Coarse Graded High Modulus Asphalt Concrete with Skeleton Embedded Structure
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Solution Overview
Problem
Current design methods for high modulus asphalt concrete are not applicable to coarse grain aggregates with nominal sizes greater than 19 mm, failing to provide adequate high temperature stability and bearing capacity for heavy traffic and long-life pavement designs, especially for middle and lower layers.
Innovation Solution
A method for determining the composition of coarse graded high modulus asphalt concrete with a skeleton embedded structure, using low labeled hard asphalt and specific aggregate gradation, and optimizing the oil-stone ratio to enhance high temperature stability and bearing capacity, resulting in a mixture with 50% higher strength and 30% higher dynamic complex modulus than standard mixes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous gradation and higher binder dosage are used to increase mix modulus, then high temperature stability is improved, but air void ratio becomes too low and bearing capacity for heavy traffic is insufficient
Solution Approach 1:
The patent divides the aggregate into three distinct size ranges (coarse aggregate 19-31.5mm, medium aggregate 9.5-19mm, fine aggregate 4.75-9.5mm) with specific gradation requirements. This segmentation creates a skeleton embedded structure where coarse aggregates form the load-bearing framework, medium aggregates fill voids, and fine aggregates complete the packing, achieving optimal air void ratio (3-5%) and bearing capacity for heavy traffic while maintaining high temperature stability.
2Strength
If low penetration asphalt is used to improve high temperature stability, then modulus value increases, but the design method is not applicable to coarse grain aggregates with nominal size greater than 19mm
Solution Approach 1:
The patent changes the key parameter of aggregate nominal maximum size from the conventional limit of 19mm to 26.5mm or 31.5mm, enabling the design method to accommodate coarse grain aggregates. This parameter change is accompanied by adjusted gradation requirements and oil-stone ratio ranges (4.5-6.0%) that are specifically optimized for coarse graded mixes, making the design method versatile for both heavy traffic and long-life pavement applications while maintaining high modulus values through low penetration asphalt (penetration 20-40).
3Strength
If higher binder dosage is used to improve compactness and fatigue resistance, then high temperature stability is improved, but project cost increases
Solution Approach 1:
The patent optimizes the oil-stone ratio parameter to a specific range of 4.5-6.0%, which is lower than conventional designs. This parameter change achieves cost reduction by reducing binder consumption while maintaining fatigue resistance and compactness through the skeleton embedded structure created by the optimized aggregate gradation, where coarse aggregates (40-50% by weight) provide the load-bearing framework.
4Strength
If conventional design method is used for high modulus asphalt concrete, then high temperature stability is improved, but bearing capacity for heavy traffic and long-life pavement is insufficient
Solution Approach 1:
The patent creates a composite skeleton embedded structure by combining three different aggregate size ranges with specific gradation requirements. Coarse aggregates (19-31.5mm) form the primary load-bearing skeleton, medium aggregates (9.5-19mm) fill intermediate voids, and fine aggregates (4.75-9.5mm) complete the packing. This composite structure simultaneously achieves high bearing capacity for heavy traffic and high temperature stability, overcoming the limitations of conventional single-gradation designs.
Data Source
AI summary
The invention relates to mix composition determination method of coarse graded high modulus asphalt concrete with skeleton embedded structure, which belongs to the road engineering design field. The invention use low labeled hard asphalt AH-30# with penetration degree no greater than 30 (0.1 mm); the nominal maximum aggregate size no smaller than 26.5 mm; building mineral aggregate gradation of the mix using course aggregate gap gradation; using gradation design method of asphalt mixture based on closest compact condition to select the optimal oil-stone ratio.