Project Highlight: US-15 - St. George, SC | Cold In Place Recycling

We visited US-15 on April 10, 2025, to witness something somewhat new to us here in SC. Cold In-Place Recycling (CIR) has been around for many years, and it has been used several times as value engineered proposals in the past. Recently SCDOT has used this tool as rehabilitation tool on roads that carry higher traffic loads and want to minimize traffic disruption and other issues that typically incur in similar deeper rehabs used by the Department. This process is usually restricted to no more than 4.0 inches due to the process of reusing 100% of existing asphalt materials in place (all asphalt – no base materials) and mixed with approximately 2.0 percent PG 64-22 (foamed) where water is added along with 0.5-1.0% cement to aid in getting early strength and quick drying. This is a cold process much like typical cold milling, in which recycling efforts can also be used at the top of the exiting pavement if too far gone, that can be used later in RAP.  

On this project, the road was pre-milled approximately two inches and hauled off for RAP, and the CIP was done to the next three inches of in- place pavement. The mix is collected using a pickup machine using a windrow method and a conventional paver is used to provide proper shaping for grade, slope, and thickness controls. The initial mat appears as a dry mix that has been spot welded together by the foamed asphalt and compacted using larger than usual pneumatic and vibratory steel wheel rollers. Very shortly, a light application of fog seal (trackless) is applied using a distributor and sanding is done to provide a quality seal coat prior to allowing traffic to ride on the temporary surface. The road can be paved the same day or later as the road holds up to traffic very well and does not require a long curing period as required in other methods. Several heavy loaded trucks were witnessed traveling on the CIR with 30-60 minutes of placement. SCDOT felt strong enough with the decision to allow the project to go to directly through the town of St. George the day prior to their Annual Grits Festival. Several vendors were beginning to set up their trailers and equipment as the work progressed later the same day. The plan moving forward is to pave the route with a new HMA surface course in the coming days ahead after the festival. See pictures taken during the CIR operations at our viist.