Durability of recycled aggregate concrete

Abstract

Synopsis: The results of an experimental investigation into the mechanical properties and durability of recycled and natural coarse aggregates concrete are reported. A total of thirty six specimens were tested. The percentages of replacement of coarse aggregates with recycled aggregates in the concrete mixes were 0%, 50% and 100%. The source of recycled aggregates in this study was from the concrete specimens tested in the laboratory. These specimens were crushed and then sieved into medium aggregates (4.75-9.5 mm) and coarse aggregates (9.5-19mm). The replacement of fine aggregates was not considered in this study. The properties of concrete mixes containing natural aggregates as control mix and those containing Recycled Concrete Aggregates (RCA) have been studied, including fresh properties, mechanical properties and durability. The influence of saturation state of RCA (dried or saturated) on the properties of concretes of identical compositions has first been studied. The theoretical amount of absorbed water is added at the beginning of mixing. Durability performance of hardened concrete made with recycled aggregates as partial or full replacement of natural coarse aggregates is reported. Resistance to pure water and sulfate attack is investigated. The results show that a replacement ratio of 50% does not have significant effect on the performance of recycled aggregate concrete mixes. Moreover, the recycled aggregate concrete performs relatively satisfactorily under various conditions and has a comparable durability to natural aggregate concrete if properly designed.