A stretch of Chestnut St near me (Rt 9 – Beacon St) has been under construction for a while.  Today’s mayor’s newsletter describes a new paving process that’s being used on that stretch as well as on the current repaving going on right now on Dedham St.  Here are the details ….

 

In a typical road rehabilitation, the old, deteriorated pavement is dug up and hauled away. Then new material, manufactured at a blacktop plant, is transported to the paving site. Our Chestnut Street and Dedham Street projects are about 1.25 miles so all those trucks and wasted existing material plus the new materials have a huge environmental impact. Also, all the steps take a lot of time.
 
The cold in-place recycling process works like this:  
  • A huge cold in-place recycling machine mills off the top 4 to 5 inches of asphalt. Inside the machine, a 12-foot wide milling drum crushes the old asphalt and mixes it with new liquid asphalt and Portland cement additives to revitalize the material.
  • Once the milled material has been well blended with the stabilizing additives, the revitalized mixture is deposited back onto the road with a paver machine.
  • Next, large compactors roll over the surface to compress the material and achieve the required density. After compaction, the recycled road can be re-opened to traffic very quickly. All of these steps are done in one day.
  • The newly paved and drivable surface then “cures” for two weeks.
  • During the two-week curing period, all manholes and other utility structures are raised in preparation for the final topcoat of pavement. 
  • After the two weeks of curing, a wearing course of 1.5 inches of new hot mix asphalt is applied. With the strong cold in-place recycled base, this wearing course can be preserved to ensure these roads last and provide a smooth ride for 15 to 20 years. (The method we used to use required repaving in about 10 years.)
By using cold in-place recycling paving instead of removing and replacing the pavement material, greenhouse gas emissions are cut by about 40%, 100% of the in-place material is reused, construction delays are dramatically reduced, and a longer lasting road is created.