酸雨对预应力体系腐蚀的试验研究

Experimental study of acid rain corrosion to the prestressed system

以重庆地区的酸雨类型为原型，采用周期浸泡法模拟酸雨加速预应力体系腐蚀的试验，研究有、无张拉状态下酸雨对预应力体系的腐蚀规律，探求腐蚀后的钢绞线、锚具和波纹管等的腐蚀深度及力学性能变化规律。试验结果表明：环氧涂层钢绞线及其使用的锚具具有更好的耐腐蚀性能；与金属波纹管相比，塑料波纹管在耐酸雨腐蚀方面具有明显的优势；普通钢绞线经3000h酸雨腐蚀试验后，钢绞线的截面损失率小于5％，其抗拉强度下降了约1．5％-2．0％，延伸率有较大的损失。锚环的强度下降幅度均在5％左右，其与钢绞线的腐蚀深度基本一致。对预应力钢绞线腐蚀深度和强度损失率的试验值与理论值进行了对比，两者吻合较好，可以使用该模型进行酸雨对预应力体系腐蚀的损伤评估。

Taking Chongqing area＇s acid rain type as a prototype, the corrosion rule of acid rain to prestressed system is studied by using periodic immersion method to simulate accelerated corrosion test under the free-tension and tension states, involving the corrosion depth and mechanical properties change rule of the PC strand, anchorage, corrugated pipe and so on after corrosion. The results show that the epoxy coat- ing steel strand and its anchorage has a better anti-corrosive performance. Compared with the metal bellows, plastic corrugated pipe has obvious advantages of corrosion resistance to acid rain. After been corroded by acid rain for 3 000 hours, cross-section loss rate of common strand is less than 5%, the tensile strength decreased about 1.5% to 2%, while the elongation ratio lost more. The strength of the anchorring decreased around 5%, and the corrosion depth is basically the same as that of steel strand. The experimental values of corrosion depth for prestressed steel strand and loss rate are well argee with the theoretical data.