Test Study On The Pavement Performance Of Semi-rigid Base Course In Seasonal Frost Region

For semi-rigid base course material, our country has on the top of the international level after nearly thirty year's investigation and application. Lime-fly ash stabilized aggregate and cement-stabilized gravel are the two semi-rigid base course materials in common use which has commonly used for high type highway because of their virtue of high strength and stability and so on. But it turns up the following short aspects when has been made use of nearly twenty years.1. The initial strength is low, impact the traffic and can not open earlier.2. It is easy to bring out brushing phenomenon and then result in the pavement broken and the working life3. In the course of the strength forming and working, it will bring temperature shrink crack because of temperature changed and drying shrinkage crack because of water content changed. When the asphalt surface course is thin, this kind of crack usually extends into the surface and forms reflect crack. The crack existed not only makes the vehicle steering quality come down, but also destroys the integrated characteristic and continuity of the pavement structure and in some extent leads to weaken of structure strength.4. When the raw material is improperly chosen or the mixture ratio is improperly designed. The semi-rigid base course is easy to come forth lack of cracking resistance and anti-brushing performance and also has defect of poor freezing and thawing resistance and poor bond of the surface.5. Lime fly-ash mixture is mainly composed of fine aggregate. It is sensitive to water and makes the base course always puzzle at the drying shrinkage crack in the course of construction and working time. Aim at the defect of semi-rigid base course material, this paper takes the pavement performance of the semi-rigid base course road in seasonal frost region as project background. By reading lots of literature, on the base of summing up the pavement performance study of lime-fly ash aggregate and cement-stabilized grain,systemically study the semi-rigid base course by experimentation with respect to raw material,mixture-ratio design,enhancing mixture's initial strength,mixing into admixture and so on, furthest enhance the pavement performance of the base course material by using the existing material.The main studying contents include:1 The pavement performance of the lime-fly ash stabilized aggregate semi-rigid base course material;2 Experimental study on the pavement performance of the cement stabilized gravel;3 Experimental study on enhancing the initial strength of lime-fly ash granule; 4 The impact of semi-rigid base course material stabilized by fiber on the compressive strength,compressive modulus of resilience,freezing resistance performance,fatigue performance,shrinkage performance,flexile and tensile strength and modulus;The studies indicate:1 Raw material indexes have great influence on the pavement performance of the semi-rigid base course material;2 Many indexes such as the content of the calcium and magnesium in lime,the fineness of the fly ash,the mud content of the aggregate,the quality of the cement,the grade of the aggregate all have impact on the performance of lime-fly ash aggregate and cement-stabilized gravel. By experimental study and investigate on situ construction, put forward some technical index requests of the raw material, and have certain effect on enhancing the pavement performance of semi-rigid base course;3 By test studying on the pavement performance indexes of lime-fly ash aggregate, analyze the structure theory and choiceness performance of interlocking dense-typed lime-fly ash aggregate, and then put forward the volume design method of lime-fly ash aggregate.4 From the study, put forward the measure of enhancing the initial strength of thelime-fly ash aggregate, sodium carbonate is adapted to lime-fly ash granule accelerating admixture in normal temperature condition. Sodium hydroxide and compound accelerating admixture is adapted to the condition in low temperature.5 Semi-rigid base course material stabilized by fiber could enhance the fatigue life of the semi-rigid material,reduce the modulus,improve the ductility,decrease the crack of pavement and improve the pavement working performance.In conclusions, this item puts forward the measure and technical index requests of the semi-rigid base course material by laboratory experiment,construction of a trial pavement and summing up the former studying researching achievement, and provides technical support for long life semi-rigid base course material.