钢纤维形状和养护制度对超高性能混凝土强度及韧性的影响  

Influence of Steel Fiber Shape and Curing System on Strength and Toughness of UHPC

作　　者：陈聪聪 吴泽媚 胡翔 史才军 CHEN Congcong;WU Zemei;HU Xiang;SHI Caijun(Key Laboratory for Green&Advanced Civil Engineering Materials and Application Technologies of Hunan Province,College of Civil Engineering,Hunan University,Changsha 410082,China;International Science and Technology Innovation Center for Green&Advanced Civil Engineering Materials of Hunan Province,Changsha 410082,China)

机构地区：[1]湖南大学土木工程学院,绿色先进土木工程材料及应用技术湖南省重点实验室,长沙410082 [2]湖南省绿色先进土木工程材料国际科技创新合作基地,长沙410082

出　　处：《材料导报》2024年第15期135-145,共11页Materials Reports

基　　金：国家自然科学基金(52008164);湖南省自然科学基金(2022JJ30144);中央高校基本科研专项资金(531118010484)。

摘　　要：热养护和掺加异形钢纤维是提高超高性能混凝土(UHPC)强度并改善韧性的有效技术手段。研究了养护制度(标准养护28 d、90℃蒸汽养护2 d、90℃热水养护2 d)和钢纤维形状(平直形、波纹形、端钩形)对UHPC立方体抗压强度、单轴抗压强度、抗折性能的影响,采用ASTM C1018、JSCE-SF4、修正的Post-Crack Energy Ratio(PCER)三种韧性表征方法对UHPC弯曲韧性进行评价,并借助三维光学扫描仪定量表征了掺加不同形状钢纤维的UHPC断裂面粗糙度。结果表明,相较于28 d标准养护,2 d热水养护和2 d蒸汽养护均能在一定程度上提高UHPC力学性能,且对UHPC抗折性能的提升较为显著。与掺平直形钢纤维的UHPC相比,掺端钩形钢纤维的UHPC的抗折强度和PCER韧性指标分别提升46.26%~58.82%和32.77%~39.81%,断裂面粗糙度提高41.67%;粗糙度参数与弯曲韧性具有良好的指数关系,可用于UHPC韧性的表征。此外,单轴抗压强度与立方体抗压强度存在线性关系,相关系数为0.83~0.93。采用ASTM C1018和PCER方法计算出的韧性结果与采用4 mm挠度处荷载-位移曲线包围的面积和抗折性能指标结果基本一致,提出的PCER方法引入初始弯曲韧度比来表征UHPC达到峰值挠度前的弯曲韧性,使得计算结果更为准确。Thermal curing and adding deformed steel fibers are effective in improving strength and toughness of UHPC.In this work,the effects of curing regime(28 d standard curing,2 d of 90℃steam curing,and 2 d of 90℃hot water curing)and steel fiber shape(straight,corrugated,and hooked)on cubic compressive strength,uniaxial compressive strength,and flexural properties of UHPC were studied.ASTM C1018,JSCE-SF4,and modified Post-Crack-Energy Ratio(PCER)were used to evaluate the flexural toughness of UHPC.The 3D optical scanner was used to quantify the roughness of the fracture surface of UHPC with different steel fiber shapes.The results show that 2 d of hot water curing and steam curing improved the mechanical properties of UHPC to a certain extent,and the flexural properties of UHPC were significantly improved,in comparison to 28 d standard curing.Compared to UHPC with straight steel fibers,UHPC with hooked steel fibers increased the flexural strength and PCER toughness index by 46.26%—58.82%and 32.77%—39.81%,respectively,and enhanced the fracture surface roughness R N by 41.67%.A good exponential relationship is found between roughness parameters and bending toughness,and the roughness parameter can be used to characterize the toughness of UHPC.Besides,a linear relationship between uniaxial compressive strength and cubic compressive strength was found,and the correlation coefficient ranged from 0.83 to 0.93.The toughness indexes evaluated using ASTM C1018 and PCER methods were basically consistent with the results obtained by using the area enclosed by load-displacement curve at 4 mm deflection and the flexural properties.The proposed modified PCER method introduced the initial flexural toughness ratio to characterize the flexural toughness before reaching the peak deflection,which rendered more accurate calculation results.

关 键 词：超高性能混凝土(UHPC) 养护制度 钢纤维形状 强度 韧性 

分 类 号：TU528[建筑科学—建筑技术科学]