TxDOT Research Library - TxDOT Research Project

Show:

Seal Coat Quality: Does Low Cost Mean Low Quality?

What Was the Need?

Recently TxDOT administration has provided direction on the types of seal coat material that can be used on a particular facility based on traffic volumes. The more expensive modified binders are reserved for use on higher volume facilities while the very low volume facilities must be sealed with unmodified binders. Given the cost-cutting needs the department faces, this guidance is justified. However, it is just as important (economically) to get the maximum life out of a seal coat. When the correct materials and application rates are used for a seal coat, the Texas Department of Transportation (TxDOT) should expect a service life of at least 7 years or more. For example, on a very low volume, rural road, a Grade 3 aggregate placed with a polymer modified asphalt (though a more expensive seal coat) may provide a surface that needs no maintenance for 12+ years. When incorrect materials and/or application rates are used, or when poor construction practices are used, the life of the seal coat can be a matter of months or weeks.

What's the Solution?

The objective of this study was to evaluate the performance of seal coats and materials used statewide and develop guidelines based on cost and performance data regarding what materials should be used and where. District were surveyed on seal coat performance and field and laboratory tests were performed to evaluate wear resistance under different environmental conditions and traffic volumes. To assist in selecting materials for best performance, "Guidelines for TxDOT in Selecting Seal Coat Materials' was published as part of this project.

Project Number

0-6747

Status

Completed

link icon Copy link to this project.