TxDOT Research Library - TxDOT Research Project

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Comparative Analysis of Tack Coat, Underseal Membrane, and Underseal Technologies

Underseal Membrane Applied with a Spray Paver.

What Was the Need?

"Several options are available for preparing a surface prior to an asphalt overlay. These include traditional tack coats, non-tracking tack coats, thicker spray-applied underseal membranes, and traditional underseals. Tack coats, with a shot rate between 0.04 and 0.14 gallon (gal)/square yard (sy), are expected to provide better bonding. Underseal membranes (0.13 – 0.3 gal/sy) and underseals (>0.3 gal/sy with rock) are expected to reduce moisture infiltration and reflective cracking. However, these benefits have not been sufficiently quantified, and neither has the overall impact on the asphalt overlay service life. Some of these approaches can have considerably higher costs of materials and equipment. Currently, it is unknown whether the added benefits of these technologies (potentially longer service life) result in cost savings to the TxDOT."

Project Summary

The objective of this study was to evaluate the performance of asphalt overlays achieved with different tacking and sealing technologies, namely: Traditional tack coats, Non-tracking tack coats, Underseal membranes from a spray-paver, and Traditional underseals. Work includes evaluating each technology with respect to: (1) Layer bonding, (2) Sealing against moisture, (3) Resistance to reflection cracking, and (4) General overlay condition."

Project Number

0-6908

Status

Completed

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