Challenge

The facility expansion of the Govind Dairy Farm in Phaltan (East of Mumbai) included the construction of access roads for their fleet of milk tanker trucks. However, the site is characterized by non-homogeneous soils, parts of which are black cotton clays. These are common inorganic clays in India of medium to high compressibility, characterized by high shrinkage and swelling properties.

Black cotton soil is very hard when dry, but loses its strength when wet. As a result of wetting and drying process, vertical movement takes place in the soil mass. These movements lead to failure of pavement, in the form of settlement, heavy depression, cracking and unevenness. Poor drainage further complicates the subgrade, as the saturated clay further weakens the bearing capacity, resulting in more heaving and undulations in the road surface.

The expansion and moderinization of the dairy farm of the facilities included the complete reconstruction of a strong and durable access road for its fleet of vehicles.

Conventional Approach

Due to the very low CBR values of black cotton soil, excessive pavement thickness and very high quality aggregate are required for flexible pavements. Pulverizing black cotton soil and mixing with cement and moorum (local type of gravel with fines) may improve the engineering characteristics of black cotton soil, but this requires deep excavation and manual/mechanical processing of enormous amounts of soil.

Neoloy Geocell Solution

The client chose Neoloy Geocell due to its simple deployment and long term strength and durability. The total pavement structure was ~1m deep, comprised of:

• Subgrade – the top 40 cm layer of black cotton subgrade was stabilized with lime and compacted.
• Subbase – an additional 40 cm of locally-available granular subbase material was added.
• Base – Neoloy was then deployed in the base layer and filled with the same granular infill.
• Surface Cover – comprised of 7.5 cm of high quality “moorum” infill.

Both international and national PRS installation supervisors were on-site for the duration of the project. Personnel from all levels for the project – from the project managers to the work crew to the dairy’s management were pleased by the on-site training, the supervision by PRS, the ease of installation and the end-performance of the built access road.

Observations of the road some time after construction show road performed well with no significant settlement or rutting, despite heavy truck trafficking and monsoon rains, to the full satisfaction of the client.