南海岛礁普通混凝土结构耐久性的调查研究

Investigation of durability of ordinary concrete structures in the South China Sea

为了探究热带海洋环境下混凝土结构的耐久性,通过对我国南海岛礁普通混凝土结构的现场调研与测试,研究了普通混凝土的破坏现状、碳化深度、自由氯离子含量（C_f）和总氯离子含量（C_t）,并计算了氯离子结合能力（R）、表面自由氯离子含量（C_s）、表观氯离子扩散系数（D_a）和自由氯离子扩散系数（D_f）。结果表明：在南海岛礁工程中,普通混凝土结构的主要破坏特征为混凝土保护层胀裂、剥落、垮塌、露筋、钢筋锈蚀等;其碳化服役寿命不足25a;海风是加速氯离子扩散渗透的主要因素之一;普通混凝土在南海岛礁环境下的D_a值大于北欧、北美及我国东海等近海环境,大致高1~2个数量级。

To investigate the durability of concrete structures in the tropical marine environment, in this study, we carried out site investigations in the South China Sea and laboratory experiments to determine the destruction status, carbonization depth, free chloride concentration （ Cf ） , total chloride concentration （ Ct ） , chloride binding ca-pacity（ R ） , surface free chloride concentration （ Cs ） , apparent chloride diffusion coefficients （ Da ） and free chloride diffusion coefficients （ Df ） of ordinary concrete. The results show that in the islands engineering of South China Sea, the main failure characteristics in ordinary concrete structures are cover cracks, exfoliation, collapse, steel bar exposure, and steel corrosion. In addition, the carbonation service life of these structures is less than 25 years, and wind is one of the main factors accelerating the chloride diffusion penetration. In the South China Sea environment, the Da value for ordinary concrete is about 1～2 orders of magnitude higher than that of the Northern Europe, North America, and East China Sea offshore environments.