Research On Representation Of Fine Aggregate Geometric Characteristics Parameters And Its Influence On Asphalt Mixture Performance

Fine aggregate as a major component of asphalt concrete materials, up to40%to50%, plays a crucial role on the performance of asphalt concrete. However, fora long time, in order to improve the performance of asphalt concrete, researchersfrom various countries generally started with graded composition and asphalt,while neglecting an important impact of fine aggregate geometric characteristics.This results in unclearness of the reasonableness of existing evaluation method tothe fine aggregate geometric characteristics evaluation. The impact fineaggregate geometric characteristics on the performance of asphalt concrete arelittle known.In this thesis, the existing geometrical evaluation indexes of fine aggregateswere evaluated. Based on the evaluation, a new method which can accuratelycharacterize the geometrical properties of fine aggregates was proposed.Utilizing image processing techniques, the geometrical evaluation indexes of fineaggregates and associated evaluation criteria were recommended. On this basis,this paper analyzed the impact of fine aggregate geometrical properties on theperformance of asphalt mortar and asphalt concrete. And asphalt concreteperformance parameters related to geometrical properties of fine aggregates weremade clearly. The main research contents and achievements are summarized inthe following:Firstly, based on the existing test methods-uncompact void rate test, theflow time test and ASTM D3398test, the sensitivity of evaluation method to fineaggregate geometrical difference were analyzed. The reasonableness andinfluencing factors of the geometrical evaluation index of fine aggregates werestudied. And the impact of the particle composition and geometricalcharacteristic on evaluation rationality is illustrated. On this basis, the Greyrelational analysis was used to analysis the degree of association betweengeometric properties of single particle size and geometric characteristics of fineaggregate (mixed materials). Then put forward the new evaluation method togeometrical properties of fine aggregates based on the typical part icle size. Secondly, an acquisition device for geometrical properties of fineaggregates combined stereo microscope with surface light source was developed.To analysis of the distribution of evaluation index of the geometrical propertiesof fine aggregates based on image processing technology. On this basis, by theuse of mathematical statistics, a research on the sensitivity evaluation indicatorsof the fine aggregate geometric characteristics was carried out based on theimage processing technology. The test results show that the difference ofgeometrical properties of fine aggregates is mainly reflected in the shapes andangularity. To put forward taking the equivalent ellipse shaft ratio1.30and SPvalue0.82under smaller resolution as the evaluation indicators and evaluationcriteria of fine aggregate shape characteristics and angular characteristics.Thirdly, based on the difference of the geometrical properties of the fineaggregates, taking viscoelastic properties of asphalt mortar as study object, aresearch on impact of the asphalt mortar viscoelastic parameters and theviscoelastic behavior in a wide temperature region by the geometrical propertiesof fine aggregates was launched in accordance with the Burgers model and CAMimproved rheological model. To analyze the variation of the viscoelasticproperties of the asphalt mortar as fine aggregate shape characteristics andangular characteristics. To clarify the role of the production process, mineralcomposition and other factors in geometric properties in the study of the impactof asphalt mortar’s viscoelastic parameters.Finally, a study on the impact of performance of asphalt concrete by thegeometrical properties of the fine aggregate was carried out based on thedifference of the geometrical properties of the fine aggregates. To analyze theinfluence rule of volume parameters of asphalt concrete pavement andmechanical properties by shape characteristic and angular characteristics of fineaggregates. To make clear the performance parameters of asphalt concrete relatedto geometrical properties of fine aggregates.This thesis carried out a series of work in the evaluation method, evaluationindex of fine aggregate geometrical properties, and the impact of fine aggregategeometric properties on the performance of asphalt concrete. These researcheswill laid the foundation for the design and evaluation of asphalt concrete.