Effect of leaching from freshly cast concrete on pH

The pollution of water through release of hydroxyl ions from freshly cast concrete exposed to water can have a detrimental effect on aquatic life by causing a rise in pH. The concentration of hydroxyl ions leached from concrete can be affected by a number of factors. A detailed study has been undertaken to ascertain the effect of parameters such as flow rate, age of concrete after exposure, air quality, cement type, surface area and the volume of concrete. This paper presents the results of the experimental programme and a predictive model for change of pH of water after exposure to freshly cast concrete. Analysis of the results showed that the flow rate was the most significant factor in both the peak pH observed and the time to the peak pH. The volume of the sample was also identified as being a significant factor in the peak pH.