Experimental Study On The Abrasion Resistance Of Rubber-modified Steel Fiber Reinforced Two-graded Aggregate Concrete

As the Yellow River with the highest sediment concentration in the world,it has a high flow velocity of 40m/s～50m/s in the drainage structures of large hydropower projects.It places higher demands on the strength and abrasion resistance of the antiabrasive material.Steel fiber has a certain improvement effect on the abrasion resistance of concrete but also needs to modify the effect of more excellent dopants.Rubber is used as an excellent material to improve the abrasion resistance of concrete.If it can be effectively used in the steel fiber reinforced two-graded aggregate concrete to enhance the abrasion resistance of concrete,it can significantly improve the abrasion resistance of concrete based on meeting the strength of concrete,which is of great significance to the safety of hydraulic concrete structural engineering.Most of the current research on concrete abrasion resistance is based on mass loss,but studies have shown that such indicators are still not reasonable.Therefore,based on the national strategic demand of "ensuring the safety of the Yellow River",the effects of rubber volume content and rubber size on the basic mechanical properties and abrasion resistance of rubber-modified steel fiber reinforced two-graded aggregate concrete were investigated,the evaluation method of concrete surface abrasion degree was proposed and the mechanism of the effects was analyzed.The main contents include:The effects of rubber volume content and rubber size on the compressive strength,splitting tensile strength,and the tension-compression ratio of rubber-modified steel fiber reinforced two-graded aggregate concrete were investigated by concrete compressive strength and splitting tensile strength tests.The test results showed that within the test range,the compressive strength,splitting tensile strength,and the tension-compression ratio of rubber-modified steel fiber reinforced two-graded aggregate concrete showed a gradual decrease with the increase of rubber volume content compared with steel fiber reinforced two-graded aggregate concrete,but its tension-compression ratio showed a gradual increase with the increase of rubber volume content.It showed that the incorporation of rubber was able to increase the toughness of the concrete although it decreased the strength of the steel fiber reinforced two-graded aggregate concrete.The microstructural characteristics of rubber-modified steel fiber reinforced twograded aggregate concrete was investigated by electron microscopy scanning and microhardness tests.The test results showed that the compactness and microhardness of the steel fiber-mortar interface transition zone were the best,followed by the aggregate-mortar interface transition zone and rubber-mortar interface transition zone.It was also further shown that the incorporation of rubber reduced the compressive and splitting tensile strength of steel fiber reinforced two-graded aggregate concrete.The effects of rubber volume content and rubber size on the impact of rubbermodified steel fiber reinforced two-graded aggregate concrete on the abrasion resistance of concrete were investigated by the underwater method test and threedimensional laser scanning tests.The test results showed that within the test range,the anti-abrasion strength,unit abrasion volume time,and unit average abrasion depth time of rubber-modified steel fiber reinforced two-graded aggregate concrete showed a gradual increase with the increase of rubber volume content compared with the steel fiber reinforced two-graded aggregate concrete.The larger the rubber size,the greater the anti-abrasion strength,unit abrasion volume time,and unit average abrasion depth time.It showed that the rubber can further improve the abrasion resistance of steel fiber reinforced two-graded aggregate concrete,and the larger the rubber size,the more obvious the improvement effect.The fractal analysis of the degree of concrete surface abrasion was carried out by the cubic cover method,and the relationship between each index of anti-abrasion and the fractal dimension was investigated.The results showed that the fractal dimension of concrete surface abrasion degree had a good linear relationship with the rubber volume content.The larger the rubber volume content,the smaller the fractal dimension,and the flatter the surface concrete surface,the better the rubber improves the abrasion resistance of steel fiber reinforced two-graded aggregate concrete.The fractal dimension of concrete surface abrasion degree had a good power function relationship with the anti-abrasion strength,wear rate,unit abrasion volume time and unit average abrasion depth time,and the abrasion resistance of concrete can be characterized by the fractal dimension.The smaller the fractal dimension,the better the abrasion resistance of concrete.