Alternative Methods for Air Voids and Field Density

The measurement of specific gravity for hot-mix asphalt (HMA) is critical in almost every topic pertaining to asphalt mixtures. Thus, being able to accurately and precisely measure this property is of paramount importance. During design and construction, the bulk specific gravity (Gmb) and maximum theoretical specific gravity (Gmm) of HMA mixes are used to calculate most of the properties that indicate pavement quality. In this study, alternative methods for Gmb and Gmm were evaluated and compared to traditional measures of these properties to assess precision and relative accuracy. Three methods for Gmm were considered (CoreLok, Kuss, and AASHTO T-209) and evaluated with regard to the effects of nominal maximum aggregate size (NMAS) (4 sizes were tested – 9.5mm, 12.5mm, 25.0mm, and 37.5mm) for a selection of aggregate types typically found in Arkansas (4 sources were tested – sandstone, syenite, gravel, and limestone). Five methods for Gmb were considered (CoreLok, CoreReader, HeightDiameter, Kuss, and SSD) and evaluated for the same sources and sizes, as well as level of compactive effort (3 levels were tested – high, medium, and low). The results indicate that, in terms of precision, the traditional methods exhibit the lowest levels of variability. Accuracy can only be assessed relatively, but it was determined that NMAS and compactive effort significantly affect test results. For Gmb measurements, the Height-Diameter method is most sensitive to changes in NMAS, while the CoreLok and Kuss methods are least sensitive to these changes. In most cases, CoreLok and SSD values are similar for small NMAS mixes, but not for large NMAS mixes. Strong mathematical correlations were developed in order to relate traditional and alternative Gmb test methods based on NNVIAS. The strongest and most practical relationships were developed between the SSD and CoreLok methods. These models can be used to assess the impacts of incorporating new test methods for both design and construction procedures. They can also be used to normalize data from different test methods, should alternative methods be incorporated into the current specification. While alternative methods do possess significant advantages, the results of this study do not support the elimination of traditional methods.

• Record URL:
  • https://www.ardot.gov/wp-content/uploads/2020/11/TRC0306_Alternative_Test_Methods_for_Air_Voids_and_Field_Density.pdf
• 
• Corporate Authors:

  University of Arkansas, Fayetteville

  Department of Civil Engineering
  Fayetteville, AR  United States  72701

  Arkansas State Highway and Transportation Department

  Planning and Research Division, P.O. Box 2261
  Little Rock, AR  United States  72203
• Authors:
  • Williams, Stacy G
• Publication Date: 2006-4

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Photos; References; Tables;
• Pagination: 93p

Subject/Index Terms

• TRT Terms: Aggregates; Air voids; Compaction; Correlation analysis; Field density; Hot mix asphalt; Specific gravity; Test procedures
• Uncontrolled Terms: Nominal maximum aggregate size
• Geographic Terms: Arkansas
• Subject Areas: Highways; Materials; Pavements; I31: Bituminous Binders and Materials; I36: Aggregates;

Filing Info

• Accession Number: 01547508
• Record Type: Publication
• Report/Paper Numbers: TRC-0306
• Files: TRIS, ATRI, STATEDOT
• Created Date: Dec 10 2014 2:17PM