“…TMPC (M/P ratio 3 and P/L ratio 3.0 g/mL) possessed the highest early compressive strength (94 MPa at day 3), higher than the international standard of ISO 5833 and similar to the commercial PMMA bone cement (Osteopal @ V) ( Fig. 5 b) [ [25] , [34] , [43] , [44] ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The porosity of TMPC-2, TMPC-3 and TMPC-4 was 19.99%, 23.72% and 22.09%, respectively. Despite the higher porosity compared to MPC cement [ 34 ], the pore size distribution was relatively small. Specifically, the average pore diameter of TMPC-2, TMPC-3 and TMPC-4 was 92.23, 27.85 and 26.7 nm, respectively.…”
“…TMPC (M/P ratio 3 and P/L ratio 3.0 g/mL) possessed the highest early compressive strength (94 MPa at day 3), higher than the international standard of ISO 5833 and similar to the commercial PMMA bone cement (Osteopal @ V) ( Fig. 5 b) [ [25] , [34] , [43] , [44] ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The porosity of TMPC-2, TMPC-3 and TMPC-4 was 19.99%, 23.72% and 22.09%, respectively. Despite the higher porosity compared to MPC cement [ 34 ], the pore size distribution was relatively small. Specifically, the average pore diameter of TMPC-2, TMPC-3 and TMPC-4 was 92.23, 27.85 and 26.7 nm, respectively.…”
“…The hydration reaction in the CSA is more exothermic than the one in the OPC. An exothermic peak with a broad shape was observed, indicating higher reactivity reaching up to 64 °C, with the final setting time for the reference sample SC0 at 10:45 h. As discussed earlier, hydration reaction products are formed in the induction period from 4 h to 24 h; here, mainly ettringite and monosulfate precipitated [ 134 ]. The hydration performance decreases steadily with the heat flux dropping to room temperature at 20 h. The partial replacement of the CSA with FA led to a temperature of 54 °C and delayed the final set to 11:15 h, while the VA delayed the set by up to 12 h and dropped the temperature to 45 °C.…”
Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements.
“…Based on the pore size, the pores in cementitious materials are classified into four types [49], which are gel pores below 10 nm, small capillary pores from 10 to 100 nm, large capillary pores from 100 to 1000 nm, and macropores above 1000 nm, among which the pores above 100 nm are the harmful pores. It negatively affects the mechanical properties and impermeability of the mortar.…”
Due to low early strength and high shrinkage, ordinary Portland cement (OPC) has difficulty meeting the actual needs of modern construction projects, while belite calcium sulfoaluminate cement (BCSA–OPC) composite cement provides a new solution. The mechanical and the drying shrinkage properties of the BCSA–OPC mortar were determined, the hydration heat of the BCSA–OPC was studied, and the pore size distribution of the mortar was investigated. In addition, the hydration products of the BCSA–OPC were analyzed by X-ray diffraction (XRD) and simultaneous thermal analysis (TG-DSC), and the microscopic morphology of the BCSA–OPC mortar was observed by scanning electron microscopy (SEM). The results show that with the increase in BCSA dosage in the BCSA–OPC, compared with OPC, the flexural strengths of the mortar of 50% dosage of BCSA at the hydration age of 1 d, 3 d, 7 d, and 28 d are improved by 33.3%, 36.6%, 23.6%, and 26.8%, and the compressive strengths are improved by 50.8%, 35.7%, 13.4%, and 27.7%. The drying shrinkage and total porosity of the mortar at the hydration age of 28 d are reduced by 117.4% and 21.55%, respectively. It is attributed to the filling effect of a large amount of ettringite (AFt) and intertwined with the fibrous C-S-H gel to form a network. This study will provide a theoretical basis for the application of the BCSA–OPC engineering.
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