Microstructure and shrinkage behavior of high-performance concrete containing supplementary cementitious materials

Abstract

This paper investigated the influence of supplementary cementitious materials (SCM, including fly ash (FA), ground granulated blast-furnace slag (GGBS), metakaolin (MK)) on the microstructure and shrinkage behavior of high-performance concrete (HPC). The prediction accuracy of some typical shrinkage models and the correction factor kSCM were evaluated with statistical parameters RE and R2new. After analysis of shrinkage models, the kSCM*B4 model and kSCM*CEB were more suitable for the drying shrinkage and autogenous shrinkage of HPC, respectively. Although the activities of FA, GGBS, and MK were different, SCM were helpful to form a dense interfacial transition zone (ITZ) microstructure. To analyze comprehensively the effect of single or binary addition of SCM on its shrinkage properties, XRD, SEM, slump and compressive strength experiments of HPC were carried out. The diffraction peaks of Ca(OH)2 decreased with the content of FA and GGBS. The setting time of HPC was prolonged with the content of SCM. Both the decrease of FA and the increase of GGBS and MK could enhance the compressive strength of HPC. Drying shrinkage decreased with the content of FA, GGBS, and MK thanks to the refined microstructure with SCM. Autogenous shrinkage decreased remarkably with the content of FA and GGBS, however, that of MK was opposite. For the same total content of SCM, effects of binary addition of FA and MK, FA, and GGBS on the shrinkage behavior of HPC were more markedly than that of single FA. The drying shrinkage of HPC with single MK was slightly less than that with single GGBS, however, the autogenous shrinkage of HPC with single MK was significantly more than that with single GGBS.