Simple Procedure for Determining Long-Term Chemical Shrinkage for Cementitious Systems Using Improved Standard Chemical Shrinkage Test

摘要

In the past 10 years, renewed research interest has shown the benefits of internal curing by incorporating prewetted lightweight fine aggregate (LWFA) in high-performance concrete (HPC). To determine the optimum LWFA content, information about the propensity for shrinkage in the cement paste, specifically the chemical shrinkage value, is needed. However, information is lacking on how to determine the long-term chemical shrinkage value for HPC with supplementary cementitious materials (SCMs) and/or shrinkage-reducing admixture (SRA). The purpose of this research was to identify a simple procedure to determine long-term chemical shrinkage values for given cementitious systems with SCMs and/or SRA. Several improvement to ASTM C1608 (dilatometry procedure) were investigated. An experimental prediction model was adopted and verified to estimate long-term chemical shrinkage values for portland cement systems containing SCMs and/or SRA. A recommended procedure is proposed to determine the long-term chemical shrinkage values for HPC systems containing SCMs and/or SRA, and a modification to a commonly used LWFA proportioning equation is suggested.