Experimental Study On Mechanical Properties And Constitutive Relation Of Fiber Recycled Concrete

With the vigorous development of China’s construction industry,a large number of waste buildings are demolished,and the amount of construction waste generated is also increasing.Construction waste not only causes serious damage to the ecological environment but also occupies a large amount of open space,thus wasting urban space.Therefore,the recycling of waste concrete is recognized as the best way to deal with these problems.This paper based on the equal volume mortar proposed by Fathifazl as the theoretical basis,replaced by a part of the natural coarse aggregate coarse aggregate,silica fume,fly ash instead of part of the cement,through appropriate admixture of water reducing agent,changing the sand rate,preparation C30 Recycled concrete,on the basis of steel and polypropylene fibers.The axial compressive strength,splitting tensile strength and flexural strength of regenerated concrete were studied,and the influence of different fiber content on the mechanical properties was analyzed.The results show that with the increase of fiber content in recycled concrete,the mechanical properties have been significantly improved.In order to successfully measure the stress-strain curve under uniaxial compression,based on the analysis of the advantages and disadvantages of the existing test methods,a method suitable for self-test was found,and the method of equal strain loading was used to successfully measure the stress-strain curves Axis compression stress-strain full curve.Polynomials and rational fractional fitting were used respectively for the ascending and descending sections of the whole curve.The polynomial and rational fractions were used to fit the rising and falling segments of the full curve respectively.Origin was used to analyze the recycled concrete mixed with steel fiber,and the parameters of the full curve rising segment ranged from 2.420 to 2.808.The parameter ranges from 1.995 to 4.470.For recycled concrete with polypropylene fiber,the parameters of the full-curve rising section range from 1.995 to 4.470,and the values of the descending section range from 1.590 to 2.254.The uniaxial compression test was conducted on different fiber content recycled concrete,and the test data of the full curve was compiled to obtain the full curve of different fiber content.The results showed that as the fiber content increased,the ascending section of the full curve became steep and the descending segment Become flat.The full-curve characteristic parameters were analyzed.The results showed that the peak stress,peak strain,and elastic modulus increased with the increase of fiber content,but there was no significant change in Poisson’s ratio.