| At present,most of the researeh on the mechanical properties of recyeled concrete is carried out at room temperature,and there are relatively few sludies on it low temperature.Therefore,it is necessary to study the mechanical properties of recycled concrete in cold areas to find out that recycled eonrete is at low temperature.The lower mechanical properities are of great significance for the better application of recycled concree in cold areas.In this paper,the dynamic impact test,static comperession tesr and Brazil split tensile test of the recycled concrete specimens after the freeze-thaw,cycle were carried out respectively,and the dynamic failure form ans atatic compression and resistance of recycled concrete were obtained.Tensile strength value;then use ANSYS software to establish a finite element model to simulate the compressive performance of recrycled concrete after freezing and thawing based on the experimental data;finally,compare the test results with the numerical simulation results,and verify each other.The main research conclsions are as follows:(1)According to the dynamic impact test of Hopkinson pressure bar,the peak value of the transmitted wave of the C30 recycled concrete specimen is smaller than that of the C40 recycled concrte,but the waveform oscillation amplitude is greater than that of the C40 specimen,indicating the dispersion of the transmitted wave in the C30 specimen The cffect is larger than that of the C40 apecimen,indicating that the recycled concrete with high strength level is less affected by the shock wave;(2)From the static compression and tensile tests,it and be seen that for the concrete with the same strength level,the tensile and compressive strengths after 50 freeze-thae cycles are on average lower than the tensile and compressive strengths before freezing and thawing by 0.27MPa and 3.68Mpa,the difference between the two is small,indicating that recycled concrete can be used to replace ordinary concrete in cold areas;(3)By comparing the macroscopic test results with the numerical simulation results,it is found that the numerical simulation results are slightly different from the experimental results,which shows that the test process and results are correct.Based on the above research results,it is concluded that under the macroscopic test conditions,the mechanical properties of fully recycled concrete with the same strength grade are similar to those of ordinary concrete in cold areas,so fully recycled concrete can be appropriately used instead of natural concrete for infrastructure construction. |
