Short Term Performance of an Innovative Cold In-Place Recycling Technology in Ontario

Cold In-place Recycling (CIR) is a pavement rehabilitation method that processes an existing asphalt pavement in situ, sizes it, mixes in additional asphalt cement, and lays it back down without off-site hauling and processing. The added asphalt cement is typically emulsified asphalt. An innovative development in CIR technology is the use of expanded asphalt, rather than emulsified asphalt to bind the mix. The Ministry of Transportation Ontario (MTO) constructed a trial section of CIR with expanded asphalt on Highway 7, east of Perth, Ontario in July, 2003. The 5 km trial section of CIR with expanded asphalt was constructed adjacent to 7 km of conventional CIR. Placement resulted in a fairly smooth, hard, uniform surface suitable for temporary traffic, and provided a good platform for hot mix paving operations. The CIR with expanded asphalt placement progressed in a continuous and efficient manner, placing 5 km over a three-day period. To evaluate this innovative technology, Falling Weight Deflectometer (FWD) testing was carried out immediately after construction and in the year following construction to compare the CIR and CIR with expanded asphalt technologies and to assess the change in strength of the pavement structure over time. Evaluation of pavement roughness and rutting was also carried out using MTO’s Automatic Road Analyzer (ARAN). FWD and ARAN results for 2003 and 2004 indicate that the CIR and CIR with expanded asphalt pavements are performing similarly. Cores were obtained of the CIR and CIR with expanded asphalt pavements and resilient modulus testing was carried out according to ASTM D4123-82, Standard Test Method for Indirect Tension Test for Resilient Modulus of Bituminous Mixtures. Analysis of Variance showed the resilient modulus results for CIR and CIR with expanded asphalt to be statistically the same. Based on short-term results, CIR with expanded asphalt appears to provide an acceptable in-place recycling rehabilitation strategy that provides an economic alternative to conventional CIR, reducing the curing time, and extending the construction season.