Study On Viscoelasticity Of Silica Basalt Fiber Asphalt Mixture

Asphalt mixture is a viscoelastic material.The high-temperature rutting and low-temperature cracking of asphalt pavement are related to the viscoelastic nature of asphalt mixture.Poor viscoelastic properties of asphalt mixture will lead to insufficient high-temperature stability and low-temperature crack resistance.As a new type of material,silica basalt fiber asphalt mixture（hereinafter referred to as SABF asphalt mixture）has improved road performance compared with ordinary asphalt mixture.It is very important to study and analyze its viscoelastic properties in essence.Therefore,based on the theory of viscoelasticity,this paper conducts the following research on the creep and relaxation of SABF asphalt mixture and ordinary asphalt mixture:（1）The viscoelasticity of SABF asphalt mixture and ordinary asphalt mixture at30℃,40℃,50℃and 60℃was studied by creep tests of static and dynamic loading methods,combined with Burgers model and modified Burgers model parameters,and the delay time and relaxation time calculated corresponding to the two model parameters,so as to analyze the creep deformation characteristics of the two asphalt mixtures.The results show that the addition of silica basalt fiber improves the asphalt mixture’s resistance to instantaneous elastic deformation,viscoelastic deformation and permanent deformation.Among them,the resistance of silica basalt fiber to asphalt mixture is about 30℃.The viscoelastic deformation ability is significantly improved;at 50℃to 60℃,the resistance to permanent deformation of the asphalt mixture by the silica basalt fiber is significantly improved.In the dynamic loading creep test,aiming at the characteristics of dynamic loading,the revised Burgers model was deduced based on the Boltzmann linear superposition principle,and the applicability of the new strain expression was verified（R²＞0.99;0.9 9）.（2）In order to further analyze the relaxation characteristics,the static relaxation modulus E_静 and dynamic relaxation modulus E_动 are calculated based on the convolution integral and Laplace transformation based on the static creep compliance J_静and dynamic creep complianceJ_动obtained from the creep tests of static and dynamic loading methods.Combined with the second-order generalized Maxwell model and Scott-Blair model to fit the relaxation modulus（SABF asphalt mixture:R²＞0.83,,092;0.99,0.8 2;ordinary asphalt mixture:R²＞0.83,0,92;0.99,0.8 1）,and analyze the parameters.The results show that:SABF asphalt mixture has higher relaxation strength G₁、G₂,indicating stronger relaxation ability;higher viscosity coefficientηand fractional orderα,indicating that the proportion of permanent deformation to the total strain is reduced,and then the ability to resist rutting deformation;G₁、G₂、ηandα,and at 30℃～40℃and 60℃enhanced performance is most obvious.（3）The static relaxation modulus G_静 and dynamic relaxation modulus_动G are calculated and analyzed through two loading methods:static loading and dynamic loading.The results show that the two numbers are basically the same,and the correlation is good（SABF asphalt mixture:R²＞0.848;ordinary asphalt mixture:R²＞0.847）,and the relaxation modulus obtained by dynamic loading creep of the same material at the same temperature is the same as that obtained by static loading creep The deviation relationship of the relaxation modulus is basically in the range of 0.9～1.1.（4）By modifying the parameters of the Burgers model,the Prony series corresponding to the two asphalt mixtures at different temperatures in the static and dynamic loading creep tests were calculated,and input into ABAQUS to establish a three-dimensional finite element model.The creep test of the static and dynamic loading methods is simulated by finite element analysis software,and the simulation calculation results are compared with the test results.The correlation between the two is very good（SABF asphalt mixture:R²＞0.99,,097;ordinary asphalt mixture:R²＞0.99,,09 6）.For the stress relaxation process,the correlation between ABAQUS stress relaxation process numerical simulation and test calculation results is also very good（SABF asphalt mixture:R²＞0.924;ordinary asphalt mixture:R²＞0.925）.It can be considered that ABAQUS finite element software can better reflect the viscoelastic mechanical response of creep and stress relaxation of asphalt mixture under static load and dynamic load.（5）According to the creep compliance of asphalt mixture at different temperatures,the WLF corresponding equations are calculated,and the temperature shrinkage cracking models of SABF asphalt mixture and ordinary asphalt mixture are established.The asphalt mixture freeze-break test（TSRST）was carried out using ABAQUS finite element analysis software,and the temperature shrinkage stress and stress accumulation inside the two asphalt mixtures were simulated under different cooling rates.The results show that SABF asphalt mixture produces slower temperature shrinkage stress rate,less cumulative temperature shrinkage stress,and lower cracking temperature.