Heat Design Equipment Inc. of Kitchener, Canada, successfully completed a hot in place joint repair with new equipment designed to heat scarify, level and compact the longitudinal joint at speeds of up to 5 feet per minute. The job involved two longitudinal cracks on Industrial Drive in Cambridge, Ontario.
The recycling train consists of twelve double rows of HDE 4 foot long infrared heaters. Attached to the last set of heaters is a simple assembly of agricultural cultivator tines that scarifies the heated asphalt to the depth of the surface course. Along with scarification an asphalt rejuvenator is sprayed on via a pump and nozzle assembly near the scarifiers. A bit of sand mix is added, then a specially constructed adjustable spreader box levels and pre-compacts. The repair is finally hand luted and then compacted with a vibratory roller.
This process solves an age old problem of the longitudinal joint being too wide for crack filling, or cracks spreading from the joint so that crack filling is not feasible. To date, the most practiced procedure for this condition is milling a strip and replacing with new hot mix, but this leaves two more edge cracks with the potential third crack reflecting through the surface repair. Heat Design's process leaves two hot seamed, structurally bonded edges and is expected to extend the life of the pavement an additional 5-6 years. If a reflection crack does occur, the owner can start back at a crack filling program.
The next phase of development is expected to allow repair speeds of up to 10 feet per minute.