|Project Name:||Fundamental Properties of Asphalts and Modified Asphalts III|
Office of Infrastructure Research and Development |
|Team:||Pavement Materials Team|
Infrastructure Research and Technology Strategic Plan and Roadmap|
|Project Description:||Identify, initiate, and complete fundamental research on conventional and modified binders. Material characterization: (1) Understand, predict, and prevent moisture susceptibility.(2) Develop procedures, tests, and models that can accurately predict long-term pavement performance.(3) Understand asphalt composition and its relationship to pavement performance.(4) Construct and monitor pavement validation sites akin to the Strategic Highway Research Program (SHRP) specific pavement studies (SPS) six sites.|
|Start Date:||January 9, 2007|
|End Date:||July 8, 2013|
Research addresses five focus areas:
This work has subsequently been repackaged in the following four areas:
|Background Information:||Moisture damage is considered to be a widespread form of pavement damage. The effects of moisture on asphalt pavements include fatigue damage, rutting, physical hardening, and aging. Consequently, progress in understanding, predicting, or preventing moisture susceptibility will aid in establishing longer lasting, less expensive roadways. Several issues are considered within the reclaimed asphalt pavement/warm-mix asphalt (RAP/WMA) research that may largely impact the long-term performance of reclaimed asphalt pavement (RAP) and warm-mix asphalt (WMA). These include:The chemical and rheological compatibility of asphalt binders obtained from reclaimed asphalt pavement (RAP) (pavements) and reclaimed asphalt shingles (RAS) with fresh asphalt and the impact of using cooler WMA production temperatures.The suitability of RAP binders for multiple recycling.The impact of lower WMA temperatures on asphalt oxidation.The level of water found in various WMA mixtures. The accuracy of, and possible improvement to, the global aging system is being studied at the Western Research Institute (WRI) by analyses of data and materials obtained from the Federal Highway Administration's Accelerated Loading Facility and WRI validation sites.|
|Test Methodology:||Evaluating how the chemistry affects physical response and its ultimate field performance. Various chemical, thermal, spectroscopic, and chromatographic techniques are being used. Developing and evaluating methods for determining the suitability of Reclaimed Asphalt Pavement (RAP) binders for multiple recycling and the impact of warm-mix asphalt (WMA) additives and RAP rejuvenators on performance. The chemical compatibility issue will be studied using automatic flocculation titrimetry, Corbett selective adsorption/desorption, and the Asphaltene Determinator. Physical measurements will be conducted with dynamic shear rheometry.|
|Fieldtest:||Six validation sites are located in the United States and Canada, as well as the Turner-Fairbank Highway Research Center Pavement Testing Facility. Within each site, nearly identical sections were placed where the only difference was the asphalt binder or type of warm-mix asphalt (WMA) application.|
|Expected Benefits:||The expected benefits for a number of the new test procedures are new capabilities, reduced lab technician times per test, lower analytical lab costs, and more accurate assessment of pavement aging.|
|Deliverables:||1. Name: (1) Rapid and microbinder characterization test methods and specifications.
(2) Draft American Association of State Highway and Transportation Officials and American Society for Testing and Materials test method for using 4-mm parallel plate rheology.
(3) Microextraction and analysis methodology.|
Product Type(s): Research report, Draft standard, specifications, or guidelines, Article, Data
Description: This methodology allows low-temperature mechanical properties of binders to be accurately measured using the Dynamic Shear Rheometer (DSR). DSR tests can now be conducted at low temperatures with approximately 25 milligrams of sample per test, about 500 times smaller than needed for current Bending Beam Rheometer (BBR) testing. This reduction in the sample size leads to many applications that previously were expensive, time consuming, impractical, or impossible. This procedure couples rapid drilling and sampling with small-scale extraction and spectroscopic analysis to estimate aging severity of pavement as a function of depth. The procedure offers an alternative to coring and large-scale extraction where time, traffic control, or cosmetic concerns preclude using traditional methods.
2. Name: Asphalt Oxidation Model and Tools for Monitoring Asphalt Oxidation. Asphaltene Determinator Asphalt Aging Index Ratio (ADAIR): Chromatographic method to track oxidative aging. Rapid infrared procedure for estimating pavement oxidation levels with depth. Inputs to Mechanistic–Empirical Pavement Design Guide (MEPDG) environmental model.
Product Type(s): Research report, Draft standard, specifications, or guidelines, Data, Article
Description: The Asphaltene Determinator (AD) is a methodology developed to separate asphaltenes (the components of asphalt that provide its structure and “skeleton” resulting in good high-temperature performance) into solvent-defined fractions. For asphalt applications, the AD appears to provide a reliable measure of aging severity. For asphalt blenders and users, this system can identify thermally degraded asphalts and air blown asphalts.
3. Name: Reclaimed Asphalt Pavement (RAP)/Warm-Mix Asphalt (WMA). Method for evaluating suitability of RAP binder for recycling. Guideline for appropriate RAP selection. Method for predicting effects of blending RAP or WMA additives with new binders.
Product Type(s): Research report, Data, Draft standard, specifications, or guidelines, Article
Description: Reports and guidelines for improving asphalt sustainability.
4. Name: Modified Karl Fischer Test. Method for assessing moisture content in warm-mix asphalt.
Product Type(s): Research report, Draft standard, specifications, or guidelines, Data
Description: Analytical method to quantitatively measure low levels of water in binders and asphalt mixtures.
|Project Findings:||MoistureDeveloped small-scale separation methods to expand knowledge of molecular components that may be contributors to moisture-related premature roadway failures.Karl Fischer titration technique appears to be the most profitable approach of the various methods tried for ascertaining moisture content of asphalt binders.RapidDeveloped rheological instrumental technique for evaluating small quantities of binder at both high and low temperatures. This approach (4-mm parallel plate) has been found useful in characterizing asphalt emulsions.Developing methods for using Atomic Force Microscopy as a nano-rheometer. At present the nano-rheometer is capable of determining the rheological phase angle but not the moduli.Reclaimed Asphalt Pavement (RAP)/Warm-Mix Asphalt (WMA)Monitored existing validation sites (constructed under previous contract) and found significant differences in performance. OxidationDeveloped and validated rapid procedure for estimating pavement oxidation levels with depth using infrared spectroscopy on minute samplesDeveloped and applied Asphaltene Determinator Asphalt Aging Index Ratio (ADAIR) to track oxidative aging.|
Warm Mix Paving Mixtures
Reclaimed Asphalt Pavements
Reclaimed Asphalt Pavement
Maintenance and Preservation|