LOCATION:

Treatment Objectives:

• Increase the strength or bearing capacity of the base layer
• Save costs by milling the existing 80 mm asphalt layer into base - rather than removing it
• Avoid having to use gravel to modify the base layer
• Reduce the weakening base layer due to moisture - particularly in the spring thaw period
• Improve workability of clay base layer during construction, particularly compaction.

Construction Method:

The asphalt layer was milled into the base layer by milling with a Caterpillar RR250 road milling machine to a depth of 15 cm, and in some places, 300 mm. The CBR PLUS was then applied in a mixture of 250 : 1 parts water to CBR PLUS. The layer was then mixed well by milling again with the Caterpillar RR250 resulting in a finely grained homogenous layer with very even particle distribution. Using a grader, the top 150 mm was windrowed and the lower layer was then compacted using a 10 ton vibrating pad foot compactor and pull-behind wobbly wheel compactors.

Result :

The final result was a road with a smooth surface made up of fine gravel. This gravel is held in place by the clay so that the result is dust free and completely trafficable in wet weather, without slipperiness. As the soil was broken up into small (8-12mm) size particles during construction, the CBR dosing was very effective and even throughout the layer and the soil was easy to work with the grader. Compaction was quick and even, without any soft spots left behind. DCP values exceeded 100 after 1 month.

Original Road	Caterpillar RR250
Soil Before Compaction	Finely Ground even Graded Soil
30 Days After Completion	Hard Concrete-like surface. Little Dust