Fix it First: Utilizing the Seismic Property Analyzer and MMLS to Develop Guidelines for the Use of Polymer Modified Thin Lift HMA vs. Surface Treatments

Funding Source: New England Transportation Consortium (NETC)
ATMC Materials Lab Involvement: Principle Investigator
Partnering Universities: University of New Hampshire
Start Date: April 2006
End Date: October 2007
Summary:

Currently many of the New England states are adopting the “Fix it First” approach when faced with decisions to construct new pavement systems versus rehabilitating the existing pavement. This approach has been further backed by many of the state legislators who have allocated funds earmarked for “Fix it First” projects.

“Fix it First” pavement projects require the critical decisions regarding selection of an appropriate rehabilitation technique and the timing of its application. In New England little guidance exists to address these questions, rather the accepted practice is to resurface the existing pavement with surface treatments like Nova Chip and Micro Surfacing or replace the roadway entirely. This practice may lead to over or under rehabilitating critical roadways, which thus leads to extra funds being expelled in scenarios where it is not warranted.

Surface treatments can effectively correct a variety of issues including rutting, raveling, skid resistance, and potholes but offer little or no addition to the structural integrity of the pavement system. Recently there has been greater interest in using thin lift hot mix asphalt prepared using Polymer Modified Asphalt (PMA) as an alternative to surface treatments because they are thought to correct the same distress as surface treatments as well as add to the structural integrity of the pavement system. Common types of thin lift hot mix asphalt mixes are fine SMA (SMA-9.5), OGFC, and sand mixes. However, to date even less guidance and data is available to industry professionals regarding the relevant material properties and optimum resurfacing time for thin overlay mixes utilizing PMA.

The goal of this research is to develop a guideline for industry professionals regarding the use of thin lift overlay mixes with PMA in New England. This guideline will include thorough research into the existing surface treatments and overlays being used in the New England States as well as development of PMA mixes that can be used in lieu of the conventional surface treatments. Also explored will be a non-destructive testing method (NDT), the seismic property analyzer (SPA) to determine the optimum time to perform resurfacing, cost/benefit analysis of the various resurfacing options as compared with PMA overlays, and the strengths/weaknesses of particular PMA mixes. Also the NDT device can be utilized to diagnose the problems that lead to the surface distresses.

In order to complete this research, the following objectives will be addressed:

1. Define and compare thin lift overlay maintenance mixes and surface treatments currently used in the New England States.
2. Evaluate the thin lift overlay maintenance mixes and surface treatments currently used in the New England States and compare to those currently used worldwide.
3. Determine the current New England DOT procedures for picking rehabilitation methodologies.
4. Perform and evaluate non-destructive testing to better determine the optimum time to apply surface treatments or thin lift overlay mixes to the existing pavements in order properly prioritize rehabilitation projects.
5. Evaluate the benefits and drawbacks of using PMA thin lift mixes versus surface treatments with lab testing.
6. Evaluate the cost comparisons between PMA thin lift mixes and surface treatments.