Post Heat Exposure Properties of Steel FiberReinforced Concrete

Abstract

In this work, five destructive and nondestructive tests using three different types of specimens were carried out to study the mechanical properties of steel fiber reinforced concrete before and after exposure to elevated temperatures. Forty-five (100 mm) concrete cubes were used to investigate both concrete compressive strength and ultrasonic pulse velocity (UPV), while the flexural strength and dynamic modulus of elasticity (ED) were studied using forty-five (100x100x500 mm) prisms. Also, the splitting tensile strength was studied using (100 mm) diameter and (200 mm) height cylinders. These specimens were heated to four temperature levels of (150, 350, 500 and 700 oC). A single concrete mix with three steel fiber contents (Vf %) of (0.0, 0.5 and 1.0 %) by weight was adopted. The test results of this study show that the use of steel fibers enhance the brittle mode of elevated temperatures affects all concrete properties, however, the amount of strength decrease depends mainly on the type of stresses in each test and on the level of temperature. Another observation is that the presence of steel fibers enhances splitting tensile strength, flexural strength, and ED significantly, while this effect seems to be less significant or even insignificant for compressive strength and UPV.