Characterization of elastic and time-dependent deformations in high performance lightweight concrete by image analysis. http://dx.doi.org/10.1016/j.cemconres.2009.03.015

Abstract

Image analysis and strain mappingwere used to examine the nature of elastic, creep and shrinkage strains in high performance lightweight concrete (HPLC). The strain maps showed non-uniform deformations related to microstructural features. Both average strain and non-uniformity increased with time under testing. Paste-rich regions exhibited higher creep plus shrinkage than the lightweight aggregate (LWA) particles examined herein; it is suggested that LWA could have a role in reducing deformations of the paste. Compared to normal weight high performance concrete (HPC), the paste and LWA in the HPLC exhibitedmore gradual spatial differences in elastic deformations, creep and shrinkage. It is proposed that this difference results from the lower stiffness of the LWA compared to granite used in theHPC. The results indicate that improvement in elastic propertymatching between the lightweight aggregate and high performance paste reduces stress concentrations at the aggregate/paste interface and contributes to reductions in deformations of HPLC compared to HPC.