An Analysis of the Shear Strength and Rupture Modulus of Polyolefin-Fiber Reinforced Concrete at Different Temperatures

Abstract

Structural engineers are generally aware of the intrinsic safety properties of concrete exposed to fire (non-flammability at high temperatures). However, the tendency of concrete for spalling at high temperatures is a significant defect, and recently many researchers have conducted studies on this issue. One of the primary objectives of this study is to assess the shear strength and modulus of rupture of concrete reinforced with different percentages of modified polyolefin synthetic fibers at different temperatures and to compare the results with the preliminary design. The other objective of the present study is to compare the behaviors of synthetic fiber concrete under the effect of the furnace temperature and direct fire. After adding fibers (1.5 volumetric percentage), a 29% increase in the tensile strength and a 56% increase in the modulus of rupture (the stress corresponding to the development of the first crack) were observed. Considering the fiber concrete results in the experimental temperature condition, it can put on an acceptable strength performance. However, at temperatures equal to or greater than 400 , the fibers lose their role in compensating the low tensile strength of concrete due to oxidation, causing porosity in the concrete and reducing its strength.