Chapter 1: General Principles
Anchor: #i1000087Section 1: Overview
Anchor: #i1000092General
Seal coats, also known as chip seals, are simple, relatively inexpensive pavement surfaces that are highly effective if adequate care is taken in the planning and execution of the work. A seal coat is an application of a layer of asphalt binder covered with a layer of aggregate applied to an existing paved surface. TxDOT spends close to $180 million maintaining 186,600 lane miles of roadway, and seal coats are a very important part of TxDOT’s preventive maintenance program. Some seal coats are placed by state forces, but the majority are placed by contract as shown below:
|
Year |
Contracted Seal Coat, lane-miles |
State Force Seal Coat, lane-miles |
|
1999 |
10,950 |
3410 |
|
2000 |
17,740 |
3035 |
|
2001 |
17,350 |
2850 |
|
2002 |
16,665 |
2990 |
The average life of a seal coat or surface treatment is about six to eight years; however, some have performed successfully for periods of up to 20 years.
TxDOT specification Item 316, Surface Treatments, defines an application of asphalt material covered with a single layer of aggregate as a surface treatment. For purposes of this manual, an application of asphalt material covered with a single layer of aggregate when applied to a prepared compacted base is a surface treatment; whereas, a seal coat is applied to a paved surface.
This manual is intended to provide guidelines for the design, construction, and inspection of seal coats and surface treatments for contract and state force work. Both full-width seal coats/surface treatments as well as strip/spot seal coats are addressed. The manual is directed primarily to office and field engineers, laboratory personnel, and field inspectors.