Study On The Influence Of Aggregate Lithology And Microscopic Characteristics On Road Performance Of Asphalt

The composition and structure of the material determine properties of thematerial, especially the aggregate in the largest amount of asphalt mixture, whichplays a significant impact not only on the performance of asphalt mixture, but also onthe project cost. Many of highway pavement damage phenomenon is closely relatedto the aggregate performance, which has not high performance and quality, is one ofthe main asphalt road surface damage phenomena, such as rutting, loose flaking,cracks, etc. Therefore, to carry out research on the characteristics of aggregate asphaltmixture performance is very important. However, owing to lack of equipment, theoryand methods, current research mostly remain on the macro indicators. Such ascrushing value, abrasion value, edges, etc. But researchers do not deeply involved inthe lithology and areas of microscopic characteristics of aggregates. Asphalt pavementdamage still exists a variety of phenomena by controlling the current proposed macroeconomic technical indicators of aggregates. Therefore,thecurrent macroeconomictechnical indicators of aggregates are not perfect. We should study more macroindicators of aggregates, at the same time, pay more attention to the microscopicproperties of aggregates.The subjecttests and analyzes aggregate lithology and microscopic featuresuseby using X-ray diffraction, SEM and EDS. Aggregates rock samples were selectedfrom three main aggregates underside layer the308project of the small Hexi toShangdu highway in Inner Mongolia, which are the tectonic breccia, sodium quartzdiorite and basalt. The subject gets the technical indicators macroeconomic of theaggregates in strict accordance with the aggregate crushing value, Los Angelesabrasion value, sand equivalent, methylene blue value, angularity, and asphaltadhesion testing and other technical indicators in specification. When researchingasphalt roadproperties, we are based on the engineering design of the optimummixture ratio, to test and analyze asphalt technical indicators which are composed ofthe three kinds of aggregates. We use XRD mainly to obtain X-ray diffraction patterns of rock samples crystal,then use the XRD data processing software to analyze mineral composition, massfraction, crystallinity and crystallite size of the rock samples. By contrast with themacro technical specifications of aggregates, we discussed the corresponding relationsbetweenaggregate rock mineral composition, structure, construction and Aggregatemacro road use indicators.By using SEM, wemainly analysis surface microscopic characteristics of therock sample, roughness information and adhesion observations. Then we calculateroughness of rock samples by Matlab software. This is the first evaluation of asphaltand aggregate adhesion level by quantitative methods. By Matlab software wetransformatefrom Grayscale images in SEM to digital and quantitativly calculate thesurface roughness of aggregate. By measuring the roughness, we discussed thecorresponding relations between aggregate microscopic characteristics and asphaltpavement performance.We found the nature of feldspar in the aggregates can reflect the crushed value ofthe rock, crystallite size and wear value are anti-correlation, the crystallite is larger,wear value is smaller, the aggregate are more wearable. And, we found the roughnesscan be evaluated the impact on asphalt mixture performance thaw splitting resistanceto water damage which is water stability from the aggregate. Therefore, the roughnessis as the micro indicators to evaluate water stability of asphalt mixture.