冻融后表层混凝土的孔结构劣化与损伤特性研究

A Study on Deterioation of Pore Structure and Damage Property of Surface Concrete Caused by Freeze-Thaw Action

采用压汞试验和中子透射成像技术研究了冻融后表层混凝土孔结构劣化及损伤特性。结果表明:冻融循环作用改变混凝土的微观孔结构的特征,临界孔径成倍数增加,毛细孔等有害孔数量明显增多;表层混凝土在冻融循环作用下孔结构劣化和强度降低更为剧烈,由表及里存在一个损伤梯度。采用表面涂覆或表面浸渍等技术提高表层混凝土抗冻性对延长结构的使用寿命具有重要意义。

The micro-porous structure and damage properties of the surface concrete in freeze-thaw environment are studied by means of mercury intrusion test and neutron radiography technique. Results show that the pore structure characteristics of concrete are deteriorated, the critical aperture doubly enlarged and the number of harmful hole significantly increased after freeze-thaw cycles. The pore structure and strength of surface concrete degradation are more serious than the internal concrete, which has a damage gradient from external to internal. So it is very important to improve the frost resistance of surface con- crete for the service life of structure by surface coating or dipping.