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 mineral acid-base reaction between NaOH or KOH, calcium hydroxide, also known as Portlandite, or (Ca(OH)), and silicic acid (HSiO, or Si(OH)). When complete and to simplify, this reaction can be schematically represented as following: However, the ASR reaction significantly differs from the pozzolanic reaction by the fact that it is catalysed by soluble alkali hydroxides (NaOH / KOH) at very high pH. It can be represented as follows using the classical geochemical notation for fully hydrated dissolved silica (Si(OH) or silicic acid: HSiO), but an older industrial notation also exists (HSiO, hemihydrated silica (does not exist), by analogy with carbonic