Shrinkage and expansive strain of concrete with fly ash and expansive agent

The effects of fly ash and MgO-type expansive agent on the shrinkage and expansive strain of concrete with high magnesia cement were investigated. The results show that high volumes of fly ash may reduce the shrinkage strain of concrete and inhibit the expansive strain of concrete with MgO-type expansive agent, but can not eliminate the shrinkage of concrete. MgO-type expansive agent may produce expansive strain and compensate the shrinkage strain of concrete, relieve the cracking risk, but the hydration product of magnesia tends to get together in paste and produce expansive cracking of concrete with high magnesia content according to SEM observation.