Case Studies Using Quality Control for Performance and Pay for Performance Specifications: Field Observations

Al-Qadi, Imad L.; Rivera-Perez, José J.; Sayeh, Watheq; García Mainieri, Javier J.; Meidani, Hadi; Huang, John; Ozer, Hasan; Hand, Adam

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https://hdl.handle.net/2142/107721 Copy

Description

Title

Case Studies Using Quality Control for Performance and Pay for Performance Specifications: Field Observations

Author(s)

• Al-Qadi, Imad L.
• Rivera-Perez, José J.
• Sayeh, Watheq
• García Mainieri, Javier J.
• Meidani, Hadi
• Huang, John
• Ozer, Hasan
• Hand, Adam

Issue Date

2020-06

Keyword(s)

• Asphalt Plants
• Asphalt Mixtures
• Hot-Mix Asphalt
• Quality Control
• Statistical Quality Control
• Quality Assurance

Abstract

Quality assurance programs for hot-mix asphalt (HMA) have evolved from method to quality assurance specifications that distribute responsibilities and risks between contractors and owners. The Illinois Department of Transportation developed two acceptance specifications, quality control for performance (QCP) and pay for performance (PFP), integrating contractor pay incentives and/or disincentives associated with air voids, voids in mineral aggregate, and in-place density limits. During 2015 to 2016, approximately 55% and 44% of QCP and PFP HMA tonnage production was paid with disincentives. The objective of this project was to understand the potential root causes of pay disincentives and test result variability in QCP and PFP contracts. Eleven contracts were visited during the 2018 construction season, and data of the observation results were analyzed. During the site visits, HMA sampling, coring, and testing procedures were observed and documented by the research team. Later, sublot test results, pay factors, datalogger outputs, and round robin test results were analyzed to identify issues with the mix production and construction. Analyses indicate that mix production, construction, and testing issues were likely to have caused pay disincentives to the contractors. The causes varied per contract. Production issues were related to aggregate consistency, handling, variability, and contamination, as well as to uncontrolled mix switches. Testing issues were related to reheating/absorption, lab gyratory compaction differences, and inconsistencies in the volumetric test weights. Construction included compaction equipment uses and condition of the milled surface. Results of the evaluations are intended to provide contractors and districts with observed best practices to improve pay factors and enhance HMA quality. The observations from this study should serve as guidelines for contractors to improve their pay factor performance and product quality and for IDOT to ensure consistent, timely, and reliable test results are used for determining contractor pay.

Publisher

Illinois Center for Transportation/Illinois Department of Transportation

Series/Report Name or Number

FHWA-ICT-20-006

ISSN

0197-9191

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/107721

DOI

https://doi.org/10.36501/0197-9191/20-007

Sponsor(s)/Grant Number(s)

IDOT-R27-189

Copyright and License Information

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.

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