Dual-Layer Asphalt Paving with Self-Compacting Mixture
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Solution Overview
Problem
Existing asphalt construction methods face challenges in achieving sufficient compaction, especially under adverse weather conditions, leading to issues like bumps and surface deformation due to the use of rolled asphalt, and mastic asphalt's inability to form a suitable road surface layer without gritting and post-compaction.
Innovation Solution
A method using an asphalt mixture with a high chippings content, sand, filler, and binder, where the chippings are between 55% to 80% by mass, sand between 6% to 20% by mass, and filler between 12% to 23% by mass, allowing for pre-compaction without post-rolling, and using a road finisher with two screeds or a combination of finishers to produce a self-compacting two-layer asphalt structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rolled asphalt is used for asphalt constructions, then the method can be applied to all asphalt construction types, but sufficient compaction cannot be achieved under adverse weather conditions leading to bumps and surface deformation
Solution Approach 1:
The patent modifies the physical parameters of the asphalt mixture by adjusting the grain size distribution (increasing fine aggregates and fillers to achieve a sand-equivalent value of at least 70), binder content (4.5-6.7%), and maximum grain size (up to 32mm). These parameter changes enable the mixture to achieve self-compaction properties that maintain manufacturing precision across different weather conditions while preserving versatility in construction types.
2Ease of operation
If mastic asphalt is used for road surface layers, then good installation properties are achieved, but gritting and post-compaction are required which increases construction time and cost
Solution Approach 1:
The patent creates a self-service system where the asphalt mixture inherently possesses the properties needed for final compaction and surface quality. The optimized grain distribution and binder content enable the mixture to self-compact to at least 97% density during placement, eliminating the need for additional gritting and post-compaction operations that would otherwise be required for mastic asphalt.
3Ease of manufacture
If high chippings content is used in asphalt mixture, then grit-rich non-slip surface is formed, but compaction becomes difficult and bumps occur
Solution Approach 1:
The patent applies local quality by creating different functional zones within the asphalt mixture: a surface layer with high chippings content (35-80%) providing grip, and an underlying structure with optimized sand-equivalent value (at least 70) ensuring compaction. This spatial differentiation of properties allows the surface to be grit-rich and non-slip while the bulk material maintains compaction capability and surface flatness.
Data Source
AI summary
The invention proposes a method for solving the problem of producing an at least dual-layered asphalt structure that can also be installed cost-effectively and in adverse weather conditions. In such a method, this at least dual-layered asphalt structure comprises at least one lower layer and one upper layer produced using a road paver that has at least two screeds arranged one behind the other, or using a road paver combination of at least two road pavers arranged one behind the other. For the at least one lower layer, an asphalt mix is used which comprises stone chippings, sand, filler, and binder, with a chipping content having an aggregate of > 2 mm between approximately 55 m.% and approximately 80 m.%, a sand content of natural and/or crushed sand having a grain size of > 0.063 mm and <= 2 mm between approximately 6 m.% and approximately 20 m.%, a filler content having an aggregate of <= 0.063 mm between approximately 10 m.% and approximately 25 m.%, and a binder content in a range of between approximately 4.5 m.% and approximately 6.7 m.%, the total mass of the asphalt mix, including any further additives, amounting to 100 m.%, and the asphalt mix for the at least one lower layer having a maximum grain size of up to approximately 32 mm.