Skip to contentUnited States Department of Transportation - Federal Highway AdministrationSearch FHWAFeedback

Pavements

<<PreviousContentsNext >>

Materials Notebook: Analysis of Noncomplying Material

Note: The following information is an excerpt from Technical Advisory T 5080.11 (April 6, 1989). The bulk of Technical Advisory T 5080.11 has been superseded by 23 CFR 637 (June 29, 1995).

  1. Basis for Evaluation. The following discussion is intended as guidance for FHWA to be used as a basis for evaluating the State's recommendations for the acceptance of construction products if other procedures have not been established by the State and approved by FHWA.
    1. Traditional pass/fail specifications typically do not have provisions for other than full payment for construction products. In most cases where there are products with test results outside of specification limits, acceptance at full pay or the determination of acceptance with equitable pay adjustments is normally ". . .as determined by the engineer." In these cases, some rational basis is necessary for the analysis of the failing products in order for a determination of Federal-aid participation to be made.
    2. Statistically based specifications usually include an analysis which determines whether the construction product will be accepted at full payment or, for marginal products, will remain in place but will be accepted at an adjusted pay. If the project specifications provide a process for the acceptance of marginal construction products at an adjusted pay, the approval by FHWA of the State's specifications constitutes an approval of other procedures as noted above and no further analysis of the products will be necessary to determine Federal-aid participation.
    3. There are a number of factors which can cause an indication that manufactured or project produced construction products do not meet the applicable specifications. In some cases, a visual inspection may be all that is necessary to determine if a product is acceptable. However, in a majority of the cases, sampling and testing of the construction product is the basis which is used to determine acceptability. The variability of a construction product which is indicated by the results of sampling and testing is not, however, an absolute measure but is the product of a combination of variables. These variables are the natural variability of the material, the variability induced through sampling procedures and the variability of testing procedures and/or equipment.
    4. The policy of the FHWA is that a project must have been constructed ". . in reasonably close conformity with the approved plans and specifications. . ." to be eligible for Federal-aid participation. However, there will be instances when test results, as a result of the above noted variability may indicate apparent nonconformance to the specification limits, yet the construction product may be acceptable for the use intended at full or reduced pay. In these cases, an analysis of the materials and/or materials test results will be necessary before a determination of Federal-aid participation can be made.
    5. There are no exact rules which can be applied to the acceptance at full pay or the acceptance at some reduced pay for any specific construction product since the final analysis should be based on equitable payment for the value of the product. However, as a general "rule of thumb," if more than 10 percent of the test values for any construction product are outside of the applicable specifications, there may be a question of "reasonably close conformity." In these cases, an analysis of the test values should be made to determine the magnitude and extent of the nonconforming materials. The following general criteria can be used as a process to determine the degree of acceptability of construction products for Federal-aid participation purposes.
  2. Categories of Compliance. Construction products which have test results not meeting specification limits can generally be classified into the following categories:
    1. Category 1 - substantial conformance to the specifications. The construction product meets the specification since the number and magnitude of the deviations are such that they fall within the expected limits of material and testing variability. The construction product will provide full service life, and the State has recommended that full payment be made to the supplier/contractor. In these cases, full Federal-aid participation may be allowed.
    2. Category 2 - marginal compliance. The number and/or the magnitude of the deviations fall outside the expected limits of material and testing variability. In these cases, an analysis must be made to determine acceptability based on performance and service life which can be anticipated. If the analysis indicates the construction product can be expected to provide a reasonable but reduced service life, limited Federal-aid participation may be allowed. The actual level of Federal-aid participation should be based on an analysis such as, but not limited to, life cycle costing, statistical evaluations of the degree of conformity to specifications, or other applicable engineering evaluations.
    3. Category 3 - noncompliance. The magnitude and the number of deviations are such that the material will not perform acceptably. In these cases, Federal-aid participation should not be allowed in the construction product. The construction product should be removed and replaced or otherwise corrected.
  3. Engineering Analysis. An analysis should be performed to determine which of the above categories describes the nonspecification construction product. The analysis should include an assessment of whether the material and workmanship are within normal construction limitations and whether the construction product can perform adequately. The following is offered as guidance on the areas which should be covered for each construction product.
    1. Asphalt Paving. Although all parts of proportioning and construction operations are important, the most critical elements of the construction product are the asphalt content, amount of material passing the No. 200 sieve, and the density of the pavement. When there is a question of conformity, the analysis should concentrate on these elements. Paragraph 6b(1)(a) centers on the void structure of the pavement, and Paragraph 6b(1)(b) concerns gradation and asphalt control
      1. Pavement sections which have densities of 96 percent of Theoretical Maximum Density (TMD) or greater will usually result in plastic flow and rutting. This situation is typically a function of excessive asphalt and/or minus 200 material. The asphalt content at which 3 percent voids occur in the laboratory mix design is the maximum asphalt content which should be approved.
        1. Pavement sections with densities of 96 percent of TMD or greater, or which have the potential for consolidation to greater than 96 percent of TMD, i.e., high percentage of minus 200 or asphalt content, could be considered being in either marginal or noncompliance.
        2. Pavement sections which have been compacted to a density of 90 percent of TMD or less have the potential for stripping, accelerated asphalt aging, and consolidation rutting. These pavements may provide a reasonable but reduced service life and could also be considered as being in either marginal compliance or noncompliance based on the magnitude and degree of the failing materials.
        3. In each of the above cases, an analysis of the test results should be conducted prior to a final determination of acceptability, to determine the magnitude and degree of the failing materials. This analysis should be used to determine the degree or extent of Federal-aid participation in the asphalt pavement.
        4. A pavement density of 92 to 94 percent of TMD is the desired density in the field. A density of 91 to 95 percent of TMD may be considered in substantial conformance without further analysis being required.
      2. The following are ranges for aggregate gradation and asphalt content for surface mixes which can be expected for normal construction. These ranges are based on standard deviations published in Public Roads, Vol.35, Nos. 6-11. The ranges include both testing variability and expected material variability for normal construction practice. With the exception of the asphalt content and the minus 200 material, the ranges will probably be within the tolerances of most State highway agencies.
        SieveRange +/-
        19.0 mm or 12.5 mm2.86 Percent Passing
        9.5 mm4.98 "
        4.75 mm7.02 "
        2.36 mm or 2.0 mm5.62 "
        850 µm or 600 µm3.48 "
        425 µm or 300 µm 2.74 "
        150 µm 2.00 "
        75 µm1.88 "
        asphalt content 0.56 Percent
        If the project test results indicate that more than 10 percent of the actual test values are outside of these ranges or the State's specified tolerances, whichever is greater, an analysis of the construction product will be necessary to determine the degree or extent of Federal-aid participation.
    2. Portland Cement Concrete. The analysis for Portland cement concrete should concentrate on three items: strength, air content, and slump. Strength and air content are directly related to performance; however, slump is generally only an indicator of workability of the mix. In some cases, slump may be considered as an indicator of the water-cement ratio of the mix. Paragraph 6b(2)(a) discusses strength, and paragraph 6b(2)(b) discusses slump and air content.
      1. The strength analysis should be based on two criteria: (1) The minimum strength to perform satisfactorily and (2) the minimum strength that could be expected with good quality control.
        1. For structural concrete, the compressive strength used for the structural design is the governing factor as to whether the concrete will remain in place. Any material that does not meet structural design requirements should be fully analyzed to determine if it may be left in place or must be removed.

          If the project test results indicate that more than 10 percent of the actual test values are outside of these ranges or the State's specified tolerances, whichever is greater, an analysis of the construction product will be necessary to determine the degree or extent of Federal-aid participation.

        2. In paving concrete, if 90 percent of the test results exceed the minimum specified compressive or flexure strengths, the material would generally be considered to be in substantial conformance to the specifications. If failing tests are not randomly distributed (i.e., represent a section or production run that can be readily identified as deficient) or exceed 10 percent of the tests, a further analysis of the construction product will be necessary to determine the degree or extent of Federal-aid participation.
      2. The following ranges for slump and air content which can be expected for normal construction are based on standard deviations published in Public Roads, Vol. 35, Nos. 6-11. The ranges include both testing variability and expected material variability for normal construction practice.
         Range (+/-)
        Air Content (%)1.6
        Slump (mm)35
        If the project test results indicate that more than 10 percent of the actual test values are outside of these ranges or the State's specified tolerances, whichever is greater, an analysis of the construction product will be necessary to determine the degree or extent of Federal-aid participation.
    3. Soils and Soils Mixtures. The analysis should be based on the density of the material. The following range for embankment density which can be expected for normal construction is based on standard deviations published in Public Roads, Vol. 35, Nos. 6-11. The range includes both testing variability and material variability for normal construction practice.
       Range
      Density (%) 90-100
      If the project test results indicate that more than 10 percent of the actual test values are outside of these ranges or the State's specified tolerances, whichever is greater, an analysis of the construction product will be necessary to determine the degree or extent of Federal-aid participation.
    4. Aggregate and Aggregate Mixtures. The analysis for acceptance of aggregate and aggregate mixtures should concentrate on aggregate gradation, density, and stabilizer content.
      1. The specification limits for both gradation and stabilizer content vary from State-to-State based on the available materials. Because of this variability, specific guidance cannot be provided for these properties.
      2. The following range for base/subbase density which can be expected for normal construction is based on standard deviations published in Public Roads, Vol. 35, Nos. 6-11. The range includes both testing variability and material variability for normal construction practice. The range should apply to the target density.
         Range
        Density (%)94-100
<<PreviousContentsNext >>

More Information

Contact

Mike Rafalowski
Office of Asset Management, Pavements, and Construction
202-366-1571
E-mail Mike

 
 
Updated: 04/07/2011
 

FHWA
United States Department of Transportation - Federal Highway Administration