U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
|This report is an archived publication and may contain dated technical, contact, and link information|
Publication Number: FHWA-HRT-10-049
Date: August 2010
The numbers of required, available, and missing tests presented in this report are based on database queries. It is not always possible to accurately determine from the database if a test is required or possible to run on a layer. For example, the open graded drainage layers on SPS-1 and -2 projects are represented as treated base layers in the database because construction specifications required that they be treated with 2 percent asphalt to add stability during construction. Although they are a treated base layer, it is not possible to extract an intact core of this material because of lack of cohesion.
Thus, the amount of missing tests is a planning number that was expected to be overstated so that resources estimates would be conservative. Because the LTPP database changes as new information is acquired, the basis for the number of required tests can change due to the identification of new material layers in the pavement structure each time a needs assessment is performed.
The status of the missing SPS materials data in April 2002 and in April 2004, after 2 years of effort, is summarized in table 1.
Percent Missing Tests
Detailed information on these counts is contained in the
As table 1 and the appendices indicate, the efforts undertaken by the LTPP program between 2002 and 2004 resulted in a significant reduction in missing SPS materials test data. The number of missing tests was reduced by 4,998 as a result of the addition of 4,060 new data sets and adjustments to the number of required tests. About one third of the materials tests were still missing in 2004-an improvement but still a significant problem.
The FHWA took into consideration recommendations from the Materials ETG and LTPP contractors to establish the following priority material test requirements for the MAP:
The following tests were not included as part of the action plan:
Some of these tests were still performed as part of other test protocols, ancillary to other tests, or based on agency participation. For example, classification of unbound soils and base materials (tests SS04 and UG08) are included in this list because they are not tests per se but computations based on other test results.
In general, the Materials ETG's rationale for recommending tests not be included in the plan was usually that the tests were somewhat outmoded and were not likely to provide valuable information in the future.
One or more layers/materials on the following SPS projects were not included as part of the 2004 MAP because they had already been removed or because the project site was out of study and not considered for further testing:
Material layers from these sites were not included in the assessment of data needs.
Another assessment of data gaps and needs was performed in 2004 using the new MAP priority test guidelines and the contents of the May 2004 national upload of the LTPP database. Table 2 contains counts by test type and type of material to satisfy the priority test requirements developed for the MAP. Based on the layer structure contained in the database at this time, approximately 12,650 tests were identified as necessary to fill material data gaps. Differences between data needs in table 2 and those reported in table 1 are due to changes in pavement structure data in the database and the more explicit test section-based requirements for the MAP.
|AC01||Core Examination and Thickness||1,167||590||1,757|
|AC02||Bulk Specific Gravity||1,744||652||2,396|
|AC03||Maximum Specific Gravity||292||110||402|
|AC04||Asphalt Content (Extraction)||284||47||331|
|AC07||Tensile Strength/Res. Modulus/Creep||357||118||475|
|AE03||Specific Gravity 16 °C (60.8 °F)||319||109||428|
|AE05||Viscosity 60 °C (140 °F), 135 °C (275 °F)||321||109||430|
|AG01||Coarse Aggregate Specific Gravity||346||110||456|
|AG02||Fine Aggregate Specific Gravity||348||116||464|
|AG04||Extracted Aggregate Gradation||289||50||339|
|AG05||NAA Test-Fine Aggregate Particle Shape||488||137||625|
|PC02||Split Tensile Strength||29||90||119|
|PC03||Coefficient of Thermal Expansion||88||93||181|
|PC04||Static Modulus of Elasticity||50||92||142|
|PC06||Core Examination and Thickness||334||511||845|
|PC08||28 Day Air Content||121||93||214|
|TB01||Type and Class. of Materials and Treatment||911||612||28||1,551|
AC = Asphalt concrete
PCC = Portland cement concrete
TB-AC = Asphalt concrete treated base
TB-PCC = Portland cement concrete treated base
TB = Treated base
While addressing the need to resolve material data gaps based on previous criteria, new and aging tests were added to improve materials structure information with little added cost. Aging tests are repeats of previous tests to capture material property aging effects.
New tests included the following:
Aging tests were only to be performed on HMA or PCC layers, not on material from unbound base, subbase, or subgrade layers nor on treated bases or subbases. They included the following:
Table 3 outlines the 2004 sampling requirements for the new and aging tests by type of SPS experiment.
|Experiment/ Project||Cores Per Project||Number of Projectsa||Total Cores|
|12-inch Cores||4-inch Cores||12-inch Cores||4-inch Cores|
a Does not include projects eliminated from the action plan. b There are 19 SPS-8 projects; 4 of them have both AC and PCC test sections.
Bulk samples of the unbound base, subbase, and subgrade materials to run the specific gravity test were designated to be obtained from the 12-inch core locations identified in table 3. Where the proper drill rig to cut 12-inch holes was not available, a saw-cut opening was requested to access the underlying unbound materials.
 The first two letters of the test designation indicate the material type. AC: asphalt concrete, AE: extracted asphalt cement, PC: portland cement concrete, SS: subgrade soil, TB: treated base, UG: unbound granular base.