Pavement Preservation Journal, Spring 2015, Vol. 8, No. 1
By Phil Vandermost
Although an ounce of prevention is worth a pound of cure, even Ben Franklin might have found himself in a quandary, faced with responsibility for an aging road network that is “de-investing” faster than it can be maintained.
While a variety of inexpensive pavement preservation tools are available to agencies to correct initial signs of distress, treatment options become more limited and the cost of restoring asphalt pavement to acceptable condition increases exponentially as surface cracking becomes widespread, and moisture is allowed to penetrate to the road’s subgrade.
As cracking becomes more extensive, the window of time narrows for an agency to act and avoid costly reconstruction, resurfacing or recycling.
More agencies that have pavements left untreated due to reduced funding and conflicting priorities are turning to a preservation treatment called the scrub seal. In the past several years, major California county public works agencies – including Los Angeles, Riverside, San Bernardino and San Diego counties – have placed scrub seal in their permanent “tool box” of annual pavement preservation strategies. In addition to California, scrub seals are successfully performed by agencies throughout the United States, including Texas, Michigan, Indiana, Ohio, Arizona, Nevada, New Mexico, Tennessee and Utah.
According to the Los Angeles County Department of Public Works, a scrub seal is an application that is very close to a chip seal treatment, in which asphalt emulsion and crushed stone are placed on an asphalt pavement surface. The difference is that the asphalt emulsion is applied to the road surface through a series of brooms placed at different angles, which helps push the asphalt emulsion down into the cracks and ensure they are better filled, creating a better seal. When chips are applied to the emulsion, the pavement is further sealed.