Hot Applied Polymer Tack Coat Pavement Bonding
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Solution Overview
Problem
The high cost and requirement of specialized machinery for the NOVACHIP bonded friction course system make it impractical for many contractors and agencies, while conventional thick emulsified polymer modified tack coats have slow cure rates and tracking issues, leading to adhesion problems and pavement failures.
Innovation Solution
A hot-applied, polymer modified tack coat that is non-adhesive at ambient temperatures but becomes adhesive at higher temperatures, allowing for application with conventional equipment and forming a strong bond with hot mix asphalt layers without tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick layer of emulsified polymer modified tack coat is used to improve adhesion, then bonding strength between layers is improved, but the cure rate becomes very slow and tracking occurs
Solution Approach 1:
The patent changes the temperature parameter of the tack coat from ambient to hot application conditions. This parameter change fundamentally alters the material properties: at high temperatures, the polymer modified asphalt becomes more fluid and adhesive, enabling rapid bonding. As it cools, it becomes less adhesive and prevents tracking, thus resolving the contradiction between achieving strong adhesion and preventing tracking delays
Solution Approach 2:
The patent utilizes the phase transition of the polymer modified tack coat material between hot and ambient states. When applied hot, the material transitions to a more fluid, adhesive phase that bonds rapidly with the new HMA layer. Upon cooling to ambient temperature, it transitions to a less adhesive phase that prevents tracking, thereby eliminating both slow cure rates and tracking issues
2Strength
If a thick layer of emulsified polymer modified tack coat is used to improve adhesion, then bonding strength between layers is improved, but tracking occurs that reduces effectiveness
Solution Approach 1:
The patent changes the temperature parameter to resolve the tracking problem. By applying the tack coat hot and allowing it to cool, the material's adhesive properties are temporally controlled: high adhesion during the bonding phase, then reduced adhesion during the cooling phase to prevent tracking. This eliminates the harmful tracking effect while maintaining strong bonding
Solution Approach 2:
The patent performs the bonding action preliminarily while the tack coat is still hot and highly adhesive. The new HMA layer is placed immediately after hot tack coat application, ensuring strong adhesion is achieved before the material cools and becomes non-tracking. This timing strategy ensures bonding effectiveness is secured before tracking can occur
3Strength
If a specialized Spray Paver machine is used to apply thick polymer modified tack coat, then bonding strength and crack sealing are improved, but equipment cost becomes prohibitively expensive
Solution Approach 1:
The patent makes the tack coat material and application process universal by using conventional hot mix asphalt paving equipment that is already widely available in the industry. The polymer modified tack coat can be applied with standard hot mix asphalt distributors and pavers, eliminating the need for specialized Spray Paver machines. This universality maintains strong bonding performance while dramatically reducing equipment costs and complexity
Solution Approach 2:
The patent replaces the expensive, specialized Spray Paver machine with conventional, widely-available hot mix asphalt paving equipment. By using standard industry equipment that contractors already possess or can easily rent, the patent eliminates the need for costly specialized machinery while achieving the same bonding and crack sealing performance through the hot application method
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
This solution eliminates the need for specialized machinery, provides improved strength and flexibility in pavement structures, and reduces the risk of premature deterioration and damage from pavement separation.
Implementation Method 1
The polymer modified tack coat is heated until it is liquid and sprayable
Implementation Method 2
The heat of the HMA layer causes the tack coat to liquefy
Implementation Method 3
The tack coat wicks into the new gap graded mix by displacement and water vaporization
Implementation Method 4
The tack coat wicks into the new gap graded mix by displacement and water vaporization
Data Source
AI summary
A method of applying building a pavement structure using a polymer modified hot-applied tack coat is disclosed. This polymer modified tack coat is non-adhesive at ambient temperatures, and, thus, also non tracking. The tack is applied while hot, but cools quickly. The subsequent application of hot mix asphalt results in a superior bond between the asphalt layer and the tack layer. It is particularly well suited to bonded friction course applications since it removes the necessity of specialized spray paving machinery and allows the use of conventional asphalt distributors and pavers.