Correlation between the adsorption behavior of colloidal polymer particles and the yield stress of fresh cement pastes

Correlation between adsorption behavior of colloidal polymers on cement grains and yield stress of fresh cement pastes (fcps) is studied using four polymer latexes with varied surface charge density and glass transition temperature (Tg). Adsorption isotherm of the polymers is divided into two stages: before and after adsorption plateau. Higher charge density and lower Tg are beneficial to adsorption of polymer on cement grains. Before adsorption plateau, the adsorbed polymer particles play a bridging effect among cement grains which firstly increases and then decreases with increasing surface coverage ratio. Maximum bridging effect occurs at surface coverage ratio of ca. 20%. After adsorption plateau, yield stress of the fcps is significantly lower than that of the blank fcp because the adsorbed polymer layer reduces interaction force between cement grains, by increasing the minimum distance between two cement grains and generating repulsive force due to negative charges of the polymer particles.

Automated summary

The correlation between the adsorption behavior of colloidal polymers on cement grains and the yield stress of fresh cement pastes was studied, revealing that higher charge density and lower glass transition temperature of polymers facilitate their adsorption on cement grains. The bridging effect of the adsorbed polymer particles peaks at a surface coverage ratio of approximately 20%. The reduction in yield stress of fresh cement pastes after the adsorption plateau is attributed to the decreased interaction force between cement grains due to the presence of the adsorbed polymer layer.