Experimental Research on the Thermal Instability of Fiber Polypropylene Concrete at 250 °C

Abstract

The high temperature in the concrete destroys the hydrates of the cement paste. This destruction means the weakness of the materials caused by the deterioration of their mechanical properties. This work aims to study the behavior of high-performance fiber concrete sets at high temperatures; specifically, we used polypropylene fibers and studied their influence on deterioration behavior. This study includes high performance concrete and three types of fiber concrete, each containing a specific ratio of polypropylene fibers (0.12 %, 0.18 %, and 0.24 %). Consequently, cubic test specimens (15 cm x 15 cm x 15 cm) were subjected to the temperature of 250 °C, with a speed of 2 °C/min followed by a step of one hour at the target temperature then cooling to the ambient temperature. The results showed that fiber-reinforced concrete exhibited a better performance when exposed to the temperature studied. The mechanical properties were improved by up to 56% for compressive strength and 86% for tensile strength.

Research Status and Outlook on High Temperature Performance of Fiber Concrete

“…The three main aspects are as follows [3]: reduction of the crosssectional area and reduction of the load-bearing capacity of the member, and the high temperature in the concrete destroys the hydrates of the cement paste. This damage implies a weakness in the material due to deterioration of its mechanical properties [4]; some of the reinforcement will be exposed to the high temperatures of the fire due to the loss of the protection of the concrete and will soften rapidly due to the heat, resulting in a drastic reduction in the load-bearing capacity of the members and thus affecting the safety of the structure. Generally speaking, ordinary concrete materials have weak tensile strength and strain capacity, poor high-temperature resistance, and are typical brittle materials.…”