Experimental study on compressive strength of recycled aggregate concrete under high temperature

Abstract

This research aims to study the effect of elevated temperature on the compressive strength evolution of concrete made with recycled aggregate. Demolished building concrete samples were collected from four different sites in Saudi Arabia, namely from Tabuk, Madina, Yanbu, and Riyadh. These concretes were crushed and recycled into aggregates to be used to make new concrete samples. These samples were tested for axial compressive strength at ages 3, 7, 14, and 28 days at ambient temperature. Samples of the same concrete mixes were subjected to the elevated temperature of 300°C and tested for compressive strength again. The experimental result reveals that the recycled aggregate concrete samples have good quality at ambient and elevated temperatures and are considered fairly close to the concrete made with natural aggregate. However, recycled aggregate concrete at high temperatures showed higher strength degradation than natural aggregate concrete, but with differences that do not exceed 5% to 10%. The concrete samples made from recycled coarse aggregates also reached the design strength. It can be considered acceptable, considering the high variation in the concrete's thermal response found in the literature.