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研究了掺CaCO_3粉及后续水养护对CO_2养护混凝土的强度的影响。采用X射线衍射和热重方法分析了两者对CO_2养护后反应产物的影响,同时采用扫描电子显微镜观察了掺CaCO_3粉及后续水养护对混凝土微观结构的影响,并用能谱仪对微区元素进行了表征。结果表明:当剩余水灰比为0.18时,掺10%CaCO_3粉混凝土CO_2养护及后续水养护后的抗压强度均达到最大值。与未掺时相比,掺10%CaCO_3粉可提高混凝土CO_2养护及后续水养护7 d的抗压强度,但后续水养护28 d的抗压强度略有降低。由于CO2养护后还存在未与CO2反应的水泥颗粒,后续水养护可进一步提高CO_2养护混凝土的强度,反应生成的碳酸钙的结晶程度也有所提高。在后续水养护过程中,CaCO_3粉作为晶核促进钙矾石的散射状生长。
The effect of CaCO_3 powder and subsequent water conservation on the strength of CO_2 cured concrete was studied. The effects of the two on the reaction products after CO 2 curing were analyzed by X-ray diffraction and thermogravimetry. Meanwhile, the effects of CaCO 3 powder and subsequent water conservation on the microstructure of concrete were observed by scanning electron microscopy. Characterized. The results show that when the residual water-cement ratio is 0.18, the compressive strength of CO 2 -containing 10% CaCO 3 powder concrete and subsequent water conservation reaches the maximum value. Comparing with non-doped, 10% CaCO_3 powder can improve the compressive strength of concrete after CO_2 curing and subsequent water conservation for 7 days, but the compressive strength of water-curing for 28 days decreases slightly. Since there is still cement particles that do not react with CO2 after CO2 conservation, subsequent water conservation can further increase the strength of the concrete cured by CO2 and the degree of crystallization of the calcium carbonate generated by the reaction also increases. In the subsequent water conservation process, CaCO_3 powder as a nucleus to promote the scattering of ettringite growth.