Equipment Development And Evaluation On Interlayer Bonding Performance Between Semi-rigid Base And Prime Coat/slurry Seal

In the domain of Chinese road construction,semi-rigid base asphalt pavement is constituted as a paramount category of pavement structures,holding immense significance throughout the nation.Nevertheless,it is found that interlayer displacements are prone to occur,potentially leading to severe complications such as congestion,pushing,and other related issues,owing to disparities in material properties and strength moduli between semi-rigid base and asphalt pavement.Enhanced interlayer bonding performance contributes to the dispersion of traffic loads across layers,ameliorating road performance and decelerating the manifestation of pavement diseases.Conversely,inferior interlayer bonding performance exacerbates tensile stress and strain at the base of each structural layer,culminating in pavement diseases and a diminished service life.Initially,the performance of raw materials,including cement and aggregates,was assessed for the production of cement-stabilized gravel mix specimens.The optimal water content and maximum dry density were ascertained through heavy compaction tests,while the7-day unconfined compressive strength test validated a cement-stabilized gravel mix ratio of5.3% water content,2.417 g/cm~3 dry density,and 5.0% cement dosage.Concurrently,the performance of emulsified asphalt,aggregate,and other raw materials was evaluated for the fabrication of emulsified asphalt thin slurry seal mix and prime coat/slurry seal specimens.The appropriate water consumption for thin slurry seal mix was determined through a consistency test,while a series of tests verified the thin slurry seal mix ratio of BC-1emulsified asphalt dosing at 13.4% and a water content of 15.0%.Subsequently,the design of prime coat/slurry seal was executed.Secondly,after scrutinizing existing interlayer bonding test methods and principles for semi-rigid base and prime coat/slurry seal,a novel instrument was developed to assess the interlayer bonding performance.The objectives and principles of instrument development,instrument construction,and component functionalities were delineated,resulting in two distinct test instruments for indoor and field testing of interlayer bonding: the UTM-based variable loading position indoor horizontal shear instrument and the field portable horizontal shear instrument.Corresponding usage methods and procedures were also devised.Thirdly,composite specimens were prepared,varying in prime coat spreading time,slurry seal laying time,and prime coat oil spreading amount.The impact of slurry seal thickness,prime coat surface cleanliness,and positive stress on interlayer bonding performance was analyzed under distinct combinations of working conditions.The Moore-Cullen theory analysis indicated that interlayer bonding performance is primarily influenced by cohesive force when the prime coat/slurry seal is applied before the water-stable age of 7 days,whereas the internal friction angle predominantly affects bonding performance after the water-stable age of 7 days.Lastly,an empirical study was conducted along the Yanyingsong Expressway in Guizhou to investigate the influence of interlayer bonding performance across five aspects: prime coat/slurry seal implementation,spreading time,sealing layer laying time,surface cleanliness,and moisture level.The results demonstrated that interlayer bonding performance is relatively unaffected by the cleanliness and wetness of the prime coat surface.This research examines the impact of various factors on the interlayer bonding performance between semi-rigid base layers and prime coat/slurry seal,effectively guiding the construction timing of prime coat/slurry seal,enhancing interlayer bonding performance,and providing substantial support for prolonging road lifespan.