Evaluation of total replacement of natural sand by CDW in masonry mortars

Abstract

The high generation of construction waste (CW) and the problems caused by the incorrect disposal of this waste as well as the scarcity of natural resources increase the number of studies to reuse CW in cementitious matrices. However, few studies are performed on non-processed fine recycled aggregates (less than 4.75mm). The objective of this work is to evaluate the use of the thin section of the CW as a total substitution of natural sand in masonry mortars by characterizing aggregates and mortar properties in the fresh and hardened state and checking temporal influence of the residue for six months. Seven mortars were made, one with the natural aggregate, and another six for each month of waste collection, with the total replacement of the natural aggregate by the recycled aggregate. The mix used in mortars was 1: 1: 6 (cement: lime: aggregate) by mass. The results show that recycled aggregate mortars had lower results for density, water retention, flexural and compressive strength and superior results for capillary water absorption when compared to natural aggregate mortar. In general, recycled aggregates remained constant over time analysed. However, the recycled aggregates have reached limits above the minimum allowed by Brazilian standards, being a viable alternative to their use in mortars.