Pradhan Mantri Gram Sadak Yojana
Low Cost Concrete Road for Villages
Dr B.B. Pandey, Emeritus Professor of Civil Engineering,
IIT Kharagpur
A bituminous road is damaged fast in high rainfall areas due
to poor drainage conditions, while a gravel road becomes
dusty, causing safety and health problems due to a cloud of
dust raised by motorised traffic, which is increasing by leaps
and bounds. Problems of dust and wet weather damage to
roads can be easily overcome by constructing a thin flexible
concrete road using innovative technology at a cost lower
than that of a bituminous pavement for equal traffic. The
surfacing layer of concrete can be as thin as 50mm for a low
volume of traffic, to about 100mm for about 50 commercial
vehicles per day. The paper describes construction of a road
in the village Rakhalgaria, close to IIT Kharagpur, using the
new technology.
The existing road had a formation width of 3.50m and the
road crust consisted of murrum/laterite boulder of 100mm
average thickness. The CBR of the subgrade was found to be
5 and the region has an average annual rainfall of 1500 mm.
The daily traffic consisted of about 30 iron-rimmed bullock
carts, 3 to 5 trucks carrying building material, 20 three
wheelers, 30 motorcycles and 100 bicycles per day. The
village has a primary school and fairs are held twice a year
with plenty of commercial activities.
Formation width was widened to 5.5m and a carriageway
width of 3.75m was adopted. A camber of 3.0% over the
subbase was provided by compacting murrum over the
existing murrum surface. An edge restraint of brick on end
edge was provided on either side of the compacted
subbase(Fig 1). A form work of cells of plastic sheets is laid
across the full width of the subbase so that a grid of square
cells with sides 150mmX150mm and depth100mm is formed
(Fig.2). The formwork is kept under tension.
300mm diameter plate. The equivalent elastic modulus of
the 100mm compacted flexible...