Effects of the Parent Concrete Properties and Crushing Procedure on the Properties of Coarse Recycled Concrete Aggregates

Abstract

Fine tuning of concrete recycling processes requires a comprehensive understanding of the overlapping interactions and effects of the various influencing parameters. The most important parameters associated with recycled concrete aggregate (RCA) production that may affect quality and yield include such properties of the parent concrete as the composition, strength and aggregate grading, type of crushers used, number of crushing stages, the size of the RCA particles, and the size reduction sequence. The effects of such parameters overlap and interact with one another and render it impossible for firm conclusions to be drawn on the effects of one parameter in isolation as evidenced by results reported in available literature. The present paper reports on the findings of an experimental study on the concomitant effects of the strength of the parent concrete, size of the natural aggregates used in the parent concrete, and the number of crushing stages on the properties of coarse recycled concrete aggregates, including mortar content, water absorption, bulk density, Los Angeles abrasion loss, and compressive strength of the recycled aggregate concrete. The study is confined only to granitic coarse aggregates, as this is the only type used in Singapore for ordinary concrete.