ACCELERATED TEST OF INGRESS OF CHLORIDE-IONS IN CONCRETE UNDER PRESSURE AND CONCENTRATION GRADIENTS

This paper describes the experimental and numerical work carried out t o study the ingress of chloride ions in concrete under pressure and co ncentration gradients. The proposed accelerated water and chloride per meability tests together with long-term soaking tests are used to deve lop a pressure gradient model, a concentration gradient model and the combination of the two for the prediction of ingress of chloride ions in concrete. It is found that the experimental results, based on OPC c oncrete with a water-cement ratio of 0.6 tested in the pressure range 0-30 MPa, agree well with the finite element solutions derived under s imilar conditions. The design and application of the specially built t esting equipment for the accelerated permeability tests are presented. The repeatability of these tests, expressed as the coefficient of var iation, is satisfactory. This confirms that the proposed test apparatu s and method can be used with confidence. It is also observed that the applied pressure gradient has little effect on the water permeability coefficient in the experimental range 0-30 MPa.