高寒地区早期受冻水泥混凝土力学性能及抗冻耐久性  

Mechanical Properties and Frost Resistance Durability of Early Frozen Cement Concrete in Alpine Regions

作　　者：赵帮轩[1] ZHAO Bangxuan(China Railway 18th Bureau Group 5th Engineering Co.,Ltd.,Tianjin 300450,China)

机构地区：[1]中铁十八局集团第五工程公司,天津300450

出　　处：《西安工业大学学报》2024年第2期171-181,共11页Journal of Xi’an Technological University

基　　金：陕西省重点研发计划项目(2018SF-391);陕西省住房和城乡建设厅科技计划项目(2017-K55);西安市科技局高校人才服务企业项目(2019217214GXRC008CG009-GXYD8.2)。

摘　　要：针对高寒地区新浇筑混凝土易受冻害,导致的路面结构安全隐患和后期服役寿命受限等问题,文中选取西藏地区实际施工材料分别拌制了C30、C40及C45三组水泥混凝土试件,试件在标准养护室养护0,3,7,28 d后移置室外继续养护150 d,研究抗压强度、抗折强度及动弹性模量变化规律,并且对自然养护150 d的试件进行300次冻融循环试验。研究结果表明:当认为标准养护龄期为28 d的混凝土无受冻状态时,标准养护龄期的增加能有效提升混凝土服役初期的抗冻能力,混凝土的受冻率随着养护龄期的增加依次降低;通过掺加粉煤灰和防冻剂,自然养护150 d的混凝土可经受275~300次冻融循环,冻融循环250次后,混凝土内部产生明显的大孔隙及裂隙,试件抗冻指标快速下降;通过建立的冻融损伤度转化公式,可快速对高寒地区不同服役年限的混凝土建筑物进行力学性能预测,进而为运行期建筑物安全性评价提供理论支撑。The newly poured concrete in alpine areas is susceptible to frost damage,which leads to potential safety hazards in pavement structure and limited service life.Three groups of C30,C40 and C45 cement concrete specimens were prepared with the actual construction materials in Tibet.The specimens were cured in a standard curing room for 0,3,7,and 28 days,and then cured outside for 150 days.The changes of their compressive strength,flexural strength and dynamic modulus of elasticity were studied,and 300 freeze thaw cycles were performed on the specimens naturally cured for 150 days.It is found that when the concrete with the standard curing age of 28 days is considered to be free from freezing,the increase of the standard curing age can effectively improve the frost resistance of the concrete at the initial stage of service and that the probability of the concrete being frozen decreases with the increase of the curing age.The addition of fly ash and antifreeze enables the concrete naturally cured for 150 days to withstand 275~300 freeze thaw cycles.After 250 freeze thaw cycles,there are obvious macropores and cracks emerging in the concrete,and its frost resistance index decreases rapidly.The established freeze thaw damage degree transformation formula can quickly predict the mechanical properties of concrete buildings with different service life in alpine regions.The prediction can provide theoretical support for the safety evaluation of buildings in operation.

关 键 词：混凝土 高寒地区 抗压强度 抗冻耐久性 损伤度 

分 类 号：TU528[建筑科学—建筑技术科学]