同济大学 地下建筑与工程系; 岩土及地下工程教育部重点实验室, 上海 200092
通讯作者:李镜培，男，教授，电话(Tel.): 13901656003; E-mail: lijp2773@tongji.edu.cn.作者简介:赵高文(1988-)，男，陕西省榆林市人，博士生，主要从事桩基设计理论及耐久性研究.E-mail：007gwzhao@tongji.edu.cn.基金资助:国家自然科学基金（41772290）, 陕西省人才托举计划项目（20170522）Influence of Corrosion Forms on the Degradation Process and Sulfate Diffusion Laws of Cast-in-Situ Piles
ZHAO Gaowen,LI Jingpei,LI Lin,CUI JifeiDepartment of Geotechnical Engineering; Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education, Tongji University, Shanghai 200092, China
摘要/Abstract
摘要： 利用室内试验模拟盐渍土地区混凝土灌注桩的腐蚀过程，对比研究灌注桩混凝土在半浸泡及全浸泡腐蚀环境下的劣化过程及硫酸盐扩散规律. 通过室内试验制备现浇混凝土试样，采用人工腐蚀环境，分别模拟全浸泡及半浸泡腐蚀作用方式下混凝土灌注桩的腐蚀过程，测定混凝土试件在1、3、6、9个月等不同腐蚀时间的尺寸、抗压强度变化及硫酸盐扩散深度，分析两种腐蚀作用下灌注桩现浇混凝土的劣化过程及差异，并探讨不同腐蚀方式对灌注桩混凝土中硫酸盐扩散的影响规律.结果显示，半浸泡与全浸泡腐蚀的灌注桩混凝土劣化过程差异显著；半浸泡的混凝土劣化速度显著快于全浸泡混凝土，强度损失也更严重；半浸泡混凝土同时遭受硫酸盐的化学及结晶腐蚀，液面附近表面发生较为严重的脱落并发生一定程度的膨胀；液面以上混凝土硫酸盐的扩散速度显著高于全浸泡下混凝土中硫酸盐的扩散.研究表明，灌注桩中处于地下水位活动范围的混凝土在硫酸盐腐蚀下的劣化速度较快，在较短时间内发生严重的损伤；全浸泡现浇混凝土则由于其环境较稳定，主要受到硫酸盐的化学侵蚀，损伤过程较慢.因此，在混凝土灌注桩抗硫酸盐腐蚀设计中，应重点考虑地下水位附近桩体混凝土的抗蚀性能.
关键词: 灌注桩混凝土, 硫酸盐腐蚀, 硫酸盐扩散, 腐蚀方式, 劣化过程
Abstract: Sulfate corrosion process of the cast-in-situ piles in the saline area was simulated by laboratory experiments. Comparison study of degradation process and sulfate diffusion laws of cast-in-situ pile concrete was conducted to reveal the degradation mechanism. Cast-in-situ concrete specimens were manufactured and immersed in sulfate solutions to reproduce the completely and semi-immersed service conditions of cast-in-situ concrete piles in practical engineering. The size changes were recorded after 1, 3, 6 and 9 months. The compressive strength test was conducted and the sulfate concentration of different depths in concrete were measured to reveal the differences of degradation process in different service conditions. The effect of service condition on diffusion properties of sulfate in pile concrete were analyzed based on the experiments. Results show that degradation process of concrete and sulfate diffusion in concrete are quite different in different service conditions. The deterioration of concrete semi-immersed in sulfate solution is faster than those completely immersed below the liquid surface. Expansion and shedding of concrete are detected since sulfate chemical and crystallization conducted on the surface of semi-immersed specimens. The sulfate diffusion ratio in concrete above the liquid surface is more rapid than that of specimens completely immersed in sulfates solution. Results indicate that pile concrete above the groundwater level suffers greater damage and encounters more serious degradation in a relatively short time. The deterioration of pile concrete below groundwater level is relatively slow since the serving environment is stable and only chemical attack is encountered. The anti-sulfate attack of cast-in-situ pile concrete near the groundwater level should be considered in the design of pile foundation in sulfate saline area.
Key words: cast-in-situ pile concrete, sulfate attack, sulfate diffusion properties, corrosion forms, degradation process
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