Size Effect On Strength Test Of Waste Fiber Recycled Concrete

In recent years,China's urbanization process has accelerated,the living standards of people continue improving,the people's living environment and infrastructure demand also increased,which led to the rapid development of the construction industry.There are many problems in the process of development,need to be busy at putting up installations consume a large amount of natural resources,and produce a large number of construction waste.As the most used building material in the world,concrete is the main component of construction waste,which causes great pollution to the environment.As a kind of environment-friendly green building material,recycled concrete can make construction waste into treasure,which not only solves the problem of construction waste disposal,but also relieves the reality of the shortage of resources.The properties of recycled concrete are inferior to ordinary concrete,and the addition of waste fiber in recycled concrete can significantly improve the defect.The mechanical properties of concrete are obviously affected by the size of the structure,and it is particularly important to accurately describe the mechanical strength of concrete under different sizes.Therefore,if the use of waste fiber recycled concrete is to be used widely,the effect of the replacement rate of recycled aggregate,the amount of waste fiber and the effect of strength grade on the size effect should be studied.According to the size effect on the strength test of waste fiber recycled concrete,the following work is carried out in this paper:(1)Based on the study of concrete size effect at home and abroad,the theory of size effect of concrete and its influence factors are discussed systematically,which lays a solid theoretical foundation for the study of the size effect on the strength test of waste fiber recycled concrete.(2)Through experiments studied recycled aggregate replacement ratio?waste fiber replacement ratio and concrete strength grade three factors influence of cube compressive strength,cube splitting tensile strength and axial compression strength size effect,the size conversion coefficient suitable for recycled fiber reinforced concrete is also given.The test shows that the size effect of cube compression strength,splitting tensile strength and axial compressive strength increased with the replacement rate of recycled aggregate increases;with the waste fiber replacement ratio increases decreases first and then increases;with the increase of concrete strength increase.(3)The size effects of mechanical parameters are studied in this paper,which are seldom involves now.such as peak strain,elastic modulus and Poisson ratio.The test shows that the size effect of the peak strain increases with the replacement rate of recycled aggregate increases,with the waste fiber replacement ratio increases decreases first and then increases,and then increases with the increase of the strength grade of concrete.The size effect of elastic modulus and Poisson's ratio is not obvious.(4)Based on Bazant size effect theory.the revises of Bazant size effect theory and multi-dimension fractal effect theory,the obtained experimental data are theoretically fit,the fitting situation is good,the parameters and strength-size fitting curve of three theories are obtained,then the critical dimensions and critical strength of waste fiber recycled concrete are predicted by strength-size curve.