Study On Mechanical Response Characteristics Of Asphalt Mixture With Basalt Fibers Of Different Diameters

Basalt fiber asphalt mixture(BFAM)has excellent resistance to high temperature deformation,low temperature cracking,freeze-thaw and fatigue cracking,and is increasingly being used in various engineering projects.The characteristic parameters(length,diameter,etc.)of basalt fibers(BF)are important factors affecting their reinforcing effect on asphalt mixtures,and existing studies have explored the suitability of fiber length and asphalt mixture grading.However,the influence of fiber diameter on asphalt mixture performance,especially mechanical response characteristics,is still lacking.Therefore,this paper intends to investigate the effect of different diameters of basalt fibers on the mechanical response properties of asphalt mixes,especially on the cracking pattern and shear strength composition of asphalt mixture.Firstly,three different diameters of basalt fibers,7 μm,16 μm and 25 μm,were used to design the AC-13 asphalt mixture mixed with BF by Marshall test design method.The results showed that the optimum oil-to-rock ratio of AC-13 asphalt mixture decreased slightly with the increase of fiber diameter under the condition that the BF dosing was fixed(0.3%by mass).Next,the road performance of BFAM was tested by high temperature rutting test,uniaxial penetration test,low temperature beam bending test,water immersion Marshall test,and freeze-thaw splitting test.The results showed that compared with AC-13 asphalt mixes without fibers,the incorporation of BF of various diameters improved the high temperature deformation resistance,low temperature cracking resistance and water damage resistance of asphalt mixes.Among them,basalt fibers of 7 μm diameter had the most prominent reinforcement effect on the asphalt mixture,followed by basalt fibers of 16 μm and 25 μm,and the reinforcement effect of mixed diameters(7 μm:16 μm:25 μm=1:1:1)was between 7 μm and 16 μm.Finally,the mechanical properties of asphalt mixes with different diameters of basalt fibers were tested by ideal cracking test,triaxial shear test,dynamic creep test,and dynamic modulus test.The results show that basalt fibers can improve the medium temperature cracking resistance,low high frequency modulus and high temperature deformation resistance of asphalt mixes.Among them,7 μm fiber can effectively prevent the occurrence of relative slip within the fiber asphalt mixture.Iso-sectional theoretical calculations show that the fiber modulus,diameter and number of roots determine the enhancement effect of fibers on the asphalt mixture performance under the same fiber dosing and fiber length.The smaller the fiber diameter,the larger the number of roots,and the larger the actual modulus,the larger the equivalent cross-sectional area,and the more significant the enhancement effect on the asphalt mixture properties.Further using the obtained dynamic modulus and phase angle master curves,it was found that the dynamic modulus values in the high frequency band were positively correlated with the fiber diameter,and the phase angle curves indicated that the finer the fiber diameter in different frequency intervals contributed to the viscoelastic conversion of the mixture.In this paper,the road properties and mechanical properties of different diameters of BFAM are investigated,and the synergistic mechanism between the diameter of BF and asphalt mixture is analyzed based on the iso-sectional theory,and the results can aid and reference for further promotion of different diameters of BF in asphalt pavements.