Sibley County, for the first time this summer, is using a procedure to recycle old asphalt pavement for the CSAH 2 south and north projects near Gibbon.
Cold In-Place Recycling grinds off the top two to six inches of old asphalt pavement, crushes and screens it to size, mixes it with an asphalt recycling agent and sometimes other additives, and then paves it on the same roadway. With a chip seal or hot-mix asphalt overlay, the Cold In-Place Recycling lift removes deep cracks to form a rut-resistant base at a cost-efficient price.
According to information provided by Sibley County Public Works Director Darin Mielke, Cold In-Place Recycling makes sense when defects in the old pavement do not run the full depth of the pavement, yet are too deep to be corrected with mill-and-fill or hot in-place recycling. The procedure doesn’t make sense when pavements have structural, drainage or base deficiencies. Cold In-Place Recycling is often popular in rural areas, far from asphalt production facilities, because it reduces the amount of new materials needed for a strong road, and it is popular in cold climates because it offers a combination of excellent flexibility and rut-resisting stone-on-stone contact.
Mielke said Le Sueur and Brown Counties have used the Cold In-Place Recycling in the recent past. He felt that CSAH 2 was an ideal place to try the procedure because the roadway had a little rutting but a lot of cracking patterns. By using Cold In-Place Recycling, Mielke estimated Sibley County will realize short-term savings of $70,000 for crack-filling the 14 miles of roadway. He also believes that by using this procedure, the roadway will be able to last longer before it will need an overlay.
Initially, however, Cold In-Place Recycling costs more per mile than the straight overlay. Mielke estimated that Cold In-Place Recycling with paving costs approximately $250,000/mile, while the one and a half to two inch standard overlay costs approximately $125,000/mile.
An advantage for the procedure is that minimal trucking of material was needed from the County gravel pit. Approximately two to three miles can be completed each day.
When watching the procedure being completed, it looks like a short train. First a machine mills the existing pavement, then it is crushed. Oil is added, and the material is placed back on the road. Central Specialties of Alexandria was awarded the contract for CSAH 2 north and south. Central Specialities subcontracted with Mid State Reclamation and Trucking of Lakeville for the Cold In-Place Recycling work. Once CSAH 2 is completed, the weight restrictions, which had varied from seven to nine tons, will be upgraded to 10 tons, according to Mielke.
Mielke hopes that Sibley County will continue to use the Cold In-Place Recycling process. It is a good technique for certain roads, he explained, but the hard part will be the funding. State aid funds won’t cover the entire cost, Mielke said. “I hope after we get this project done and get good results, that the County will want to continue to do the Cold In-Place Recycling,” he said.