Effect of cement type on hydration, microstructure and thermo-gravimetric behaviour of chloride admixed self-compacting concrete

This study reports effects of admixed chloride and cement type on behaviour of self-compacting concrete (SCC). Tests for fresh properties, compressive strength, chloride, X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) analyses, and Thermo-gravimetry analysis (TGA) were performed on SCC. Results obtained from the study indicated that admixed chloride has no significant effect on fresh properties of SCC. Ordinary Portland cement (OPC) based SCC admixed with chloride ions showed lower compressive strength as compared to control mix whereas in Portland pozzolana cement (PPC) based SCC, opposite variation was observed. Obtained results indicated higher chloride binding in OPC than PPC, which was confirmed by XRD results indicating formation of higher amount of calcium chloroaluminate (CCA) in OPC. Variations in calcium hydroxide (CH) content indicated by XRD spectra with cement type and curing age are corroborated with that calculated from mass loss in TGA. Departure of combined water due to dehydration of C-S-H, CH and CCA was higher in OPC than PPC. (C) 2019 Elsevier Ltd. All rights reserved.