Evaluation of Curing Effects on Cold In-Place Recycling (CIR)

Status:  Complete
Report Date:  05/31/2022


A cost-effective and environmentally friendly asphalt repaving method will now be more efficient. Cold in-place recycling (CIR) involves pulverizing the top layer of old pavement, mixing it with a stabilizing agent such as emulsified asphalt, and repaving and compacting the CIR, typically in a 3-4” thick lift. A final layer is added to seal and preserve the recycled pavement layer. This process minimizes the need for using new material and transporting materials to and from the construction site. The recycled asphalt layer, however, must sufficiently harden before the top layer can be placed. Local road engineers needed to know how long it will take for curing to occur. New research identifies the factors that impact CIR pavement curing, including the types of materials used, the outside temperature and the compacted density of the recycled asphalt. Researchers developed a Curing Prediction Model spreadsheet and guidance to reliably estimate the process time. This new knowledge will help to optimize construction schedules and minimize traffic disruptions.

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