Coefficient of surface water absorption: A non-destructive test index for evaluation and quality grading of cover-concrete

Surface Water Absorption Test (SWAT) has long been proposed as a non-destructive testing device for evaluation and grading of the quality of the cover concrete and standardization of SWAT is still in process. In this study, the acceptability and validity of a new water sorptivity index of the SWAT method - the coefficient of surface water absorption (CSWA), are appraised by a correlative assessment between CSWA and the coefficient of air permeability (kT values) measured by the Torrent’s double chamber air permeability device. The tests were conducted on fourteen different kinds of concrete at different ages, produced with three different cement types, four water-to-binder ratios, and four curing conditions. The results revealed a good correlation between CSWA and kT for both the specimens with uniform moisture content and the ones with varying degrees of moisture gradients. The findings validate the CSWA as an effective quality control index during design as well as a durability quantifier for evaluating the water absorption resistance of in-situ concrete structures