干燥处理后水泥石抗碳化性能研究

Study on Carbonation Resistance of Cement Pastes after Drying Treatment

将水泥石试件在60℃干燥24h后进行加速碳化试验。通过酚酞喷涂法、碳酸盐定量分析法、X射线衍射分析(XRD)、差示扫描量热法(DSC)和热失重法(DTA)等对水泥石及大掺量粉煤灰水泥石的碳化性能进行研究,利用扫描电镜(SEM)和能谱分析(EDS)观察水泥石碳化产物的晶体形貌及分布情况。结果表明,干燥处理大大加速了水泥石的碳化进程,使碳化程度较严重且不均匀;由于缺少化学反应所需的水分,碳化反应不充分;碳化反应产物CaCO3晶体的晶粒细小,并在孔隙中集中生成,堆积成束。

The cement paste specimens were treated by drying under 60℃ for 24h and subsequently carbonated in an accelerated way. The carbonation related performances of pure Portland cement paste and cement paste with high content of fly ash were investigated through phenolphthalein spraying, carbonate content measuring, XRD, DSC and DTA. Meanwhile, SEM and EDS were incorporated to study the crystal morphology and distribution of carbonate products. The results show that the previous drying process highly accelerated the carbonation rate, increasing the carbonation degree and making the carbonation degree different with the position. The carbonation process was incom- plete due to the lack of water caused by drying. Calcium carbonate, the main carbonate product, mostly precipitated in the pores and possessed a relatively smaller crystal size.