关键词: 氧化镁;收缩;相对湿度

Abstract: The deformations of cement pastes containing light calcined MgO expansive agent cured in different curing conditions were measured.The hydration properties of MgO of cement pastes were analyzed by X-ray diffraction(XRD),thermogravimetric analysis(TG)/differential scanning calorimetry (DSC)and backscattered electron microscopy(BSEM).The results show that shrinkage of cement pastes is decreased by improving the relative humidity and prolonging pre-cured age.Light calcined MgO expansive agent produces effective expansion in the dry air curing conditions,has an excellent ability to compensate for shrinkage of cement pastes cured in low relative humidity.This is attributed to the formation of Mg(OH)2owing to the hydration of light calcined MgO expansive agent, and hence decreasing the shrinkage of cement pastes.

Key words: MgO;shrinkage;relative humidity