复合盐蚀环境下喷射混凝土离子分布规律及氯离子扩散系数

通过分析(干湿循环+复合盐侵蚀)共同作用下普通混凝土、普通喷射混凝土和钢纤维喷射混凝土孔隙液中pH值、Cl-、SO2-4和Ca2+分布情况,研究了喷射混凝土离子分布规律和氯离子扩散系数.结果表明:各混凝土pH值和Ca2+浓度随深度分布规律相似,均为表层最低并随深度增加而升高,且在同一深度随龄期增加而降低;普通混凝土表层Cl-浓度最高且扩散深度最大,钢纤维喷射混凝土的表层Cl-浓度最低和扩散深度最小;SO2-4在各混凝土内部的分布大致分为富集区、过渡区和稳定区三段;表面自由Cl-含量Cs为普通混凝土>普通喷射混凝土>钢纤维喷射混凝土,且随侵蚀龄期的增长而逐渐上升;混凝土的Cl-扩散系数D随侵蚀龄期的增长而降低,符合幂函数变化规律.

Ions Distribution Regularity and Chloride Diffusion Coefficient of Shotcrete under the Environment of Compound Salt Attack

The pore solution of pH value, Cl-, SO2-4 and Ca2+ distribution situation of ordinary concrete, ordinary shotcrete and steel fiber shotcrete are analyzed under the combined action of (wetting and drying cycles + compound salt erosion), the ions distribution regularity and chloride ion diffusion coefficient of shotcrete are investigated.The results show that the pH value and Ca2+ concentration distribution regularity with depth of each concretes are similar, and all lowest on surface, increase with depth increasing, and decrease with the age increasing in the same depth.The Cl-concentration of ordinary concrete surface is the highest, and its diffusion depth is the lowest, but steel fiber shotcrete contrasting with ordinary concrete.The distribution of SO2-4 in the concrete can be divided into three segments, rich region, transition region and stable region.The Cs of ordinary concrete > ordinary shotcrete > steel fiber shotcrete, and increase gradually with the age increasing.The D reduced gradually with the age increasing, which is in accordance with the law of the variation of power function.