Influence of crushing methods on the properties of recycled concrete aggregate

Abstract The main challenge regarding the use of recycled concrete aggregates (RCA) in high-performance building materials refers to the remaining cement paste from previous constructions that remains attached to natural aggregates surface. The properties of RCA can be improved through the selection of comminution equipment capable of promoting release in this interface zone. However, crushing methods are rarely discussed in the scientific literature. This paper aims to contribute to change this scenario, comparing the properties of RCA crushed by jaw and impact crushers, both adjusted in order to generate a product with the same granulometry. The result obtained was a similar product in terms of particle shape, and chemical and mineralogical composition, leading to the conclusion that the liberation of the residual cement paste on both crushing methods was analogous. This similarity between properties challenges the common belief that the impact crusher generates a product with lower grade of adhered cement paste and excessive fines.