高碱含量水泥净浆的显微结构特征及碳化速率

发布时间：2018-05-25 22:20

本文选题：硬化水泥净浆 + 碳化　；参考：《硅酸盐学报》2014年08期

【摘要】：将硬化后的水泥净浆分别浸泡在NaOH饱和溶液和水中,干燥后测定孔结构参数和碳化速率,评价孔结构特征相近时高碱含量对水泥净浆碳化速率的影响。结果表明:水灰比为0.3、0.4及0.5时,硬化水泥净浆孔结构特征相近时,碱含量越高,碳化速率越慢;NaOH溶液浸泡后的水泥净浆,孔结构和密实度均与同条件水中浸泡过的水泥净浆相近,水泥净浆内尚未出现氢氧化钠碳化后可能出现的碳酸钠晶体,未对水泥石孔结构产生影响。碳化由表向里进行过程中,水泥净浆的碳化区易出现微裂缝并延伸到试件内部,致使水泥净浆的各部位碳化深度不均匀,说明使用酚酞溶液的呈色反应评价水泥混凝土的碳化程度时应结合X射线电子计算机断层扫描和X射线衍射技术。明确了碳化不仅可以降低混凝土的pH值,而且由于碳化区易于出现裂缝使钢筋表面暴露于空气中,增加了钢筋腐蚀的概率。
[Abstract]:The hardened cement paste was soaked in NaOH saturated solution and water, the pore structure parameters and carbonation rate were measured after drying, and the effect of high alkali content on the carbonation rate of cement paste was evaluated when the pore structure was similar. The results show that the higher the alkali content, the slower the carbonation rate of cement paste after soaking in NaOH solution when the ratio of water to cement is 0.3o 0.4 and 0.5, and the pore structure of hardened cement paste is similar. The pore structure and compactness are similar to the cement paste soaking in the same condition, and the sodium carbonate crystal after carbonation of sodium hydroxide has not appeared in the cement paste, which has no effect on the pore structure of cement. In the process of carbonation from the surface to the inside, the carbonation zone of cement paste is prone to appear micro-cracks and extend to the inside of the specimen, which results in uneven carbonation depth in different parts of cement paste. It is suggested that the color reaction of phenolphthalein solution should be combined with X-ray computed tomography and X-ray diffraction to evaluate the carbonation degree of cement concrete. It is clear that carbonation can not only reduce the pH value of concrete, but also increase the probability of corrosion of steel bar due to the cracks in carbonization zone and the exposure of steel bar surface to air.
【作者单位】：宁波大学建筑工程与环境学院;
【基金】：国家自然科学基金(51078189,51278255) 宁波市重大科技计划项目(2013C51006)资助
【分类号】：TU528

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