grading of RCA was within the limits for crushed-rock aggregate to BS 882 [11]. The main physical and mechanical characteristics of coarse RCA and NA are given in Table 1. It can be seen that RCA had 7 to 9% lower relative density and 2 times higher water absorption than NA, reflecting the porosity of the hydrate cement paste attached to RCA. The mechanical properties of RCA, as expected, were found to be somewhat lower than NA. A 42.5 N Portland cement conforming to BS 12 [12], a superplasticizing admixture to BS 5075: Part 3 [13], to maintain workability at a nominal slump of 75 ram, and for freeze-thaw test specimens, an air-entraining admixture conforming to BS 5075: Part 2 [14] were used.