Effect of partially hydrated cementitious materials and superabsorbent polymer on early-age shrinkage of UHPC

In this study, the effect of adding partially hydrated cementitious materials (PHCMs) on the early-age shrinkage of ultra-high-performance concrete (UHPC) was investigated. The PHCM were added at rates of 25%, 33% and 50% of the overall batch weight. UHPC mixtures incorporating a superabsorbent polymer (SAP) were also tested for comparison. Combined effects of PHCM and SAP techniques in reducing early-age shrinkage were investigated. Results indicate a significant improvement in early-age compressive strength of UHPC mixtures due to PHCM addition. PHCM achieved excellent early-age shrinkage reduction when used alone or combined with SAP. PHCM mitigated undesirable behaviour induced by SAP, including high drying shrinkage and reduction in mechanical properties. The addition of PHCM provides an ecological and economic technique for producing precast and cast-in-place self-restraining shrinkage concrete. Indeed, recycling leftover/unused concrete as PHCM in new mixtures can enhance the sustainability of concrete and minimize disposal in ready mixed concrete operations. (C) 2012 Elsevier Ltd. All rights reserved.