Effect of Polypropylene Fibers on the Behavior of Dune Sand Concrete Subjected to Elevated Temperatures

Abstract

In the field of civil engineering, concrete is one of the most used materials. Above a particular temperature, concrete can exhibit thermal instability during fire events. Improving the safety of buildings and structures is an important issue of this study. This paper investigates the effects of adding polypropylene fibers to dune sand concrete at high temperatures. Prismatic specimens (4 x 4 x 16 cm³) are produced, and stored until the concrete is hardened. The samples are then subjected to a heating-cooling cycle, starting from room temperature and increasing by 0.1 °C/min until reaching 600 °C. The length and the rate of polypropylene fibers are examined to determine their impact on compressive strength, porosity, and weight loss at temperatures of 80, 150, 300, 450, and 600 °C. Also, the partial replacement of dune sand (DS) with river sand (RS) is investigated. The results show that, for temperatures below 450 °C, the strengths of dune sand concretes varied from 29 to 39% compared to those obtained with concretes subjected to an ambient temperature (20 °C). However, it should be noted that residual compressive strength values decrease at most temperatures with the addition of polypropylene fibers. Furthermore, sand concrete with 50% DS and 50% RS shows an increase in compressive strength of 43.77% compared to that obtained by 100% DS concrete.