Residual mechanical properties of polypropylene fiber-reinforced concrete after heating

Abstract

This paper presents results from experimental studies on residual mechanical properties of fiber-reinforced concrete specimens exposed to elevated temperatures. Seven series of concrete mixes, including six series of polypropylene fiber-reinforced concrete and one series of plain concrete specimens, were tested after exposure to various heating temperatures and cooled down. The residual mechanical properties including compressive and tensile strengths, modulus of elasticity and cracking modes, as well as ultrasonic pulse velocity of fiber-reinforced and plain concretes are evaluated after heating-cooling cycle. The effect of temperature level, length and amount of polypropylene fibers content on residual mechanical properties is studied. Results from the experiments show that polypropylene fiber-reinforced concrete exhibit better performance compared to plain concrete. Different strategies, through varying amount of polypropylene fiber content (1–2 kg/m3) and fiber length, proposed to enhance residual compressive and tensile strengths and also minimize the splitting and cracking in concrete after exposure to fire.