The Influence of Fine Sand from Construction-Demolition Wastes (CDW) in the Mortar Properties

Abstract

A fine fraction of recycled aggregates from the processing of construction and demolition waste (CDW), have a very effective potential use in mortar as a partial fine aggregate replacement for natural sand, an also contribute to the development of sustainable materials, specifically to produce coating mortar. This paper presents the results of a study using recycled aggregate in mortar as a replacement for natural sand, analyzing the effects of pre-wetting and the performance in mortar composition with a fine sand (1.2/ 0.15 mm). In this study was investigated the behavior of recycled aggregate dry and wet previously until to saturated surface dry condition (reaching this value by capillary absorption test of the granulometric prepared curve). Five different compositions have been defined, varying the quantity of fine and determined the physical properties of recycled aggregate. Then the mortars were prepared and evaluated in the fresh state: specific gravity, water retention and workability, and in the hardened state: hygrothermal and mechanical properties. The results showed that the wetting of the aggregate affects the properties of the mortar, as well the addition of fines. There is an advantage when is realized wetting of the recycled aggregate CDW. The addition of fine in mortars must be controlled, and the fine aggregates improved the almost properties and in excess can reduce the hygrothermals properties.