基于分形理论研究RTSF混凝土冲击压缩性能

Impact Compression Properties of Recycled Tyre Steel Fiber Reinforced Concrete Based on Fractal Theory

为了研究回收轮胎钢纤维(RTSF)混凝土的冲击压缩性能,利用分离式霍普金森压杆对普通混凝土(F0)、工业钢纤维(ISF)混凝土和RTSF混凝土进行冲击压缩试验,统计冲击破坏后的碎块数量并计算分形维数.结果表明:RTSF混凝土冲击破坏形态分为三种类型,即周边张应变破坏、留芯破坏和整体破坏;应变率在55~125 s^(-1)左右时,不同掺量RTSF混凝土的分形维数范围为1.33~2.25;分形维数随RTSF掺量增加出现先减小后增大的趋势,RTSF 0.75混凝土分形维数最小;不同掺量的RTSF混凝土的分形维数随应变率增加而增大;不同应变率下RTSF混凝土的动态抗压强度及断裂能均随分形维数的增加而增大;ISF 1.00的分形维数、动态抗压强度和断裂能均介于RTSF 0.75和RTSF 1.00之间,RTSF 0.75比ISF 1.00(纤维长度为35 mm,长径比为65)能更有效提高混凝土的冲击压缩性能.

In order to study the impact compression properties of recycled tire steel fiber(RTSF)reinforced concrete,the impact compression tests of general concrete(F 0),industrial steel fiber(ISF)reinforced concrete and RTSF reinforced concrete were carried out by using split Hopkinson pressure bar.The crushed specimens were sieved and fractal dimensions were calculated.The results indicate that the impact failure modes of RTSF reinforced concrete can be divided into three types:peripheral tensile strain failure,core retaining failure and overall failure.The fractal dimension of RTSF reinforced concrete ranges between 1.33 and 2.25 under strain rates of 55 to 125 s^(-1).The fractal dimension decreases and then increases with the increase of RTSF content.The fractal dimension of RTSF 0.75 reinforced concrete is minimal.The fractal dimension of concrete reinforced with various fiber contents increases with the increase of strain rates.Under different strain rates,the dynamic compressive strength and fracture energy of RTSF reinforced concrete enhance with the increase of fractal dimension.The fractal dimension,dynamic compressive strength and fracture energy of concrete reinforced with ISF 1.00 are between those of concrete reinforced with RTSF 0.75 and RTSF 1.00.In terms of impact compression,RTSF 0.75 outperforms ISF 1.00(the fiber length is 35 mm and the aspect ratio is 65).