Cao Huan, Mao Zhongyang, Huang Xiaojun, Deng Min
College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211800, China.
Materials (Basel). 2022 May 15;15(10):3538. doi: 10.3390/ma15103538.
In this paper, the dolomitic limestone determined as alkali-carbonate-reactive by various methods is used as an aggregate. Inhibition experiments were carried out on the basis of the concrete microbar method (RILEM AAR-5 standard), in which 10%, 30%, and 50% fly ash and metakaolin were used to replace cement. Thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffractometry (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS) were used to analyze the inhibition mechanism of fly ash and metakaolin on ACR. The results show that the expansion of samples at the age of 28 days are less than 0.10% when the fly ash contents exceed 30% and the metakaolin contents exceed 10%, which proves that the ACR is inhibited effectively. Meanwhile, the Ca(OH) content of the samples was reduced and the pore structure of the samples was optimized after adding fly ash and metakaolin. The dolomite crystals in the samples containing 50% fly ash and metakaolin are relatively complete.
本文采用多种方法测定为碱碳酸盐反应性的白云质石灰石作为集料。基于混凝土微棒法（RILEM AAR - 5标准）进行抑制试验，其中使用10%、30%和50%的粉煤灰和偏高岭土替代水泥。采用热重 - 差示扫描量热法（TG - DSC）、X射线衍射法（XRD）、压汞法（MIP）和扫描电子显微镜 - 能量色散X射线光谱法（SEM - EDS）分析粉煤灰和偏高岭土对碱碳酸盐反应（ACR）的抑制机理。结果表明，当粉煤灰含量超过30%且偏高岭土含量超过10%时，28天龄期样品的膨胀率小于0.10%，这证明ACR得到了有效抑制。同时，添加粉煤灰和偏高岭土后，样品的Ca(OH)含量降低，孔隙结构得到优化。含50%粉煤灰和偏高岭土的样品中白云石晶体相对完整。
