Production of high quality fine recycled aggregates using low energy grinding

Abstract

he recycling of construction and demolition waste (CDW) can contribute as a source of aggregates, materials whose production is increasingly difficult. It will also contribute to a reduction of inappropriate disposal of these residues. Different authors show that it is possible to produce high quality recycled aggregates, with low cement paste on its surface, using mineral processing operations. One option that has a good potential application is selective comminution, where an autogenous or a low charge ball mill can be used to remove the cement past adhered to the aggregates without much comminution of the aggregates itself, i.e., in a grain polishing mechanism. Despite the good results obtained for water absorption reduction as reported in the literature, there is a lack of research focused on the selective comminution of CDW quantifying the energy usage. The present work investigated the influence of selective grinding on the properties of fine recycled concrete aggregate, between 4.8 mm and 0.15 mm. The results indicated that it was possible to reduce the water absorption below 3% with an energy consumption of less than 5 kWh/t, thus confirming that low-energy selective comminution can be a useful alternative to obtain a high-quality recycled aggregate.