Performance Evaluation of Sustainable High-Strength Lightweight Concrete Incorporating Wastes as Aggregates at Elevated Temperatures

Abstract

The purpose of this paper was to assess the effect of upcycling crushed lightweight bricks and plastic waste on the hardened properties of structural lightweight high-strength concrete before and after exposure to elevated temperatures. The lightweight concrete under study was prepared with sand, lightweight crushed bricks as fine aggregate, dolomite, coarse plastic waste, crushed lightweight bricks as coarse aggregate, Portland cement, silica fume (SF), and high-range water-reducing admixtures (HRWR). Besides the slump test, dry density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were investigated on the produced lightweight concrete. At the age of 28 days, the prepared samples were exposed to high temperatures of 100-800 °C in a preheated test furnace to evaluate the residual mechanical properties of the concrete. The experimental results showed that by increasing the aggregate replacement ratio, the workability slightly increased, and the mechanical properties of lightweight concrete decreased. It is also indicated that crushed lightweight bricks can be recycled as a replacement for natural aggregates to obtain high-strength lightweight concrete with appropriate properties. It has also been proven that crushed lightweight bricks and plastic waste can be used as fine and coarse aggregates to conserve natural resources without significantly deteriorating the properties of concrete. The incorporation of crushed lightweight bricks and coarse plastic waste into high-strength lightweight concrete showed better strength under elevated temperatures.