Expansion of ordinary Portland cement paste varied with nano-MgO

• Nano-MgO is used as the expansive agent for cement and concrete.
• The maximum content of nano-MgO in ordinary Portland cement can reach 8% for soundness.
• The hydration rate of nano-MgO cured in water at (20 ± 2) °C was low, and a little of nano-MgO existed till the age of 365 days.
• The paste expansions increased gradually with the increase of the content of nano-MgO cured at 20 °C in water within 365 days.

Based on the application of MgO in clinker and light burnt MgO to the thermal and autogenous shrinkage compensation of dam concrete, the variation of expansion properties of cement paste with nano-MgO was studied. Results indicated that the maximum content of nano-MgO added in ordinary Portland cement reached up to 8% for soundness. The hydration rate of nano-MgO cured in water at 20 °C was low, and a little of nano-MgO existed till the age of 365 days. The paste expansions increased gradually with the increase of the nano-MgO content cured at 20 °C in water within 365 days and through autoclaving after the ages of 365 days. The results suggest that added with nano-MgO and mixed with light burnt MgO, the shrinkages of dam concrete may be completely compensated in safety.