Unified Approach Of The Materail Design Parameters And Structure Design Parameters Of Skeleton Dense Structure Of Semi-rigid Base

For the high strength,large stiffness,greatly improved pavement bearing ability,and the lower materials price trend,the semi-rigid base is the most common base in the high-grade highway in china presently.But for the shrinkage cracking of semi-rigid base and the causing reflection crack of the asphalt pavement, these disadvantages bring the early damage of pavement structure, effect the normal use of the pavement. Eliminating and reducing the reflection crack is the most important task of road engineer.With the better performance of drying shrinkage,temperature shrinkage and the lower reflection crack, the skeleton dense structure of semi-rigid base was wildly used in high-grade highway.But presently there are no theoretical recognition of material design method,material design control index and detection method. Especially the design parameters(modulus of compressive,splitting strength).In the new Specification:《Specifications for Design Highway Asphalt Pavement》JTGD50-2006, each type design parameter are all in a scope,and have little difference between the old Specifications,these differences cause big variance between the design result and actual situation,it may lead to two adverse result:too thick pavement structure to economy,and too thin pavement structure to safe.With these, having a unified research on the material design parameters and structure design parameters of the skeleton dense structure of semi-rigid base.This paper begin with the gradation design of the skeleton dense structure of stabilized macadam,guiding step filling test by establishing mathematical embedded -extrusion model,getting a gradation closely related to the material and establishing mixture volume index relationship,theoretical caculation to verify the gradation of step filling method. Making three groups gradation related to the regulating scope, getting the volum-index of mixed aggregates by laboratory test,and in combination with the volume-index of cementation,Putting forword volume control index of materials design and it's scope of the two kind skeleton dense structure. Getting the material's modulus of compressive,splitting strength by laboratory test, building relationship between parameters and curing age,and guiding the scope of material design parameters with a given confidence level.To reduce the workload,for a scientific test,theoretical derive the maximum dry density and optimum water content.With the layered elastic theory,using BISAR Mechanical Calculation Software to caculation analysis the changes regularity of the material design parameters when the semi-rigid asphalt pavement design parameters changes,and proposed the limit required scope of the material design parameters,guiding the semi-rigid basement material design basing on this scope.Using structure design parameters to guid material design.With the purpors of material design structured.On the BinZhou-DaTong expressway, using FWD to test the bottom and top of the basement,adopting the transfer matrix method to derive the theoretical calculation of the compressive modulus of the monolayer.Developing the reverse-caculation program, reverse -caculate the compressive modulus of the monolayer with the test result of FWD.Making a comparision with the indoor test result, geting to know that the reverse-caculation program is reliable.