Experimental Study On Axial Compression Performance Of Clay Brick Recycled Coarse Aggregate(CBRCA)concrete Columns

Under the vigorous promotion of the national strategies of "old city transformation","urbanization" and "rural revitalization",old buildings of cities are being demolished and new projects are increasing.The demolition of old buildings has produced a large amount of construction waste,of which the construction waste containing sintered bricks has reached 30% to 50%.With the increasing of new construction projects,the consumption of natural aggregates is enormous,which makes natural resources increasingly scarce.Faced with the contradiction between the huge output of sintered brick construction waste and economic and social development,and the contradiction between the growing construction projects and the increasingly scarce resources,developing recycled concrete technology with clay brick recycled coarse aggregate(CBRCA)and extendting it to engineering construction is of great importance.But at present,the research on recycled concrete with CBRCA is still in its infancy,and most of the research focuses on the material performance level.There are few studies on the performance of components,especially on the reinforced concrete column with CBRCA.This has led to the fact that the theoretical system of the axial compression performance of CBRCA concrete columns has not been formed,and no relevant specifications of CBRCA have been issued,which seriously hinders its promotion in practical projects.Therefore,this paper will study the mechanical properties of recycled concrete with CBRCA and the axial compression performance of recycled concrete column with CBRCA.The main contents of the research are as follows:(1)Study on physical properties of CBRCA.The physical properties of recycled coarse aggregate containing sintered brick,such as apparent density,bulk density,water absorption,moisture content,crushing index and mud content,are studied in this paper.(2)Experimental study on compressive properties of recycled concrete with CBRCA.In this paper,30 cubic and 30 prismatic specimens of recycled concrete are tested under axial compression with polypropylene fiber content and substitution rate as variables.The effects of substitution rate and polypropylene fiber content on elastic modulus,cubic and prismatic compressive strength of recycled concrete are studied.(3)Axial compression test of recycled concrete column with CBRCA.In this paper,40 heel recycled concrete columns are tested under axial compression with the substitution ratio,reinforcement ratio,stirrup ratio and polypropylene fiber content as variables.The effects of stirrup ratio,reinforcement ratio,substitution ratio and polypropylene fiber content on experimental phenomena,strain,deformation capacity and bearing capacity of steel bar and concrete are studied.Finally,a formula for calculating the bearing capacity of reinforced concrete columns with recycled coarse aggregate containing sintered bricks confined by stirrups is proposed.(4)Peak strain model,peak stress model and constitutive model of recycled reinforced concrete with CBRCA are analyzed.Five classical models are introduced and the test results are fitted.Considering the influence of substitution ratio,reinforcement ratio,stirrup ratio and polypropylene fiber content,the peak strain model,peak stress model and constitutive model of recycled reinforced concrete with CBRCA are proposed.(5)ABAQUS finite element analysis of recycled concrete columns with CBRCA.In this paper,15 CBRCA recycled concrete columns are simulated and analyzed,and the simulated failure state,load-displacement curve and bearing capacity are compared with the experimental results.