聚合物改性砂浆和混凝土的微观形貌

Study of Morphology of Polymer-modified Mortar and Concrete

研究了盐酸腐蚀时间对聚合物改性砂浆和混凝土微观结构的影响.研究发现,没有腐蚀的聚合物改性砂浆的砂子表面上具有宽度为10～15μm的界面过渡区,但聚合物的形态结构难以分辨;经过30s腐蚀的试样,聚合物的形态结构容易辨认,但界面过渡区的界限变得模糊.在水泥浆本体区域内的聚合物由宽度为0.1～0.5μm,长度为2～3μm条形物聚集成圆环形网状结构,而在接近砂子表面区域内的聚合物条形物宽度较大.砂子体积分数较小的改性砂浆中细条形物较少,可看到小块的薄膜状结构,说明浆体中含更多的聚合物.随着砂子体积分数的增加,聚合物改性砂浆中的聚合物倾向于向砂子表面转移,这是聚合物改善水泥浆体与集料界面过渡区结构的重要因素.

The mortar and concrete specimens were etched with 1% hydrochloric acid for the SEM observation. The influence of the etching time on the microstructure was studied. The investigation show that a very obvious interfacial transition zone (ITZ) with a wide of 10～15 μm can be observed at the non-etched specimen, but the structure of the polymer is difficult to identify. After 30 s etching, the consitution of the polymer is easy to recognize, but the border line of the ITZ is blurred. From the etched specimen, an amphitheatric polymer-network composed of strips of 0.1～0.5 μm wide and 2～3 μm long can be observed in the cement paste matrix. In the ITZ area, the polymer strips are wider than that in the matrix. There are less small polymer strips in the matrix of specimen with low sand volume fraction, instead of that, some small pieces of polymer film can be observed. This indicates that more polymers are distributed in the cement paste matrix for the specimen with low sand volume fraction, and the polymer in the mortar with higher sand volume fraction tends to transfer from matrix to the ITZ area. Such a process benefits the modification of the ITZ structure of the mortar, this indicates the mechanism of polymer modification.