Effect of polymer latex on the efflorescence, drying shrinkage and microstructure of alkali-activated slag paste

This study investigated the performance of alkali-activated slag (AAS) paste modified with different levels of styrene-acrylic resin (SAR) polymer latex. The AAS paste samples were prepared using GGBFS of two different fineness levels and NaOH solutions with respective molarities of 10 M, 12 M, and 14 M. Polymer latex was added at levels of 2.5%, 5%, and 7.5% of GGBFS weight. The AAS paste with fine GGBFS and NaOH 12 M performed the better strength than that with coarse GGBFS. The AAS paste samples modified with SAR polymer latex up to 5% exhibited slightly increased compressive strength results but reduced the ultrasonic pulse velocity (UPV) values. Furthermore, the addition of polymer latex enhanced the microstructure and significantly reduced efflorescence and drying shrinkage results. C-(A)-S-H gel and hydrotalcite phase were the main reaction products of both the latex-free and latex-modified AAS paste samples, with no new reaction products generated by the addition of polymer latex.