Effect of wetting-drying cycles on physical and mechanical properties of a recycled construction and demolition material

Abstract

Recycled Construction and Demolition (C&D) materials are progressively being used in civil engineering applications, such as base and sub-base layers of transport infrastructures. However, the knowledge related to the long-term behaviour of recycled aggregates in geotechnical and pavement applications is very scarce. The breakage of the particles, particularly when the recycled aggregate has clay masonries, is commonly pointed out as an issue for the usage of these recycled materials. A laboratory study was undertaken to investigate the effect of wetting-drying (W-D) cycles on geometrical, physical and mechanical properties of a mixed recycled aggregate coming from C&D waste. The effects of the number of cycles (10 and 20 W-D cycles) on particle size distribution, shape and flakiness indexes, particles density, water absorption, sand equivalent, methylene blue, water-soluble sulphate content, Los Angeles abrasion and aggregate crushing value were assessed. This study shows that W-D cycles have caused a slight degradation of the recycled aggregate, even if the effect of the number of cycles (above 10) is not quite relevant. LA abrasion loss of this mixed recycled aggregate is high, making its application as unbound material in pavement layers impracticable without additional measures.