粗骨料及混杂纤维对UHPC力学性能的影响
Effect of coarse aggregates and hybrid fibers on mechanical properties of ultra high performance concrete
边晨 1赵长军 2黄卫军 3郭君渊 4肖建庄 5叶建龙2
作者信息
- 1. 浙江数智交院科技股份有限公司,杭州 310030;同济大学土木工程学院,上海 200092
- 2. 浙江数智交院科技股份有限公司,杭州 310030
- 3. 湖州市交通投资集团有限公司,湖州 313098
- 4. 同济大学材料科学与工程学院,上海 201804
- 5. 同济大学土木工程学院,上海 200092
- 折叠
摘要
为评议粗骨料超高性能混凝土(CA-UHPC)的基体配合比设计方法及探究混杂纤维对其力学性能的影响,基于修正的安德森(MAA)模型提出CA-UHPC基体配合比的两种设计思路,对不同粗骨料体积掺量(10%,12%,14%,17%)及混杂纤维形式(平直钢纤维、端钩钢纤维、共聚甲醛(POM)纤维)的CA-UHPC开展轴拉试验、抗压强度及工作性能测试及微观结构分析.结果表明:采用MAA模型计算CA-UHPC的基体配合比,不论是否将粗骨料引入计算体系,均可实现CA-UHPC的紧密堆积状态,两种思路设计的CA-UHPC中粗骨料-UHPC基体界面及纤维-UHPC基体界面的粘结强度均较高;制备的混杂纤维CA-UHPC可实现工作性能与轴拉韧性的协同提升,其中平直钢纤维与端钩钢纤维混杂的CA-UHPC具备更优异的轴拉韧性,平直钢纤维与POM纤维混杂的CA-UHPC具备更优异的工作性能;拔出的POM纤维表面存在较多的细长絮状物,说明POM纤维对CA-UHPC轴拉韧性提升的机理为优异的化学粘结作用.
Abstract
The development direction of ultra high performance concrete(UHPC)is shifting toward realizing a balance between its comprehensive properties,such as low cost,high mechanical performance,and environmental friendliness,in a bid to facilitate its large-scale application.Accordingly,coarse aggregate UHPC(CA-UHPC)has recently attracted considerable attention from academia and engineering.CA-UHPC has a satisfactory application prospect in long-span lightweight composite bridges,wet joints of bridges,and other fields.Two concepts of the CA-UHPC matrix mix design are proposed based on the modified Andreasen&Andersen(MAA)model to evaluate the accuracy of the mix design method for the CA-UHPC matrix and the effect of fiber hybrid on the mechanical properties of CA-UHPC are explored.Subsequently,direct tensile tests,compressive strength and workability measurements,and microstructural analysis are conducted on CA-UHPC with different CA volume fractions(10%,12%,14%,and 17%)and fiber hybrid types(Straight steel fiber,hook-end steel fiber,and copolymeraldehyde(POM)fiber).The influence rules of CA volume fractions and fiber hybrid types on the tensile stress-strain curves,tensile toughness ratios,cubic compressive strength,and slump flow of CA-UHPC are revealed.A fiber image analyzer(microscope)is used for observing microstructures of the CA-UHPC matrix and fibers.The test results demonstrate that a dense particle packing skeleton of CA-UHPC can be realized via the MAA model,irrespective of the inclusion of CAs.The interfacial bond behavior between the CA and UHPC matrix and that between the fiber and UHPC matrix are concluded to be excellent for CA-UHPC designed using the two concepts of the MAA model based on the interfacial microstructural analysis.Additionally,the prepared CA-UHPC with hybrid fibers can achieve the synergistic improvement of workability and tensile toughness.CA-UHPC with the hybrid type of straight steel and hook-end steel fibers exhibits more considerable tensile toughness,while CA-UHPC that with the hybrid type of straight steel and POM fibers shows superior workability.The surface morphology of the POM fiber pulled out from the UHPC matrix shows that some slender flocs exist on the POM fiber surface,corresponding to several curly filaments scraped and torn from the POM fiber to release the tensile stress during the drawing process.This indicates that the action mechanism of POM fibers on the tensile toughness enhancement of CA-UHPC is the effective chemical bond behavior between the POM fiber and the CA-UHPC matrix.Relative research achievements on the mechanical properties of hybrid fiber CA-UHPC in this paper provide data support for the optimal design of the CA-UHPC matrix mix and establish a theoretical foundation for improving the toughness of CA-UHPC.
关键词
桥梁工程/配合比设计/纤维混杂增韧/轴拉试验/微观分析/粗骨料超高性能混凝土Key words
bridge engineering/mix design/fiber hybrid toughening/direct tensile test/microstructural analysis/coarse aggregate ultra high performance concrete引用本文复制引用
基金项目
浙江省交通厅科技项目(2021030)
国家自然科学基金青年基金(52108239)
国家自然科学基金(52078358)
出版年
2024
国家科技期刊平台
NSTL
维普
万方数据