Study on bonding compression-shear performance between industrial green fiber-reinforced concrete and old concrete

Industrial green fiber-reinforced concrete, a new hybrid high performance environmental protection material, can be made by adding recycled steel fibers into concrete in a certain proportion. As a composite material used in the construction industry, it can provide a new research direction for national green and sustainable development. This paper studied the interface bonding mechanism of normal steel fiber-reinforced old and new concrete and industrial green fiber-reinforced concrete and old concrete by using a self-made new fixture, and discussed the influence of compressive stress, types of steel fibers and recycled steel fiber content on the bonding compression-shear performance of specimens. The results show that the bonding compression-shear performance of specimens gradually increases with the increases of the compressive stress acting perpendicular to the shearing surface within the range of low compressive stress, and when the compressive stress is from 0.2 MPa to 1.0 MPa, the increased amplitude of the bonding compression-shear performance of specimens gradually increases, when the compressive stress is from 0.6 MPa to 1.0 MPa, the increased amplitude of the bonding compression-shear performance of specimens reaches the maximum, and when the compressive stress is from 1.0 MPa to 1.4 MPa, the increased amplitude of the bonding compression-shear performance of specimens decreases. Under the same conditions, the effect of the recycled steel fibers on improving the bonding compression-shear performance between old and new concrete is better than normal steel fibers. The bonding compression-shear performance between old and new concrete gradually increases with the increases of the volume ratio of recycled steel fibers, and when the fiber content is from 0.0 % to 1.0 %, the increased amplitude of the bonding compression-shear performance of specimens gradually increases, when the fiber content is from 0.5 % to 1.0 %, the increased amplitude of the bonding compression-shear performance of specimens reaches the maximum, and when the fiber content is from 1.0 % to 1.5 %, the increased amplitude of bonding compression-shear performance of specimens decreases. The simulation results of industrial green fiber-reinforced concrete and old concrete specimens with fiber content of 1.5 % under different compressive stresses are basically in agreement with the experimental results. This study can provide references for the research of bonding compression-shear behavior of steel fiber-reinforced old and new concrete materials and the recycling of steel wire from waste tires.