摘要
为了研究外掺钢纤维对内养护混凝土力学性能的影响,采用高吸水性聚合物(super absorbent polymer,SAP)作为内养护材料,开展了普通混凝土(normal concrete,NC)、内养护混凝土(internal curing concrete,ICC)和钢纤维内养护混凝土(steel fiber internal cured concrete,SFRICC)的动态抗压试验以及四点弯曲梁试验。使用核磁共振仪(nuclear magnetic resonance,NMR)和扫描电子显微镜(scanning electron microscope,SEM)研究混凝土内部孔隙结构和微观结构特征,揭示SAP和钢纤维对混凝土力学性能影响机理。结果表明:SFRICC残余强度随钢纤维掺量增加呈现增大趋势;钢纤维显著降低了SAP对混凝土力学性能的削弱作用;SFRICC的力学性能随钢纤维掺量的增加呈现先增大后减小趋势,钢纤维体积含量为1.5%时的SFRICC力学性能增强效果最好。混凝土力学性能呈现出明显的应变率效应。在高应变速率下,钢纤维掺量与SFRICC的动态增强因子(dynamic increase factor,DIF)呈负相关。SAP在促进水泥水化反应的同时,增大混凝土孔隙率和孔径,减少混凝土结构面有效面积,而钢纤维桥接纤维两侧的裂缝,增强了混凝土的完整性,弥补了SAP对混凝土的强度损失,两种材料可以发挥良好的耦合作用。
In order to study the effect of steel fiber on the mechanical properties of internal curing concrete,super absorbent polymer(SAP)was used as the internal curing material,and dynamic compressive and four-point bending tests were carried out on normal concrete(NC),internal curing concrete(ICC),and steel fiber internal cured concrete(SFRICC).Pore structure and microstructural features analysis was made using nuclear magnetic resonance(NMR)and scanning electron microscope(SEM)to reveal the mechanism of SAP and steel fibers effect on the mechanical properties of concrete.The results show that the residual strength of SFRICC increases with the increase of steel fiber content.Steel fiber significantly reduces the weakening effect of SAP on the mechanical properties of concrete.The mechanical properties of SFRICC increase first and then decrease with the increase of steel fiber content.In addition,the mechanical properties of SFRICC are enhanced best when the volume content of steel fiber is 1.5%.The mechanical properties of concrete show an obvious strain rate effect.At high strain rates,the steel fiber content is negatively correlated with the dynamic increase factor(DIF)of SFRICC.SAP not only promotes cement hydration reaction,but also increases concrete porosity and pore size and reduces the effective area of concrete structural surface.And the steel fiber bridges the cracks on both sides of the fiber,which enhances the integrity of concrete and makes up for the damage of SAP to the internal structure of concrete.The two materials can play a good coupling role.
作者
司政
宋健
刘润
杜晓奇
黄灵芝
张飞跃
SI Zheng;SONG Jian;LIU Run;DU Xiaoqi;HUANG Lingzhi;ZHANG Feiyue(State Key Laboratory of Water Engineering Ecology and Environment in Arid Area,Xi'an University of Technology,710048 Xi'an,China;CHN Energy Dadu River Jinchuan Hydropower Project Construction Co.,Ltd.,624100 Aba,China;Phase III Construction Management Office,Xi'an University of Technology,710048 Xi'an,China)
出处
《应用力学学报》
北大核心
2025年第3期609-619,共11页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金资助项目(No.51879217)。
关键词
混凝土
钢纤维
SAP
力学性能
微观机理
concrete
steel fiber
SAP
mechanical property
microscopic mechanism
