单面盐冻作用下混凝土约束应力测试装置设计及参数优选  

Design and optimization of restraint stress testing device for concrete under the attack of single-side freezing and thawing

作　　者：高志浩 王玲 赵霞 王振地 GAO Zhihao;WANG Ling;ZHAO Xia;WANG Zhendi(State Key Laboratory of Green Building Materials,China Building Materials Academy,Beijing 100024,China)

机构地区：[1]中国建筑材料科学研究总院有限公司绿色建筑材料国家重点实验室,北京100024

出　　处：《混凝土》2020年第12期26-30,34,共6页Concrete

基　　金：“十三五”国家重点研发计划课题“严寒环境高耐久混凝土制备与应用成套技术”(2017YFB0309901)。

摘　　要：为模拟研究实际服役混凝土的单面盐冻破坏行为和机理,设计采用壁厚1、4、8、12 mm的钢环约束混凝土膨胀及约束长度为28、33 mm的约束锚栓约束混凝土收缩,通过应变片采集盐冻循环全程钢环膨胀应变和拉杆收缩应变,计算约束应力。测试了水灰比0.40的混凝土试件盐冻循环28次的应变、质量和相对动弹性模量,获得约束态混凝土约束应力峰值拟合曲线。试验结果表明:约束应力峰值随冻融次数增加呈阶梯状上升分布;约束应力峰值拟合曲线描述了混凝土试件在盐冻循环进程中经历的饱水过程,包括吸水阶段、临近饱水阶段和饱水阶段;约束态和自由态试件质量和相对动弹性模量变化趋势一致;试验确定了约束应力测试装置的适宜参数,钢环厚度8 mm、约束长度为28 mm的约束组合,有利于应变收集、应力计算和相对动弹性模量采集。In order to simulate and study the behavior and mechanism of single-side salt freezing and thawing of concrete in service,steel rings with thicknesses of 1,4,8 and 12 mm were used to restrain expansion of concrete and anchors with restraint length of 28 and 33 mm were used to restrain shrinkage of concrete.The strain gauges were used to collect the expansion strain of steel ring and shrinkage strain of anchor during the all freezing and thawing cycles.The strains,masses and relative dynamic elastic modulus of the concrete specimens with water cement ratio of 0.40 were tested in 28 cycles of freezing and thawing,and the fitting curves of peaks stress of the restraint concrete were obtained.The results show that the peaks of the restraint stress increase stepwise with the number of freeze-thaw cycles.The saturation process of concrete specimens in the salt-freezing cycle can be fully described by the restraint stress fitting curve,including the absorption stage,the near-saturation stage and the saturation stage.The restraint and free state specimens have the same trend of changes in relative dynamic elastic modulus.The appropriate combinations of the restraint device are determined.The restraint combination with a steel ring thickness of 8 mm and a restraint length of 28 mm is beneficial to strain collection,stress calculation and relative dynamic elastic modulus collection.

关 键 词：混凝土 单面盐冻 应变 约束应力 

分 类 号：TU528.01[建筑科学—建筑技术科学]