Influence of steam curing on hardened properties of recycled aggregate concrete Available to Purchase

The effects of steam curing on the hardened properties of recycled aggregate concrete were investigated. In this study, two series of concrete mixtures with water/cement ratios of 0·55 and 0·45 were prepared. Recycled aggregates were used as 0, 20, 50 and 100% by volume replacements of natural coarse aggregate in the concrete mixtures. The concrete specimens underwent standard water-curing and steam-curing regimes. The test results showed that the strength of concrete decreased as the recycled aggregate content increased. An initial steam-curing regime increased the one-day strength of the concrete, but the corresponding 28- and 90-day strengths decreased. Furthermore, steam curing reduced the static modulus of elasticity of concrete compared with that of the water cured concrete. However, the negative effect of steam curing diminished as the recycled aggregate content increased. Moreover, steam curing decreased the drying shrinkage and increased the resistance against chloride ion penetration of the recycled aggregate concrete. The results demonstrate that one of the practical ways to utilise a higher percentage of recycled aggregates in concrete is ‘precasting’ with an initial steam curing stage immediately after casting.