A Comparative Study on Mortar Containing Silica Fume and High Reactivity Metakaolin in Relation to Restrained Shrinkage Stress Development and Cracking

摘要

Silica fume (SF) and high reactivity metakaolin (HRM) are two highly reactive pozzolans that offer excellent potential for use in high-performance concrete since concrete mixtures containing them demonstrate superior performance in term of strength, and durability. High-performance concrete applications, such as pavements and bridge decks, are also required to demonstrate superior performance against early age shrinkage cracking. This paper describes a comparative study of the effects of SF and HRM on the early age stress development and cracking in restrained mortar mixtures due to shrinkage. The restrained ring test was used to assess early age residual stress development in mortar ring specimens. In addition, free shrinkage strains and splitting tensile strength measurements were performed to assess the cracking potential. It was found that the addition of SF and HRM increased the shrinkage level in the mixtures which resulted in increases in residual tensile stressd development due to restraint. In addition, their addition in the mixtures increased the cracking potential and resulted in early cracking in the ring specimens.