An advanced insights into the effect of diethanol-isopropanolamine on chloride distribution and mechanical strength of high-volume slag cement with chloride addition

A portion of chloride salt is usually introduced to improve the early strength of slag cement, but it increases the possibility of chloride corrosion. This study investigates the effect of diethanol-isopropanolamine (DEIPA) on the chloride distribution and mechanical strength in a high-volume slag cement (HVSC) system containing 60 wt% slag and 1.11 wt% NaCl. In the absence of NaCl, DEIPA enhanced the aluminate reaction of HVSC, producing more hemicarbonate. As a result, DEIPA addition increased the formation of Cl-AFm phases, leading to the improved chloride binding capacity in the presence of NaCl. Instead of pure Friedel’s salt, a solid solution (FS SS ) between hemicarbonate and Friedel’s salt was formed throughout the entire hydration period. The molar ratio of Friedel’s salt within this solid solution was influenced by the hydration age rather than the DEIPA content. An increase in DEIPA content decreased the amount of reversibly bound chloride on C–A–S–H, which was closely associated with water-soluble chloride contents. Irreversible chloride binding on C–A–S–H was also indirectly confirmed but seemed to remain unaffected by DEIPA dosage. Consequently, DEIPA improves the irreversible chloride binding capacity of HVSC by enhancing the formation of FS SS , which provides stable chemical binding sites. Regarding mechanical performance, A higher DEIPA content decreased 7-day strength by reducing the C-A-S-H formation, which offset the effect of improving the early strength of HVSC by chloride salt. The 56-day strength partially recovered with increasing the DEIPA content as it improved slag reaction.