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-  2018 

盐沼泽环境下公路桥梁桩基材料耐腐蚀试验
Experiment on erosion-resistance of highway bridge pile foundation material under salt marshes environment

Keywords: 桥梁工程,盐沼泽,混凝土掺和料,抗侵蚀系数,微观机理
bridge engineering
,salt marsh,concrete admixture,erosion-resistance coefficient,microscopic mechanism

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Abstract:

为解决盐沼泽环境下桥梁桩基础混凝土材料的耐久性,通过分别埋置在现场地表、水中、地下0.25 m深和地下1.25 m深的13个不同配合比的混凝土试件,历时360 d的自然条件盐碱腐蚀环境下公路桥梁桩基混凝土材料腐蚀试验,系统地研究了掺和料(粉煤灰、矿粉、硅灰、膨胀剂、水泥基自愈合防水材料)种类及阻锈剂、抗硫酸盐水泥、钢护筒等对公路桥梁桩基混凝土抗侵蚀性能的影响,分别测试了混凝土立方体抗压强度和质量;采用扫描电镜、能谱仪和X衍射仪对混凝土进行微观分析,进而揭示其内部腐蚀机理;并提出混凝土抗侵蚀系数随龄期变化的回归公式。研究结果表明:埋置条件对混凝土抗侵蚀性能有一定影响,4种埋置条件中,放置在地表上的混凝土受侵蚀最严重,埋置在土中1.25 m深处的混凝土腐蚀最轻,但不同混凝土试件略有差别;矿物掺和料的合理搭配能有效提高混凝土的抗侵蚀性能,其中矿渣应与膨胀剂掺和(CMP3),粉煤灰应与硅灰掺和(CMP7),水泥基自愈合防水材料应与硅灰掺和(CMP9);几种情况下360 d内混凝土抗侵蚀系数均在0.85以上,具有较好的抗侵蚀性能;钢筋阻锈剂对混凝土的抗侵蚀性能有负面影响;所得回归公式可为混凝土耐久性的预测提供参考;腐蚀产物中发现了钙矾石、方解石、Friedel盐和硅灰石膏,这些腐蚀产物共同作用加速了混凝土的腐蚀;粉煤灰中活性成分Al2O3较高时,会加速钙矾石的生成,对混凝土不利。
To solve the durability of concrete materials for bridge pile foundation in salt marshes environment, 13 concrete specimens with different mix proportion designs were adopted, which were embedded in sites with four conditions (field surface, underground water, 0.25 m deep from ground and 1.25 m deep from ground) for 360 d under natural conditions of saline corrosion environment of highway bridge pile foundation, and the influences of various factors, including the admixture type (fly ash, slag, silica fume, expansion agent, cementitious calillary crystalline waterproofing material) rust-inhibitor, sulfate-resistant cement and steel liners on the mechanical properties of concrete erosion-resistance of highway bridge pile foundation were studied. The cube compressive strength and concrete quality were test respectively, and the corrosion mechanism of concrete was revealed by conducting microscopic analysis through scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and X-ray diffraction(XRD). In addition, a regression formula of erosion resistance coefficient of concrete with age was put forward. The results show that embedment condition influences the performance of the erosion-resistance of concrete in some degree. For four embedment conditions, specimens of concrete placed on the surface are most seriously corroded. Otherwise, specimens of concrete buried 1.25 m deep in the soil have the least corrosion, but there is a slight difference between different concrete specimens. The mineral admixtures choosing the right mixing (slag with expansive agent(CMP3), fly ash with silica fume (CMP7), cementitious calillary crystalline waterproofing material with silica fume (CMP9)) can effectively improve the erosion-resistance of concrete, and erosion-resistance coefficients of concrete are all above 0.85 under several conditions, which has a good erosion-resistance performance. Reinforcing bar rust-inhibitors have negative effects on the

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