ACP Texas Contractor, Volume 160, Number 12, December 2012
By Paul Fournier
Slurry seal preventive maintenance treatment gets a boost from advanced highly modified asphalt emulsion in street trials
The city of Dallas recently applied micro surfacing containing an advanced asphalt emulsion as part of its annual preventive maintenance program.
Highly modified asphalt (HiMA) emulsion was substituted for latex modified asphalt emulsion by the Department of Street Services in the micro surfacing of 4-1/2 lane miles of local streets.
Responsible for maintaining 11,800 lane-miles of streets serving the city’s 1.2 million residents, Street Services has an annual operating budget of more than $70 million that includes a substantial allotment for preventive maintenance. This funding allows the department to treat about 245 lane-miles of pavement each year with slurry seal and micro surfacing. These surface treatments play important roles in the city’s preventive maintenance program, according to Ben Cernosek, P.E., Assistant Director of Street Services.
“Over the last several years our budgets have included the financial resources approved by the City Council to not only keep our streets from deteriorating but to improve their overall condition. A big reason for this is our use of micro surfacing and slurry seal,” said Cernosek.
He said they have a systematic approach to pavement management that utilizes sophisticated sensors and instruments to read and record various pavement characteristics. This approach enables them to rate street pavements, establish maintenance and repair priorities, and choose the most cost-effective treatments to correct problematic conditions.
“With this type of approach we’ve been able to continuously upgrade the overall condition or our city streets, from an evaluation of 60% satisfactory in the 1990s, to approximately 87% satisfactory this year.
“We really believe in preventive maintenance because it can extend the service life of pavements by a factor of three at one tenth the cost of a hot mix overlay,” Cernosek said.
“And we’re always looking for ways to improve, to try ways that can extend the life of our pavements even longer. That’s why we decided to apply the HiMA micro surfacing on a trial basis,”
he said.