National Concrete Pavement Technology Center

Project description

The American Concrete Institute (ACI) and most state highway agency (SHA) organizations limit the amount of chlorides in fresh concrete to lower the risk associated with corrosion of steel reinforcement. It is often required to measure the chloride concentration of concrete powder samples to ensure that the published chloride limits are not exceeded. However, the standard documents provide no information on number of samples required for chloride testing for different concrete mixtures. This study explores the influence of concrete material proportions and the admixed chloride levels on the mean and variability of the chloride test results. Results from this research indicate that the maximum size and proportion of the coarse aggregate and the admixed chloride level significantly influence the chloride test results. Based on the estimated variability of chloride measurements from this research, a method to determine the number of samples for chloride testing is presented for different concrete mixtures.