Frost Damage Resistance of Portland Blast-Furnace Slag Cement Concrete Cured Internally by Using Roof-Tile Waste Aggregate

The purpose of this study was to clarify the relationship between the internal curing effect of roof-tile waste aggregate and frost damage resistance, and to investigate the effects of the replacement ratio of roof-tile waste aggregate as well as curing conditions on the frost damage resistance of concrete. Five types of concrete using Portland blast-furnace slag cement were prepared with a water-to-cement ratio of 0.50 and different replacement ratios of roof-tile waste coarse aggregate (20% and 50% by volume) and roof-tile waste fine aggregate (23% and 58% by volume). Concrete specimens were cured at 20 °C under sealed condition for 3, 7, or 28 days, and they were subsequently exposed to air at 20 °C and 60%R.H. until the age of 28 days. Then, the tests for resistance of concrete to freezing and thawing were carried out for 300 cycles in water, and the relative dynamic modulus of elasticity as well as the mass loss was assessed at the designated periods. As a result, it was found that sufficient frost damage resistance could be secured when the replacement ratio of roof-tile waste aggregate was approximately 20% by volume, and the improvement in frost damage resistance was observed especially when fine aggregate was replaced.