An experimental study on the residual mechanical properties of fiber reinforced concrete with high temperature and load

The effects of high temperature and fiber content on the residual mechanical properties of concrete have experimentally investigated. In this paper, residual mechanical properties of high-strength and normal strength concretes made with different water to cement (w/c; 0.55, 0.42 and 0.32) ratios exposed to high temperature were compared with those obtained in fiber reinforced concretes with similar characteristics ranging from 0.05 to 0.20 % polypropylene (PP) fibers by volume of concrete. Also, variables including pre-load level of 20 and 40 % of the maximum load at room temperature were considered. Concrete specimens prepared with the variables were tested for outbreak time, thermal strain, length change, weight loss, compressive strength, modulus of elasticity and energy absorption capacity. It is seen that the cross-sectional area of PP fiber can influence the residual mechanical properties and the spalling tendency of concrete of fiber reinforced concrete exposed to high temperature from the results. Especially, the external loading influenced to increase not only the residual mechanical properties of concrete but also the risk of spalling and the brittle failure tendency.