WATER-REPELLANT EFFECT OF REINFORCED CONCRETE (RC) BEAM COATED WITH A SURFACE-PENETRANT

Concrete coated with surface-penetrant is an efficient method to improve durability because it can decrease the ingress of deterioration factors such as water and chloride ions. Our previous study had focused on a silane-based penetrant having high water-repellant effect and examined the freeze-thaw (F-T) durability of the concrete coated with the penetrant. As well as F-T action, the water-repellant effect must decrease the possibility of deterioration related to water and chloride ions ingress. It is well known that water in pore of concrete is a compromising factor to decrease the fatigue durability of RC structures. The effect of surface-penetrant may be significantly varied by microscopic pore structures in concrete. Hence, the study prepared concrete cylinders and RC beam specimens made by wide range of water-cement ratios (w/c) from 0.55 to 1.0. Noting that the low-strength concrete made by the w/c = 1.0 is very unusual for structural concrete. However, such low strength properties are occasionally observed in short-span RC bridges constructed in 1960s or earlier. Hence, the study examined the effect of the surface-penetrant by using various w/c concretes. The paper reports the fundamental investigations of penetration depth and fatigue durability of the coated RC beams.