GRT India Managing Director Ben James highlights the need to stabilize soil or aggregate to construct better roads & optimally use scarce resources in India.
Construction World – January 2017 page
Indian
road
infrastructure
is undergoing
phenomenal
growth for the
15 years and
will continue
to grow at
higher rates in
coming years
under the
Ministry of
Road.
Transport
and Highways. .
Accordingly,
the requirement
of soil or
aggregate for
infrastructure
has increased
and reached a
level where
availability of
basic materials
has become a
constraint on
development.
Non-availability
of suitable
soil and
aggregates has
made projects
unviable and
cost-prohibitive.
Some projects
are running
into
significant
overruns as a
direct
consequence.
All these
factors have
delayed several
important
projects, and
in some cases
state
governments are
even denying
development in
certain
aggregate-deficient
regions. This
scarcity will
increase
further
considering
environmental
conservation
and restriction
on mining in
several states.
Although
aggregate
scarcity is a
pan-India
problem, it is
most pronounced
in northern
Uttar Pradesh,
Bihar, Odisha,
West Bengal,
Punjab and
Haryana.
It
is public
knowledge that
the ministry is
considering
making the use
of road
recycling
(reusing
in-situ
materials)
technologies
mandatory for a
significant
percentage of
road
development in
these states.
This will help
increase the
speed of
construction
and close the
gap on Minister
Nitin
Gadkari’s
target of 40 km
of National
Highways per
day. Also,
India has an
existing road
network of over
4,689,842 km.
the second
largest in the
world. Most of
these roads are
in poor
condition and
need
rehabilitation
and constant
maintenance.
The government
is also
widening and
extending these
existing
highways and
state
expressways.
Stabilizing Soil
The
stabilization
of soil or
aggregate is
being used
worldwide
towards optimal
usage of scarce
resources.
Although soil
stabilization
has existed in
Indian codes
for the past
several
decades, in
reality, the
concept is yet
to be utilized
on ground in
any
significance,
whereas other
western
economics use
recycling
technology
extensively.
The concept of
cold in place
recycling’
(CIPR.) has
recently been
incorporated in
I RC-37(2012)
and CIPR. and
cement-treated
base (CTB) has
been approved
by NHAI in a
few projects,
such as NH-2 by
contractor CRT.
This is only
just starting
to be applied
as general
practice.
These
two concepts
– soil or
aggregate
stabilization
and CIPR
provide a
comprehensive
solution for
rehabilitation
of the existing
road network
and greenfield
road
construction.
The
incorporation
of proper
stabilization
techniques
involves
sophisticated
and heavy
equipment of
German make,
ensuring more
durable and
longer lasting
roads.
Irrespective of
which region we
refer to, the
techniques work
for all roads
pan-India.
The GRT India Process
The GRT India road stabilization process can be divided into three major components:
- Design process and codes: Stabilization and CIPR requirements in Indian design codes have been adopted from AUSTROADS. (Australia) and need further updating with respect to gradation requirements of materials to be stabilized. The material requirements and envelope shall include larger size particles and shall be flexible as soon as strength requirements arc met. The use of CTB and ClPR. provide far greater strength than conventional methods. This modification will allow engineers to utilise existing materials up-to GSB layer (granular base layer). This will also allow usage of locally available marginal materials. Specialized laboratory equipment also needs to be developed in India; currently, this is being imported at a high cost. After witnessing the incredible speed of construction when CIPR technology is used, many firms arc now opting for ‘redesign’ of their pavements and requesting the same be approved for incorporation by NHAI.
- Stabilization agents (materials): The stabilization process is the recycling of damaged wear surface homogenised with in-situ base lair beneath char can use a wide range of agents, i.e. soil-aggregate mix, lime, cement, fly-ash, foundry sand, slag, foamed bitumen, emulsion, polymers and other proprietary chemical stabilizers. These materials are readily available in India and there is a shift to ensure further incorporation of these materials in road construction.
- Stabilization equipment: Specialized GRT India heavy road recyclers capable of cutting existing soil or aggregate or asphalt, mixing in place, adding water and other stabilization agents as per requirement, speed independent stabilization agent spreader (cement, lime. polymer etc.), heavy pad-foot rollers (20 tonne static and 40 tonne dynamic capacity) and pneumatic tyre rollers are essential components of the stabilization process in general. Currently, only a select few have these type of machineries and capabilities in India. There is also only a handful of specialized manufactures who have taken the initiative to set up in India. However, there is no current production of these machines in India. Both ClPR. and equipment manufacturing are potentially massive growth sectors, especially once ClPR becomes mainstream. Through this technique, one can expect approximately 5-10 per cent reductions in the cost.