The Department has examined several asphalt cement additives over the last 6 - 8 years in an attempt to produce an increased strength dense graded asphaltic concrete or an acceptable mix using marginal sand aggregates. Trinidad Lake Asphalt, a naturally occurring asphalt, is another material purported to enhance mix properties. Trinidad Lake Asphalt in both an epure and a powder form was examined in the laboratory. Laboratory testing included: binder properties testing of combinations of Trinidad with three asphalt cements at three levels of addition; binder durability testing using the Thin Film Oven; Marshall optimization of mix design for a low stability dense graded mix, a high stability dense graded mix and sand mix each at three Trinidad addition levels; water susceptibility testing; and, fundamental properties testing. Also, an economic analysis was performed. In general, Marshall stabilities were found to increase with increasing Trinidad Lake Asphalt content for all mix designs. Modulus values and tensile stress at failure were increased with the use of the Trinidad material while the tensile strain at failure was decreased. Due to the mineral matter in the naturally occurring asphalt, viscosities were higher and penetration and ductilities were lower than values normally associated with conventional binders. Viscosity indices after thin film oven treatment, however, demonstrated no unexpected hardening. An economic analysis on either a first cost or life cycle basis showed that a Trinidad mix would have to perform an additional two years beyond a conventional mix in order to achieve economic parity.

Media Info

  • Features: References;
  • Pagination: 40 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00457087
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA/LA-85/172, 172
  • Contract Numbers: 82-2B(B)
  • Created Date: Aug 27 2004 9:39PM