干湿循环作用下盐分对桥墩混凝土耐久性影响实验研究

Experimental Study of Effect of Salt on Durability of Bridge Pier Concrete Under Dry-wet Cycle

以青海德香高速公路大桥桥墩混凝土为依托,对其沿线主要易溶盐含量进行分析,通过室内模拟实验,配制了7种腐蚀溶液,并设计4种配合比混凝土,通过外观形貌、质量损失率和相对动弹模量3方面研究干湿循环作用下,盐分对混凝土耐久性的影响.结果表明:干湿循环作用下,单一盐类如Na_2SO_4、MgSO_4、NaCl溶液对混凝土破坏形式和程度均不相同;在复合盐溶液中,复盐对混凝土的腐蚀损伤效应会发生叠加,而且溶液浓度越大,混凝土腐蚀破坏越严重;掺加水泥基自愈合材料、粉煤灰能够提高混凝土抗盐蚀破坏能力.

In this paper,based on bridge pier concrete of Dexiang highway bridge in Qinghai province,the concentration and the main types of the dissolved salts along Dexiang highway were analyzed,and seven solutions of different concentration of salt were prepared and four kinds of concrete were designed by laboratory experiments. Surface morphologies,weight loss rate and relative dynamic elasticity modulus were used to study the effects of salt on concrete durability under dry-wet cycles. The results show that the corrosion damage forms and extents of concrete are different when different single salt solution is adopted such as Na_2SO_4,MgSO_4,NaCl under dry-wet cycles. The superposition effects of multiple salt corrosion of concrete damage can happen in the multi-salt solution,and the higher the concentration of solution,the more severe the concrete is damage under wet-dry cycles. CCSM concrete and fly ash concrete can improve the resistance to salt corrosion under wet-dry cycles.