Effect of calcium sulfate whiskers on mechanical properties and enhancement mechanism of metakaolin-based polymer mortar

Abstract

Abstract In consideration of the requirements of the repair mortar environment and in conjunction with the characteristics of the CaSO4 whisker, the addition method of the CaSO4 whisker was employed to enhance metakaolin-base polymer mortar, aiming to achieve reinforcement and toughening effects. Through experimentation, the influence of varying mass percentages (0.5%, 1%, 1.5%, 2%, 2.5%, and 3%) of calcium sulfate whisker on metakaolin-based polymer mortar was studied, focusing on rational energy utilization and mechanical properties. Optimal performance and mechanical strength were determined by proposing an appropriate content of calcium sulfate whisker and liquid-solid ratio for metakaolin-based polymer mortar, while microscopic experiments were conducted to analyze the strengthening mechanism behind polymer mortar with calcium sulfate whisker. The experimental findings show that with an increase in the calcium sulfate whisker content, the setting time of metakaolin-based polymer mortar initially rises, then declines, reaching the maximum setting time at 1% content. Additionally, at a liquid-solid ratio combined with a content level of 1.5% for calcium sulfate whisker, both bending and compressive strength are optimized for metakaolin-based polymer mortar. Calcium sulfate whiskers can alleviate the stress concentration at the tip of cracks within the geopolymer mortar, hindering crack development, and the bridging effect of the whiskers and the interface of the geopolymer mortar matrix in the high territories realizes the overall strengthening and toughening.