixture. Rarely, the T2 variety has been observed. The alite phase generally has an impurity level of 3–4% and its density increases to 3.15 from 3.12 of pure C3S. It seems that the changes in hydraulic properties of alite are due more to structural defects, disorders, etc. than to its polymorphic form.
Alkali-free shotcrete accelerator interactions with cement and admixtures
Published in Erik Stefan Bernard, Shotcrete: More Engineering Developments, 2004
Set accelerating admixtures used for shotcrete typically act by accelerating the initial aluminate hydration, thus producing aluminate based hydrates that combine with significant amounts of water. This leads to setting as the mix rapidly stiffens, but relatively low strength development for portland cement based mixes until the main strength giving phase, alite, begins to hydrate. Figure 2 shows a typical calorimetric illustration of the set accelerating effect of calcium nitrite. Note that the aluminate induced set acceleration also leads to an acceleration of the onset of the alite hydration peak, as long as there is sufficient sulfate available to balance the aluminate hydration.
Chemo-mechanical properties of synthesized tricalcium silicate
Published in A. Kumar, A.T. Papagiannakis, A. Bhasin, D. Little, Advances in Materials and Pavement Performance Prediction II, 2020
Shayan Gholami, Yong-Rak Kim, Hani Alanazi
A typical Portland cement clinker contains about 50-65% of Alite which is an impure tri-calcium silicate (C3S) phase. Alite’s (alongside Belite) hydration reactions play an important role in concrete strength development (Poulsen et al. 2009; Thomas et al. 2001). The hydration reaction products are calcium silicate hydrate (C-S-H) and calcium hydroxide (CH) gels which C = CaO, S = SiO2, H = H2O (Cuesta et al. 2018). Since the C3S phase is the main phase in the un-hydrated cement composition, various studies have been conducted on its properties whereupon the pure synthesized powder was hydrated (or carbonated) which led to a paste consisted of C-S-H and CH gels (Huan et al. 2007; Kjellsen & Harald 2004; Kjellsen et al. 2007; Grech et al. 2013). Although the obtained C-S-H and CH gels have similarities to the C-S-H and CH found in Portland cement-based materials, the impurities (i.e., the presence of Alumina and Iron at kiln) and different crystal structures (i.e., different spacing of the atoms in the crystals) could result in different properties (Maki & Kato 1982; MIT Concrete Sustainability 2013). In order to understand the fundamental characteristic of the two primary hydration products (C-S-H and CH) in OPC, this study investigated nanomechanical and chemical properties between hydration products resulting from pure tri-calcium silicate and Alite found in Portland cement clinker. The findings can be used to optimize the performance of Portland cement based concrete pavement within tailoring early strength hydration reactions. Nanoindentation can provide nanomechanical properties in various types of heterogeneous materials (Constantinides et al. 2003; Němeček 2009), it was thus employed in this study, and the nanomechanical properties were mapped with chemical characteristics detected by energy dispersive X-ray spectroscopy (EDS) method.
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.