摘要
以青藏铁路桥涵冻土层中混凝土灌注桩为背景,进行了不同引气剂掺量混凝土在持续-3℃养护环境下的抗压强度和冻融循环试验,结果表明:持续-3℃养护环境下龄期84d时的抗压强度与标养下龄期28d时的抗压强度相当,前者存在明显的“龄期滞后”现象,但混凝土抗压强度龄期滞后的天数与含气量关系不大,仅与养护环境有关;随着含气量的增大,混凝土的抗冻性能先增强后减弱,在抗压强度相同的情况下,混凝土的含气量在3.2%时,抗冻融耐久性指标降低幅度最小,抗冻性能最优;持续-3℃养护环境下混凝土的抗压强度虽能够最终达到标养下28d的抗压强度,但抗冻性能降低幅度较大,对于寒冷地区混凝土灌注桩耐久性的这一特点应引起使用者高度重视。
Based on the cast-in-place concrete piles in the permafrost layer of Qinghai-Tibet railway bridges,the compressive strength and the freeze-thaw cycle tests of concrete with different air-entraining admixture in a continuous -3 ℃ curing environment were carried out. The results show that compressive strength of the concrete at the age of 84 d in a continuous -3 ℃ curing environment is similar to the compressive strength at 28 d under standard curing. The former has a significant “age lag” phenomenon,but the number of days of age lag of concrete compressive strength is only related to the curing environment,rather than air content. With the increase of air content,the frost-resistance performance of the concrete increases first and then weakens. Under the same compressive strength condition, the freeze-thaw resistance is the best when the decreased degree of frost-resistance performance of the concrete at 3.2% air content is minimum. Although the compressive strength under continuous -3 ℃ curing condition can finally reach 28 d compressive strength under standard curing, the frost-resistance performance is greatly reduced. Great attention should be paid to this feature of cast-in-place concrete pile durability in cold area.
作者
张凯
王起才
杨子江
王庆石
梁柯鑫
ZHANG Kai;WANG Qicai;YANG Zijiang;WANG Qingshi;LIANG Kexin(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;National and Provincial Joint Engineering Laboratory of Road & Bridge Disaster Prevention and Control,Lanzhou 730070,China;Linyi Public Works Section Jinan Railway Administration,Jinan,250001,China)
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2019年第5期156-161,共6页
Journal of the China Railway Society
基金
国家自然科学基金(51768033,51808272)
长江学者和创新团队发展计划(IRT_15R29)
兰州交通大学青年科学基金(2018016)
关键词
抗压强度
抗冻性能
含气量
龄期滞后
compressive strength
frost resistance
air content
age lag
