EFFECT OF COARSE AGGREGATE CONTENT ON STONE MATRIX ASPHALT DURABILITY AND LOW-TEMPERATURE CRACKING

The effects of coarse aggregate content on the resistance of stone matrix asphalt (SMA) mixtures to moisture damage, aging, and low-temperature cracking were evaluated. Extractions were also performed to determine whether the Marshall hammer crushed aggregates during the mixture designs. The coarse aggregate content was varied by changing the percentages of aggregate passing the 4.75- and 2.36-mm sieves. These sieves control the degree of gap in an SMA mixture. The percentages of aggregate passing the other sieve sizes were not varied. Moisture susceptibility was affected more by the type of aggregate and the type of stabilizer than by gradation, or coarse aggregate content. Decreases in long-term aging with increasing coarse aggregate content were provided by three of four sets of coarse aggregate contents. (The use of two stabilizers and two aggregate types provided the four sets of coarse aggregate contents.) However, these decreases in aging only occurred at the highest test temperatures, which were 16 deg C and 32 deg C. Long-term aging had no significant effect on the data compared with no aging at lower temperatures; therefore, coarse aggregate content could have no effect. Studies concerned with the effects of coarse aggregate content on low-temperature cracking were inconclusive. The amount of aggregate broken during compaction increased with an increase in coarse aggregate content. The cumulative percentage passing the 4.75-mm sieve increased by more than 5% for the gradations closest to those recommended by FHWA's "SMA Model Material and Construction Guidelines". The increases were as great as 15.8%.

Language

  • English

Media Info

  • Features: References; Tables;
  • Pagination: p. 26-35
  • Monograph Title: Hot-mix asphalt design, testing, evaluation, and performance
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00714830
  • Record Type: Publication
  • ISBN: 309061563
  • Files: TRIS, TRB
  • Created Date: Dec 4 1995 12:00AM