Lime Pellets with Asphalt Binder for Dust Control
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Solution Overview
Problem
The use of lime fines in asphalt manufacturing poses health hazards due to airborne particulates and environmental concerns from contamination, and they cause equipment wear and handling difficulties due to their fine nature.
Innovation Solution
Lime pellets are created by binding lime fines with an asphalt-compatible binder, forming a rigid structure that is dissolvable in liquid asphalt, preventing airborne issues and improving handling and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lime fines are used to improve asphalt pavement durability, then bonding between aggregate and asphalt cement is enhanced, but airborne particulates cause health hazards and equipment wear
Solution Approach 1:
The patent encapsulates lime fines within a binder matrix forming a pellet structure. This shell-like encapsulation prevents lime fines from becoming airborne while allowing controlled release of lime particles during asphalt mixing, thus maintaining pavement durability benefits while eliminating health hazards and equipment wear from airborne particulates.
Solution Approach 2:
The patent changes the physical state of lime from fine powder to pelleted form by controlling particle size, binder content, and pellet density. This parameter transformation maintains the chemical reactivity of lime for improving asphalt-aggregate bonding while physically containing the particulates that cause health and equipment problems.
2Reliability
If lime fines are added in bulk to hot mix asphalt ingredients, then anti-strip characteristics are improved, but accurate measurement and control of lime amount becomes difficult
Solution Approach 1:
The patent divides bulk lime fines into discrete, uniformly sized pellets with consistent weight and composition. This segmentation enables precise measurement and dosing of lime content in asphalt mixes, while each pellet maintains the necessary lime concentration to provide anti-strip characteristics when dispersed in the hot mix asphalt.
Solution Approach 2:
The patent replaces the mechanical challenge of measuring and controlling bulk powder lime with a simplified system where pre-portioned pellets are used. This substitution eliminates the need for complex dust-free weighing systems while maintaining accurate lime dosing for anti-strip performance.
3Ease of operation
If lime fines are transported and handled in powder form, then they can be easily distributed, but they become airborne and contaminate the environment and groundwater
Solution Approach 1:
The binder matrix acts as a containing shell that prevents lime fines from escaping during handling and transportation. This encapsulation eliminates environmental contamination from airborne particulates and groundwater leaching, while the pellets remain easy to distribute using standard conveying and dosing equipment.
Solution Approach 2:
The patent creates a composite material combining lime fines with a binder to form pellets. This composite structure provides the distribution ease of solid particles while eliminating the environmental hazards of loose powder, and the binder ensures controlled release of lime during asphalt mixing for effective anti-strip performance.
4Reliability
If small particulate lime fines are used, then they can penetrate and bond with asphalt cement, but they cause excessive wear and fatigue in equipment
Solution Approach 1:
The binder serves as an intermediary carrier that delivers lime fines to the asphalt mix in a controlled manner. The pellets break down during mixing, releasing lime particles that bond with asphalt-aggregate interfaces, while the binder protects equipment from direct contact with abrasive lime particles, reducing wear and fatigue.
Solution Approach 2:
The patent changes the delivery form of lime from loose fine particles to encapsulated pellets. This parameter change allows the lime to maintain its small particle size for effective bonding with asphalt cement while the pellet structure prevents direct contact with equipment surfaces, thereby reducing mechanical wear.
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
The lime pellets enhance asphalt pavement durability, reduce health risks, and minimize environmental impact by preventing particulate contamination and equipment damage, while maintaining effective binding properties.
Implementation Method 1
The binder is mixed with the lime in an amount and disposition sufficient to form a pellet
Implementation Method 2
the pellet is compatible with a hot mix asphalt and/or asphalt cement and dissolvable in liquid asphalt
Data Source
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AI summary
A lime pellet for use in asphalt applications can include lime fines and an asphalt-compatible binder. The pellet is characterized as having a rigid structure with a dimension greater than about 1.5 mm and being compatible with a hot mix asphalt so as to dissolve in liquid asphalt. Optionally, the binder is characterized by having less than about 50% by weight of total binder being sulfur, or the pellet is characterized by having lime in an amount of at least 31% by weight, or being storage-stable and agglomeration resistant. The pellet is manufactured by mixing the lime fines with the asphalt-compatible binder and forming pellets therefrom. The pellets are useful for conditioning an end product of hot mix asphalt during the manufacture of such an asphalt. The method of conditioning includes providing the lime pellet, and mixing the lime pellet with a hot mix asphalt ingredient, wherein the ingredient is at least one of an aggregate or asphalt cement. Additionally, the lime pellets can be used for bonding a first asphalt layer with a second asphalt layer by being deposited therebetween.