Construction Program Management and Inspection Guide

Appendix B: Quality Assurance Resources
CONSTRUCTION PROGRAM MANAGEMENT AND INSPECTION GUIDE (5/01/04)
B–50 SAMPLE
All physical Acceptance samples of material will be split prior to testing in accordance with
relevant AASHTO and NETTCP procedures. The split sample portion of material not used for
testing will be retained in the original sample bag with proper identification. The split sample will
be stored in the Sample Storage Room at the Laboratory which performed the test for a minimum
of 60 Days following testing.
8.3 – Correlation Testing Prior to Production
Transportation Agency Acceptance personnel and ABC Contractors QC Personnel will
perform Correlation Testing on split samples prior to the start of construction. The purpose of the
Correlation samples is to correlate the laboratory and field Acceptance testing results with the
laboratory and field QC testing results to determine any between laboratory/field testing
equipment variability before production begins. The results of Correlation testing will be
documented on the relevant Standard Test Report Forms contained in Appendix __ (see Note,
page B–17).
8.4 – Validation of QC Test Results
Validation is defined as the process of comparing two independently obtained sets of test results
(i.e. Transportation Agency’s Acceptance test results to ABC Contractors’ QC test results)
during the progress of the work to determine whether they came from the same Population of
material. The Validation will be performed through a statistical comparison of Transportation
Agency’s Acceptance test results and ABC Contractors’ QC test results. The statistical
comparison of test results will be made using the test result standard deviations (F-test) and the
test result means (t-test) at a significance level of 0.01 and in accordance with the procedures
contained in Appendix F of the AASHTO Implementation Manual For Quality Assurance (February
1996).
If the Validation results indicate that ABC Contractors’ QC test results and Transportation
Agency’s Acceptance test results came from the same Population, then the QC test results will be
included with the Acceptance test results in the final acceptance determination as outlined in
Sections 8.6 and 8.7 below. If the Validation results indicate that ABC Contractors’ QC test
results and Transportation Agency’s Acceptance test results are not from the same Population,
then only Transportation Agency’s Acceptance test results will be used in the final acceptance
determination.
8.5 – Quality Limits
Two types of Quality Limits will be applied to Validated QC and Acceptance testing results for the
acceptance determination. These are “Engineering Limits” and “Specification Limits”, which
are defined as follows:
Engineering Limits – Absolute limits, established on the basis of Engineering study or
judgment, which each individual test result for a given Lot must fall within. Work represented
by individual test results which are above or below the Engineering Limits will not be
accepted.
Specification Limits – Limiting values, established on the basis of statistical concepts and
analysis, which are used to assess the Percent Within Limits (PWL) for a given Lot. The
Mean of all individual test results for a given Lot must fall within the Specification Limits and
the PWL must meet or exceed the specified PWL in order for the Lot to be accepted.