Mechanical Properties Of Recycled Aggregate Concrete Under Complex Tension Compression Dynamic States

At present,Chinese infrastructure is increasing development,high-speed rail has been rapid development,and the construction of large municipal sewage treatment and engineering such as dam,require large volume concrete.With the arrival of the building's service life,some buildings have been demolished to produce a large amount of waste concrete.The slag as aggregate agitation made of recycled concrete(recycled aggregate concrete,RC)can save resources and reduce cost of waste disposal.It can also be considered in the application of large hydraulic structures.In order to apply the recycled concrete to these structures,it is necessary to study the strength law of the recycled concrete under multiaxial stress.I were in my school laboratory structure pouring specimens,and then shipped to the structure laboratory of Dalian University of Technology,using a variety of concrete stress ratio under the condition of recycled concrete uniaxial and multiaxial tensile compressive test three triaxial testing machine.The stress combination included:dynamic uniaxial tension,dynamic uniaxial compression,dynamic biaxial tension compression,dynamic three axial tension compression;loading rate of 10-5/s,10-4/s,10-3/s,10-2/s.The main research work of this paper was as follows:1.Uniaxial tensile test of recycled concrete in strength of C20,C40 and C60 was carried out.The dynamic failure mode of recycled concrete under uniaxial tension was presented.The failure strength formula with 1 parameter was given.The dynamic uniaxial tensile failure surface of recycled concrete was more uneven.The stress-strain curve of recycled concrete was also different from that of ordinary concrete,and the decline stage was more steep and also coincides with the fracture failure.2.The strength of recycled concrete C20,C40 and C60 in different stress state(?=?1:?2:?3 = 0.00:0.05:-1;0.00:0.1:-1;0.00:0.25:-1;0.00:0.50:-1,0.00:1:-1)of the biaxial tension compression test were conducted.According to the test results,it was found that the failure of recycled concrete under biaxial tension compression stress was tensile failure,and the failure mode was related to the strain rate.The replacement rate of recycled aggregate did not change the macroscopic failure mode of recycled concrete.The strength of recycled concrete under biaxial tension compression was affected by the dynamic loading rate.The greater the loading rate was,the greater the tensile strength was.The 2 parameter failure criterion was established in plane coordinates.The stress and strain curves of the main tensile direction were also consistent with the fracture of the specimen.3.The recycled concrete with strength of C20,C40 and C60 in different replacement ratio and different stress state(?=?1:?2:?3=0.1:1:-1;0.25:-0.25:-1;0.25:-0.5:-1)three uniaxial tension compression test were conducted.According to the test results,it was found that the failure modes of recycled concrete under the condition of three axis tension compression stress were all fracture failure,and the failure mode was tensile failure under the condition of three axial tension compression.The strength increased with the increase of strain rate.The higher strain rate of fracture was and the surface was neater.According to the test results,the 2 parameter failure criterion was established under the condition of eight plane stress space.The stress and strain curves in the direction of the main draw coincided with the fracture failure.