Fiber-Reinforced Tack Coat for Trackless Roadway Renovation
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Solution Overview
Problem
Existing pavement renovation methods are costly, inefficient, and result in poor bonding between layers due to residual bitumen adhering to construction machinery and soiling, while conventional tack coats using 'clean' bitumen emulsions compromise bonding quality, especially in cold weather.
Innovation Solution
A method involving a single-pass application of a 'clean' bitumen emulsion tack coat, followed by a fibre layer, and a 'clean' bitumen emulsion surface coat, with the residual binder having low penetrability and high softening point, eliminating the need for a protective gravel coat and allowing immediate application of bituminous asphalt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective gravel coat is applied over the membrane, then the membrane is protected from construction machine traffic, but the bonding quality between asphalt coat and membrane deteriorates
Solution Approach 1:
The patent removes the protective gravel coat from the construction process. By eliminating this intermediate layer, the membrane remains directly exposed to allow optimal bonding between the asphalt coat and membrane, while the membrane itself is designed to withstand the traffic of construction machines without requiring gravel protection.
2Manufacturing precision
If soft bitumen emulsion is used for tack coat, then bonding between layers is improved, but the residual binder adheres to machine tyres causing soiling and bonding deterioration
Solution Approach 1:
The patent modifies the physical-chemical parameters of the bitumen emulsion by using harder bitumen with specific penetrability (5-40 dmm) and softening point (50-100°C) characteristics. This parameter change allows the emulsion to provide adequate bonding between layers while the harder residual binder does not adhere to machine tyres, eliminating soiling problems.
3Reliability
If multiple coats and protective layers are applied, then pavement durability is improved, but the renovation process becomes complex and time-consuming
Solution Approach 1:
The patent combines multiple functions into a simplified process: the membrane provides both crack prevention and structural reinforcement, the hard bitumen emulsion provides both bonding and tyre-protection properties, and the fibres provide both reinforcement and surface stabilization. This merging of functions reduces the number of separate operations needed while maintaining pavement durability.
4Object-generated harmful factors
If hard bitumen emulsion is used, then tyre adhesion is reduced (clean/trackless), but bonding quality may deteriorate
Solution Approach 1:
The patent optimizes the bitumen emulsion parameters within a specific range: penetrability of 5-40 dmm and softening point of 50-100°C. This parameter optimization ensures the emulsion is hard enough to be trackless and resist tyre adhesion, while still maintaining sufficient bonding capability between pavement layers through proper formulation and application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances bonding, reduces material usage, simplifies implementation, and enables faster road reopening by preventing residual bitumen from adhering to machinery and soiling, while maintaining effective layer adhesion even in cold weather.
Implementation Method 1
tack coats consisted of bitumen emulsions are used to ensure bonding between the layers of a pavement structure
Implementation Method 2
a second coat of fibres, then a third bituminous coat called the surface coat are spread in a single passage of a spreading machine
Data Source
AI summary
In a method for renovating a roadway, a first tack coat including a bitumen emulsion, a second coat of fibres and then a third surface coat that is a “clean” bitumen emulsion or includes an anhydrous asphalt binder, is spread by a spreading machine from bottom to top and overlaid on the milled or planed roadway. The fibres are sprayed onto the tack coat and the sprayed fibres having a maximum length of 12 cm, an asphalt mix being subsequently spread over the surface coat, the residual binder of the “clean” bitumen emulsion having a penetrability of less than 40 dmm and a ball-ring temperature greater than 50° C., the ‘clean’ bitumen emulsion including between 30% and 70% bitumen, between 30% and 70% water, and between 0.1% and 10% surfactants, stabilisers and/or additives, the percentages being by weight. The application also relates to a spreading machine.