Increasing Crumb Rubber Modifier (CRM) Use
CalAPA 2015 Fall ConferenceChuck Suszko
October 28, 2015
Copyright 2015 California Department of Transportation. All Rights Reserved
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Caltrans has used Rubberized Hot Mix Asphalt (RHMA) for more than 20 years.
Usage of crumb rubber increased as RHMA became commonly used on Caltrans projects.
Caltrans Crumb Rubber Usage
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Rubberized Hot Mix Asphalt Usage
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New Caltrans RHMA policy: RHMA is the pavement surface course of choice when evaluating
alternatives for a project.
Rubberized Hot Mix Asphalt
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In July 2013, Caltrans implemented the use of Performance Graded Modified (PG-M) asphalt binder with minimum 10 percent CRM.
PG-M
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Public Resources Code 42703 requires Caltrans use crumb rubber in asphalt paving materials.
To meet this crumb rubber usage goal Caltrans must continue to seek new ways of using recycled tires in California pavements..
Legislative Mandate
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Caltrans has recently changed its mission statement to include sustainability.
Caltrans goals include both Sustainability and Stewardship.
Increased Crumb Rubber Usage Going Forward
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It is time for an innovative approach for drastically increasing the amount of crumb rubber used in California’s pavements to support these environmental related goals.
Increased Crumb Rubber Usage Going Forward
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The proposed increased use of crumb rubber in pavements is not based on the historical engineering approach of using crumb rubber to improve pavement performance, but instead is based on creating an asphalt binder which has less impacts on the environment.
Increased Crumb Rubber Usage Going Forward
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Caltrans proposal to increase the use of crumb rubber in pavements will be accomplished by a dramatic change that will require all asphalt binder used in California be “Green” asphalt.
A Proposed Alternative For Increasing Crumb Rubber Usage
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This “Green” asphalt proposal would require the use of 5 percent crumb rubber in all asphalt binder that is currently classified as unmodified.
Caltrans Proposed Solution
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Implementation of Performance Graded Asphalt with 5 percent crumb rubber in place of unmodified asphalt binders in California would result in use of 8,300,000 to 10,000,000 tires in asphalt pavement each year.
Estimated Passenger Tire Equivalents Diverted From
Disposal
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For Caltrans an additional 2,300,000 PTE’s could be used by requiring Performance Graded Asphalt with 5 percent crumb rubber.
With PG+5 and Asphalt Rubber Binder (Wet Process) for RHMA, Caltrans would be able to divert 6,800,000 PTEs.
Estimated Additional Passenger Tire Equivalents
(PTEs) Used by Caltrans
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Caltrans could increase PTEs used in pavements by 51 percent which is a dramatic increase in crumb rubber usage.
Estimated Additional Passenger Tire Equivalents
Used by Caltrans
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In March 2015 Caltrans met with industry stakeholders to discuss Caltrans PG+5 proposal and other industry proposed alternatives.
Update on Low Volume of Crumb Rubber in Hot Mix
Asphalt
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March 2015 meeting alternatives:
1. Caltrans PG+52. Caltrans PG+5 with changes3. Dry Process4. Field blend
Update on Low Volume of Crumb Rubber in Hot Mix
Asphalt
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The alternatives will be evaluated in four phases:Phase 1: Laboratory TestingPhase 2: Field Construction
EvaluationPhase 3: Environmental and Life
Cycle Cost AnalysisPhase 4: Specification
Update on Low Volume of Crumb Rubber in Hot Mix Asphalt
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Update on Low Volume of Crumb Rubber in Hot Mix
Asphalt
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This effort will follow the the Rock Products Committee process.
Draft Scoping document for Increasing Crumb Rubber Usage with Small Amounts of CRM in Hot Mix Asphalt.
Update on Low Volume of Crumb Rubber in Hot Mix
Asphalt
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Secure needed research funding.The total estimated research costs for this project is $635,000.
Caltrans is partnering with CalRecycle on funding the research for this project.
Update on Low Volume of Crumb Rubber in Hot Mix Asphalt
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Increasing Crumb Rubber Usage - Small Amounts of CRM in Hot Mix Asphalt scoping document approved on October 09, 2015.
Next step is that the Asphalt Task Group appoint Caltrans and Industry Sub Task Group Co-Chairs.
Update on Low Volume of Crumb Rubber in Hot Mix
Asphalt
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Sub Task Group to evaluate the alternatives in terms of the following factors:
1. Technical2. Environmental3. Economic4. Expected Performance
What next for Low Volume of Crumb Rubber in Hot Mix Asphalt?
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Target TimelineLab Testing (December 2016)Environmental and Life Cycle Analysis (July 2017)
Pilot Projects (October 2017)Specification (April 2018)
What next for Low Volume of Crumb Rubber in Hot Mix Asphalt?
