Pavement Preservation Journal, Spring, 2012
Drivers in the San Antonio District of the Texas Department of Transportation (TxDOT) are benefiting from the use of a new high performance asphalt emulsion for seal coats that is providing longer-lasting chip seals and optimizing traffic flow through work zones. There are three “tools” from the “Pavement Preservation Toolbox” that the San Antonio District uses to prolong road life. They are thin asphalt overlays, micro surfacing, and seal coats.
“You might call them chip seals, but we call them seal coats,” said John Bohuslav, P.E., director of maintenance, TxDOT San Antonio District 15. Some 99 percent of San Antonio District pavements are surfaced with either chip seals — called “seal coats” in the local lingo — or asphalt lifts.
Seal coats are critical to keeping San Antonio District pavements in keeping with TxDOT goals of achieving 90 percent of roads in good or better condition. A pavement condition index (PCI) of 70 or greater is considered good or better.
Today, a CHFRS-2P asphalt emulsion — a cationic, high-float, rapid-set emulsion in the No. 2 viscosity range with polymer added — is solving adhesion and slow break problems endemic to lower-performance emulsions that had been experienced by the district.