Research on autogenous volume deformation of concrete with MgO

The autogenous volume deformations of concrete with MgO expansive materials and fly ash cured in different ages were measured, and the morphologies of it were observed through scanning electron microscope. The results showed that the autogenous volume deformation of the concrete increased with the curing ages and the content of MgO expansive materials. The expansions of concrete with MgO became less in later ages and unlimited expansion did not appear. Fly ash may inhibit the autogenous volume expansion of concrete with MgO expansive materials, and the effect became more significant with the dosage increase of fly ash. The micro-expansion caused by the additive MgO expansive materials filled the pores of paste and made the structure denser, and might compensate the shrinkage of concrete, decrease the cracking of concrete works and improve the durability of concrete.