Author(s):
C.K. Estakhri, S.P. Senadheera
Publication Date
April 2017
Abstract
The primary functions of a seal coat are sealing and protecting underlying pavement layers while providing an abrasive surface with adequate skid resistance. Many factors affect the performance of seal coats, including properties of the asphalt and aggregates, strength and condition of the existing pavement, construction techniques, and the amount and types of traffic. The useful service life of a seal coat generally ends due to cracking or loss of skid resistance. Loss of skid resistance can be the result of aggregate polishing, loss of macrotexture from aggregate reorientation, or asphalt flushing. Loss of macrotexture is sometimes due to the use of softer aggregates that polish, wear, and break down under traffic.
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. 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.
The research team conducted a laboratory test program to evaluate the durability and wear characteristics of aggregates commonly used for seal coat construction. They also sampled commonly used seal coat binders from construction projects and tested the binders in the laboratory to evaluate their propensity for flushing characteristics.
To assist in selecting materials. the Guidelines for TxDOT in Selecting Seal Coat Materials was developed as part of this project.
Report Number:
0-6747-S
Link(s):
Document/Product
http://tti.tamu.edu/documents/0-6747-S.pdf
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