煤系高岭土活化及其抗硫酸镁侵蚀性能研究

将煤系高岭土矿样进行焙烧活化,得到高火山灰活性的偏高岭土,对偏高岭土物相变化进行分析,考察偏高岭土抗硫酸镁侵蚀性能,并通过X射线衍射(XRD)、场发射扫描电子显微镜-能谱仪(FESEM-EDS)研究了抗硫酸镁侵蚀机制。结果表明,煤系高岭土经800℃焙烧活化可完全脱除其结构中的羟基,制得最高活性的偏高岭土。偏高岭土掺和至水泥砂浆中,会显著降低其受MgSO_4侵蚀时的膨胀率和强度损失,偏高岭土会增加水化硅酸钙(C-S-H)凝胶的Al含量,降低内层钙硅比和Mg、S含量,使得C-S-H凝胶更为密实稳定,侵蚀产物石膏与单硫型水化硫铝酸钙(AFm)含量显著降低,表现出优良的抗硫酸镁侵蚀性能。

Study on Activation of Coal-Series Kaolin and Its Erosion Resistance to MgSO4

This paper firstly activated coal-series kaolin by roasting to prepare metakaolin with high pozzolanic activity and its phase transformation was researched,then the erosion resistance to MgSO4 was studied and its mechanism was analyzed by XRD and FESEM-EDS.The results showed that the optimal activation temperature was 800℃accompanied with complete dehydroxylation and the highest active metakaolin was obtained.The blending of metakaolin into cement mortar would reduce the expansion and strength loss under MgSO4 erosion.The XRD and FESEMEDS analyses showed that metakaolin would increase Al content and decrease ratio of Ca to Si and Mg,S contents of inner layer,which resulted in the denser and stable C-S-H gels and remarkable reduction of erosion products(gypsum and AFm),showing the excellent erosion resistance to MgSO4.