Experimental Study On Performance Of Gussasphalt Mortar And Mixture Considering Raw Material Index

As the throat of the transportation network,the long-span steel bridge bears extremely heavy traffic loads,and its high-efficiency heat conduction and heat storage effect make the temperature environment of the bridge deck pavement more harsh compared with ordinary asphalt pavements.Gussasphalt has high water tightness and strong deformation ability,and has gradually developed into the mainstream paving material for large-span steel girder bridge decks in my country.Existing studies have shown that when the gussasphalt is used for steel bridge deck paving,the dynamic stability of rutting at 60℃is usually less than 1000 times/mm,and other asphalt mixtures（modified asphalt SMA/AC）are only used for steel bridge deck paving.The high temperature stability is"very poor",and the industry has always been concerned about its high temperature and heavy load resistance.This is mainly due to the material’s suspended compact structure,with very high asphalt content and mineral powder content,which has a great influence on the test results of rutting dynamic stability.At the same time,the special asphalt binder and powder-binder ratio used have a greater impact on the construction fluidity and other properties of the mixture.Therefore,the performance of asphalt binder,mineral powder and the asphalt mortar composed of it has become a key factor in determining the performance level of the mixture.This paper takes asphalt mortar as the research object,analyzes the influence of the raw material index of the mortar on its high temperature performance,and at the same time uses the mixture to verify it to establish the correlation between the two.The main research is as follows:（1）According to current industry specifications and engineering application conditions,three asphalt binders,polymer composite modified asphalt,lake asphalt composite modified asphalt,and hard composite modified asphalt,which are commonly used in gussasphalt,are selected to pass indoor modification Methods Prepare modified asphalt with different performance index levels.Based on the analysis of its main performance evaluation indicators,three indicators of softening point,penetration and viscosity are selected as key indicators,and their basic performance is compared and analyzed.Select six different types of mineral powders,based on the analysis of their basic indicators and test methods,put forward four key indicators of specific surface area,fineness D₅₀,plasticity index and SiO₂content from both physical and chemical properties and conduct a comparative analysis..（2）Through the analysis of the preparation process and test method of asphalt mortar,the dynamic shear rheological test（DSR）and the brinell rotational viscosity test were adopted to determine the asphalt mortar formed by 3 types of asphalt binder,13performance levels,and 6 types of mineral powder.The pulp undergoes key performance tests.Based on grey correlation method and random forest method,the influence degree of key indicators of raw materials is determined,and the high temperature stability evaluation model of asphalt mortar performance is established.According to the established evaluation model,analyze the relationship between the softening point,penetration,viscosity of asphalt binder and the rutting factor G^*/sinδand viscosityη’of asphalt mortar;in the same way,analyze the specific surface area and fineness of mineral powder The relationship between D₅₀,plasticity index,SiO₂content and asphalt mortar rutting factor G^*/sinδand viscosityη’,and then integrate the asphalt binder and mineral powder indicators,and calculate the optimal asphalt mortar high temperature performance through genetic algorithm.The best combination of key indicators of mineral powder.（3）According to the performance design goals of asphalt mortar,select typical asphalt and binder composition patterns,prepare gussasphalt,conduct test evaluation tests such as penetration and increment,and analyze high-temperature performance indicators of gussasphalt.Correlation with raw materials.Based on this,for different types of raw materials,formulate the composition type and key performance quality assurance design requirements of the asphalt binder and mineral powder.The research results show that the softening point,penetration,viscosity,specific surface area,fineness D₅₀,plasticity index,and SiO₂content of the asphalt binder have a greater impact on the high-temperature performance of asphalt mortar.Through the analysis of the performance level of asphalt mortar,The relationship between the mixture and the raw material indicators can be established,which is of great significance for guiding the performance improvement design of the gussasphalt and ensuring the quality objectives of the steel bridge deck paving project.