Effect of potential of Hydrogen (pH) on compressive strength with variations in soaking concrete

The pH level plays a crucial role in the properties of concrete, including compressive strength, durability, and resistance to corrosion of reinforcement. The influence of pH still requires in-depth investigation to determine its effect on concrete strength under varying pH levels and immersion durations in seawater. The compressive strength test was carried out on a total of 540 concrete samples. The test specimens used in this study were cylindrical in shape, with a height of 30 cm and a diameter of 15 cm. The target compressive strengths in this research were 25 MPa, 35 MPa, and 45 MPa. The selected pH values were 5, 7, 9, and 11. Concrete specimens were immersed in pH-adjusted solutions od seawater for 7, 14, and 28 days, with daily monitoring of the pH levels. The aim of this study was to determine the effect of hydrogen potential pH on concrete. The test results confirmed that pH variation during immersion in seawater had a significant impact on the compressive strength of concrete. The effect of both acidic and alkaline hydrogen potential pH on the compressive strength fc' at different immersion durations indicated that the 7-day immersion period had the greatest impact in reducing concrete strength. The predictive equations for the relationship between pH and compressive strength are fc' = 5.85x + 0.55 (acidic pH) and fc' = -2.67x + 63.50 (alkaline pH).