Investigation of Low Temperature Cracking in Asphalt Pavements - Phase II
Low temperature cracking is the most prevalent distress found in asphalt pavements built in cold weather climates. As the temperature drops the restrained pavement tries to shrink. The tensile stresses build up to a critical point at which a crack is formed. Thermal cracks can be initiated by a single low temperature event or by multiple warming and cooling cycles and then propagated by further low temperatures or traffic loadings.
The current Superpave specification attempts to address this issue by specifying a limiting low temperature for asphalt binders. However, the first phase of this project made it clear that testing asphalt mixtures is necessary to accurately predict low temperature cracking performance in the field. Furthermore, the testing must include more sophisticated techniques based on fracture mechanics rather than the current practice of stiffness and strength testing.
To this end, a comprehensive research effort is underway led by Dr. Mihai Marasteanu at the University of Minnesota. This project is a unique partnership between MnDOT and four universities: University of Minnesota, Iowa State University, University of Illinois at Urbana-Champagne, and University of Wisconsin at Madison. This project is using an integrated approach of laboratory mixture fracture testing, sophisticated modeling, and field evaluation to develop a low temperature cracking specification for asphalt mixtures. This pooled fund study will result in a tool that can be used by the 7 partner sponsors to select the optimal materials resistant to thermal cracking.
Reports and Publications
- LTC Research Brief
- Low Temperature Cracking Phase I Executive Summary
- Task 1: Literature Review - An Update on Low Temperature Cracking research.
- Task 2: Field Testing - Expansion of Phase I test matrix with additional field samples.
- Task 2a: Physical Hardening
- Task 3.1 and 3.2: Low Temperature Mixture Specifications
- Task 3.3a: Creep Compliance from DCT & SCB
- Task 3.3b: Creep Compliance from BBR
- Task 3.3c: Single Edge Notched Beam
- Task 4: Illi-TC Model
- Task 5: Thermal Modeling
- Task 6: Specification Validation
- Discussion of Disc- Shaped Compact Tension Test vs. Semi- Circular Bend Test
- TRB Article - Specifying Low - Temperature Cracking Performance for Hot-Mix Asphalt
- Final Report
September 2012 TAP Meeting
Implementing LTC Spec in MN
Implementing LTC Spec in IA
Project Summary & Significant Contributions
ILLI - TC Demonstration
Towards a Low Temperature Performance Specification for Asphalt Mixtures
December 2011MAAPT Presentations
November 2010 TAP Meeting
University of Minnesota Update
November 2009 TAP Meeting
University of Minnesota Update
November 2009 LTC Meeting
University of Illinois Update
- MnDOT 2009 - 42: Asphalt Mixture and Binder Fracture Testing for 2008 MnROAD Construction
- MnDOT 2007 - 43: Investigation of Low Temperature Cracking in Asphalt Pavements, National Pooled Fund Study 776
- MnDOT 2006 - 15: Investigation of Low Temperature Fracture Properties of Three MnROAD Asphalt Mixtures
- MnDOT 2004 - 23: Low Temperature Cracking of Asphalt Concrete Pavement