Study On Mechanical Properties Of Asphalt Mixture Mixed With Diatomite And Basalt Fiber Based On Viscoelasticity

With the development of economy,the number of cars in our country and the traffic flow on the road are increasing rapidly.Based asphalt mixtures have been difficult to meet the requirements of long-term service of asphalt pavement.In order to improve the mechanical properties and service life of asphalt pavement,adding diatomite and basalt fibers into the asphalt mixture is proposed to strengthen its performance.The multi-objective orthogonal experiment L₁₆?4³?is designed with diatomite content,basalt fiber content and asphalt-aggregate ratio as experimental factors,and bulk volume density(?_f),volume of air voids?VV?,voids filled with asphalt?VFA?,Marshall stability?MS?,and splitting strength at-10??Sb?are chosen as the evaluation indexes.According to the results of the orthogonal experiment,the grey correlation grade analysis is used to obtain the optimal mixing scheme.Furthermore,the rutting tests,uniaxial compression creep tests,low temperature trabecular bending tests,low temperature indirect tensile tests,Marshall residual stability tests and freeze-thaw splitting tests are conducted to evaluate the performance of asphalt mixtures with diatomite and basalt fibers,and the scanning electron microscopy?SEM?tests are carried out to analyze the improvement mechanism of diatomite and basalt fibers in asphalt mixtures.In addition,the uniaxial compressive strength tests and indirect tensile tests at different temperatures are performed to analyze the variation of mechanical properties of compound strengthened asphalt mixture with temperature.Further,in order to characterize the effect of diatomite and basalt fibers on the viscoelastic performance of asphalt mixture,the creep flexibility in different temperature of compound reinforced asphalt mixture are obtained by uniaxial compression creep tests,and the corresponding relaxation modulus is calculated by the viscoelastic mechanics'theory and convolution integral.Subsequently,the improvement of diatomite and basalt fiber on the viscoelastic response of asphalt mixture is compared and analyzed.Finally,the influence of adding diatomite and basalt fibers on the rutting deformation characteristics of asphalt pavement and the bending tensile stress at the bottom of each layer is simulated and analyzed by ABAQUS finite element software.The results show that when the content of diatomite is 14%,the content of basalt fibers is 0.32%,and the ratio of oil to stone is 5.45%,the volume index and performance of compound reinforced asphalt mixture are excellent;and the addition of diatomite and basalt fiber can improve the road performance of asphalt mixture in many aspects.Moreover,adding diatomite and basalt fiber can significantly improve the creep and stress relaxation performance of asphalt mixture,and enhance the permanent deformation resistance and temperature shrinkage cracking resistance of asphalt mixture.The simulation results of ABAQUS finite element software show that the asphalt pavement mixed with diatomite and basalt fiber has excellent ability to resist bending and tensile damage.This study provides some reference for the practical application of diatomite and basalt fibers in pavement engineering.