Cold in Place Recycling (CIR)

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Cold-in-Place Recycling (CIR)A cost-effective paving solution with minimal traffic disruptions.

Presented by: Quirin Klink, PE


Leading this CIR paving train are two trucks in tandem (far right) delivering water and liquid asphaltic material into the CIR machine (middle machine). Inside the CIR machine, the hot asphaltic material foams when combined with the cold water. The CIR machine removes 3-4 inches of existing pavement, crushes it to specified size Recycled Asphalt Pavement (RAP), and then mixes it with the foamed asphalt. Once adequate coating is made to the RAP material, the CIR machine sends the coated RAP via conveyor to the separate asphalt paver (far left) that trails behind, ending the paving train.


Close up of the water truck (yellow) and asphaltic material truck (silver) as they ride tandem. The worker is reattaching the water truck to CIR Machine.


This is the first project in Wisconsin to utilize this specialized type of CIR machine (foreground) that combines the milling operation, foamed asphalt injection, and RAP processing/mixing operations in one machine. Many interested Wisconsin DOT engineers and an asphalt industry magazine attended the field day hosted by Mathy Construction, parent company of DL Gasser Construction of Baraboo, WI, the contractor on this project.


Bobbi Maxwell, PE and Quirin Klink, PE of MSA, view the CIR process. MSA designed the CTH H project.


Just ahead of the CIR paving train, a separate milling machine removed several inches of existing pavement on the outside four feet of pavement and lays it down in a wind-row for pick-up by the CIR machine that follows. This separate milling operation was required because the CIR machine was not equipped to remove the full width required on this CTH H project.


A closer view of the CIR machine, travelling slowly left to right. This is the first time this type of specialized machine has been used in Wisconsin.


The CIR machine mills off several inches of existing pavement, as well as picking up the wind-row of material from the previously milled outside edge (described in a previous slide).


The last part of the CIR paving train is a standard asphalt paver, which lays down the CIR material similar to a normal Hot Mixed Asphalt application.


Bobbi Maxwell, PE, project designer for MSA, watches as the CIR machine’s conveyor drops the CIR material into the trailing asphalt paver.


The standard asphalt paver lays down the CIR material similar to a normal Hot Mixed Asphalt application. After a specified curing process, the CIR material will be covered by traditional Hot-Mixed Asphalt (HMA).


Roller compaction process follows the CIR paving train.


On this two-lane rural highway, the CIR construction process was performed under live traffic with moving lane closures using flag persons.


The finished product of the CIR process, shown on the left lane here, can carry traffic shortly after the roller compaction has been completed. After a specified curing process, the CIR material is normally covered by traditional Hot-Mixed Asphalt (HMA). The thickness of the final HMA layer are thinner than what would normally be required over normal base aggregate because the CIR material is a stronger, more durable base, creating the economic viability of the process. The Sauk County Highway Department applied this process to another county road 10 years ago and the Highway Commissioner has indicated it has held up exceptionally well, with approximately 50% reduction in cracking.

Engineering

Cold in Place Recycling (CIR)