Evaluating percent within limits (PWL) specifications volume 1 : HMA specifications.

749916717Final report.PDFTech ReportFHWA/OK 06(05)Item 2172PavementsAsphalt pavementsConcrete pavementsQuality assuranceQuality controlOklahomaOklahoma State UniversityCross, Stephen A.Frantzen, Jeffrey A.Oklahoma State University. School of Civil & Environmental EngineeringOklahoma. Dept. of Transportation. Planning & Research DivisionNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionThe Oklahoma Department of Transportation (ODOT) has let four paving jobs for construction wherepercent within limits (PWL) specifications were employed. The PWL specifications are intended to beused as part of the Quality Assessment program to determine the statistical probability of conformance tospecified material properties and construction details, and to base the pay factor (PF) off the probability ofconformance to the specifications. There is a need to evaluate the performance of the PWL specificationsand assess the suitability of the PWL specifications for future jobs.Two hot mix asphalt (HMA) projects were let for construction using the proposed HMA PWLspecifications. In addition to the normal quality control, acceptance and assurance sampling and testing,the ODOT Materials Division performed more extensive sampling and testing on randomly selected lotsfrom each pavement which were designated \ue2\u20ac\u153super lots.\ue2\u20ac?The data obtained were to analyzed 1) to determine whether the PWL specifications are working asintended, 2) to recommend changes to the PWL specification if necessary, including possible changes tothe limits and ranges contained within the specifications, and 3) to recommend whether ODOT shouldcontinue to pursue PWL specifications as matter of policy in their overall QA/QC programs.The examination of the draft HMA PWL specification and analysis of the super lot data demonstrated thatthe specification concept is sound and will require very little additional work to develop fully. The F andt-test procedure for process verification is recommended for use