Research On Compressive Properties Of High Ductility Recycled Micropowder Concrete (HDRPC) Columns

With the acceleration of urbanization in China and abroad,increasing construction waste.How to recycle,process and reuse the huge amount of construction waste has become a focus problem faced by all countries in the world.Recycled concrete technology can realize recycling and reuse by processing a large amount of waste concrete,which is the most effective measure to solve the problem of resource utilization of waste concrete.About 15% to20% of the total mass of recycled fine powder is produced during the preparation of recycled aggregate.How to apply the recycled fine powder in engineering practice is of great significance for the resource utilization of construction solid waste.This thesis replaces cement with recycled powder,and prepares High Ductility Recycled Powder Concrete(HDRPC)by compounding polyvinyl alcohol(PVA)fiber and basalt fiber(Basalt fiber,BF),and explores the axial compression of HDRPC material.The main research contents and achievements of the thesis are as follows:1.By making 48 prism test blocks to conduct experimental research on the axial compression performance of HDRPC,to explore the axial compression strength,peak strain and ultimate strain,and elastic modulus of HDRPC under factors such as water-to-binder ratio,regenerated powder substitution rate,fiber type and content,etc.The variation law was established,and the constitutive equation of HDRPC under uniaxial compression was established.The test results show that the peak strain of HDRPC is greater than 0.005 under different mixing ratios,and it has the characteristics of high ductility and good deformation ability.The fiber is the optimal mix ratio of HDRPC,and it is applied to the casting of HDRPC column in the later stage.2.Design 3 ordinary concrete columns and 4 HDRPC columns,determine the test loading plan and measurement plan,and explore the compressive performance of HDRPC columns and ordinary concrete columns with the initial eccentric distance,longitudinal reinforcement ratio and concrete type as the influencing factors of the test the similarities and differences.The experimental results show that the multi-crack cracking phenomenon is obvious during the failure process of the HDRPC column,the final failure degree is small,the deformation capacity is good,the expected bearing capacity can be reached,and the ductility of the column member is improved;The impact of compressive performance is the same as that of ordinary concrete columns.It is verified by the concrete strain that the HDRPC column basically conforms to the assumption of plane section.Based on the existing test and specification calculation results,in order to reduce the error,it is recommended to introduce the hybrid fiber increase coefficient ? into the HDRPC column bearing capacity calculation formula.3.The ABAQUS finite element software is used to simulate the HDRPC column,and the failure form and results of the HDRPC material applied to the component under ideal conditions are obtained.Analyze the concrete stress nephogram,steel bar stress nephogram and deformation displacement diagram,and compare the load-displacement curve and bearing capacity with the test results to verify the accuracy and reliability of the HDRPC column model,and provide a reference for practical engineering applications.