The Federal Highway Administration (FHWA) has completed one of the most extensive highway research projects in history. The project known as LTPP (Long Term Pavement Performance) had the goal of improving pavement design, pavement performance and pavement preservation processes.
As part of this research, pavement temperature data from thousands of locations across the United States and Canada were collected. This information has been compiled in a database called LTTPBind. This information is commonly used in the Super Pave binder selection process.
Crafco has used this data to develop a product selection process for sealant to be used in pavement preservation treatments. Coupled with a treatment selection process you now have the ability to accurately determine the right Crafco product, for the right process, for the right pavement at the right time.
Product Selection Process
1. Evaluate pavement and determine pavement preservation treatment.
A) Crack Sealing: This process should be performed on pavements that are in good condition. That is defined as a pavement with a sound base and exhibits distress in the form of thermal or working cracks with greater than 1/8 inch movement. The procedure generally consists of sealing transverse cracks spaced 20 feet apart or more in order to prevent moisture from entering and deteriorating the subbase and incompressible material from interfering with thermal movement. See the Crafco Application Instructions for your chosen sealant to get specific directions on preparation and application. Generally, all crack seal operations include mechanically widening the crack. The expected life of this procedure is 5 to 9 years in most cases.
B) Performance Crack Filling: This procedure consists of filling cracks with low (<1/8 inch) movement in order to stop moisture from penetrating to the subbase of the pavement. If moisture is not checked, catastrophic pavement failure such as potholes will form. Another reason for crack filling is to stop crack raveling. Crack filling is a very cost-effective method of pavement repair that will add years to its life. Crack fill pavements that are in fair to poor condition on a regular basis to maintain or slightly improve their condition. A life of 6 to 8 years can be expected in most instances.
C) Joint Sealing: The sealing of concrete pavement joints is required to stop moisture from entering and deteriorating the subbase of the pavement. The most cost-effective method of ensuring optimum performance of a PCC pavement is by constructing a sound joint seal system that will last. For detailed information see the Crafco joint seal Product Data Sheet and Application Instructions.
2. Determine pavement temperature
Find the area of the country you are interested in on the map titled High Temperature on the Evaluation Guide. The dot will correlate to a temperature zone listed on the legend. For extreme traffic conditions (heavy, slow moving, pedestrian, parking lots) when crack filling the high temperature extreme should be increased one or two grades. Next, locate your zone on the Low Temperature map. When this is done you will have two Celsius numbers that represent a range of temperatures. The hot or highest number is always first. Please note that some of the -10°C areas on the low temperature map do not actually get that cold, and will classify as a -4°C area. This can be determined from the LTPPBind program.
3. Select appropriate Crafco product for your application.
Using the temperature range numbers determined in step one above, go to the Product Selection Grids corresponding to the treatment process you selected in step two above. These grids list the highly recommended products for specific temperature ranges. There are letters listed in the cell correlating to the hot and cold ranges you selected. Use the Product Summary page to match the letters to a specific Crafco product. Many products may also be used in other climates, as listed on the Product Data Sheets. Use the Product Summary page to check the specifications, and other characteristics such as if the product is thick or thin or if it has any other unique properties. If you have any further question your Crafco representative will be glad to assist you.
For a more detailed explanation of the selection process, refer to Crafco Product Selection Procedures, Product Data Sheets, and Application Instructions. Items contained in the grids are the most commonly used. Agency specified products are also available.