纳米MgO对水泥硬化浆体膨胀和强度的影响

Effects of Nano-MgO on Expansion and Strength of Hardened Cement Pastes

对比轻烧MgO,对水泥硬化浆体的膨胀和抗压强度随纳米MgO掺量的变化规律进行研究.结果表明:经压蒸安定性试验后,在浆体中的纳米MgO和轻烧MgO均已水化,其体积安定性合格的最大掺量(质量分数)分别约为10%和4%;在40℃水中养护至730d时,纳米MgO和轻烧MgO均已水化;水泥硬化浆体膨胀率随MgO掺量和养护时间的增加而增加,掺纳米MgO浆体的膨胀较易趋于稳定;水泥硬化浆体抗压强度随纳米MgO掺量的增加而增大,随轻烧MgO掺量的增加而降低.纳米MgO具有较高的安定性掺量和较好的强度稳定性,其膨胀可用于补偿大体积混凝土的收缩.

The variation of expansion and compressive strength of hardened cement paste with nano-MgO added was studied compared with that for light-burnt MgO.Results indicate that nano-MgO and light-burnt MgO in the paste are hydrated after the test of cement autoclave soundness,and their qualified maximum for soundness is about 10% and 4%（by mass）respectively.Cured in water at 40℃ till 730 days,both nano-MgO and light-burnt MgO in pastes are hydrated,paste expansions increase with the increase of MgO and curing time,and the paste expansion added with nano-MgO tend to be stable more easily than that with lightburnt MgO.Meanwhile,the paste compressive strengths increase with the increase of nano-MgO,but decrease with the increase of light-burnt MgO.For cement-based materials,nano-MgO has advantages of higher soundness and higher stability for strength as compared with light-burnt MgO.The results suggest that expansions from nano-MgO hydration may be used to compensate the shrinkage of mass concrete.