This paper was presented at the `Pavement cost and performance evaluation strategies' session. Cold in-place recycling is a technically established, cost-effective method of strengthening and maintaining a wide range of deteriorating asphalt pavements. A significant reduction in reflection cracking of asphalt concrete overlays is achieved. Laboratory work and a number of projects have demonstrated that modification of the cold in-place recycling process to incorporate new aggregates results in closer voids and stability control, addressing observed problems such as flushing, high passing 4.75 mm and 75 m, rutting and strengthening. The overall performance of eight Ontario cold in-place recycled asphalt projects, completed since 1991, was evaluated in the field and laboratory. All of the pavements were in good condition with no rutting or reflection cracking. Pavement structure equivalency factors for cold in-place mix, compared to conventional binder course asphalt concrete, have been developed. Resilient properties were determined with the Nottingham Asphalt Tester and used in the BISAR mechanistic design program. There is an increase in structural equivalency factors with time, as anticipated with the use of emulsions, reaching a granular base equivalency of 1.8 to 1.9 after two years. The modified cold in-place process can be coupled with asphalt concrete overlay Superpave technology for enhanced cracking resistant flexible pavements. (A)
Abstract