城市热岛效应下浅层土中混凝土的酸腐蚀试验研究

针对城市热岛效应引起城区浅层土地温场升高这一观测结果,采用室内快速模拟试验方法,对城区酸性土壤腐蚀混凝土材料的温度效应开展了试验研究。试验研究了在温度为5℃、20℃和40℃条件下,混凝土试样在酸浓度分别为0%、5%和10%的沙土介质中放置30d、90d后的抗压强度变化规律,并对混凝土试样在腐蚀过程中的腐蚀系数变化规律和微观机理进行了分析;最后,对南京城区热岛效应环境下浅层土中混凝土材料酸腐蚀的强度变化规律进行了分析。试验结果表明,在同一腐蚀浓度下,混凝土试样抗压强度的下降速度随着温度的升高而不断加快,其腐蚀系数也随着温度的升高而不断增大;腐蚀介质的浓度越大,环境温度对混凝土腐蚀系数的影响就越明显;在温度为40℃、硫酸浓度为10%的沙土中放置30 d后,混凝土的腐蚀系数K达到45.21%,约是在5℃条件下腐蚀系数的2倍,相当于环境温度每上升1℃,混凝土腐蚀系数平均增加0.64%。该研究成果对于减轻城市热岛效应对岩土工程的影响具有重要意义。

Laboratory Study on Urban Heat Island Effect on the Acid Corrosion of Concrete in Superficial Soil Layers

This research was conducted to evaluate the concrete acid corrosion in the superficial soil layers of urban area at the higher ground temperature owing to the urban heat island effect.The compressive strength properties of concrete specimens,which were held in the situation of temperature 5℃,20℃and 40℃,acid concentration 0%,5%and 10%,and erosion time 30 d and 90 d were studied.And the mechanism of concrete acid corrosion and the urban heat island effect on the concrete strength in superficial soil layers for Nanjing area was analyzed.The test results indicate that the coefficient of corrosion of concrete specimens increases with the increasing of the temperature;and the temperature has an increasingly powerful influence on the coefficient of corrosion with higher acid concentration.Under the situation of sulfuric acid concentration 10%and immersing time 30 d,the coefficient of corrosion of concrete specimen reaches 45.21%at the temperature 40℃,which was almost twice of the corrosion coefficient at temperature 5℃. In other words,the coefficient of corrosion increases 0.64%with the rising 1℃of the environment temperature. The research achievement has a clear meaning to reduce the urban heat island effect in geotechnical engineering.