Research On The Effect Of Basalt Fiber Reinforcing The Rheological Properties Of Asphalt Mastic

Adding basalt fibers to asphalt mixtures has become one of the important ways to improve the performance of asphalt mixtures comprehensively.In recent years,domestic and foreign researchers have systematically studied asphalt mortar and mastic mixed with basalt fibers from a meso-scale to reveal the internal relationship between the meso-structure and macroperformance of asphalt mixtures mixed with basalt fibers at a smaller scale.Although some achievements have been achieved,most of the research is based on experiments and few reliable models have been built to be applied to further research from the perspective of numerical simulation.A method for constructing a 3D numerical model of asphalt mastic mixed with basalt fibers is proposed in this paper.The rheological properties of asphalt mastic at a high temperature are used as judgments for comparation between experiments and numerical simulation.The fiber length,content and orientation are studied as influencing factors of the rheological properties of asphalt mastic.On the one hand,the principle of basalt fibers reinforcing the rheological properties of asphalt mastic at a high temperature can be revealed,on the other hand,accuracy of numerical model and numerical simulation can be verified,and establishing a procedure of the numerical simulation of asphalt mastic mixed with basalt fibers is the aim,which can provides the theoretical support for the application of basalt fibers in asphalt mixtures.Firstly,a DSR(Dynamic Shear Rheometer)is used at 64°C to do Repeated Creep Recovery Tests for asphalt mastic mixed with four lengths(3mm,6mm,9mm,12mm)and four contents-the mass proportion of fibers in the mastic(1%,2%,3%,4%)of basalt fibers.The strain curve of pure asphalt mastic is analyzed to obtain the viscoelastic parameters of the mastic.The strain and creep stiffness modulus of mastics mixed with various fibers are compared to obtain regulations of basalt fibers reinforcing rheological properties of asphalt mastics from the experiments.The experiments’ results show that when fiber length is 3mm,it is easily to be pulled out from mastic,so it is not suitable to be used in mastic.Meanwhile,fibers with lengths of 6mm,9mm and 12 mm have good performances.When the fiber length is fixed,the increase of the fiber content is beneficial for decreasing the rheological deformation of the mastic,and when the fiber content is increased from 3% to 4%,the reduction of rheological deformation of the mastic is smaller than before.When the fiber content is fixed,the reduction of the fiber length has a positive effect on the reduction of rheological deformation of the mastic.Considering the economic benefits and the difficulty of material preparation,it is recommended that the fiber length should be 6mm and the content be 2%～3%.Then,a 3D numerical model of asphalt mastic mixed with basalt fibers of random directions is established in MATLAB,which aims to simulate the condition of fibers in the mastic.This numerical model is imported into the ABAQUS for numerical analyzation of repeated creep tests.The creep strain and the stress of mastic in one second are analyzed,revealing the principles of basalt fibers reinforcing the rheological properties of asphalt mastic at a high temperature from the perspective of numerical simulation.A comparation between results of experiments and numerical simulation is made to prove the effectiveness of numerical model and the finite element simulation,which provides the basis and guidance for the subsequent research.Finally,based on the numerical model and finite element simulation mentioned,the fiber orientation is considered as the influencing factor to be studied with finite element simulation.A 3D model of mastic mixed with fibers,whose angles with XY plane are 0°,15°,30°,45°,60°,75° and 90°,are built in MATLAB and imported into ABAQUS for repeated creep loading during one second.The simulation results show that when the angle is 0° and 90°,the fibers do not have an impact on the reduction of rheological deformation of mastic.When the angle increases from 15° to 75° at 15° intervals,the contributions to the reduction of mastic strain are27.84%,55.06%,46.11%,24.83%,and 5.39%,which increases first and then decreases,reaching a peak of 55.06% at 30°,indicating that when the fibers’ angle is about 30°,the fibers have the most beneficial effect on the reduction of rheological deformation of the asphalt mastic.Based on the premise that asphalt mastic is homogeneous and continuous,the regulation and principle of basalt fiber length,content and direction reinforcing the rheological properties of asphalt mastic are revealed.However,the research work is limited to the rheological properties of asphalt mastic at a high temperature.The research results should be applied to asphalt mixtures subsequently,aiming to revealing the principle of basalt fibers reinforcing asphalt mixtures’ performances.