Research On The Construction Techniques For Xin Jiang Cement Stabilized Gravel Base Course Of Surper Thickness And Broad Width In Arid Desert Region

In recent years,the thickness and width of cement stabilized gravel base course of newly-built highways in Xinjiang have gradually increased to 30cm~40cm and the overall average width is more than 10 m.At the same time for the most area in Xinjiang with less rainfall and strong evaporation,temperature differences and in arid desert climate characteristics of the temperature difference is bigger,can easily lead to dry shrinkage and temperature shrinkage in cement stabilized gravel base course.Therefore,by studying the composition of cement stabilized gravel materials,the crack deformation mechanism of the base course and the different construction techniques of the ultra-thick and wide-width cement stabilized gravel base course,concluding the suitable cement stabilized gravel material raw material proportioning and construction methods,has important practical significance by selecting typical road sections for comparative study,the dry shrinkage test,temperature shrinkage test,strength test,stiffness test and CT scan analysis of cement stabilized gravel base materials with different gradation types and composition ratios were carried out,and the range of skeleton compacted anti-crack cement stabilized gravel materials gradation suitable for Xinjiang arid desert areas was given Based on the study of the influencing factors and action rules of the pavement performance of the cement stabilized gravel base course with large thickness,the method of improving the mechanical performance of the base course is put forward.It is concluded that the cement-stabilized macadam base with large excitation vibration has better performance than the standard static pressure base.Finally through the introduction of one-time paving construction of 34 cm thick cement stabilized gravel base course of one highway and the parallel machine layering process which is used in 34 cm thick cement stabilized gravel base course in section of another highway line,proved that one-time whole paving,vibration compaction process is suitable for cement treated base with super thickness and broad width.The results show that in arid desert area,the increase of cement dosage and strength grade will lead to the increase of dry shrinkage and temperature shrinkage of cement stabilized gravel materials.The higher the course aggregate content and the smaller the fine aggregate content,the smaller the deformation of the cement stabilized gravel materials.Under the same condition,skeleton compacted type for cement stabilized gravel materials has minimum temperature shrinkage and dry shrinkage deformation.By enhancing the continuity between layers,reducing the difference of compaction degree between the upper and lower layers,and adopting the vibration molding process with large excitation force,the mechanical properties and construction quality of the ultra-thick and wide-width cement stabilized gravel base course can be effectively improved.Adopting the overall one-time construction process to carry out the construction of thick cement stabilized gravel base course base,not only the integrity and flatness of the base course are better than the layering and parallel machine laying process,but also the segregation phenomenon of materials is obviously reduced,and the former is 50% higher than the latter engineering progress,which can save 32,860,000 yuan per km,with good economic benefits and promotion value.