酸和硫酸盐耦合作用下混凝土试件耐久性修复试验研究

EXPEREMENTAL RESEARCH ON DURABILITY REPAIR OF CONCRETE STRUCTURE UNDER COUPLING ACTION OF ACID AND SULFATE

某些工业厂房中混凝土结构受酸和硫酸盐耦合作用,加之干湿循环作用,使其耐久性问题非常突出,需进行修复加固处理。通过将分别经环氧砂浆、聚合物乳液砂浆、聚合物水泥砂浆、超高性能混凝土、表面涂层、修复砂浆+耐酸粉、修复砂浆+抗硫酸盐防腐剂修复的受损混凝土试件浸泡在不同浓度酸(p H=2,5)与硫酸盐(SO24-=5%,10%)的混合溶液中,并进行干湿循环试验。短期修复效果评估结果表明:环氧砂浆和表面涂层在各种情况均表现出优异的修复效果;强酸+硫酸盐情况下,修复效果的优劣依次为:聚合物乳液修复砂浆、超高性能混凝土、聚合物水泥修复砂浆,掺加耐酸粉可提高修复性能,掺加抗硫酸盐防腐剂无明显效果;弱酸+硫酸盐情况下,超高性能混凝土修复效果最佳。

Concrete used in some industrial plants are continuously eroded by corrosive medium coupled with environmental factors such as dry and wet cycles.Thus the durability problems of concrete strutures in such environment are very prominent and many structures need to be repaired and strengthened.In the paper,the damaged concrete specimens were repaired by epoxy mortar,polymer modified mortar,polymer cement mortar,Ultra high performance concrete(UHPC),surface coating,repairing mortar+acid-proof powder,repariring mortar+sulfate corrosion-resistance admixture,respectivly.Then the specimens were soaked in a mixture of acids(pH=2,5)and sulfates(SO4 2-(wt%)=5,10),and dry and wet cycles were performed simultaneously.The evaluation results of short-term repair effects indicated that epoxy mortar and surface coating had shown excellent repair properties in all situations.Under coupling action of strong acid and sulfate,repair effects were:polymer modified mortar>UHPC>polymer cement mortar.Adding acid-proof powder could improve repair effect significantly while adding sulfate corrosion-resistance admixture had no obvious effect.Under coupling action of weak acid and sulfate,UHPC showed the best repair effect.