Effect of the combined use of polyacrylamide and accelerators on the static yield stress evolution of cement paste and its mechanisms

Abstract Chemical admixtures enhance concrete’s properties and performance, addressing diverse construction needs. This study investigates the effects of polyacrylamide (PAM) in combination with the accelerators calcium chloride (CaCl 2 ) and triethanolamine (TEA) on the early hydration of cement, with a particular focus on static yield stress. To assess the impact of these admixtures on hydration kinetics and material properties, we employed various analytical methods, including calorimetric tests, thermogravimetric analysis, X-ray diffraction, inductively coupled plasma experiments, and the penetration method. The results indicate that CaCl 2 accelerates the early hydration of C 3 S, promoting the formation of C–S–H and CH while facilitating the conversion of AFt to Friedel’s salt. PAM helps to regulate AFt behavior, reinforcing the beneficial effects of CaCl 2 . Additionally, TEA influences the hydration of C 4 AF, enhancing AFt precipitation, while higher dosages modify early hydration dynamics by delaying C 3 S hydration. The interaction between PAM and TEA enhances clinker dissolution, significantly increasing static yield stress through complexation reactions mediated by iron ions. These findings highlight the potential for tailored admixture formulations that combine PAM with traditional accelerators to optimize cement hydration and improve material performance.