Rational Procedure for Composition of Screed Mortar with Recycled Sand at a Construction Site

Abstract

The aim of this work is to present a rational procedure for the composition of screed mortar with recycled sand at a construction site. Seven samples of construction and demolition waste were collected and milled in a hammer mill. The properties of the recycled sands were analyzed: water absorption, material finer than 75 μm, bulk density, fineness modulus, and presence of contaminants. Mortars were produced with different amounts of cement and by replacing the natural sand with recycled sand in the proportions of 50, 75, and 100% by mass. These mortars were characterized for tensile and compressive strength, density, and consistence. The screed mortars were applied over a concrete base and their performance was evaluated with regard to cracking, bond tensile strength, and impact resistance. Several correlations were obtained between the properties of aggregates, mortar, and screed, leading to a proposed methodology for recycling, dosage, and quality control of screed mortar prepared with recycled sand at a construction site. It is recommended for the screed mortar to have a cement consumption between 250 and