Recent advance of MgO expansive agent in cement and concrete

Thermal shrinkage compensation of mass concrete in Baishan Dam was discovered by accident in the 1970s, due to the delayed hydration and expansion of periclase (4.7% MgO) in cement clinker. The concrete added with MgO expansive agent (MEA) is then developed and it has been applied for shrinkage compensation in dam concrete, bridge and road structures, oil well cement, etc. The manufacturing technology determines the physical and chemical characteristics of MEA, and the desired expansion performance can be obtained by adjusting the type and dosage of MEA. Nevertheless, there are still some problems in the production and use of MgO. This paper reviews the recent advance of MEA in cement and concrete, including the hydration kinetics, expansion mechanism, MgO reactivity, soundness, compound MgO expansive agent, MEA in self-healing cement, and applications. The MEA has broad application prospects in cement and concrete, and the perspectives suggested in this paper will be useful for further study on the MEA. • Recent studies on the MEA in cement and concrete are reviewed. • Hydration kinetics, expansion, and reactivity of MEA are elucidated. • Compound MgO expansive agent and applications of MgO concrete are discussed. • Potential studies of MEA for future research are suggested.