冻融循环下秸秆纤维混凝土损伤特性及动态力学性能研究  

Study on damage characteristics and dynamic mechanical properties of straw fiber reinforced concrete under freeze-thaw cycle

作　　者：孙霄[1] 刘茂野 SUN Xiao;LIU Maoye(Shanxi Conservancy Technical Institute,Yuncheng 044000,China;China United Engineering Co.,Ltd.,Hangzhou 310051,China)

机构地区：[1]山西水利职业技术学院,山西运城044000 [2]中国联合工程有限公司,浙江杭州310051

出　　处：《混凝土》2024年第2期114-119,125,共7页Concrete

摘　　要：为研究冻融循环对不同纤维掺量的秸秆纤维混凝土动态力学性能的影响,采用非金属超声波检测仪测量不同冻融循环次数下秸秆纤维混凝土试件纵波波速,利用直径74 mm变截面分离式霍普金森压杆试验装置对试件开展动态单轴压缩试验,分析试件纵波波速、峰值应力、劣化度、韧性及破碎耗能密度与冻融循环次数及秸秆纤维掺量间的关系。结果表明:纤维的掺入能够提高混凝土材料的纵波波速及整体性,随着冻融循环次数的增加,秸秆纤维混凝土纵波波速随之降低,冻融循环会对试件造成损伤;秸秆纤维的掺入会增强混凝土材料的力学性能,掺量为0.2%时效果最佳,冻融循环作用试件峰值应力不断降低,劣化度不断增加,相较于冻融循环0次素混凝土试件,冻融循环30、60、90、120次试件峰值应力分别降低6.96%、19.4%、34.2%、53.3%,冻融循环后期应力降幅显著增加,纤维的掺入在一定程度上减缓了冻融作用下试件劣化程度;纤维掺量为0.2%时试件的韧性与破碎耗能密度提升最大,冻融循环会对试件造成劣化,降低其韧性及吸能效果。秸秆纤维的掺入使混凝土材料力学性能大幅增加,秸秆纤维的绿色可再生性对秸秆纤维混凝土的推广具有重大意义。In order to study the effect of freeze-thaw cycle on the dynamic mechanical properties of straw fiber concrete with different fiber content.The longitudinal wave velocity of straw fiber reinforced concrete specimens under different freeze-thaw cycles is measured by non-metallic ultrasonic detector.The dynamic uniaxial compression test of the specimen was carried out by using the variable cross-section split Hopkinson compression bar test device with a diameter of 74 mm.The relationships between the longitudinal wave velocity,peak stress,deterioration degree,toughness and crushing energy consumption density of the specimen and the times of freeze-thaw cycles and the content of straw fiber were analyzed.The results show that the addition of fiber can improve the longitudinal wave velocity and integrity of concrete materials.With the increase of freeze-thaw cycles,the longitudinal wave velocity of straw fiber concrete decreases,and the freeze-thaw cycles will cause damage to the specimens.The addition of straw fiber will enhance the mechanical properties of concrete materials,and the effect is the best when the content is 0.2%.The peak stress of the specimen under freeze-thaw cycle is decreasing and the deterioration degree is increasing.Compared with the plain concrete specimen under freeze-thaw cycle 0,the peak stress of the specimen under freeze-thaw cycle 30,60,90 and 120 times is reduced by 6.96%,19.4%,34.2%and 53.3%respectively.The stress decline increases significantly in the later stage of freeze-thaw cycle,and the addition of fiber slows down the deterioration degree of the specimen under freeze-thaw to a certain extent.When the fiber content is 0.2%,the toughness and crushing energy consumption density of the specimen increase the most.The freeze-thaw cycle will degrade the specimen and reduce its toughness and energy absorption effect.However,the incorporation of straw fiber greatly increases the mechanical properties of concrete materials.The green renewable nature of straw fiber is of great significance

关 键 词：冻融循环 秸秆纤维 纵波波速 峰值应力 劣化度 韧性 破碎耗能密度 

分 类 号：TU528.572[建筑科学—建筑技术科学]