Early-age Cracking Control on Concrete with MgO Compound Expansive Agent

The expansion of MgO compound expansive agent composed of MgO-based expansive agent with different reactivities and other types of expansive agents can well compensate for the shrinkage of concrete at early hydration stage and later age. In this chapter, early-age cracking control on concrete through MgO compound expansive agent was investigated. The results showed that the early-age autogenous shrinkage was effectively compensated with the addition of MgO compound expansive agent. The maximum free strain, temperature drop, failure age, failure stress, and failure stress-to-axial tensile strength ratio of concrete increased with increasing dosage of MgO compound expansive agent when the dosage was not more than 4%. The early-age tensile creep of concrete increased with increasing dosage of MgO compound expansive agent. The rate of tensile stress and cracking failure potential of concrete evaluated by integrated criterion decreased with increasing dosage of MgO compound expansive agent when the dosage was not more than 4%, but increased with increasing dosage from 4% to 6%.