Comparison of the retarding mechanisms of sodium gluconate and amino trimethylene phosphonic acid on cement hydration and the influence on cement performance

ATMP and SG were effective hydration retarders of cement. The goal of this study was to provide the comparison of the influence of ATMP and SG on the performance and hydration of Portland cement. The setting time at 20 °C and 35 °C, compressive strength and fluidity of cement pastes containing either ATMP or SG at different dosages from 0.02% to 0.10% were tested respectively. The hydration behaviors of Portland cement with ATMP and SG were investigated by the means of isothermal calorimetry measurements, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The results showed that the retarding effect of ATMP was much intensive than SG, especially in the case of a higher temperature; the “dispersion loss resistant” of ATMP were superior to SG; The limitation dosage of ATMP and SG was 0.15%; Although SG could reduce cement hydration cumulative heat and hydration evolution rate at some degrees, the effect was much weaker than ATMP. ATMP continued to inhibiting the hydration of C3S effectively during the whole hydration period. SG was also inhibiting the hydration of C3S during the hydration of 1d, but it promoted the hydration of C3S beyond 1d at some degrees.