Soil Stabilization and Dust Control Blog: Gravelock

We recently rehabilitated a section of a haul road, in a sugar cane plantation near Laibin in Guangxi Province, in Southern China. This haul road carries approximately up to thirty to fifty, two axle, trucks ranging from 10 to 30 ton loads per day.

The road was treated with CBR PLUS to improve its performance in both wet and dry weather and most importantly to reduce maintenance. Typically, when untreated, these roads have to be rebuilt once a year or at times even more frequently. The area is also prone to high rainfall with a monsoon season and during the sugar cane harvesting season, there is rainfall almost daily.

The soil is reddish brown, silty clay, with 15% coarse material content in the range of 2 to 10 mm sized particles. The rest of the soil is very fine grained and contains some very fine-grained silt and clay. The liquid limit 42.7, plastic limit 23.7, plastic index is 19%. Actual clay content is 33%.

In view of the high axle loads and essentially a good sub base, it was decided to scarify and treat to a depth of 20 cm. The dosage rate of the CBR PLUS was 0.008 liters per square meter.

The first step was to clear and reshape the road with the drains being cleared and formed at the same time. Three hoes were used for this purpose. The hoes were then used to break up the surface of the road and break lumps to a depth of 20cm. Half the dosage amount of CBR PLUS was poured into the water tanker and sprayed onto the road surface. The layer was then scarified using a tractor and rotary hoe, which mixed the layer and broke down the larger lumps. The rest of the CBR PLUS/water mixture was then sprayed onto the surface and the layer was then scarified again.

Final shaping was done with a hoe and some hand labor. The layer was then compacted with a smooth drum roller compactor. The road was then sprayed twice a day with a light application of water to cure.