Study On Performance Of Compression Member And Impermeability Of A New Type Of Concrete

Owing to its fast construction speed,high construction efficiency and strong adaptabilityto high rise building,pump concrete is widely used in civil engineering construction.In order to ensure the pumpability,the pump concrete has the characteristics of high sand content,large slump,small size of coarse aggregate and large amount of cementitious material.Moreover,because of the large amount of cementitious material,the pump concrete has a high cost and serious early cracking in the actual construction.Based on the coarse aggregate interlocking concrete concept,scattering –filling coarse aggregate concrete is a new type of concrete construction technology.In order to solve the problem that the high coarse aggregate content and the larger coarse aggregate diameter can’t be used in the pump concrete,the original concrete and the added coarse aggregate are transported to the pouring surface respectively,and are remixed.Since coarse aggregate has the best volume stability and a relatively low cost,the improvement of coarse aggregate content can solve the problem of high cost and early cracking of pumping concrete to a certain extent.The purpose of this research is to study the flowability,the basic mechanical properties and the anti-chloride ion permeability of scattering–filling coarse aggregate concrete and to investigate the compression performance of reinforced scattering – filling coarse aggregate concrete members.According to the construction process of scattering – filling coarse aggregate concrete,the mix proportion of C40,C50 and C60 scattering – filling coarse aggregate concrete are designed,and the workability of C40,C50 and C60 scattering–filling coarse aggregate concrete are analyzed.According to the test specification,the compressive strength and elastic modulus of C40,C50 and C60 scattering – filling coarse aggregate concrete are measured,and the variation trend are analyzed when the substitution rate are 0%,10%,20%,25% and 30% respectively.15 reinforced scattering – filling coarse aggregate concrete axial compression columns and 10 reinforced scattering – filling coarse aggregate concrete eccentric compression columns are designed,and their failure modes,load-displacement curves,load-strain curves,ductility and ultimate bearing capacity are analyzed.The chloride ion penetration resistance of C40,C50 and C60 scattering – filling coarse aggregate concrete are analyzed.In order to obtain the change regulation ofanti-chloride ion permeability of scattering – filling coarse aggregate concrete when the substitution rate varies from 0% to 30%,the 6h electric flux and chloride diffusivity are studied respectively.The results show that with the increase of coarse aggregate content,slump of concrete gradually decrease,but the minimum slump is 90 mm,which can meet construction requirements.After scattering–filling coarse aggregate,the compressive strength and modulus of elasticity of concrete are improved,and the maximum value is obtained when the substitution rate of coarse aggregate is 20%.The ultimate bearing capacity of axial compression of the reinforced scattering–filling coarse aggregate concrete members increases first and then decreases with the increase of the replacement rate.When the substitution rate of coarse aggregate is 10%,the ultimate bearing capacity of axial compression of the concrete members is the highest,while the ultimate bearing capacity of eccentric compression is maximum when the substitution rate of coarse aggregate is 20%.After scattering – filling coarse aggregate,the resistance to chloride ion permeation of concrete is improved,and the anti-chloride ion permeability is best under the 30% substitution ratio.The study of this paper provides a reference for the application of the scattering–filling coarse aggregate concrete in the actual construction and the basis for the design of the scattering – filling coarse aggregate concrete structural members.This paper also provides reference and data support for the formulation of technical specifications and specifications of the scattering–filling coarse aggregate concrete.