Study on long-term volume stability and microstructure of concrete containing magnesia expansion agent

Long-term performance of concrete containing tiny magnesia expansion agent which has been used in the water conservancy and electricity engineering of China for 13 years was studied. The main projects included the mechanics performance, autoclave test and microstructure analysis. The results showed the mechanics performance of magnesia concrete was good and the expansion ratio of autoclave test was high though the relative strength loss after autoclave test was little. The results of microstructure analysis showed the hydration of magnesia tiny expansion agent was almost completely hydrated.