The Moisture Condition of Field Concrete Exhibiting Alkali-Silica Reactivity

The moisture condition of field concretes exhibiting evidence of alkali-silica reactivity was investigated utilizing relative humidity (RH) measurements. Prior determinations were made on laboratory mortar specimens to determine the threshold level required to sustain expansive reactivity. Results indicated that RH values greater than 80 percent, referenced to 21 degrees to 24 degrees Centigrade, are required to support expansive alkali-silica reactivity. Field measurements revealed that most of the concrete in highways and dams in desert areas are sufficiently damp to sustain expansive ASR.