Self-compacting concrete incorporating filler additives: Performance at high temperatures

An experimental investigation was conducted to evaluate the performance of self-compacting concrete (SCC) subjected to elevated temperatures. For this purpose, Portland cement (PC) was replaced with limestone powder (LP), basalt powder (BP) and marble powder (MP) in various proportioning rates. Half of the total specimens for each mix type were studied by adding polypropylene (PP) fibers to improve the understanding of the effect of PP fibers on the behavior of SCCs subjected to high temperatures. SCC mixtures were prepared with water to cement ratio of 0.33 and polypropylene fibers content was 2 kg/m3 for the mixtures containing polypropylene fibers. Specimens were heated up to elevated temperatures (200, 400, 600 and 800 °C) at the age of 56 days. Then, tests were conducted to determine loss in weight and compressive strength. Moreover, the change of ultrasonic pulse velocity (UPV) was determined and surface crack observations were made after being exposed to elevated temperatures. Experimental results indicate that a severe strength loss was observed for all of the SCC mixtures after exposure to 600 °C, particularly the concretes containing polypropylene fibers though they reduce and eliminate the risk of the explosive spalling. At higher replacement levels of LP, BP and BP further lower resudial strength was observed. In terms of percent residual properties, control mixture specimens performed better than filler additive specimens for all heating cycles.