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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
Subject(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.
Issue Date:2020-06
Publisher:Illinois Center for Transportation/Illinois Department of Transportation
Citation Info:Al-Qadi, Imad L., José J. Rivera-Perez, Watheq Sayeh, Javier J. García Mainieri, Hadi Meidani, John Huang, Hasan Ozer, and Adam Hand. 2020. Case Studies Using Quality Control for Performance and Pay for Performance Specifications: Field Observations. A report of the findings of ICT-R27-189. Illinois Center for Transportation Series No. 20-007. Research Report No. FHWA-ICT-20-006. Illinois Center for Transportation, Rantoul, IL.
Genre:Technical Report
Rights Information:No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.
Date Available in IDEALS:2020-06-26

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