聚合物改性水泥砂浆界面过渡区的交流阻抗谱研究

STUDY ON THE ALTERNATING CURRENT IMPEDANCE SPECTROSCOPY OF POLYMER MODIFIED MORTARS

水泥砂浆可视为由水泥浆体、细集料和水泥浆体 -集料界面过渡区 (interfacialtransitionzone ,简称ITZ)所组成 ,聚合物改性水泥砂浆中 ,较小的聚合物颗粒有利于集料表面的紧密堆积 .用交流阻抗方法研究了不同砂子粒径和不同砂子体积分数的聚合物改性砂浆在不同龄期的表现 .结果表明 :交流阻抗方法是研究聚合物改性砂浆界面过渡区发展变化的一种新手段 .聚合物改性砂浆的阻抗谱随龄期延长出现二次明显变化 ,这种特征分别与聚合物在砂浆界面过渡区的聚集、凝结、形成紧密堆积的颗粒结构以及聚合物颗粒相互扩散渗透 ,形成具有一定力学强度的膜的过程有关 .同时 ,聚合物在界面过渡区的成膜情况与砂子粒径及其体积分数有关 。

The formation and the development of the interfacial transition zone (ITZ) in polymer modified mortar (PMM) were studied by means of the alternating current impedance spectroscopy (ACIS). The test results show that the alternating ACIS can be used as a new method to investigate the film formation process of latex in the ITZ according to the change of the AC impedance spectra. With the increase of curing time, the AC impedance spectra of the PMM show two obvious changes which can be related to the processes of aggregation and condensation, the formation of close-packing structure and the inter-diffusion of polymer particles to form the mechanically rigid film. It is found that the film formation process of latex in the ITZ depends on the particle size and the volume fraction of sand.