Accelerated test of ingress of chloride ions in concrete under pressure and concentration gradients

This paper describes the experimental and numerical work carried out to study the ingress of chloride ions in concrete under pressure and concentration gradients. The proposed accelerated water and chloride permeability tests together with long-term soaking tests are used to develop 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 concrete 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 similar conditions. The design and application of the specially built testing equipment for the accelerated permeability tests are presented. The repeatability of these tests, expressed as the coefficient of variation, is satisfactory. This confirms that the proposed test apparatus 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.