Crack Resistance Analysis Of Fiber Reinforced Asphalt Concrete Based On Digital Image Correlation Technology

Asphalt pavement is widely used for its excellent pavement performance,such as comfortable driving,fast construction and good continuity.However,the temperature stability of asphalt is poor,and cracking inevitably occurs under the action of temperature and driving,and cracking is one of the main forms of pavement damage.How to improve the crack resistance of asphalt pavement has always been a problem in the field of road engineering.With more and more kinds of fibers coming into people's vision,more and more attention has been paid to adding fibers to improve the crack resistance of asphalt concrete.In this paper,different lengths of glass fiber,basalt fiber and steel fiber are selected to study the influence of fiber on the crack resistance of asphalt concrete.As a new optical nondestructive measurement method,digital image speckle correlation technology has the advantages of simple operation and high accuracy.In this paper,digital image speckle correlation technique is used to measure the deformation of asphalt concrete specimens,and indirect tensile test and semicircle bending tensile test are used to evaluate the influence of fiber on the low temperature crack resistance of asphalt concrete.The main contents and achievements are as follows:(1)The manufacturing process of fiber-reinforced asphalt mixture is determined.The open-source digital image speckle correlation analysis software Ncorr is introduced for the first time.The applicability of the software is studied and analyzed,and its application method and analysis process are explored and determined.(2)The mechanical properties of asphalt concrete,such as Poisson's ratio,modulus,ultimate tensile strength,ultimate tensile strain,fracture energy and dissipation creep strain energy,are analyzed by indirect tensile test at low temperature.The results show that the type of fiber has an important influence on the mechanical properties of asphalt concrete at low temperature.After adding fiber,the modulus of asphalt concrete at low temperature decreases and the ultimate tensile strain increases by 3-5 times.At the same time,fiber asphalt concrete has high fracture energy and dissipation creep strain energy.In general,basalt fiber is better than glass fiber and steel fiber in crack resistance,basalt fiber is more suitable for asphalt concrete,and steel fiber is not suitable for modified reinforced asphalt mixture because of poor interface bonding.(3)At last,the influence of basalt fiber on the fracture mode of asphalt mixture is analyzed by the semicircle bending test.The results show that basalt fiber can increase the critical stress intensity factor at low temperature,but decrease it at normal temperature.However,basalt fiber can effectively improve the deformation resistance of asphalt concrete at low or normal temperature,and the effect is better at normal temperature.The critical fracture energy G_F of different temperature and fracture mode is increased.The critical fracture energy G_F of asphalt concrete mixed with basalt fiber reaches the maximum value when M~e=0.5,which indicates that basalt fiber has the best crack resistance effect under the tension shear fracture mode.