In Rhode Island, Corrao says micromilling avoids any damage to the asphalt below the milled surface. With conventional cold planing, Rhode Island officials were seeing some pavements break apart before the overlay was placed. “That may have had to do with the age and condition of the pavement, but it also had to do with the aggressive nature of the wider corduroy surface, the larger teeth of the cold planing machine hitting the pavement,” says Corrao.
Over the past couple of years, Rhode Island has micromilled and overlaid virtually all of the state’s Interstate and limited access highways. “We would usually micromill off the friction course, which is usually 1.25 to 1.5 inches,” says Corrao. “Then we would put back a new friction course of an inch to 1.25 inches.
“The benefits that we see are that micromilling is less damaging to the underlying pavements, and you get a much smoother ride in that interim period between milling and paving the new friction course,” says Corrao. “We are very pleased with the micromilled surface that is left and with the ability of that surface to accept the new riding surface.”