Abstract
Completely non-destructive technique of surface water absorption test (SWAT) for newly-constructed and existing concrete structures was developed by the authors. SWAT can measure absorped water volume continuously and accurately immediately after filling up water. Through the measurement by SWAT in 10 minutes, several indicators for resistance against water absorption are obtained, and covercrete quality from the surface to some depth can be evaluated by these indicators.
In this research, the following three investigations were conducted; 1) tests for concretes with different constituent materials, W/C, and curing conditions without the effect of rainfall, 2) tests for concretes in different exposure environment, 3) measurement of actual structures.
SWAT could detect the effects of W/C and curing condition on covercrete quality for concretes with OPC and slag cement. It was proved that water absorption rate at 10 minutes obtained from actual structures could be considered to follow normal distribution. In order to establish inspection system with SWAT, a method to set threshold value and a way of judgment in inspection were proposed based on a statistical approach. As practical applications of SWAT, analyzing the adverse effect of microcrack on covercrete quality, and detecting the effects of expansive additive and silane type water repellent on improving covercrete quality were introduced.
