基于结晶劈裂作用的再生粗骨料冻融改性方法
作者:
作者单位:

浙江大学 建筑工程学院,浙江 杭州 310058

作者简介:

弓扶元(1988—),男,陕西西安人,浙江大学研究员,博士生导师,博士. E-mail:gongfy@zju.edu.cn

通讯作者:

弓扶元(1988—),男,陕西西安人,浙江大学研究员,博士生导师,博士. E-mail:gongfy@zju.edu.cn

中图分类号:

TU528.01

基金项目:

国家自然科学基金资助项目(52008367);浙江省自然科学基金资助项目(LQ20E080016)


A Freezing-Thawing Modification Method for Recycled Coarse Aggregate Based on Crystallization Fracture of Pores
Author:
Affiliation:

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China

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    摘要:

    利用多孔水泥基材料在冻融循环中的孔隙水结晶劈裂原理,开展了不同工况下再生粗骨料的冻融改性试验,以部分或全部去除再生粗骨料表面附着的旧砂浆.结果表明:冻融最低温度越低,附着砂浆的剥除速率越快;经过一定次数的冻融循环后,附着砂浆几乎全部剥离,且改性后的再生粗骨料各项物理力学性能接近天然骨料;高温干燥预处理对后续冻融改性有较好的促进作用.最后,基于孔隙水相变的热力学原理以及冻胀开裂的孔隙介质力学机理,对再生粗骨料的冻融改性进行了理论分析,构建了再生粗骨料细观模型,从细观尺度解释了附着砂浆冻胀开裂及剥离的全过程.

    Abstract:

    Based on the crystallization fracture principle of ice forms in porous cement-based materials and initiates cracking during freezing-thawing cycles, freezing-thawing modification experiments of recycled coarse aggregate under different working conditions were carried out to remove part or all of the attached old mortar. The results show that the lower of the minimum freezing-thawing temperature is, the faster of the peeling of the attached mortar is. After a certain number of freezing-thawing cycles, the attached mortar is almost completely peeled off. Besides, the physical and mechanical properties of the modified recycled coarse aggregate are close to those of natural aggregate. In addition, the high temperature drying treatment before freezing-thawing cycles improves the efficiency of the method. Finally, based on thermodynamics and poromechanics principles, the process of freezing and cracking to remove the attached mortar is analyzed and simulated in a mesoscopic model.

    表 2 RBSM模型使用的材料参数Table 2 Material parameters used in RBSM
    表 1 各组试样处理工艺Table 1 Treatment process of each group of materials
    图1 不同粒径的再生混凝土骨料Fig.1 Recycled concrete aggregates of different particle sizes
    图2 再生混凝土骨料试样及温度传感器布置Fig.2 Recycled concrete aggregate sample and temperature sensor distribution
    图3 冻融循环过程中试样中心的温度历程Fig.3 Temperature history of sample center during freezeing-thawing cycle
    图4 再生混凝土骨料吸水率和砂浆剥落率随冻融循环次数的变化Fig.4 Absorption and spalling ratio of recycled concrete aggregate with different freezing-thawing cycles
    图5 冻融改性试验前后的再生骨料和剥落附着砂浆Fig.5 Recycled aggregate before and after freezing-thawing cycles and attached mortar
    图6 冻融改性再生骨料附着砂浆完全剥落后的压碎指标及吸水率Fig.6 Crushing index and absorption of freezing-thawing modified recycled aggregate without attached mortar
    图7 孔隙水结冰的应力-应变关系Fig.7 Stress-strain relationship during the freezing of pore water
    图8 冻融循环中水分吸收与损伤积累Fig.8 Continuous water uptake and damage accumulation during freeze-thaw cycles[20]
    图9 细观RBSM模型示意图Fig.9 Schematic diagram of the mesoscale RBSM
    图10 冻融循环再生骨料模型Fig.10 Simulation of RCA under freeze-thaw cycles
    图11 ITZ裂缝宽度与砂浆、骨料应变的关系Fig.11 Correlation between ITZ crack width and strain of mortar and aggregate
    图12 40次冻融循环前后各个模型的单轴抗拉曲线Fig.12 Uniaxial tensile behaviors of models before and after 40 freezing-thawing cycles
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弓扶元,支点,吴庆培,赵羽习.基于结晶劈裂作用的再生粗骨料冻融改性方法[J].建筑材料学报,2022,25(11):1210-1218

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  • 收稿日期:2022-05-05
  • 最后修改日期:2022-06-30
  • 在线发布日期: 2022-11-30
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