High-Temperature Residual Compressive Strength in Concretes Bearing Construction and Demolition Waste (CDW): An Experimental Study

Abstract

The steady rise in the amount of waste generated daily worldwide and its concomitant stockpiling poses significant environmental issues. In an attempt to alleviate that problem while reducing the consumption of natural resources and contributing to a more sustainable construction industry, concrete technology research has focused on replacing natural aggregate with different types of waste. Little is known about the behaviour of such waste materials at high temperatures, however. The present study consequently aimed to analyse the effect of high temperatures on compressive strength in recycled aggregate-bearing concretes. Masonry, mixed and concrete waste products, jointly known as construction and demolition waste, CDW, were used as partial replacements for the natural material at ratios of 20% or 30%. The specimens were subsequently tested for compressive strength at 20 °C and after exposure to temperatures of 350 °C and 500 °C. The findings showed that at 350 °C compressive strength declined by 21% in materials containing 20% masonry waste, while the decline in materials bearing mixed recycled and recycled concrete waste ranged from 0 to 5%. The concrete with 30% masonry waste in lieu of natural aggregate exhibited a 32% loss in strength at 500 °C, whereas the loss in the other materials studied under the same conditions did not exceed 9.5%. The highest performance under heat stress was observed for concretes bearing 20% mixed recycled aggregate.