LAUSR

Abstract Indicators of durability are nowadays key-parameters in the design of reinforced concrete structures. One way to guarantee durability is usually to design concrete mixtures with low porosity and low transfer properties. An alternative or in addition to this performance-based approach is the use of treatments such as water repellent, applied on surface of both new and existing concrete structures. The aim of the present study is to evaluate the efficiency of two water repellents with respect to water capillary absorption. Both studied water repellents were applied on a concrete with relatively low mechanical performances (28-day compressive strength equal to 20 MPa). Porosity, pore structure and capillary absorption kinetics were determined according to the AFREM recommendations (Arliguie et al., 2008) for both treated and non-treated concrete samples. The water repellents were found to significantly reduce the water absorption kinetics. However, this reduction was shown to be temporary. The surface treatments slow down the water transfer but when the water passes through the physical barrier, the kinetics capillary absorption becomes similar to that of non-treated concrete. A pore network model was used to support this explanation of the observed absorption kinetics and to model the effect of water-repellent.