Microstructural and Residual Properties of Self-Compacting Concrete Containing Waste Copper Slag as Fine Aggregate Exposed to Ambient and Elevated Temperatures

Abstract

In recent times, with rapid development in the construction sector, the use of enormous amounts of materials is required for the production of concrete. Fire penetrates concrete, leading to chemical contamination, small cracks, and lightening. These effects can significantly change the properties of concrete’s structure, reduce its strength and durability, and also change the behavior of the structure and lead to effects on the environment. An attempt was made to study the effects of elevated temperature on the mechanical characteristics of self-compacting concrete (SCC) with by-products including fly ash as a partial replacement for cement and waste copper slag as a partial replacement for fine aggregate at 0%, 10%, 20%, 30%, 40%, 50%, 60%, and 70%. The SCC specimens were subjected to elevated temperatures ranging from 200, 400, 600, and 800 °C, respectively, for a steady-state of two hours in a digital muffle furnace. The residual compressive strength, mass loss, ultrasonic pulse velocity, and residual density along with a visual inspection of cracks and color changes were observed. In this study, with over 400 °C temperatures, surface fractures appeared. The residual compressive strength (R-CMS) of all the individual temperatures of the SCC-WCS% mixes exhibited a gain in strength range from 31 to 34 MPa at 400 °C, 26 to 35 MPa at 600 °C, and 22.5 MPa to 33.5 MPa at 800 °C, respectively. Microstructural analysis of SCC-WCS% mixtures subjected to elevated ambient temperatures is carried out with a scanning electron microscope (SEM) and X-ray diffraction (XRD).