Mechanical Properties and Microstructural Changes in EVA Polymer Mortar Exposed to Elevated Temperature

The contribution of ethylene vinyl acetate (EVA) to enhancing cement properties, especially in terms of thermal stability and microstructural changes under elevated temperatures, has not been fully clarified. This research conducted comprehensive experiments to determine the heat-induced damage of EVA mortar and contrasted it with the control group subjected to high temperatures. The results indicate that EVA improves mortar’s resistance to heat-induced degradation through gasification and decomposition processes. Notably, a strong correlation between compressive strength and ultrasonic pulse velocity (UPV) is observed. Moreover, the new phase existence of calcium acetate (CA) further reveals EVA’s active participation in the cement hydration, increasing the content of ettringite (AFt) and calcium hydroxide (CH). Finally, microscopic analysis reveals voids formation due to calcium silicate hydrate (C-S-H) dehydrates after high thermal treatment. This research offers valuable insights for the utilization of EVA in construction projects subjected to elevated temperatures.