Study On The Correlation Between The Durability Of Asphalt Fine Aggregate Matrix And Asphalt Mixture Under Freeze-thaw Cycles And UV Aging Conditions

Asphalt mixtures are composed of different shapes and sizes,strong temperature sensitivity,and disordered spatial distribution,which lead to the multi-scale and rheological properties of the formed asphalt mixture.In the meso-scale of asphalt mixture,it undertakes the role of a cross-scale bridge for the study of micro-scale equivalent to meso-scale and meso-scale averaging to macro-scale.The rheological behavior of asphalt mixture is a complex mechanical behavior,in which asphalt Fine Aggregate Matrix(FAM)has viscoelasticity similar/equivalent to asphalt mixture.FAM is also the main bearer of rheological properties in asphalt mixtures,and it plays an important role in resisting high-temperature rutting,medium temperature fatigue,low-temperature cracking,and other durability properties.However,it is difficult to provide supporting material indicators and accurately predict the durability characteristics of asphalt mixtures only by studying FAM.Based on the above,carry out the correlation analysis of the durability of FAM and asphalt mixture under indoor and outdoor environmental factors,and provide a strong research basis for the in-depth understanding of the durability of asphalt mixture;Furthermore,the digital image correlation method at the meso-scale is used to verify the importance of FAM in the design of asphalt pavement materials.To explore the relationship between the durability of FAM and asphalt mixture under indoor environmental factors,the optimal oil-stone ratio of asphalt mixture was determined by the Marshall test,and then the oil quantity and gradation of FAM were determined.FAM and asphalt mixture specimens at the meso-scale were obtained by machine;With the help of a dynamic shear rheometer,the feasibility of using a rectangular fixture was verified by frequency scanning;After the linear viscoelastic range of the specimen was determined,the effects on the complex shear modulus,fatigue properties and creep properties of FAM and asphalt mixture under the conditions of freeze-thaw cycles and UV accelerated aging were analyzed,and the asphalt was analyzed.Correlation of durability between FAM and asphalt mixtures.The results show that:under the condition of freeze-thaw cycles,the complex shear modulus of FAM and asphalt mixture decreases with the increase of freeze-thaw cycles,the fatigue life decreases,the proportion of delayed elastic compliance decreases,and the proportion of viscous flow compliance decreases.than increase;Under UV aging conditions,with the increase of UV accelerated aging time,the complex shear modulus of FAM and asphalt mixture increases,the fatigue life decreases,the proportion of delayed elastic compliance increases,and the proportion of viscous flow compliance decreases;The change law of the modulus curve of FAM and asphalt mixture,the decreasing trend of fatigue life and the change of the proportion of viscoelastic compliance are related.To study the relationship between the durability of FAM and asphalt mixture under outdoor environmental factors,a dynamic shear rheometer was used to analyze the complex shear modulus,complex shear modulus,and FAM,and asphalt mixture under outdoor natural water loss and outdoor natural aging conditions.The influence and correlation analysis of fatigue performance and creep performance,and the correlation analysis of the modulus change rule under the influence of indoor and outdoor aging environment using the master curve;To verify the importance of FAM in the design of asphalt pavement materials,the strain field and displacement field of FAM and skeleton were analyzed using digital image correlation method and multifunctional material testing machine.The results show that:under the influence of the outdoor natural environment,the modulus of FAM and asphalt mixture changes as follows:one year of outdoor aging>one year of outdoor water loss>six months of outdoor aging>one year of outdoor water loss>untreated、The fatigue life is:untreated>outdoor aging for half a year>outdoor water damage for half a year>outdoor aging for one year>outdoor water damage for one year、Creep compliance is:one year of natural aging<one year of natural water loss<six months of natural aging<six months of natural water loss<untreated;The vertical and horizontal displacement and strain of FAM are larger than those of the skeleton,and the vertical displacement,vertical strain and horizontal strain of asphalt mixture,skeleton and FAM have a certain correlation.