Influence of dusty material content (<75 μm) in fine aggregate of construction and demolition waste in Portland cement mortars

Abstract

Recycled aggregates have a large amount of dusty material in their constitution, which in excess causes damages to the mortar properties. Here, the study of the influence of the dusty material contained in the fine recycled aggregate, from construction and demolition waste (CDW), on the properties of aggregate and mortars, is proposed. For that, the aggregate was characterized, and the contents of 0, 12%, 20%, and 30% of dusty material of CDW were added to the mortars. Tests were done for the determination of consistency, compressive strength, mass density, absorption (capillarity and immersion), and dimensional variation. The results showed that the CDW dusty material did not interfere significantly in the properties of consistency, immersion absorption, and void index for additions of up to 12%. However, from the limit value of 20% of the NBR 15116 standard, the higher the content of dusty material used, the greater was the damage of the mortar properties. It was observed for the content of 30% of dusty material, a 40% drop in the compressive strength, and an increase of 28% in the immersion absorption in relation to the dusty content of 20%.