The mechanical properties of lightweight (volcanic pumice) concrete containing fibers with exposure to high temperatures

Fire is considered one of the main risks leading to building collapse. Lightweight concrete comprises a variety of components, each of which has a distinct behavior under the effect of temperature change. A total of 16 concrete mixtures were investigated in this article. A reference mix of concrete comprising simply ordinary Portland cement and ten mixes having varying percentages of fine and coarse lightweight aggregates (pumice), which were replaced gravel and sand by fine pumice and coarse aggregates pumice by 20, 40, 60, 80, and 100%, respectively. In addition, the study focused on the effects of adding fibers to lightweight aggregate concrete mixtures. Polypropylene fibers, carbon fibers, and steel fibers were employed as fiber additions. The binary mixture had higher density than the remaining mixtures containing one substitute. The behavior of six concrete mixes in addition to the reference mix of ordinary concrete after exposure to temperatures 100, 250, 350 and 450°C for 2 h and then cooled in two ways (water and air) as well as examined directly and the results showed that the concrete mixes containing fiber had better behavior compared to other mixtures, especially at high temperature. If left to cool in the air, the lightweight concrete containing volcanic pumice can recover its compression strength after being exposed to high temperatures.