Assessment of water migration distance in internal curing of high-strength concrete

The paper deals with internal curing of High-Strength Concrete using presoaked lightweight aggregate (LWA). The effect of internal curing depends directly on the distance over which the internal curing water can travel. The effectiveness of internal curing is a function of the ratio between the water penetration depth and the paste-lightweight aggregate proximity, which is related to the spacing between the aggregates. Estimates of these parameters were developed in this study, based on a combination of modeling and experimental work. The results indicate that water can penetrate from the LWA into the surrounding matrix to a distance of up to several millimeters during the first seven days of hydration. The water penetration was sensitive to the pore structure of the aggregate, ranging from about I to 6 mm, and it was reduced in systems having lower w/b ratio and silica fume by almost a factor of 2.