Hot In-Place Recycling (HIR) is an in-situ rehabilitation process that involves heating and scarifying an existing pavement surface, mixing in rejuvenator (recycling agent), fine aggregate or beneficiating hot mix as required, placing an optional integral hot mix overlay and then compacting the mixture in one continuous operation. The Ministry of Transportation of Ontario has been utilizing HIR technology since 1987 as one method of rehabilitating structurally-sound pavements that are exhibiting surface distresses. Over the past nine years, HIR has proven to be a viable alternative to conventional recycling of asphaltic concrete pavements. HIR has been shown to have advantages over conventional rehabilitation treatments including: the ability to the place a thin integral overlay as a wearing surface; conserve non-renewable resources and energy; and allowing for 100% recycling of the reclaimed asphalt pavement (RAP), resulting in zero-waste. This paper provides an overview of the evolution of HIR technology in Ontario and the effectiveness, limitations and performance of HIR, including a review of pavement distress surveys and roughness measurements. Also discussed is the progress made by the construction industry and the Ministry to improve the equipment, quality assurance testing procedures, and mix design methodology to produce a pavement that meets the Ministry's high standards in providing a safe, comfortable and durable roadway for the travelling public. (A)
Abstract