聚甲醛纤维高强混凝土孔隙特征及动态力学特性  

Pore Characteristics and Dynamic Mechanical Properties of Polyoxymethylene Fiber-reinforced High-strength Concrete

作　　者：秦楠 李琼[2] 徐博 QIN Nan;LI Qiong;XU Bo(School of Civil Engineering and Architecture,Zhengzhou University of Economics and Trade,Zhengzhou 451191,China;School of Architectural Engineering,Zhongyuan Institute of Technology,Zhengzhou 450007,China;Henan Local Coal Group Co.,Ltd.,Zhengzhou 450000,China)

机构地区：[1]郑州经贸学院土木建筑学院,郑州451191 [2]中原工学院建筑工程学院,郑州450007 [3]河南地方煤炭集团有限公司,郑州450000

出　　处：《长江科学院院报》2023年第6期180-186,共7页Journal of Changjiang River Scientific Research Institute

摘　　要：为探究聚甲醛(POM)纤维高强混凝土内部孔隙特征及在冲击荷载作用下的安全性,制备混凝土设计强度等级为C60、POM纤维长度为6 mm、体积掺量分别为0%、0.15%、0.3%、0.45%、0.6%的聚甲醛纤维高强混凝土,采用核磁共振(NMR)技术分析不同纤维掺量下试件T_(2)图谱分布规律,利用岩石力学试验机对不同纤维掺量下试件进行准静态压缩试验,利用霍普金森压杆(SHPB)装置对试件开展不同应变率下(64.8 s^(-1)、87.0 s^(-1)、116.4 s^(-1)、149.1 s^(-1))的动态单轴压缩力学试验,分析不同纤维掺量下的POM纤维高强混凝土内部孔隙结构及在不同应变率下应力-应变曲线、峰值应力、韧性及能量耗散的变化规律。结果表明:POM纤维的掺入使T_(2)图谱峰值降低,图谱曲线向左偏移,试件内部孔隙数目减少,孔隙直径减小,孔隙率降低;试件存在明显的应变率效应,POM纤维的掺入增强了试件整体性能;不同应变率下试件峰值应力随纤维掺量的增加先增大后降低,当纤维掺量达到0.45%时试件动态压缩强度达到峰值,掺入过量纤维试件强度有所降低;纤维的掺入增强试件在抵抗外荷载时的韧性;试件耗散能随入射能的增大而增大,两者呈良好的线性关系;试件破碎耗能密度随纤维掺量的增加先增大后减小,掺量为0.45%时效果最佳,应变率的增大会使试件耗能密度变化幅值增大。In this study,we aimed to investigate the pore characteristics and safety of high-strength concrete reinforced with polyoxymethylene(POM)fibers under impact loads.We prepared high-strength concrete samples with a design strength grade of C60,incorporating POM fibers with a length of 6 mm.The volume fractions of POM fibers used were 0%,0.15%,0.3%,0.45%,and 0.6%.We further analyzed the distribution patterns of the T_(2) relaxation time spectrum for specimens with different fiber contents by using nuclear magnetic resonance(NMR)technology.Additionally,we conducted quasi-static compression tests on the specimens with various fiber contents using a rock mechanics testing machine,and carried out dynamic uniaxial compression tests on the specimens at different strain rates(64.8 s^(-1),87.0 s^(-1),116.4 s^(-1),and 149.1 s^(-1))using a split Hopkinson pressure bar(SHPB)apparatus.Through these experiments,we analyzed the internal pore structure of POM fiber-reinforced high-strength concrete,as well as the changes in stress-strain curves,peak stress,toughness,and energy dissipation under different strain rates and fiber contents.The results reveal several key findings.The inclusion of POM fibers leads to a reduction in the peak value of the T_(2) relaxation time spectrum,accompanied by a leftward shift in the spectrum curve.This indicates a decrease in the number of internal pores,a reduction in pore diameter,and a lower porosity within the specimens.The results also unveil a significant strain rate effect in the specimens,with the addition of POM fibers enhancing the overall performance.The peak stress of the specimens exhibited an initial increase followed by a decrease as the fiber content increased.Notably,when the fiber content reached 0.45%,the dynamic compressive strength of the specimens reached its peak,while excessive fiber content resulted in a decrease in strength.Moreover,the inclusion of fibers improved the toughness of the specimens in resisting external loads.The dissipated energy of the specimens increased

关 键 词：聚甲醛纤维 高强混凝土 核磁共振 应力-应变曲线 峰值应力 韧性 破碎耗能密度 

分 类 号：TU528[建筑科学—建筑技术科学]