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Road rehabilitation by COLD IN-PLACE RECYCLING of asphalt roads on clay.
Wed Dec 07 2011 at 9:46 pm +0000

Gravel preservation on unpaved rural roads has become the prime concerns for road maintenance by the Saskatchewan Regional Municipalities. This concern was highlighted in the recent study of the Department of Highways and Transportation on graveled roads in Saskatchewan and is heightened by the new practice whereby heavy axle load traffic gets diverted off the paved highways onto the gravel paved roads.

While current practice of Counties is to treat the surface on gravel surfaced roads with the application of dust palliatives such as calcium or magnesium chlorides, lignin sulfonates and asphalt emulsions in an effort to reduce gravel loss and dust, these mediums have been proven to be a temporary measure, which at best last one season or less. Gravel loss is mitigated and surface gravel is retained somewhat until these materials become leached out or otherwise ineffective. In areas with clay in the road base, this surface treatment is much less effective and gravel loss is exacerbated by the effects that the clay exhibits on the road and, particularly in wet weather, the gravel is pounded into the road base. Also due to the effects of poor base strength rutting and other deformation occurs in the wheel paths. Loose gravel is ground up onto fine powder and increases the dust on the roads.

Gravelock Technology addresses this problem and reduces gravel consumption on gravel surfaced roads by locking gravel into the road surface and so reducing gravel loss as well as reducing the need for gravel during initial construction by strengthening local soils. Gravelock improves road traffic-ability in wet weather and also helps to reduce dust in dry weather.

Gravelock is designed to increase the osmotic and matric suction of typical clay based soils, while reducing the moisture susceptibility. It is this behavior that increases the strength and stiffness of typical clay based soils, while also locking in the gravel to minimize gravel loss. This treatment is long term and reduces both maintenance and dust by up to 80%. Roads can be repaired after treatment without having to re-apply more Gravelock. Payback for many clients in Canada is less than 18 months.

Road rehabilitation by COLD IN-PLACE RECYCLING of asphalt roads on clay.
Wed Dec 07 2011 at 9:46 pm +0000
Cold in place recycling or Full Depth Rehabilitation, is the most cost effective method available today for the rehabilitation of existing paved roads.

The top layer of asphalt or seal is milled with a Road Re-claimer or road milling machine to various depths (usually 15 to 30 cm.) depending on the thickness of the asphalt layer, so that the existing asphalt is broken down into small pieces. This milled asphalt is then mixed with the base material during this milling process.

Gravel (course grained materials) bases or sub bases are then stabilized by the injection of hot foamed asphalt during the milling process to compact and bind the gravel particles. This treatment binds the gravel particles together during their placement and also reduces the future effects of moisture in the treated layer.

This foamed asphalt process however cannot be used where the base contains fine-grained or clay soil with a plastic index higher than 6.

 

CLAYS, or fine-grained soils, can likewise be treated by injecting a CON-AID / Water mixture instead of the foamed asphalt into the milled layer during milling.

The effects of the CON-AID is to release the adsorbed or bound water from the clay particles and facilitate better compaction for higher resulting densities, while at the same time stabilizing the clay to reduce the effects that moisture will have on the treated layer.

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