Experimental study on high temperatures performance of rubberized geopolymer mortar

Nowadays, fire accidents occur frequently, and both buildings and structures or traffic roads are threatened by fire to varying degrees, and the mortar structure is often in direct contact with fire. Therefore, it is necessary to study the performance of mortar under high temperature. Geopolymer is a new type of green environmental protection building material with good high temperature resistance. Waste rubber will soften and decompose under high temperature, and the holes formed can release the steam pressure inside the structure, which is helpful to ease the internal cracking of the structure. At present, it has been proved that waste rubber has a beneficial effect on the resistance of mortar to high temperature. The research of waste rubber in Portland cement mortar has made relevant achievements, but the research on the combination of geopolymer rubber is relatively small. Therefore, in view of this lack, this study supplements the material properties of geopolymer mortar under four rubber particle sizes (4, 1.7, 0.83, and 0.27 mm) and five temperatures (25, 200, 400, 600 and 800 °C), namely, surface observations, mass loss, compressive and flexural strengths, ultrasonic pulse velocity (UPV) and microstructure change. The results show that the addition of rubber particles will increase the mass loss of rubberized geopolymer mortar (RGM), but the advantage is that it can reduce the burst risk. The addition of fine particle rubber can improve the ability of RGM to resist cracking and deformation at higher temperatures. The results shows that the UPV can reflect the mass and intensity change of RGM laterally. The microscopic results shows that the main reason for the lower strength is the expansion of microcracks and pores in RGM matrix at high temperature. •The performance of rubberized geopolymer mortar (RGM) under high and normal temperature is tested.•The relationship between UPV and strengths (mass) of RGM at high temperature is discussed.•The microcracks and pores distribution, compound composition and matrix state of RGM at high temperature are characterized.