Effect of Elevated Temperatures on Concrete Made with Ash from Wood Biomass and Recycled Polymer Fibers from Waste Rubber

Abstract

With the increasing awareness of global warming, largely due to the emission of large amounts of CO2, some attempts have been made to develop strategies to help combat the growing trend of global warming. To reduce the harmful effects of concrete production, efforts are being made to reduce the amount of cement used by replacing the cement with mineral additives to maintain or improve the properties of the concrete. In addition, the use of waste materials as substitutes for cement and other concrete constituents is being promoted and investigated. This paper presents an experimental study on the influence of ash from wood biomass (used as a cement substitute up to 30%) and the addition of recycled polymer fibers from waste rubber in an amount of 2 kg/m2 (used as a substitute for industrial polypropylene fibers) on the residual mechanical and durability properties of concrete exposed to high temperatures up to 600 °C. In addition, reference concretes were prepared using only cement and industrial polypropylene fibers for the comparison purposes. A total of 5 different mixes were tested. The following tests were performed on the concrete specimens before and after thermal treatment: compressive strength, static modulus of elasticity, ultrasonic pulse velocity and gas permeability. These properties represent the input parameters for the evaluation of the condition of reinforced concrete elements after exposure to fire. The obtained results show that the use of the investigated waste materials in concrete leads to comparable or slightly better properties after fire exposure compared to the reference concrete.