In road construction, a worn-out Portland Cement concrete can be rubblised and then overlaid with a new surface, usually asphaltic concrete. Specialised equipment breaks up the old roadway into small pieces to make a base for new pavement. This saves the expense of transporting the old pavement to a disposal site, and purchasing/transporting new base materials for the replacement paving. The result is a smoother pavement surface than would be obtained if a layer of asphalt were to be applied to the unbroken concrete surface. The technique has been used on roads since the late 1990s although it is relatively new to the Australian market. It can also be used for concrete airport runways.
The rubblising process provides many benefits versus other methods of road rehabilitation, such as crack and seat or removal and replacement of a concrete surface including: rubblising a concrete surface is 52% less expensive than remove and replacing concrete; rubblising reduces road reconstruction time, from days of lane closures to hours, providing large savings to contractors and reduced impact on travelling public; and rubblisation is an environmentally friendly “green” process.
The RPQ Group has acquired a “Badger”machine and has had a number of successful trials in NSW including the Newcastle Express Way and in Qld on various construction sites and on the M1 at Ready Creek. The Badger” is fitted with two lines of multiple falling weights called hammers that stick the pavement at pre determine intervals causing the pavement to break and then pulverised by the 2nd line of hammers and the machine travels over the surface.
This machine also can provide Crack and Seat as an alternative treatment. The Badger is set for the falling hammers to hit the surface one meter apart causing the concrete surface to crack into large 1mt x 1mts slabs. Following the cracking process, a heavy Multi Tyred Roller drives over the slabs and seats them into the subgrade to prevent the slab from shifting and during resurfacing. Hence the name crack and seat. It has been shown to be a cost effective method of re-purposing a concrete pavement that has reached its end of useful life.