Internal Curing of High-Strength Concretes Using Artificial Aggregates as Water Reservoirs

Abstract

This paper investigates the shrinkage cracking performance of high-strength concrete (HSC) containing artificial fly ash (AFA) and artificial blast furnace slag aggregates (ASAs) used as water reservoirs to provide internal curing. Artificial aggregates (AAs) were produced through cold bonding pelletization of 90% fly ash or slag with 10% portland cement. At a constant water-cement ratio (w/c) of 0.28, a total of nine HSCs incorporating varying amounts of AFA or ASA (0%, 5%, 10%, 15%, and 20%) by total aggregate volume were designed. The hardened concretes were tested for compressive strength, splitting tensile strength, and modulus of elasticity at 28 days for assessment of mechanical properties. Drying shrinkage accompanied by water loss, restrained shrinkage, and autogenous shrinkage were also monitored for a drying period of 57 days. Test results indicated that the highest mechanical properties were achieved for HSC with 20% ASA. Using ASA extended the cracking time of the HSCs and resulted in finer cracks associated with the lower free shrinkage. Moreover, there was a marked decrease in the autogenous shrinkage for all HSCs including artificial aggregates.