Effects of Temperature Segregation on the Volumetric and Mechanistic Properties of Asphalt Mixtures

Thermal segregation is a non-uniform temperature distribution across the mat of uncompacted asphalt mixtures during paving operation. The first investigation on temperature segregation was attempted in the late 1990s. The primary concern of temperature segregation phenomenon is the detrimental effect that may occur on the quality and performance of asphalt pavements. This is because some areas of the asphalt mat are cooler than the required compaction temperature resulting in lower field densities. The objective of this research is to determine the impact of temperature segregation on the quality of asphalt mixtures as defined by measurements of density and mechanistic properties of asphalt mixtures. Seven asphalt rehabilitation projects across Louisiana were selected. A multi-sensor infrared bar (Pave-IR) system and a hand-held portable thermal camera were used to measure the temperature of asphalt mats. Field core samples were collected from areas with varying levels of temperature segregation. Densities and mechanical properties from Loaded Wheel Tracking test, Semi Circular Bent test, and Indirect Tensile Dynamic Modulus test of roadway cores at uniform and non-uniform temperature zones were conducted. Two distinctive patterns of non-uniform temperature distribution of asphalt mats were observed, namely, cyclic and irregular temperature segregations. Cyclic temperature segregation occurred as a fairly consistent cyclic fluctuation of temperature with a certain range of interval (typically 100 to 250 feet) due to continuous cooling of asphalt mixtures during the normal operation, while the irregular temperature segregation occurs at no specific intervals when the paving operation is stopped for an extended amount of time. Results showed that the use of material transfer vehicle (MTV) and 12.5-mm nominal maximum aggregate size (NMAS) mixtures can improve the consistency of asphalt mat temperature. Laboratory test results showed that highly temperature segregated asphalt pavements (i.e., temperature differentials ≥ 75°F) can have significantly lower densities and the mechanistic properties than non-segregated area, especially when the temperature differentials are measured prior to the first breaking roller application.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 108p

Subject/Index Terms

Filing Info

  • Accession Number: 01711237
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/LA.17/604, LTRC Project Number: 14-1B, State Proj. No.: DOTLT1000008
  • Files: NTL, TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Jun 25 2019 4:32PM