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对氯盐侵蚀环境下普通硅酸盐混凝土内锈蚀HRB335级变形钢筋表面上的蚀坑的形状、数量和尺寸进行了详细的观测和研究.通过统计分析建立了不同形状蚀坑的概率分布模型.结合金属腐蚀学的知识对蚀坑的生长机理进行了分析,并得到了蚀坑生长演变的规律.结果表明:在锈蚀初期,22%的微观蚀坑在闭塞电池作用下发展为深椭球形蚀坑,但多数蚀坑的纵横向腐蚀速率大于径向,使得40%的蚀坑呈圆球形,35%的蚀坑呈长椭球形;随着锈蚀率的逐渐提高,径向腐蚀速率下降,纵向腐蚀速率逐渐增大,深椭球形逐渐演变为其他形状,圆球形蚀坑逐渐演变为长椭球形;当锈蚀率超过4%以后,蚀坑横向曲率逐渐为0,长椭球形蚀坑逐渐演变为凹槽形.
The shape, number and size of pits on the surface of HRB335 deformed bar in ordinary silicate concrete under chloride salt environment were observed and studied in detail.The probability distribution model of pits with different shapes was established by statistical analysis. Combined with the knowledge of metal corrosion, the growth mechanism of etch pits was analyzed and the rule of the growth of etch pits was obtained. The results showed that 22% of microscopic etch pits developed into deep ellipsoidal corrosion However, the corrosion rates in most vertical and horizontal pits are larger than those in the radial direction, resulting in 40% of the pits being spherical and 35% of the pits being ellipsoidal. As the corrosion rate gradually increases, the radial corrosion rate decreases. The corrosion rate gradually increases, the deep ellipsoid gradually evolves to other shapes, and the spherical pits gradually evolve into oblong spheres. When the corrosion rate exceeds 4%, the transverse curvature of the pits gradually becomes zero, and the ellipsoidal pits gradually evolve into Groove shape.