Early-Age Shrinkage of Ultra-High-Performance Concrete under Drying/Wetting Cycles and Submerged Conditions

Abstract

Concrete is usually subjected to early-age variation in temperature, relative humidity (RH), wind, and other environmental loading that can alter its behavior. In this study, the early-age shrinkage behavior of ultra high-performance concrete (UHPC) is investigated under simulated field conditions. In this article, the effects of shrinkage mitigation methods, including a shrinkage-reducing admixture (SRA) and a super-absorbent polymer (SAP), were explored. The simulated field conditions included drying/wetting (DW) cycles and submerged (SM) conditions, and were compared to sealed and drying conditions under constant temperature and RH. The results in this article show the substantial influence of environmental conditions on the shrinkage behavior of UHPC. It was discovered that exposure to simulated field conditions dismisses the effectiveness of using SRA through a washing-out mechanism. Moreover, incorporating SRA and SAP simultaneously optimized their benefits and allowed for overcoming their deficiencies under various exposure conditions. The article concluded that adequate consideration of in-place conditions in testing protocols of UHPC should allow for gaining a better understanding of shrinkage mitigation mechanisms and developing suitable performance specifications before a wide implementation of UHPC in full-scale field construction.