Effects of chloride exposure conditions on calculated apparent diffusion values for concrete

Prediction of the onset of chloride-induced corrosion of steel-reinforcement in concrete is a very complex problem. Different test methods have been developed to quantify the resistance of concrete against chloride penetration through calculated parameters. However, these parameters are affected by test variables and exposure conditions. In this research the effects of various exposure conditions using the NT BUILD 443 bulk diffusion test were studied. The variables analyzed were: (1) exposure temperature, (2) associated cation of the salt exposure solution, (3) exposure solution concentration, and (4) exposure time. Three types of concrete mixtures were used in this research: OPC with water-cement ratio of 0.4, OPC with water-cement ratio of 0.6, and OPC with 25% slag replacement and water-cement ratio of 0.4. Additionally, compressive strength tests and RCPT values were monitored over a 1-year period for control quality purposes. It was found that the concentration of the salt solution plays an important role in the calculated parameters obtained from the different test conditions.