PH PH In chemistry, pH () is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. The neutral value of the pH depends on the temperature, being lower than 7 if the
Alkali–silica reaction ASR in the presence of siliceous aggregates and water is to maintain the concentration of soluble alkali (NaOH and KOH) at the lowest possible level in concrete, so that the catalysis mechanism becomes negligible. The alkali-silica reaction mechanism catalysed by a soluble strong base as NaOH or KOH in the presence of Ca(OH) (alkalinity buffer present in the solid phase) can be compared with the carbonation process of soda lime. The silicic acid (HSiO or SiO) is simply replaced in the reaction by the carbonic acid (HCO or CO). In the presence of water or simply ambient moisture, the strong