Short Term Performance of Innovative Precast Concrete Slab Repairs on Highway 427, Toronto

In 2004, the Ministry of Transportation Ontario (MTO) carried out a trial project to evaluate construction techniques for precast concrete slab repairs in concrete pavement. The trial was carried out on Highway 427, in Toronto. The trial project included demonstrations of three precast concrete pavement full-depth repair methods: the Fort Miller Super-SlabTM Intermittent Method, the Fort Miller SuperSlabTM Continuous Method, and the Michigan Method. Each method involves designing and fabricating precast concrete slabs to replace deteriorated concrete pavement. The methods differ in how the base is prepared and how the precast slab is installed and dowelled into the existing concrete pavement. Nondestructive testing using a Falling Weight Deflectometer (FWD) was undertaken after construction to assess load transfer efficiency (LTE) and to detect loss of support underneath the precast slab. Details of the methodologies, site conditions, contract specifications, construction, FWD analysis and post construction monitoring are presented. Based on MTO experiences with this trial contract, a specification has been developed and additional precast work will be carried out in 2007. This is the first construction experience in Canada with innovative precast concrete slab repairs for concrete pavements. MTO will continue to monitor the field performance of these technologies and assess the cost effectiveness of this alternative to full-depth fast-track concrete repairs.