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Construction Program Management and Inspection Guide
Appendix B (Part 1)
This memorandum transmits to you the companion reports AASHTO Quality Assurance Guide Specification and AASHTO Implementation Manual for Quality Assurance dated February 1996. The AASHTO initially published these two documents as one report in 1993 under the title AASHTO Quality Control/Quality Assurance Specification and Implementation Guide. We have also attached a copy of 23 CFR 637(b), Quality Assurance Procedures for Construction, which controls material acceptance on NHS projects. This regulation became effective June 29, 1995.
Please note that the Guide Specification is not yet approved as an official AASHTO Specification, but rather it has been approved as a report of the AASHTO Subcommittee on Construction. The process of incorporating this into the official AASHTO Guide Specifications is just beginning the normal rewrite process. Ultimately, the specification must be approved by the AASHTO Board of Directors.
Even though a majority of agencies recognize the positive elements of implementing quality assurance programs for construction, the individual procedures often vary. These AASHTO reports provide uniform guidance to develop and implement quality assurance standard specifications. While these reports substantially follow 23 CFR 637(b), Quality Assurance Procedures for Construction, some differences exist.
One key difference between the AASHTO Implementation Manual for Quality Assurance and 23 CFR 637(b) is that the AASHTO guide provides for the use of either split or independent samples for verification of contractor test results while 23 CFR 637(b) allows only independent samples for verification. As explained on page 16 of the AASHTO guide, the use of split samples only verifies the contractor's test procedures and equipment, not the quality of the material. The use of samples obtained and tested independently assesses material, sampling, and testing variability. Therefore, an acceptance program which uses split samples or witnessed tests for verification does not ensure the material quality and meets neither the letter nor the intent of 23 CFR 637(b).
On the other hand, the use of split samples in the independent assurance program provides a check on testing equipment and procedures. This complements the verification program and ensures the credibility of the testing program. We point out that the AASHTO Implementation Manual for Quality Assurance (page 22) offers the option of using either split or independent samples for independent assurance. This does not agree with the regulation that independent assurance testing may only be performed on split samples. We recognize the value of both split and independent samples, however, they do not provide interchangeable information.
Should you have any questions, please contact Mr. Frank Bednar of the Quality Initiative Group at 202-366-1565, or Mr. Roger Surdahl of the Materials Group at 202-366-1563, both of the Highway Operations Division.
Signed James Daves for Donald P. Steinke