海洋环境下珊瑚混凝土中钢筋表面蚀坑发展的研究

Development of Corrosion Pits on Reinforcement Surface in Coral Concrete under Ocean Environment

为了研究不同海洋环境下珊瑚混凝土中钢筋表面蚀坑的发展情况,通过浸泡和干湿循环两种养护方式来模拟水下区和潮汐区两种环境,对比分析了两种环境下珊瑚混凝土中HPB300钢筋的锈积率、失重率以及其与蚀坑数目之间的关系;建立了表面蚀坑的尺寸分布模型并阐述了蚀坑的生长演变机理。研究表明,对比浸泡条件,在干湿循环条件下的混凝土中钢筋失重率及锈积率更高,且在60 d时蚀坑数量出现小规模的集中增长;不同时期钢筋表面蚀坑尺寸分布函数均可表示为P=α+βeεS,且其中大部分都属于亚稳态的微观蚀坑;在干湿循环养护方式下首先发育出尺寸较大的宏观蚀坑;90 d内随着混凝土龄期的增长,干湿循环下蚀坑尺寸分布不均,而浸泡条件下蚀坑尺寸渐趋接近。

In order to study the development of corrosion pits on the surface of steel bars in coral concrete under different marine environments, the corrosion rate and weight loss rate of HPB300 steel bar in coral concrete and the relationship between them and the number of corrosion pits were obtained and analyzed by immersion and dry-wet cycling curing methods to simulate the underwater and tidal environments. The size distribution model of surface pits was established and the growth and evolution mechanism of pits was expounded. The results show that compared with soaking conditions, the weight loss rate and rust accumulation rate of steel bars in concrete under dry-wet cycling conditions are higher, and the number of corrosion pits increases centrally in a small scale in 60 d. The size distribution function of pits on steel bars in different periods can be expressed as P=α+βeεS, and most of them belong to metastable micro-pits. In the dry-wet cyclic curing mode, the macroscopical corrosion pits with larger size are first developed. Within 90 d, with the increase of concrete age, the size distribution of pits is uneven under dry-wet cycling, while the size of pits tends to approximate under immersion conditions.