冻融环境下钢纤维增强自密实轻骨料混凝土弯曲韧性研究  

Study on Flexural Toughness of Steel Fiber Reinforced Self-compacting Lightweight Aggregate Concrete Under Freeze-thaw Environment

作　　者：李京军 张雪莲 李哲 张加瑞 石子钊 LI Jingjun;ZHANG Xuelian;LI Zhe;ZHANG Jiarui;SHI Zizhao(School of Civil Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,China;Key Laboratory of Civil Engineering Safety and Durability of Inner Mongolia Autonomous Region,Baotou 014010,China)

机构地区：[1]内蒙古科技大学土木工程学院,内蒙古自治区包头014010 [2]内蒙古自治区土木工程安全与耐久重点实验室,内蒙古自治区包头014010

出　　处：《工程科学与技术》2025年第2期214-222,共9页Advanced Engineering Sciences

基　　金：内蒙古自治区重点研发和成果转化项目(2023YFHH0086,2022YFHH0118);内蒙古自治区高等学校青年科技英才支持计划(NJYT24060);2023年度自治区直属高校基本科研业务费项目(2023QNJS162);内蒙古科技大学建筑科学研究所开放基金项目(JYSJJ-2021Q04)。

摘　　要：为推动纤维增强自密实轻骨料混凝土在北方严寒及寒冷地区的应用,亟需对该新型混凝土冻融后的性能指标展开研究。将不同体积掺量微细钢纤维与自密实轻骨料混凝土相结合制备出钢纤维增强自密实轻骨料混凝土,首先通过开展快速冻融试验研究相对动弹性模量、质量损失率的变化规律,继而对经历0、25、50、75次冻融后的试件开展三点弯曲试验,并采用新提出适用于大峰值跨中挠度特征的弯曲韧性评价方法,明确纤维对低温冻融环境下自密实轻骨料混凝土弯曲韧性的影响,揭示纤维对不同加载阶段的增强增韧效果。结果表明:随着冻融次数增加,相对动弹性模量呈降低趋势,但其质量损失率一直为负值,试件质量呈增大趋势;微细钢纤维能够提升受冻自密实轻骨料混凝土的抗折强度;在选定的冻融循环次数内,不同纤维掺量的纤维增强自密实轻骨料混凝土的初始弯曲强度比随冻融次数的增加呈高低起伏变化;当冻融次数<50次时,残余弯曲韧度比、残余弯曲强度比均随着纤维掺量增加呈增大趋势,但当冻融次数≥50次时,两个韧性指标已不具备明显的规律性变化趋势;对于未冻融的纤维增强自密实轻骨料混凝土试件,纤维峰前贡献率指标随纤维掺量增加先增后减,而纤维峰后贡献率指标呈增大趋势;经历冻融循环后,纤维增强自密实轻骨料混凝土试件的纤维峰前和峰后贡献率指标随纤维掺量增加没有明显的规律性变化趋势。Objective Fiber-reinforced self-compacting lightweight aggregate concrete(FSLC)is characterized by its lightweight properties,thermal insulation,and excellent frost resistance,making it suitable for applications in buildings prone to freeze-thaw damage in the severe cold and cold regions of the north.Currently,most research focuses on qualitative predictions of the porous properties of the aggregate,highlighting the necessity of studying its frost resistance to promote its application in northern regions.Methods The rapid freeze-thaw test measures the frost resistance of FSLC but does not clarify the fiber reinforcement and toughening effects under freeze-thaw conditions.It remains uncertain whether the conclusions regarding fiber reinforcement and toughening at room temperature apply to the low-temperature freeze-thaw environment.Therefore,based on the rapid freeze-thaw test method,the study first determined the freezing resistance index of the specimens,followed by a bending toughness test after a specified number of freeze-thaw cycles.In an earlier stage,the bending toughness evaluation method proposed by the group was employed to assess the flexural toughness characteristics with a large peak span wise deflection.This evaluation aimed to clarify the effect of fibers on the frost resistance of self-compacting lightweight aggregates under cold temperature freeze-thaw environments.The study focused on the influence of fibers on the flexural toughness characteristics of self-compacting lightweight aggregate concrete under low-temperature freeze-thaw conditions.A systematic analysis of the enhancement and toughening effects of fibers on different loading phases under various freeze-thaw cycles was conducted to provide theoretical support for applying FSLC in engineering.Results and Discussions Fibers improved their compressive strength to a certain extent when incorporated into SLC.The compressive strength increased and then decreased with the increase in fiber content.At 0.5%fiber content,the compressive strength

关 键 词：自密实轻骨料混凝土 钢纤维 冻融循环 弯曲韧性 试验研究 

分 类 号：TU528.01[建筑科学—建筑技术科学]