Drying Shrinkage of MKG

The drying shrinkage of geopolymers represents a significant constraint on their potential application as construction materials. This chapter investigates the drying shrinkage of MKG with different initial water/solid ratios and pore structures. Experiments using mini-bar shrinkage techniques reveal a two-stage behavior in the relationship between drying shrinkage and water loss of MKG. Although the initial water/solid ratio affects the crucial water loss and length of the shrinkage curves’ stopping phase, it has little impact on the overall trend. Through microstructure analysis and physical estimate, the underlying dependence of the shrinkage on the pore structure of the binder is clarified. During different stages of water loss, capillary pressure, surface energy changes, and gel densification are the dominant factors that contribute to the drying shrinkage of MKG. The findings indicate that in addition to porosity control, finer tuning of the pore size distribution is necessary to regulate the drying shrinkage of MKG.