Using Washed Construction and Demolition Waste as Recycled Aggregate in Structural Concrete

Abstract

The construction industry consumes large amounts of natural resources and generates vast quantities of waste. This has motivated the scientific community and construction sector to promote the use of construction and demolition waste (CDW) and industrial by-products as raw materials to improve the sustainability of construction materials. This work analyzes the possibilities of reusing CDW provided by a waste management company as recycled aggregate in structural concrete. This CDW was washed several times to reduce its sulfate content. The particle size distribution, percentage of fines, water absorption and density of the natural and recycled aggregates were analyzed, and three different concrete mixes were developed: reference (Ref., 100% natural aggregates); 50 vol.% and 100 vol.% replacement of the natural limestone sand with the recycled CDW sand (CDW50 and CDW100, respectively). After determining the concrete mixes’ workability, samples were cured at 20 ℃ and 95% relative humidity for 7 and 28 days, and their compressive strength and density were determined. The results showed that the CDW recycled aggregates were lighter and had higher water absorption values than the natural limestone sand. Fresh concrete workability improved in the recycled aggregate concrete. Although the density and compressive strength values progressively lowered with increasing amounts of the recycled sand, the strength values were high enough for use in several applications. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.