Mechanisms of mechanical performance variations in cement with diethanol-isopropanolamine addition: Insights from a hydration perspective

This study systematically investigates the effects of diethanol-isopropanolamine (DEIPA) on the mechanical properties of pure and limestone powder (LP) composite cement systems. The underlying mechanisms driving the observed strength changes were explored from a hydration perspective using QXRD , ICP, calorimetry and thermodynamic calculations . The results demonstrate that DEIPA effectively improves the compressive strength of pure cement, although a temporary reduction in strength was observed at 3 days. In contrast, DEIPA consistently enhanced the strength of the PC-LP composite cement system throughout hydration. DEIPA significantly increased the concentration of iron ion in the pore solution , thereby promoting the hydration of C 4 AF. While DEIPA also stimulated the hydration of silicate minerals , a slight delay was noted at 3 days, likely due to the preferential hydration of C 4 AF at this stage. In the PC-LP system, DEIPA accelerated the activation of C 4 AF, alleviating the early inhibition of silicate mineral hydration. The presence of LP further influenced the hydration of C 3 A and C 4 AF after gypsum depletion, promoting greater volume expansion through the formation of the Hc- and Mc-dominated AFm phases. QXRD results are integrated into thermodynamic simulations to calculate solid volume changes during hydration, showing good agreement with the measured compressive strength development. • DEIPA substantially promotes C 4 AF hydration at 3 days, though it slightly inhibits the hydration of C 3 S. • The different stages of hydration of C 3 A/C 4 AF are revealed from the perspective of volume expansion. • DEIPA lowers 3-day strength, but LP mitigates this, enhancing early compressive strength . • QXRD and GEMS thermodynamic simulations are employed to calculate the solid volume of each sample.