Research On Influence Of Aggregate Chemical Composition And Apparent Characteristics On Aggregate Surface Energy

As one of the main pavement forms of expressways,asphalt concrete pavements often experience water damage during their service.Water damage occurs due to insufficient adhesion.Studies have shown that the chemical composition and apparent characteristics of aggregates can affect the adhesion between asphalt and aggregates.In order to reduce the occurrence of water damage,it is necessary to optimize the asphalt and the aggregate.At this stage,the more advanced international surface energy method based on Gv OC theory is used for research.Using surface energy method to explore the influence of aggregate chemical composition and apparent characteristics on aggregate surface energy.This paper studies the aggregate surface energy from two aspects of aggregate chemical composition and apparent characteristics.In terms of chemical composition:Aiming at the deficiencies of considering only effects of five chemical components on the aggregate surface energy and the existing test methods,established a model which is expessing the relationship between the content of aggregate chemical components and the surface energy of powdery aggregate samples.In terms of apparent characteristics:Calculating the difference between the surface energy of the powdery aggregate sample and the surface energy of the aggregate.Besides,using the image acquisition system to measure the apparent characteristics of aggregates.On this analysis,study the effect of apparent characteristics on aggregate surface energy.Finally,established the surface energy prediction model of powdery aggregate and the surface energy prediction model of granular aggregate.Based on the above research,the following research results are obtained:（1）Apparent characteristics and chemical composition are the most important factors affecting the surface energy of aggregates:In terms of chemical composition:The traditional capillary rise test only applicable to stable contact angle between the test reagent and the sample.Based on the above deficiencies,using the method which is suitable for complete wetting status to tested the chemical composition and powder samples;Based on the mass content of chemical components in the aggregate,proposed a method for calculating the content of Ca CO₃ in the aggregate;When the surface energy of the chemical component is considered,the order of impact is Fe₂O₃>Si O₂>Ca O>Ca CO₃>Al₂O₃>Mg O;When considering the surface energy and content of chemical components,it is found that Si O₂ is the main factor affecting of the aggregate,and Fe₂O₃ and Al₂O₃are the secondary factors.Engineering using Si O₂ content to judge the adhesion between the asphalt and the aggregate has rationality,but still has certain limitations;（2）In terms of apparent characteristics:For different aggregate types:the correlation coefficients of the three indicators of apparent characteristics are ranked as angularity>surface texture>sphericity;For different types of aggregates,angularity has the greatest influence on diabase,and limestone has the smallest degree;Sphericity has the greatest influence on angular amphibolite,and limestone has the least;Surface texture has the greatest influence on quartz sandstone,and limestone has the smallest degree.According to the same aggregate type,different origins and processing methods:Angularity has the greatest impact on diabase,and limestone is the smallest;sphericity has the greatest impact on basalt;Surface texture has the greatest impact on basalt,and limestone has the smallest;（3）Establish a prediction model of aggregate surface energy,which can predict the aggregate surface energy by the chemical composition content and apparent characteristics of the aggregate.It is also suitable for mineral powder and aggregate.