LTPP Specific Pavement Studies (SPS) Materials Action Plan Final Report

Chapter 3. Execution of the MAP

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3.1 Task 1: Award of a Central LTPP Laboratory Contract

One of the first steps in the MAP was to award a laboratory contract to perform the majority of the MAP tests. This contract was awarded in September 2005.

Prior to the start of testing, the lab contractor was required to establish a quality control (QC) program. The QC program was to provide for the review, assessment, and necessary corrective actions of the following:

• Qualified personnel, proper equipment, and adequate facilities.
• Project supervision.
• Sample identification and receipt.
• Laboratory handling of samples.
• Sample storage and disposal.
• Pavement layering and laboratory test assignment.
• Adherence to the specified laboratory testing protocols.
• Accuracy in measurements.
• Equipment maintenance and calibration.
• Data review and checking.

The startup visit to audit the laboratory contractor's QC program was conducted in October 2005. Subsequent quality assurance visits to inspect resilient modulus testing procedures and quality management compliance were conducted in 2005, 2006, and 2007. The lab was confirmed to have American Association of State Highway and Transportation Officials (AASHTO) certification for performing standard AASHTO and/or American Society for Testing and Materials procedures on soils, aggregates, asphalt binder, asphalt emulsion, or HMA. The laboratory quality management system was also certified for compliance with AASHTO Standard Practice R18, and the laboratory had a current laboratory assessment from the Cement and Concrete Reference Laboratory.

The use of an independent laboratory to perform round-robin comparison testing on select prepared samples for select test methods was not performed due to cost considerations. Thus, no comparisons of replicated data tests were performed.

3.2 Tasks 2 and 3: Project-SPECIFIC Documentation

Under the leadership of the FHWA LTPP team, the following tasks were performed by various members of the LTPP program contractor team:

• Guidelines were established for preparation of project-specific MS&T plans, including details for sampling, labeling, shipping, and tracking of material samples.
• MAP materials data needs reports were generated from the central LTPP database for each project site.
• Detailed MS&T plans were developed for each project site based on input from participating highway agencies regarding support for materials sampling to address new and aging tests and MRL sample storage.
• A process of central review, modification, and approval was performed for each project site MS&T MAP document.
• Documentation was prepared on use of the Internet-based MAP data tracking system developed specifically for this effort.

3.3 Task 4: Database Development for New Tests

Four new tables were added to the LTPP database to store results of new tests added as a result of the MAP. The TST_UNBOUND_SPEC_GRAV table was added in 2004 for the specific gravity of unbound base and subgrade materials. Three tables were added in 2007 to store the results of the DCP test. Adding new tables to the LTPP database required development of technical specifications, database programming to create table storage space and data entry methods, programming of automated QC checks of entered data, checks on proper functioning of computer programs, and development of required implementation documentation.

3.4 Tasks 5-7: Implementation of Field and Lab Portions of MS&T Plans

FHWA LTPP contractors coordinated field activities with participating highway agencies to acquire needed material samples, document sampling events, label and ship material samples, perform field tests, and repair the pavement structure from destructive sampling. At most sites, participating highway agencies provided traffic control, material sampling equipment, core rigs, and pavement saws. At some sites, LTPP contractor equipment was used to supplement highway agency resources to improve productivity and reduce lane-closure times.

LTPP contractors began the laboratory testing quality management process by entering sampling information and assigning laboratory tests into the Internet-based MS&T tracking system. This system was used to register essential inventory information on material data samples and to track their progress through the laboratory test process. The LTPP laboratory test contractor also used the tracking system to document receipt of samples, performance of tests, and reporting of test results. While the laboratory test contractor performed primary QC checks on laboratory test results following LTPP guidelines, another central LTPP contractor was responsible for performing secondary QC checks on the data prior to entry into the LTPP database. A third level of QC checks was performed by other LTPP contractors after the data had been entered into the database.

3.5 Task 8: MRL Sample Collection

While the MAP included material sample collection for storage in the MRL for future tests, collecting MRL samples was assigned a lower priority than addressing data gaps and carrying out new and aging tests. In reality, more samples were shipped to the MRL than originally planned. In some cases, the extra cores that were cut through the bound pavement layers in order to sample underlying unbound materials did not have assigned lab tests. Many of the new "advanced" tests designated HMA materials whose tests were originally designated to be performed using complementary research resources and laboratories, and these were also shipped to the MRL for future testing considerations.

In some cases, it was possible to collect material samples inside the monitoring portion of test sections as part of a forensic investigation prior to a planned rehabilitation activity. Projects where core samples from within test-section limits were obtained for forensic evaluations are listed in table 4. Some material samples from this activity were shipped to the MRL.

Table 4. SPS projects forensic