摘要
现浇钢筋混凝土桩、码头等构筑物自浇筑起便暴露于氯离子环境中,这可能对其后续强度和耐久性发展产生不利影响。为探究这一问题,本工作通过抗压强度测试、快速氯离子迁移(RCM)试验及人工海水浸泡等室内试验,系统研究了不同类型早龄期混凝土的力学性能与抗氯离子侵蚀性能随养护时间的变化规律,并对不同龄期接触海水混凝土结构的服役寿命进行了预测。结果表明:早龄期混凝土抗压强度随养护时间延长逐步提高,其中1~7 d内增速较快,而7 d后增幅减缓;氯离子扩散系数(D_(RCM))则随养护龄期延长而降低,在1~14 d内迅速下降,14 d后趋于稳定;此外,早龄期混凝土接触海水后,其表面氯离子浓度及表观扩散系数均随养护龄期延长而逐步降低,显示出海水侵蚀对早龄期混凝土后期氯离子扩散具有显著加速作用。然而,早龄期接触海水对混凝土抗压强度发展的影响较小。综合来看,保证足够的养护龄期对受海水侵蚀的早龄期混凝土结构耐久性至关重要,而内掺疏水化合孔栓物的应用则可显著延长结构的使用寿命。
Cast-in-place reinforced concrete piles,wharfs,and other structures are exposed to chloride ion environments from the moment of placement,which may adversely affect their subsequent strength development and durability.To investigate this issue,this study systematically examines the evolution of mechanical properties and chloride ion resistance of various early-age concretes under different curing periods through compressive strength tests,rapid chloride migration(RCM)tests,and laboratory immersion in artificial seawater.Service life predictions are also made for concrete structures exposed to seawater at different curing ages.The experimental results indicate that the compressive strength of early-age concrete gradually increases with curing time,with a rapid increase observed from 1 to 7 days and a slower rate thereafter.Meanwhile,the chloride ion diffusion coefficient(D_(RCM))decreases with increasing curing age,showing a sharp decline from 1 to 14 days followed by stabilization after 14 days.In addition,after early-age exposure to seawater,both the surface chloride ion concentration and the apparent diffusion coefficient in concrete gradually decrease with increasing curing age,indicating that early seawater erosion significantly accelerates subsequent chloride diffusion.However,early seawater exposure has only a minor effect on the development of compressive strength.In summary,ensuring sufficient curing time is crucial for enhancing the durability of early-age concrete structures subjected to seawater erosion,and the incorporation of hydrophobic pore-blocking agents can significantly extend the service life of these structures.
作者
唐博文
曹宁
杨海成
丁平祥
李安
TANG Bowen;CAO Ning;YANG Haicheng;DING Pingxiang;LI An(CCCC Fourth Harbor Engineering Institute Co.,Ltd.,Guangzhou 510000,China;Key Laboratory of Harbor&Marine Structure Durability Technology,Ministry of Transport of PRC,Guangzhou 510000,China;Key Laboratory of Construction Materials,CCCC,Guangzhou 510000,China;Rizhao Port Minggang Crude Oil Terminal Co.,Ltd.,Rizhao 276800,Shandong,China)
出处
《材料导报》
北大核心
2025年第S2期190-195,共6页
Materials Reports
基金
国家重点研发计划项目(2022YFB2603000)。
关键词
现浇混凝土
早龄期混凝土
力学性能
氯离子侵蚀
服役寿命
cast-in-place concrete
early-age concrete
mechanical property
chloride ion corrosion
service life
