Study On The Influence Of Many Factors On The Dynamic Modulus Of Asphalt Mixture

For a long time,the structural design of asphalt pavement in China is based on the static elastic layered system as the theoretical framework,but the asphalt mixture has the typical characteristics of viscoelastic plasticity,heterogeneity and diversity,and is not a simple elastic material.It is very important to study the actual stress and material properties of asphalt pavement under dynamic load.The actual stress state of the pavement can be reflected by the dynamic modulus of the asphalt mixture.In this paper,SPT is used to test the dynamic modulus of different asphalt mixture samples formed by rotary compaction to study the influence of different factors on the dynamic modulus of the asphalt mixture,and the feasibility of testing the dynamic modulus of the small-size core drilling instead of the sample is studied The dynamic modulus can be better applied to pavement disease analysis and other field surface layer evaluation.Finally,according to the principle of time temperature equivalence,the main work and conclusions are as follows:(1)When the test temperature is the same,the dynamic modulus of asphalt mixture increases with the increase of load frequency.When the temperature is lower(<20 ℃),the phase angle decreases with the increase of load frequency.When the temperature is higher(≥ 40 ℃),the phase angle increases with the increase of load frequency.When the load frequency is the same,the dynamic modulus of asphalt mixture increases obviously with the increase of temperature The phase angle of asphalt mixture increases first and then decreases when it decreases.(2)With the increase of temperature,the dynamic modulus of SBS modified asphalt mixture is smaller than that of matrix asphalt mixture,and its sensitivity to temperature is lower;the dynamic modulus of asphalt mixture with the same gradation type increases with the increase of nominal maximum particle size;under the condition of the same asphalt type and temperature,the dynamic modulus of dense graded asphalt stabilized macadam is smaller than that of dense graded asphalt mixture Under the same temperature,the dynamic modulus of dense gradation is the largest,the semi open gradation is the middle,and the open gradation is the smallest;when the asphalt mixture is in the appropriate void ratio,the dynamic modulus of the mixture will gradually decrease with the increase of void ratio.(3)It is determined that the small-sized core drilling test piece drilled in horizontal direction is a feasible alternative to the standard test piece for dynamic modulus test;it is determined that the feasible alternative to the standard test piece for asphalt mixture with the nominal maximum particle size of 26.5mm is the small-sized core drilling test piece with the diameter of 50 mm,and the asphalt mixture with the nominal maximum particle size of 13.2mm uses the diameter of 38 or 50 Mm small size core test piece shall be replaced.(4)On the basis of dynamic modulus test,this paper draws the main curves of different asphalt mixtures according to the time temperature displacement principle,verifies the influence trend and law of different factors on the dynamic modulus of asphalt mixtures in a broader time temperature space,and demonstrates the substitutability of small-size core drilling specimens.