Experimental Research On The Performance Of Basalt Fiber Rubber Asphalt Stress Absorbing Layer

The semi-rigid base layer is easy to have the reflection cracks under the coupling effect of load and temperature and other factors,making the pavement performance and durability significantly reduced.The addition of the paving of fiber asphalt stress absorbing layer can effectively inhibit or alleviate the expansion of the cracking of semi-rigid subgrade.Basalt fiber as a new type of inorganic high-performance fiber material,its mechanical properties is excellent,and its material properties is stable.There are now many researches about the effect of basalt fibers on the road performance of asphalt mixtures,but there is a few researches on its application to rubber asphalt stress absorption layer.Therefore,this paper selected basalt fiber as the research object to study the influence of different fiber combinations on the performance of rubber asphalt stress absorbing layer.Firstly,the mix proportion design of cement stabilized crushed stone base and the surface layer of AC-20 asphalt mixture is carried out through indoor tests,and the mineral material composition,the optimal moisture content and cement content are determined;The mineral material composition and optimum asphalt content of AC-20 is determined and the design of rubber asphalt stress absorbing layer is carried out.The particle size of the crushed stone on the rubber asphalt stress absorbing layer was determined as 4.75mm～9.5mm,and the spreading amount of crushed stone was 14kg/m2,and the sprinkling amount of asphalt was 2.3kg/m2,and the number of indoor molding and rolling was three times.Secondly,four kinds of fiber lengths（3 cm,6cm,9cm,12cm）and four kinds of fiber blending contents（120g/m2,140g/m2,160g/m2,180g/m2）were selected to interweave to determine the fiber blending combination.The interlayer shear test,interlayer pull test,threepoint bending test,overlay test（OT）test were conducted to study the effect of basalt fibers on the performance of rubber asphalt stress absorbing layer from two aspects including interlayer performance and anti-reflection crack performance.The results showed that compared with the non-fiber-doped rubber asphalt stress absorbing layer,the performance of the rubber asphalt stress absorbing layer with basalt fiber was significantly improved,the extent of improving could reach by 305.5%,and the interlayer performance was enhanced to some extent.This indicates that rubber asphalt stress absorbing layer could effectively absorb and disperse the external load,and the network structure formed by the fibers and the asphalt layer helps to disperse the external stress at the cracks,which plays an excellent crack resistance effect.Finally,the extreme difference analysis is used to explore the main factors affecting the performance of basalt fiber rubber asphalt stress absorbing layer.The results show that main and secondary factor affecting the interlayer shear strength of basalt fiber rubber asphalt stress absorbing layer are fiber length and fiber content,and the main and secondary factors affecting the interlayer adhesion strength and reflection crack resistance of basalt fiber rubber asphalt stress absorbing layer are fiber content and fiber length.Based on the comprehensive analysis of the performance and economy property of basalt fiber rubber asphalt stress absorbing layer,the recommended best fiber blending combination is that the fiber length is 9cm and fiber dosage is 160g/m2.This study can provide technical reference for the design of basalt fiber rubber asphalt stress absorbing layer,which has certain theoretical significance and application value.