Abstract:The effects of calcium sulphoaluminate calcium oxide expansive agent and magnesia expansive agent on the volumetric stability of high strength grouting material under different dosage and curing conditions were studied. The results show that both kinds of expansive agents can all exhibit their expansive properties well in the high strength grouting system. Under the condition of adequate water, calcium sulphoaluminate calcium oxide expansive agent has more obvious early expansive effect, better than magnesia expansive agent, but its expansion efficiency is not as good as that of magnesia expansive agent in middle and late stage. Under the conditions of absolute humidity, magnesia expansive agent has a better effect on the volume stability of high strength grouting material. Depending on different curing conditions, different types of expansive agents can be selected reasonably to improve the volume stability of the grouting material and improve the application effect.