ABSTRACT
Recycling of elements of concrete structures at the end of their working life as components of new structures is difficult, with the exception perhaps of some precast elements. This chapter discusses the recycling of unused fresh concrete and the recycling of structural concrete after it has been crushed and processed into aggregate-sized particles to produce recycled aggregates. After demolition, the large lumps of concrete are fed through a crushing machine; the steel reinforcement and timber and others are removed and the resulting particles are then passed through screens to divide them into size fractions, as for primary aggregates. Only the coarse aggregate sizes are normally used since the finer material often has a high absorption, which can lead to an excessive water demand in the fresh concrete. The recycled concrete aggregate (RCA) particles will comprise the original aggregate with quantities of mortar and paste bonded to the surface.
