Improvement of Properties of Portland Blast Furnace Cement Type B Concrete by Internal Curing Using Ceramic Roof Material Waste

The present study aims to investigate the effects of porous ceramic waste aggregate (PCA) coarse aggregate as an internal curing material on the compressive strength, porosity, and shrinkage of portland blast furnace cement type B concretes (BB) with a water-to-cement ratio (W/C) of 0.55, in which the replacement ratios of conventional coarse aggregate by PCA were 10 and 20% in volume and the specimens were exposed to drying at the ages of 3 and 7 days and cured under sealed condition. The results showed that internal curing using PCA to replace coarse aggregate by 10 and 20% in volume was effective in improving the compressive strength of BB compared with ordinary portland cement concrete and BB at the age of 28 days, independent of the exposure conditions. Moreover, 10% replacement by PCA was more effective than 20% replacement. Internal curing for BB was found to be effective in decreasing pore volume for specimens exposed to drying at the age of 3 days. However, the total pore volume of BB cured internally was almost unaffected by the starting age of drying as well as the replacement ratio of coarse aggregate by PCA. In specimens exposed to drying at 3 and 7 days and measured at 28 days, the compressive strength was increased by internal curing, corresponding to the decrease in pore volume for sizes larger than 0.02μm. However, in specimens subjected to sealed curing, both the compressive strength and pore volume for sizes larger than 0.02μm, which were measured at 28 days, were found to be increased by the internal curing. The internal curing was not effective in reducing autogenous shrinkage owing to the comparatively high W/C of 0.55 of the present concrete.