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Performance Specifications Implementation Guide

Description:

Many public transportation agencies are in the process of implementing some type of performance specifications for asphalt mix and concrete. Reasons for doing so include a desire to improve long-term durability, encourage contractor innovation, better align design requirements with construction, and to have rational pay adjustments tied to predicted project life.

Ongoing initiatives such as balanced mix designs for asphalt mixes and performance engineered concrete mixes lend themselves to a performance specification approach by introducing higher level test methods that are intended to be more directly related to material performance than current methods. Introduction of these test methods and mix design criteria will have a major impact on existing quality assurance programs. Agencies will need to make informed decisions regarding applicability of new tests to process control, quality control, and/or acceptance. Lot and sublot sizes may need to be adjusted to account for test time and complexity. Quantity of material obtained for testing may need to be increased. Technician training and certification programs will need to be addressed, as will laboratory qualification/accreditation programs. Independent assurance procedures will need to be developed, and the impact on dispute resolution programs must be assessed. Precision and bias of the newer test methods will need to be determined, along with appropriate specification limits for various quality characteristics. New approaches to pay adjustments will need to be developed.

Agencies will benefit from a performance specification implementation guide for asphalt and concrete. The transition from current QA practices which often rely on properties such as aggregate gradation or mixture volumetrics to performance-related criteria will be challenging, and will introduce new risks for DOTs and contractors. Understanding the impact on performance-related testing on the core elements of quality assurance will help this transition to occur in a controlled fashion, and could help minimize risk to both parties during the implementation process.

Objective:

Develop a guide to assist public transportation agencies with implementation of performance specifications for asphalt and concrete materials.

Benefits:

Performance specifications have the potential to dramatically improve the long-term durability of pavements and structures. Even a small increase in project life would result in millions of dollars in annual savings for state DOTs. Guidance on proper implementation of performance specifications could help avoid early failures which could slow or prevent implementation, and could help minimize risk to DOTs and contractors.

Related Research:

There have been several recent studies related to this subject. NCHRP Synthesis “Performance Specifications for Asphalt Mixtures” documents the current state of practice with regards to performance tests used in conjunction with volumetric properties for asphalt mixtures. One of the suggestions for future research identified by the authors is “Guidance to agencies and contractors on how to successfully implement the use of [Performance-Based Specifications] for asphalt mixtures.” This proposed research would help achieve this goal.

The SHRP2 report “Strategies for Implementing Performance Specifications: Guide for Executives and Project Managers” provides excellent guidance on high-level implementation strategies considering organizational, cultural, legal, and project delivery considerations. It identifies areas for agencies to consider regarding sampling, testing, and acceptance/payment, but does not drill down to provide guidance on these issues.

McCarthy, Leslie Myers; Callans, Jonathan; Quigley, Robert; Scott III, Sidney V.: “Performance Specifications for Asphalt Mixtures” - Transportation Research Board, NCHRP Synthesis 492, 2016.

Scott III, Sidney; Konrath, Linda; Ferragut, Ted; Loulakis, Michael C.: “Strategies for Implementing Performance Specifications: Guide for Executives and Project Managers” - SHRP2 Report S2-R07-RR-2, 2014.

Scott III, Sidney; Konrath, Linda; Ferragut, Ted; Anderson, Stuart; Damnjanovic, Ivan; Huber, Gerald; Katsafansa, Jim; McGhee, Kevin; Sprinkel, Michael; Ozyildirim, Celik; Diefenderfer, Brian; Merritt, David; Dawood, Dan; Molenaar, Keith; Loulakis, Michael C; White, David; Schaeffer, Vernon R.: “Performance Specifications for Rapid Highway Renewal” - Transportation Research Board, SHRP2 Report S2-R07-RR-1, 2014.

Each of the studies referenced below provide information regarding test methods, quality control and acceptance procedures, and recommended specifications, but none of them provide guidance on implementing performance specifications while considering all the core elements of a quality assurance program.

Smith, D.; Lee, S.B.; Kazmierowski, T.: “Development of Performance Specifications for Flexible Pavements in Ontario” - Proceedings of the Sixtieth Annual Conference of the Canadian Technical Asphalt Association, 2016.

Grobler, J.; Rebbechi, J.; Denneman, E.: “National performance-based asphalt specification framework” - Austroads Project APT1953, 2018.

“Report on Performance-Based Requirements for Concrete” – American Concrete Institute, 2015.

Tasks:

Task 1 – Literature review.

Task 2 – Provide clear, consistent definition of terms related to performance specifications.

Task 3 – Identify existing test methods and mix design procedures that are likely to be included in performance specifications for asphalt and concrete.

Task 4 – Determine the impact of implementing these tests and procedures on DOT QA programs, including: technician training and certification; laboratory accreditation; Lot and sublot sizes; material sample sizes; turnaround time for test results; cost of testing; applicability of various tests for design approval, process control, quality control, acceptance; IA procedures; dispute resolution process.

Task 5 – Develop guidance for agencies to use during implementation of performance specifications. Include guidance on setting up pilot projects/shadow specifications, setting appropriate control and specification limits, and suggest ways to gain buy-in from agency and industry personnel.

Task – Publish the final guide as an AASHTO recommended practice.

Implementation:

Implementation of the guide will be accomplished through presentations at the AASHTO Committee on Materials and Pavements, adoption as an AASHTO recommended practice, and through presentation at various regional and national meetings and conferences, including the TRB annual meeting. Challenges will include aversion to the real or perceived risks by both agencies and contractors, lack of trained personnel, and cost of associated equipment, training and specification development. Inconsistent terminology related to QA and performance specifications will present challenges by inhibiting effective communication at the national level.

Relevance:

This project would be suitable for NCHRP funding. It may be suitable for PhD research, but the research team would need familiarity with the current state of practice for public agency quality assurance practices, requirements of Title 23 CFR 637, and have contacts at state transportation departments.

Sponsoring Committee:AFH20, Quality Assurance Management
Research Period:12 - 24 months
Research Priority:High
RNS Developer:Richard Bradbury, Director of Materials Testing and Exploration, Maine Department of Transportation
Source Info:Members of AFH20; the AASHTO COMP technical subcommittee on Quality Assurance and Environmental.
Date Posted:10/10/2018
Date Modified:12/31/2018
Index Terms:Performance based specifications, Asphalt mixtures, Admixtures, Mix design, Quality assurance, Concrete tests, Asphalt tests,
Cosponsoring Committees: 
Subjects    
Highways
Construction
Materials
Pavements
Bridges and other structures

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