西安建筑科技大学学报(自然科学版)

采用全轻陶粒混凝土加固普通混凝土构件,可在实现既有结构性能提升的同时降低加固体自重,改善加固结构承载特性.为研究新老混凝土环氧树脂粘结界面冻融损伤后抗剪性能退化规律,开展了7组新老混凝土试件和2组整浇试件的冻融试验,测试各组试件分别在经历0、5、10、15、20、25及30次冻融后的界面抗剪强度,分析试件外观损伤、抗剪破坏形态及抗剪强度退化规律.研究结果表明:冻融次数低于15时试件剪切破坏均发生在普通混凝土与环氧树脂界面剂之间,冻融次数超过25时发生在全轻陶粒混凝土与环氧树脂界面剂之间,15～25次时为过渡状态; 冻融后试件界面抗剪强度出现明显退化,经历5、10、15、20、25、30次冻融循环后,界面抗剪强度较冻融前的下降率分别为7.83%、20.91%、25.54%、31.11%、36.54%、45.27%.建立了环氧树脂界面的抗剪强度退化计算公式,可较准确地预测出冻融后环氧树脂界面抗剪强度.研究结论可为工程结构加固及类似新老混凝土连接界面研究与设计提供参考.

Using lightweight ceramsite concrete to strengthen ordinary concrete members can improve the performance of existing structures, reduce the dead weight of added solids, and improve the bearing characteristics of strengthened structures. In order to study the degradation law of shear performance of epoxy resin bonding interface of new and old concrete after freeze-thaw damage, the freeze-thaw tests of 7 groups of new and old concrete specimens and 2 groups of cast-in-place specimens were carried out. The interfacial shear strength of each group of strengthened specimens after 0, 5, 10, 15, 20, 25 and 30 freeze-thaw cycles was tested, and the appearance damage, shear failure morphology and degradation law of shear strength of specimens were analyzed. The results show that when the freeze-thaw times are less than 15, the shear failure occurs between ordinary concrete and epoxy resin interface agent, and when the freeze-thaw times are more than 25, the shear failure occurs between all lightweight ceramsite concrete and epoxy resin interface agent, and it is in a transitional state when the freeze-thaw times are 15-25. After freezing and thawing, the shear strength of the interface of the specimen shows significant degradation. After 5, 10, 15, 20, 25, and 30 freezing and thawing cycles, the shear strength of the interface decreases by 7.83%, 20.91%, 25.54%, 31.11%, 36.54%, and 45.27%, respectively, compared with that before freezing and thawing. The shear strength degradation formula of epoxy resin interface is established, which can accurately predict the shear strength of epoxy resin interface after freezing and thawing. The research conclusions can provide reference for the research and design of engineering structure reinforcement and similar new and old concrete connection interface.

引言
1 混凝土配合比及试件制作
2 冻融后试件界面抗剪性能退化试验
3 冻融后试件界面抗剪性能
4 结论

表1 水泥性能指标<br/>Tab.1 Cement performance indexes

表1 水泥性能指标
Tab.1 Cement performance indexes

表2 环氧树脂乳液性能指标<br/>Tab.2 Performance index of epoxy resin emulsion

表2 环氧树脂乳液性能指标
Tab.2 Performance index of epoxy resin emulsion

表3 普通混凝土配合比(单位:kg/m3)<br/>Tab.3 Mix proportion of ordinary concrete(Unit: kg/m3)

表3 普通混凝土配合比(单位:kg/m3)
Tab.3 Mix proportion of ordinary concrete(Unit: kg/m3)

表4 页岩陶粒性能指标<br/>Tab.4 Performance indexes of shale ceramsite

表4 页岩陶粒性能指标
Tab.4 Performance indexes of shale ceramsite

表5 陶砂物理性能指标<br/>Tab.5 Physical performance indexes of ceramic sand

表5 陶砂物理性能指标
Tab.5 Physical performance indexes of ceramic sand

表6 全轻陶粒混凝土配合比(单位:kg/m3)<br/>Tab.6 Mix proportion of full lightweight ceramsite concrete(Unit: kg/m3)

表6 全轻陶粒混凝土配合比(单位:kg/m3)
Tab.6 Mix proportion of full lightweight ceramsite concrete(Unit: kg/m3)

图1 环氧树脂界面试件整体示意(单位: mm)<br/>Fig.1 Overall schematic diagram of epoxy resin interface specimen(Unit: mm)

图1 环氧树脂界面试件整体示意(单位: mm)
Fig.1 Overall schematic diagram of epoxy resin interface specimen(Unit: mm)

图2 浇筑陶粒混凝土后试件照片<br/>Fig.2 Photos of test pieces after ceramsite concrete pouring

图2 浇筑陶粒混凝土后试件照片
Fig.2 Photos of test pieces after ceramsite concrete pouring

表7 试验分组及冻融后界面抗剪强度<br/>Tab.7 Test groups and interface shear strength after freezing and thawing

表7 试验分组及冻融后界面抗剪强度
Tab.7 Test groups and interface shear strength after freezing and thawing

图3 冻融后试件外观损伤(W-30-E组试件1)<br/>Fig.3 Appearance damage of specimen after freezing and thawing

图3 冻融后试件外观损伤(W-30-E组试件1)
Fig.3 Appearance damage of specimen after freezing and thawing

表8 冻融后环氧树脂界面试件表面缺陷<br/>Tab.8 Surface defects of epoxy resin interface specimen after freezing and thawing

表8 冻融后环氧树脂界面试件表面缺陷
Tab.8 Surface defects of epoxy resin interface specimen after freezing and thawing

图4 试件加载示意(单位:mm)<br/>Fig.4 Loading diagram of specimen(Unit: mm)

图4 试件加载示意(单位:mm)
Fig.4 Loading diagram of specimen(Unit: mm)

图5 环氧树脂界面试件剪切破坏形态<br/>Fig.5 Shear failure pattern of epoxy resin interface specimen

图5 环氧树脂界面试件剪切破坏形态
Fig.5 Shear failure pattern of epoxy resin interface specimen

图6 冻融后环氧树脂界面抗剪强度<br/>Fig.6 Shear strength of epoxy resin interface after freezing and thawing

图6 冻融后环氧树脂界面抗剪强度
Fig.6 Shear strength of epoxy resin interface after freezing and thawing

图7 环氧树脂界面抗剪强度拟合曲线<br/>Fig.7 Fitting curve of epoxy resin interface shear strength

图7 环氧树脂界面抗剪强度拟合曲线
Fig.7 Fitting curve of epoxy resin interface shear strength

表9 环氧树脂界面试件界面抗剪强度计算公式验证<br/>Tab.9 Verification of calculation formula for interface shear strength of epoxy resin interface specimen

表9 环氧树脂界面试件界面抗剪强度计算公式验证
Tab.9 Verification of calculation formula for interface shear strength of epoxy resin interface specimen

[1]中华人民共和国住房和城乡建设部. 混凝土结构加固设计规范: GB50367—2013[S]. 北京: 中国建筑工业出版社, 2013.
[2]邓明科, 李彤, 樊鑫淼. 高延性混凝土加固砖柱轴压性能试验研究[J]. 工程力学,2019,36(5):92-99.
[3]陈建国, 吴光军, 孙桂山, 等. 硅灰和聚丙烯纤维净浆界面剂对新老混凝土粘结力学性能的影响研究[J]. 新型建筑材料, 2018, 45(4): 52-55.
[4]刘博研, 薛伟辰, 孙哲. 界面构造对预制混凝土柱接缝抗剪性能的影响研究[J].西安建筑科技大学学报(自然科学版), 2022,54(2):164-173.
[5]乔连朋, 袁群, 冯凌云. 新型界面剂作用下新老混凝土黏结的耐久性能[J]. 公路, 2020, 65(7):33-37.
[6]朱红兵, 张娜, 余志武, 等. 钢-聚丙烯混杂纤维陶粒混凝土与螺纹钢筋的黏结力学特性[J].工业建筑, 2022, 52(2): 32-36,114.
[7]张菊辉, 李粤. 新老混凝土结合面黏结强度影响因素研究综述[J]. 混凝土, 2017(10): 156-159,162.
[8]冯侠, 乔连朋, 袁群, 等. 新混凝土与碳化混凝土黏结抗冻性能研究[J]. 施工技术, 2014, 43(2): 108-110.
[9]ZHU H, FAN J, YI C, et al. Characterization of freeze-thaw resistance of new-to-old concrete based on the ultrasonic pulse velocity method[J]. Journal of Testing and Evaluation, 2021, 49(1): 20190639.
[10]乔连朋, 袁群, 张国岑, 等. 新老混凝土黏结力学性能的时间效应研究[J]. 人民黄河, 2017, 39(4): 111-114.
[11]ZHANG X, ZHANG S, LUO Y, et al. Effects of interface orientations on bond strength between old conventional concrete and new self-consolidating concrete[J]. ACI Structural Journal, 2020, 117(5):191-202.
[12]黄伟, 方张平. 冻融条件下新老混凝土粘结后抗折性能[J]. 材料科学与工程学报, 2021, 39(5):745-749,767.
[13]FAN J, WU L, ZHANG B. Influence of old concrete age, interface roughness and freeze-thawing attack on new-to-old concrete structure[J]. Materials, 2021, 14(5): 1057.
[14]HU Bo, MENG TengFei, LI Yuan, et al. Dynamic splitting tensile bond behavior of new-to-old concrete interfaces[J]. Construction & Building Materials, 2021, 281:122570.
[15]李秀, 徐文康, 朱红兵, 等. 清水及氯盐环境下陶粒混凝土冻融损伤规律试验研究[J]. 混凝土与水泥制品, 2020(4): 29-32.
[16]李嘉, 董亮, 张坚, 等. UHPC-沥青薄面层环氧界面剂黏结性能试验[J]. 长安大学学报(自然科学版), 2020, 40(1): 49-57.
[17]谢剑, 陈玉洁, 孙雅丹. UHPC与普通混凝土试件界面黏结抗冻性能试验研究[J].硅酸盐通报, 2021, 40(12): 3945-3955.
[18]李妍, 贺柱国. 冻融环境下废旧纤维混凝土与旧混凝土粘结面劈拉试验[J]. 吉林建筑大学学报, 2020,37(2): 19-22,42.
[19]叶果. 新老混凝土界面抗剪性能研究[D]. 重庆:重庆大学, 2011.

备注

引言

1 混凝土配合比及试件制作

2 冻融后试件界面抗剪性能退化试验

3 冻融后试件界面抗剪性能

4 结论

期刊信息