中文摘要：

为探究白云石微粉（DM）在水泥中的物理化学效应,以石灰石微粉（LS）为参照,研究40℃和60℃养护时DM掺量（10%、20%和30%）对水泥砂浆强度的影响,并分析混合水泥浆体的水化产物。结果表明：随养护温度和掺量不同,两者对砂浆强度的影响有明显差异。40℃时,LS优于DM促进早期强度发展,但两者差异随掺量增加和龄期延长而减小甚至反转,养护90 d时,掺量超过20%的DM砂浆强度高于LS砂浆。提高养护温度到60℃,对DM砂浆各龄期强度的促进效应均比对LS体系更为显著,且掺量愈大,两者对温度效应的差异愈明显。40℃时,两种微粉均参与反应,早期形成单碳铝酸钙（Mc）,但龄期延长至90 d时,DM浆体中出现少量水滑石（Ht）。60℃时,两种微粉体系中均未生成Mc,而是形成单硫型硫铝酸钙（AFm）;随龄期延长,LS体系中水化产物无明显变化,DM体系中AFm减少直至消失,同时生成大量Ht,且Ht量随DM掺量增加而增多。DM在高温和后期的化学活性效应强于LS,是导致两者在40℃养护后期和60℃养护全龄期强度差异的主要原因。与集料的去白云石化反应导致碱碳酸盐反应不同,白云石微粉在水泥浆体中反应并未形成水镁石,而是与浆体中铝质组分反应生成碳铝酸盐或/和水滑石。该反应不仅未对砂浆强度产生不利影响,反而具有促进效应。

英文摘要：

To clarify the physical and chemical effects of dolomite powder （DM） in cement, the strength of blended cements mortars with dolomite powders replaced at different contents （ i.e. 10%, 20% and 30%, mass fraction） and cured at 40 ℃ and 60 ℃ were investigated. A limestone powder （LS） was used for the comparison purpose. The hydration products of blended cements were examined by X-ray diffraction. The results indicate that DM and LS both show their effects on the mortar strength at different replacement contents of DM and LS and curing temperatures. At 40 ℃, LS shows a positive impact on the promotion of the early strength, compared to DM, but this difference reduces and even reverses with the increase of the replacement content and the curing age. When the replacement content is over 20% and the curing duration is 90 d, the strength of mortars with DM is greater than that with LS. Comparing to LS mortars, increasing the curing temperature to 60 ℃ gives a promoting effect on the strength of mortars with DM, and the effect is more pronounced with the increase in the replacement content. When cured at 40 ℃, LS and DM both involve in reaction, forming monocarboaluminate （Me） hydrates at early ages, but developing a few hydrotalcite （Ht） in DM pastes at 90 d. At 60℃, however, single sulphur calcium aluminate （AFm） is formed in blended cement pastes instead of Me. When the curing duration increases, no significant change in the hydration products in the LS pastes, and the amount of AFm decreases and AFm disappears while Ht develops and increases considerably with the increase of DM replacement content in the DM pastes. DM gives a more intense chemical effect at a high temperature and a late duration. Compared to the dedolomitization of aggregate leading to alkali carbonate reaction instead of brucite and calcite, Mc and/or Ht were formed in the reaction of dolomite powders in the paste. The reaction of dolomite powders with aluminous constituent in the paste has a positive effect on th