CALCUTTA METRO RAILWAY
A CASE STUDY
THE USE OF CICO PLAST
SUPER AS AS ADMIXTURE
Metro Rail Project :
Requirements
The Metro Rail Project at Calcutta involved
construction of an underground tunnel in the city. During the first phase of the
construction work, the job was divided amongst a number of contractors.Numerous
difficulties were experienced by the contractors working on the project especially in mass
concreting by conventional methods.
The numerous construction joints and porous
concrete, turned out to be a source of heavy water ingress into the tunnel. And the tunnel
had to be reasonable dry for operating Metro Services on schedule and undisrupted. The
heavy water ingress during construction disrupted work schedule delaying the services
significantly.
The second phase overcomes
the problem
With the experience gained
during the first phase of the construction work, Metro Rail Authorities wanted to ensure
that the second phase had a smooth sailing.Especially because the route of the RTS box in
this phase passed through very densely populated areas of the city with very heavy
traffic.It was impossible to carry out concreting in this phase by conventional method
because of space constraint at site.
New Method of Construction
The operational problems stated above called
for setting up of the batching plant about three to four Kms away from actual
site.Transportation of the concrete mix to the site of placement by means of transit
mixtures and agitator cars.
With this planned solution the Metro Rail
authorities awarded the contract for the entire job to Mesrs. Hindustan Construction Co.
Ltd who had all the resources, infrastructure techniques & Technologies available with
them to handle the project.
CICO - Becomes a Partner
in Progress
The concrete specifications required that the
initial slump of the batching plant should be around 190 - 200 mm but not less than 150mm
at the pouring point. The time estimated between making and placement of the concrete was
around 1.5 hrs.to 2 hrs.This is the time when CICO got involved with Hindustan
Construction Ltd. and set about designing a concrete mix with a super placticiser as an
admixture to provide the desired results laid down.The process of designing a concrete mix
involved many critical trials and the concrete mixed design finally evolved, using CICO
PLAST SUPER - a new generation superplasticiser based on a blend of molecular weight
polymers to suit Indian conditions.
CICO PLAST SUPER is a superplasticiser with
that degree of slump retention characteristics which enable a flowing concrete to placed
despite a considerable time gap between mixing and placing.The significant advtg. of this
admixture over conventional European Superplasticiser lies in its compatibility with high
ambient temp. in places like in India.
CICO-Concrete Mix Design Deliver Result
The concrete produced out
of the concrete mix design with admixture of CICO PLAST SUPER got an initial slump of
200mm at the batching plant. After 1.5hrs the slump was 150mm at the pouring point.And the
concrete was still plastic enough for placement by means of a variable discharge concrete
pump at the rate of 60 CUM per hour
the desired results
obtained thus enabled Hindustan Construction Co. and Metro Rail Authorities to decide
finally on adapting mix design with CICO admixture for the concreting work of the second
phase.
Metro
Rail Project's Second Phase Progressing Smoothly
Hindustan construction Co. has already placed
30,000 CUM out of a total of 2,00,000 CUM of concrete till date without any problems .And
the construction work is going on schedule.CICO is proud of this achievement and becoming
a partner in progress.Saving time and cost over runs for Metro Rail Authorities.Helping
modern means transit system reach millions of residents of Calcutta Metropolitan city on
schedule. |
