Physico-chemical interaction between mineral admixtures and OPC–calcium sulfoaluminate (CSA) cements and its influence on early-age expansion

Abstract

The present study aims at examining the physico-chemical factors influencing the expansion characteristics of OPC-CSA blend in the presence of mineral admixtures. Three different admixtures: Class ‗F' fly ash (‗F'FA), Class ‗C' fly ash (‗C'FA) and silica fume (SF) were used as 15%, 15% and 5% replacement of total cementitious binder. Longitudinal expansion of cement pastes prepared at w/cm-0.44 showed that the Class ‗F'FA increased the expansion whereas the Class ‗C'FA and SF reduced the expansion. The pore solution of the OPC-CSA cement pastes was extracted at different ages to monitor the concentration of various ionic species. The saturation level of ettringite was determined using a geochemical modeling program (GEMS). Furthermore, an upper bound of crystallization stress was estimated. The expansion behavior in the presence of Class ‗F'FA and SF was found to be influenced by the changes in the stiffness, whereas the expansion of the Class ‗C'FA-based mixture was governed by faster hydration of ye'elimite.

Recycling of Reverse Osmosis (RO) Reject Water as a Mixing Water of Calcium Sulfoaluminate (CSA) Cement for Brick Production

“…Thus, sample C showed the strongest peaks of monosulfate and kuzelite, whereas the RO sample showed the strongest peaks of Friedel's salt in the XRD results, particularly at 28 days. In addition, in all samples without gypsum, despite the small amount of calcium sulfate (~0.7 wt%) in the CSA cement of this study, ettringite (Ca 6 Al 2 (SO 4 ) 3 (OH) 2 •26H 2 O) was also identified, although its XRD peaks were relatively weak, a result similar to those found in earlier studies [36][37][38].…”

Advances in understanding ye'elimite-rich cements

“…• Densification of the microstructure; similar to what observed with the reactions of SCMs at advanced ages in the OPC system, the space occupied by the water at the beginning is gradually filled by hydrates which limits further hydration [130][131][132].…”

Utilization of Several Industrial Wastes as Raw Material for Calcium Sulfoaluminate Cement

“…The refined parameters included phase scale factors, background coefficients, zero-shift error, lattice parameters, peak shape parameters, and preferred orientation, if needed. As for reliability of the data, with the software’s “goodness of fit” setting fixed to <4, the fitted curve matched well with the raw data [23,24,25].…”