Background of the Emulsion Task Force
Pavement Preservation gained national importance in 1991 with the passage of the Intermodal Surface Transportation Efficiency Act (ISTEA) that gave state and local governments more flexibility in determining highway transportation solutions and management systems to guide them in making the best choices. The Act mandated each state to have a Pavement Management Program. Pavement preservation is a critical element in cost-effectively managing pavement assets by using treatments that retard pavement deterioration and extend pavement lives when applied to the right pavements at the right time. Prior to the enactment of ISTEA, Federal funding for state DOTs could only be used for building new roads or reconstructing roads in a poor or failed condition. In 2004, pavement maintenance was made eligible to use Federal funding for the first time. However, the DOTs would be required to have Pavement Maintenance Programs to obtain those funds.
In 2009, Moving Ahead for Progress in the 21st Century (MAP-21) Act was passed, and for the first time in a highway bill, pavement preservation was addressed. MAP-21 required state DOTs to: (1) develop performance measures for highway assets (pavements and bridges), and (2) formulate management plans in which highway asset performance is tracked over time. State spending of Federal funds would be linked to highway asset performance. In the case of pavements, this has a game-changing implication because states would not only have to maintain their pavements but also show the resulting performance. To be successful, states will have to employ Preservation Measures as the means of attaining performance goals in a cost effective manner.
The majority of pavement preservation treatments (chip seals, micro surfacing, slurry seals, etc.) are emulsion-based and generally inexpensive when compared with the traditional treatments using hot mix asphalt (HMA). In the past, and until recently, emulsions were not given as much importance and technical support as HMA, which had the support of the National Asphalt Associations, HMA vendors, Academics, and the FHWA. However, in the mid-1990s, recognition of the importance of emulsions began to increase slowly with the support of the FHWA, FP2, NCPP, and asphalt emulsion industry groups (ISSA, AEMA, ARRA) leading to the formation of the Pavement Preservation Expert Task Group (PPETG). In 2008, Jim Sorenson (FHWA) with the cooperation of industry initiated the Emulsion Task Force (ETF).
The ETF comprises representatives of DOTs, Academia and Industry.
A major shortcoming of emulsion technology/treatments was the lack of National Standards available in the AASHTO/ASTM format. It is well known that for a technology to be widely accepted by state and local agencies, National Standards for that technology must be developed and made available.
Beginning in 2015 the ETF moved under the umbrella of the AASHTO Transportation System Preservation-Technical Services Program (TSP·2). In 2023 AASHTO rebranded the TSP2 program as “AASHTO Preservation Management”. The ETF strives to fulfill the tasks:
Task I – Advance the Effort to Develop Performance-Based Methods and Specifications for Emulsions. A goal will be development of Performance-Graded Emulsions.
- Within the ETF, establish a special work group (SWG) to address all the emulsion binder issues.
- Upgrade the existing AASHTO Emulsion Binder Specifications M140, M208, and M316.
- Work to develop an Emulsified Asphalt Performance Grade (EAPG) Specification.
Task II – Encourage Adoption of Uniform National Standards
- Develop AASHTO Standards for Emulsion Treatments (Material Specifications, Design Practices, Construction Guide Specifications) for the following treatments:
- Chip Seal
- Micro Surfacing
- Tack Coat
- Fog Seal
- Slurry Seal
- Scrub Seal
- Sand Seal
- Bonded Surface Treatment (Nova Chip)
- Cold Mixes – Virgin, Recycled, Cold In-place Recycling (CIR)
- The NCHRP Program developed Construction guidelines for Chip Seals and Micro Surfacing through its Project 13-47. NCHRP will be used for construction guide specifications for the other treatments.
Task III – Quality Assurance, Training, and Certification
- A Quality Assurance Program is required to ensure that checks and balances are in place for good performance and a long lasting treatment. Development of QA (Acceptance, Quality Control, and Independent Assurance) protocols are being addressed by an ETF Subcommittee.
- Training and Certification – Proper placement of emulsion treatments depends on good workmanship, i.e., a trained workforce and well maintained, calibrated equipment. Coordination with Industry and AASHTO Resource is ongoing. The following actions are being implemented or planned:
- Training programs for each treatment for all personnel categories are being developed.
- Quality Control plan requirements are being formulated.
- Calibration and equipment performance checklists are being developed.
- Certification of Vendors and Technical Staff is under way.
Task IV – Miscellaneous Specifications, Test Methods, Quality System and Research
This is an all-encompassing area to ensure that emulsion issues not addressed in previous tasks are captured, e.g., emulsion residue recovery methods, future developments in emulsion technologies, and research needs from the Pavement and Bridge Preservation Research Roadmap.