Effects of nonionic surfactants and external factors on stability of latex in cement paste

ABSTRACT To clarify why different surfactants affect stability of latex in cement paste and why many latexes qualified in standard stability test still coagulate when mixed with cement, several kinds of nonionic surfactants with different structures were selected to improve stability of latex and the interactions among cement, latex, and surfactant were discussed. Results show that a higher affinity of surfactant to polymer contributes to a higher stability of latex in cement paste. When surfactants have similar hydrophilic group with each other, surfactants with phenyl in hydrophobic group can more effectively improve stability of styrene–acrylate (SA) latex in cement paste than that with n‐alkyl. With the same hydrophobic group (octyl phenyl) in molecules, surfactants with shorter hydrophilic group show better stabilization effect on SA latex. The combined action of high Ca2+ concentration, high solid concentration, and mechanical shear during agitation process of cement paste is the decisive factor causing coagulation of latex. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45946.