Research On Viscoelasticity Of Vilane Vilica Modified Asphalt And Its Mixture

Asphalt pavement includes construction surface and all kinds of base and cushion,and it is mainly composed of bituminous material as binder.Compared with the cement concrete pavement,it has a smooth and comfortable surface,and it improves adhesion in mineral aggregates,strength,stability,quality and durability.The asphalt pavement developed rapidly in China,and increased gradually in the proportion of highway.In recent years,the increasing highway traffic,heavy load,the influence of precipitation and aging bituminous materials,accelerate the diseases of the asphalt pavement,which caused premature deformation,cracking,fatigue,aging,bleeding and other phenomenas.Because the asphalt is a typical viscoelastic material,the diseases of it is essentially related to its viscoelaticity.This paper proposes to use silane silica modified asphalt,to improve the viscoelastic pavement,thus improving asphalt pavement performance.The general theory of viscoelasticity is briefly introduced in this paper,and the basic mechanical behavior of viscoelastic material is creep,relaxation and recovery.In classical mechanics,the spring is the basic element for elasticity,and dashpot is for viscosity,so viscoelastic model is a simple combination of the two kinds of components in different series and parallel connection,and the Burgers model is adopted to analyze the viscoelasticity of asphalt materials in this paper.The main contents and conlusions of this paper are as follows:(1)The viscoelasticity of asphalt was studied from the chemical composition of asphalt,based on the four components of asphalt,the colloidal structure of asphalt was determined by combining the penetration and viscosity tests with modern slurry theory.The effect of silane silica on the temperature sensitivity and viscosity of asphalt and the relationship between viscosity and temperature were analyzed.The results show that: silane silica can reduce the penetration of the pitch,increase the viscosity of the asphalt,and reduce the temperature sensitivity;the asphalt colloid belongs to the soluble-gel type asphalt,and the viscosity and temperature shows a simple exponential relationship.(2)DSR experiment is a basic test method to study the viscoelastic behavior of asphalt.The base asphalt and 3% silane silica modified asphalt were scanned with frequency at different temperatures.The results show that: complex shear modulus G*,elastic shear modulus G`,viscous shear modulus G`` and anti-rutting factor G* / sin ? decreased with the increase of temperature;When silane silica was added,the results increased obviously while Phase angle ? decreased;according to the principle of time-temperature equivalence,the displacement molecules can be calculated according to the WLF formula,and the principal curves of different rheological indexes can be drawn.The influence of frequency and temperature on the material can be analyzed by the main curve and displacement factor,and the viscoelastic properties of the material can be evaluated comprehensively.The parameters of Burgers model are solved by the method of objective function.(3)The viscoelasticity of silane silica modified asphalt mixture was studied by static load creep test.The results show that: Creep can be divided into three parts,instantaneous elastic part,delayed elastic part and viscous flow part;the strain increased with the increase of temperature,but the growth rate slowsed down with time;the addition of silane silica can obviously reduce the strain value at the same temperature.According to the L-M optimization algorithm based on the least square method,the parameters of the burgers model were obtained.The mechanical test parameters were transformed into the finite element model Prony series,and the static creep test of asphalt mixture was simulated by the finite element software ABAQUS.The experimental error of static load creep simulation by Abaqus was less than 3%,which met the requirement of precision and embodied the reliability of theory and practical application value.(4)Based on the dynamic creep test data,the time parameters of burgers model are transformed into the action times of the dynamic load test,and the permanent deformation formula under the dynamic load creep test was derived by using the Boltzmann linear superposition principle of viscoelastic material.Combined with the rutting experiment,the theoretical and experimental values of dynamic stability are compared to verify the accuracy of the model.A sensitivity analysis of various model parameters was made to find out which parameters has a significant influence on the viscoelasticity of the model.The results show that: The influence of 1? on the dynamic stability of the rut is the biggest.