A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Aggregate is one of the major components in the asphalt mixture system whose properties and packing characteristics have significant impact on the stability, durability and field performance of the asphalt mixtures. Current Superpave mix design method selects aggregate gradations mainly based on maximum density line and a few control points which is a trial-and-error process and is costly and time-consuming. Most importantly, the quality and the mechanical performance of the mixtures are not warrant when designed purely based on volumetrics. Some recent studies have been conducted to improve the gradation design methods and attempt to correlate aggregate gradation design with performance. However, there is still not a systematic approach that can be practically used by the State of Washington to guide gradation design and evaluation to achieve better performing mixes. This study conducted a comprehensive analysis of aggregate packing characteristics and the degree of aggregate contact and interlocking based on packing theories and discrete element modeling simulation. Dense graded aggregate gradations were first categorized into three types, coarse-graded, medium-graded, and fine-graded. Gradations within each type are found to share similar packing characteristics and can use the same set of parameters to estimate the volumetric properties (VMA). Experimental tests were conducted to evaluate the impact of aggregate gradations (both individual size impact and the overall gradation impact) on dynamic modulus, compactability, and rutting resistance of the mixtures. A modified Hirsch model was proposed to be used as both a designing tool and a screening tool to estimate the mixture's dynamic modulus at the early stage of the mix design. The pavement performance can be determined by integrating the dynamic modulus information into the mechanistic-empirical pavement design guide (MDPDG) program and the results can be utilized to guide the mix design adjustment. By establishing the correlations between aggregate gradation, volumetric properties, and the mechanical properties (dynamic modulus), this study developed a method and guideline on adjusting aggregate gradations to achieve better long-term field performance.
Aggregate is one of the major components in the asphalt mixture system whose properties and packing characteristics have significant impact on the stability, durability and field performance of the asphalt mixtures. Current Superpave mix design method selects aggregate gradations mainly based on maximum density line and a few control points which is a trial-and-error process and is costly and time-consuming. Most importantly, the quality and the mechanical performance of the mixtures are not warrant when designed purely based on volumetrics. Some recent studies have been conducted to improve the gradation design methods and attempt to correlate aggregate gradation design with performance. However, there is still not a systematic approach that can be practically used by the State of Washington to guide gradation design and evaluation to achieve better performing mixes. This study conducted a comprehensive analysis of aggregate packing characteristics and the degree of aggregate contact and interlocking based on packing theories and discrete element modeling simulation. Dense graded aggregate gradations were first categorized into three types, coarse-graded, medium-graded, and fine-graded. Gradations within each type are found to share similar packing characteristics and can use the same set of parameters to estimate the volumetric properties (VMA). Experimental tests were conducted to evaluate the impact of aggregate gradations (both individual size impact and the overall gradation impact) on dynamic modulus, compactability, and rutting resistance of the mixtures. A modified Hirsch model was proposed to be used as both a designing tool and a screening tool to estimate the mixture's dynamic modulus at the early stage of the mix design. The pavement performance can be determined by integrating the dynamic modulus information into the mechanistic-empirical pavement design guide (MDPDG) program and the results can be utilized to guide the mix design adjustment. By establishing the correlations between aggregate gradation, volumetric properties, and the mechanical properties (dynamic modulus), this study developed a method and guideline on adjusting aggregate gradations to achieve better long-term field performance.
Performance Based Aggregate Gradation Design and Evaluation Method for Washington Asphalt Mixtures
2011
140 pages
Report
No indication
English
Construction Equipment, Materials, & Supplies , Highway Engineering , Construction Materials, Components, & Equipment , Aggregate gradations , Asphalt mixture systems , Volumetric properties , Mechanical performance , Design guidelines , Recommendations , Figures , Tables (Data) , Packing theories , Literature reviews , Design methods , Packing characteristics , Discrete element modeling simulations
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