Best Practices for Implementation of Tack Coat

Imad Al-Qadi, University of Illinois at Urbana-ChampaignEnad Mahmoud, Bradley Universityhttp://ict.illinois.edu/Publications/report%20files/FHWA-ICT-12-004.pdf http://ict.illinois.edu/Publications/report%20files/FHWA-ICT-12-004.pdf

Problem Statement

Interlayer bond is critical to performance

Tack coat is the sole material bonding layers

Optimum tack coat application must be identified

Objectives

Assess laboratory performance of tack coats

Determine optimal residual application rate of tack coats

Evaluate field-optimal tack coat application

Optimize tack coat materials, application rate, placement methods, and surface preparation techniques

Research Performed LABORATORY

Research Performed

FIELD

Research Performed

FIELD TEST

I-80 - 26 test sections 3 existing surfaces: milled HMA, milled

PCC, and fresh binder stone mastic asphalt (SMA)

Illinois 98 – 19 sections 1 existing surface – milled HMA

Findings

Specify tack coat application rate based on residual AC rate, not truck applicator rate

Developed optimal application rates for all possible surfaces

Identified methods for surface cleaning that provide best bond strength

Determined viable options for rapid set tack coats

Emulsions outperformed cutbacks

Why were Findings Important? Identification of the optimum

tack coat application rate will Ensure cost-effective and efficient

tack coat application Enhance pavement performance Help the industry to better optimizeresources

Recommendations

Based on this research, and the good correlation of laboratory and field results, new products in the future can be tested in the laboratory to determine their expected performance in the field

Implementation

Special Provision for selected projects

Worked with: Tack Coat Manufacturers Materials Personnel Construction Personnel HMA Contractors Applicator Manufacturers

Benefits Improved Pavement

performance Reduced

delamintation Improved rutting

resistance Faster opening to

traffic Some of the tested

products allow traffic over tack coat (trackless tack coat)

Questions?

Amy SchutzbachIllinois Department of Transportation217-782-2631Amy.Schutzbach@illinois.gov

Megan SwansonIllinois Department of

Transportation217-782-3547

Megan.Swanson@illinois.gov