Asphalt milling has a rich history. It is mainly a process of removing thin layers of asphalt (typically up to one inch in depth) from the roadway surface. Full-depth milling, a preparation commonly used for asphalt road repaving, became economically viable due to reusing milled aggregates as reclaimed asphalt pavement (RAP).
This recycling method, which gained prominence during the oil crisis in the early 1970s, led to the creation of the Roto-Mill milling machine. Modern milling machinery has evolved into precise, sophisticated equipment that can control the depth and grade and create smooth surfaces when required.
Micro-Milling and Other Methods of Resurfacing Bridge Decks
The current asphalt milling process stands out for its precision and adaptability. With its customizability, modern milling machinery can address various road issues. Whether it's improving road quality, preparing for overlaying, enhancing water drainage, or addressing distressed asphalt, this adaptability makes asphalt milling a reliable and effective solution for various road maintenance and construction needs.
Related Article: Improving Asphalt with Balanced Mix Design
Roadway Milling Machine
The Benefits of Micro-Milling and Scarification
Concrete scarification is a mechanical process that removes a thin layer of surface material from concrete without creating deep grooves. Bridge deck scarification is usually specified when a smoother surface is desired for applying waterproofing materials or placing overlay courses. Modern milling machines with the cutting drum bits spaced as little as 2/10" apart can produce tighter groves in the pavement, called micro-milling.
Micro-milling can achieve a smoother surface that holds less water and does not reduce tire friction. The dense graded asphalt mix surface can be micro-milled with similar results. This process was recently utilized in New York City on the Verrazzano-Narrows Bridge upper bridge deck overlay project.
The transportation agency, MTA Bridges and Tunnels, needed to reduce the deadload on the bridge. They decided to partially mill the existing waterproof wearing course as a solution. This approach allows MTA to preserve the existing overlay without replacing it with a thinner one. They achieved this using a micro-milling machine on the bridge's Rosphalt-modified wearing course. The Rosphalt mixes can be used in a thin 1.0-2.0-inch deck overlay that is highly resistant to rutting and shoving.
Related Article: Repairing Waterproof Membranes for Bridge Decks
Initially, the micro-milled area was created and tested for skid friction, which showed better results than from the exiting surface.
Micro-Milled Bridge Overlay Surface
Chase Construction Product's asphalt additive, Rosphalt 50, creates a one-step solution for waterproofing wearing courses for bridges and can be used in high-stress areas where superior performance is necessary, such as toll booths, airports, racetracks, and industrial pavements. If you have any questions or require information for your next paving project, please visit the Chase website at www.chasecorp.com/Rosphalt.
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