Internal Curing of Structural Concrete: A Closer Look

Abstract

Utilizing Internal Curing (IC) technology in the production of high performance concrete (HPC) for structural purposes is the main focus of this investigation. Pre-wetted lightweight aggregates of perlite and pumice in addition to recycled aggregates were utilized to produce internally cured HPC mixtures. Results show that 10% replacement of crushed sand with pre-wetted perlite yields acceptable compressive strength of the concrete. Also, flexural strength was improved with up to 15% replacement of coarse aggregates with pre-wetted recycled aggregates. Shrinkage testing revealed the superiority of internal over conventional curing through decreased shrinkage and minimized surface cracking, as a result of the enhanced hydration process. However, the results of air permeability and chloride ingress testing showed worsened behavior of internally cured concrete as indicated by the amount of internal cracking and air pockets present after the end of curing process. The empty pores in the lightweight aggregates created an interconnected network of voids that eased penetrability of chlorides to reinforcing bars.