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Polymers-Based Self-Healing Cementitious Materials
Published in Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban, Self-Healing Cementitious Materials, 2022
Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban
In this study, the OPC was collected from the Holcim Cement Manufacturing Company (Malaysia), following ASTM C150 standard [27] to prepare the mortar. The X-ray fluorescence (XRF) spectra were analyzed to determine the main chemical compositions of the OPC by weight percentage, including the CaO (63.1%), SiO2 (20.1%), and Al2O3 (5.4%), whereby the total of loss on ignition (LOI) was 2.2% of the weight percentage. The mineral compounds of OPC, provided by the X-ray diffraction (XRD) pattern analyses, consist of dicalcium silicate (C2S), tricalcium silicate (C3S), tricalcium aluminate (C3A), and calcium aluminoferrite (C4AF) with the proportion of 9.3%, 74.9%, 6.7%, and 9.1%, respectively, as shown in Figure 5.1. The low amorphous part of OPC was shown between 2θ 25–55 degrees. The XRD pattern of OPC exhibits high pecks of C2S and C3S. These kind of elements will contribute to formulate the portlandite (Ca[OH]2) during the hydration process. Silicate minerals in non-crystalline or an amorphous state are highly reactive with Ca(OH)2 produced from the hydration of cement to form additional calcium silicate hydrate (C-S-H) gels.
Cement
Published in A. Bahurudeen, P.V.P. Moorthi, Testing of Construction Materials, 2020
[SSC JE 2012] Out of the constituents of cement, namely, tri-calcium silicate (C3S), di-calcium silicate (C2S), tri-calcium aluminate (C3A) and tetra-calcium aluminoferrite (C4AF), the first one to set and harden is C3AC4AFC3SC2S
Mechanisms of Concrete-Polymer Interactions
Published in Satish Chandra, Yoshihiko Ohama, in Concrete, 2020
At this time the structure consists mainly of long, interlocked fibrous CS hydrates, which bridge a considerable part of the originally water-filled space. During the next stage of hydration from about 24 h up to the end of the reaction, the pores (still empty) become filled by new hydration products. During this stage aluminoferrite C4AF hydrates and tetra calcium aluminoferrite hydrate C4AFH13 are formed. Aluminoferrites form hydration phases similar to those of the aluminates in which F replaces part of A. Further, the formation of ettringite is almost complete at this point. This means that all the sulfate ions are consumed. The C3A, still present in this case, reacts with ettringite and is converted to monosulfate:
Solidification/stabilisation of Pb (II) and Cu (II) containing wastewater in cement matrix
Published in Environmental Technology, 2023
Soumitra Maiti, Jaideep Malik, Basheshwer Prasad, Ashwani Kumar Minocha
Ordinary Portland Cement (OPC) of 43 grade (IS: 8112:1989) was utilised as a cementitious binder in the present work. Physico-chemical properties of the raw materials determined as per IS: 4031: 1988 (Methods of physical tests for hydraulic cement method) and IS: 4032:1985 (Method of chemical analysis of hydraulic cement) are given in Tables S1 and S2, respectively. In cement sample around 90% of the particles are smaller than 66.58 μm and 10% of the particles are smaller than 7.32 μm as observed from particle size distribution (PSD) analysis. The mean size of the cement particles was found to be 30.81 μm. XRD pattern of unhydrated cement (see Figure S1) exhibits significant peaks of crystalline phases at 2θ value of 29.5°, 32.3°, 34.4°, 41.5°, 51.7°, 56.4° for alite; tri-calcium silicate (C3S) and at 23.2°, 32.4°, 47.5° for belite; di-calcium silicate (C2S). Minor peaks identified at 33.4° and 34.8° corresponds to tri- calcium aluminate (C3A), and tetra-calcium aluminoferrite (C4AF) interstitial phases, respectively. These four are the core crystalline phases of unhydrated OPC predominantly composed of oxide components of the calcium, silicon, aluminum, and iron. Major phase proportions of the cement are given Table S3. The TGA of OPC is given in Figure 1 for reference and explained in TG-DTG section.
Utilization of accelerated carbonation to enhance the application of steel slag: a review
Published in Journal of Sustainable Cement-Based Materials, 2023
Yue Wang, Jianhui Liu, Xiang Hu, Jun Chang, Tingting Zhang, Caijun Shi
Steel slag is an industrial co-product of steel manufacturing, which accounts for 15 to 20 wt. % of crude steel production [1,2]. The main minerals of steel slag include tricalcium silicate (C3S), dicalcium silicate (C2S), tetra-calcium aluminoferrite (C4AF), dicalcium ferrite (C2F), and RO phases (solid solution containing magnesium, iron, and manganese oxides) [3,4]. The low content of C3S and high content of γ-C2S phase result in poor hydraulic property of steel slag. When steel slag used as a mineral admixture for concrete directly, high content of f-CaO and f-MgO (about 5 to 10 wt. %) in steel slag might produce expansive internal stress, and causes volume instability at late ages [5]. Several methods including physical, chemical, and thermal activation have been proposed to improve the hydration activity and eliminate the soundness problem of steel slag [6]. However, these methods usually need high temperature and high gas pressure, which consume great amounts of energy and are diseconomy [7].
Nonlinear models to predict stress versus strain of early age strength of flowable ordinary Portland cement
Published in European Journal of Environmental and Civil Engineering, 2022
Wael Emad, Ahmed Salih, Rawaz Kurda, Panagiotis G. Asteris, Aram Hassan
The characteristic peaks of brushite and cassiterite at 25° are visible at 2θ = 19°, and 23.15° for both polymers with more intensity for polymer A than polymer B (Figure 3(a)). Aluminate Tricalcium (Ca3Al2O6), Tricalcium Silicate (Ca3SiO5), Tetra calcium Aluminoferrite (Ca4Al2Fe2O10), Quartz (SiO2) and Dicalcium Silicate (Ca2SiO4) are the main components of the cement as presented in Figure 3(b). Figures 4 and 5 show the percentage of the composition of the cement which was used in this study. The scanning electronic microscope results for the polymeric admixture, cement, and cement treated with 0.06% polymeric admixture after one week of curing. The SEM results are presented in Figure 4 showed that the cement particle size is composed of various sized particles ranging between 14.4 µm and 42 µm. According to the scanning electron microscope test analysis, the polymeric admixture particles did not have a crystalline shape and were amorphous. Figure 4(b) showed that most polymers A is made up of close-spherical particles with rough surfaces. Compared to polymer A, polymer B particles were near-spherical with a smooth surface, as shown in Figure 4(c). The polymeric admixture particles and the particles of other materials have an attractive property to each other.