抗裂型外加剂对混凝土硫酸盐腐蚀行为的影响

为了解抗裂型外加剂对混凝土耐久性能的影响,考虑不同外加剂种类和掺量,分析了混凝土受硫酸盐侵蚀后质量、腐蚀深度、抗压强度随腐蚀龄期的变化,并通过吸水特性试验研究了混凝土硫酸盐腐蚀损伤程度的差异。结果表明:掺抗裂外加剂混凝土受硫酸盐腐蚀后质量变化可分为3个阶段,即增长、稳定及显著下降阶段; 掺不同抗裂外加剂混凝土试件的腐蚀深度变化规律不同,长腐蚀龄期下,相同掺量的HME-V抗裂剂相较于UEA膨胀剂具有更优异的抗硫酸盐腐蚀能力; 掺UEA膨胀剂的混凝土90 d后出现膨胀破坏,导致腐蚀速率加快; 掺HME-V抗裂剂的混凝土未出现膨胀破坏,始终保持均匀的腐蚀速率; 外加剂掺量相同时,掺HME-V抗裂剂混凝土腐蚀后强度均大于掺UEA混凝土; 腐蚀层结构较未腐蚀层相对疏松,吸水量大; 表层吸水量随着腐蚀程度的增加而增大; 掺HME-V抗裂剂混凝土表层受腐蚀损伤程度小于掺UEA膨胀剂混凝土; 总体而言,相同外加剂掺量的HME-V抗裂剂相较于UEA膨胀剂具有更优异的抗硫酸盐腐蚀能力。

Effect of Anti-cracking Admixture on Sulfate Corrosion Behavior of Concrete

In order to understand the effect of anti-cracking admixture on the durability of concrete, considering the different contents and types of anti-cracking admixture, the changes of concrete quality, corrosion depth and compressive strength with corrosion age after sulfate corrosion were studied, and the difference of sulfate corrosion damage degree of concrete was studied by water absorption test. The results show that the quality change after corrosion can be divided into three stages, namely, growth, stability and significant decline. The change rules of corrosion depth of concrete specimens with different anti-crack additives are different. Compared with UEA expansive agent, the HME-V anti-cracking agent with the same content has better sulfate corrosion resistance under long corrosion age. The concrete with UEA expansive agent appears expansion failure after 90 d, which leads to the accelerated corrosion rate. The concrete with HME-V anti-cracking agent has no expansion failure, and keeps the same corrosion rate. At the same content of admixture, the strength of concrete with HME-V anti-cracking agent is higher than that with UEA expansive agent after sulfate corrosion. The water absorption of the corrosion layer is large due to the looser structure compared with the non-corrosion layer, and the water absorption of the surface layer increases with the increase of the corrosion degree. The surface corrosion damage degree of concrete with HME-V is less than that with UEA expansive agent. In general, HME-V anti-cracking agent with the same amount of admixture have better sulfate corrosion resistance than UEA expansion agent.