Study On The Effect Of Basalt Fiber Diameter On Performance Of Asphalt Mortar And Asphalt Mixture

Basalt fiber asphalt mixture has been more and more used in highway,national and provincial trunk lines and urban expressway projects in recent years because of its excellent road performance.Geometric parameters such as length and diameter are important factors affecting the enhancement effect of basalt fiber in the mixture.The influence of fiber length on asphalt mixture is the main direction of current research,and the adaptability of fiber diameter and asphalt mixture performance is still lack of corresponding research.At the same time,due to the limitations of the production process,there are now various diameters of basalt fibers on the market,and the same batch of fibers produced by the same manufacturer will also be mixed with diameter fibers.The applicability of this type of fiber in engineering needs to be further clarified.Therefore,this paper intends to carry out research on the performance of different diameter basalt fibers on asphalt mortar and asphalt mixture,and analyze its comprehensive benefits and reduce the project cost.The results can provide reference for the application of different diameter basalt fibers in asphalt pavement.Firstly,basalt fibers with diameters of 16 μm and 25 μm were selected and added to the asphalt mixture in the form of single blending and different proportions.The mix ratio of basalt fiber AC-13 and basalt fiber AC-20 was designed by Marshall test design method.The results show that the optimum asphalt-aggregate ratio of asphalt mixture increases by 0.1～0.2 percentage points after adding basalt fiber.The smaller the fiber diameter,the higher the optimum asphalt aggregate ratio of the mixture;however,the oil-stone ratio of fiber asphalt mixture with mixed diameter is at the same level.Secondly,based on the powder-binder ratio determined by the mix design,the fiber asphalt mortar sample was prepared.The adhesion properties of fiber-asphalt mortar interface and the rheological properties of fiber-asphalt mortar were determined by novel fiber-asphalt pullout test,dynamic shear rheology tests,multiple stress creep recovery test,linear amplitude sweep test,bending beam rheological tests.The results show that the interfacial adhesion strength of 16 μm fiber-asphalt mortar is larger than that of 25 μm fiber at low and medium temperatures.Compared with asphalt mortar without fiber,basalt fiber can improve the high temperature rheological properties and fatigue properties of asphalt mortar.The high temperature performance and fatigue performance of 16μm basalt fiber asphalt mortar are better than those of 25 μm fiber.Then,the high temperature rutting resistance and shear resistance,medium temperature and low temperature crack resistance and water stability of basalt fiber asphalt mixture were studied by the rutting test,uniaxial penetration test,uniaxial compression test,indirect tensile asphalt cracking test,low temperature beam bending test,immersion Marshall test,freeze-thaw splitting test.The results show that the smaller the diameter of single basalt fiber is,the better the high temperature performance of asphalt mixture is.16 μm fiber can greatly improve the medium and low temperature cracking performance of asphalt mixture,but the improvement effect of 25 μm fiber is not significant.The approximate performance of the composite fiber asphalt mixture is that the more the 16 μm fiber content,the better the high temperature performance and crack resistance;in addition,the fiber diameter has little effect on the water stability of asphalt mixture.Finally,the road performance and economy of basalt fiber asphalt mixture with different diameters were comprehensively evaluated by the efficiency coefficient method.The results show that the compound mixing of different diameters can effectively reduce the project cost;the asphalt mixture with 16μm and 25μm basalt fiber mixed at a ratio of 1:1 has high cost performance and can be used on a large scale for various grades of pavement.