LAUSR

Due to the addition of mineral admixtures, early-age shrinkage cracking is a common feature in high-performance concrete (HPC). Chloride diffusivity of HPC due to early-age shrinkage cracking was investigated through rapid chloride migration (RCM) method. Restrained/unrestrained slabs made of HPC containing fly ash (FA) and ground granulated blast-furnace slag (GGBS) were left outdoors for early-age shrinkage cracking, and then cylindrical samples were drilled from slabs for RCM test to quantify the chloride diffusion coefficient, wherein a crack influence factor was introduced to account for the contribution of cracking in the chloride diffusivity progress. Test results from unrestrained HPC reveal that the addition of mineral admixtures could densify the pore structure of HPC thus improved the chloride diffusion coefficient, though FA had a delayed effect. The RCM tests from restrained HPC indicate that the crack indeed had an effect on the chloride ion transportation, but pore structure still dominated the chloride ingress. For a fixed cement replacement, the more the GGBS in the mix, the higher the contribution of cracking to chloride ion penetration.