Abstract

Reducing the use of natural resources and replacing it with waste material to avoid problematic landfills has been the principal focus of an emerging and important recycling market in most developed countries. Crushed concrete and masonry waste can be suitable for replacing coarse aggregate in concrete. When crushed masonry is used, compressive strength is lower and the material’s high porosity affects durability and shrinkage. With crushed concrete aggregate the compressive strength and durability depend on the quantity of attached mortar, which is responsible for higher porosity, weak zones in the aggregate, and is also related to the new concrete durability. Smart crushers liberate more adhered mortar and could provide a good solution.

Methods to guarantee the quality of production are applied, but in homogeneity of the concrete waste of different origins continues to inspire distrust in many consumers, who continue to prefer the use of sub base material in roads. Irregularity of the distribution of chlorides or other contaminants makes the quality control a complicated process, but combined analysis of durability and sustainability as well as the use of indicators and models can be a solution. In situ recycling with only one origin of concrete can assure homogeneity.

Many research papers imply the need of using more cement to compensate for the differences in properties compared to concrete with primary aggregates.