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Manhole
Cover / Assembly System
Open
Manholes: A Social Problem: Open manhole in cities and
towns are traffic hazards, eye-sores to the citizens and
road users, if not properly and firmly covered, these became
death traps. Conventional solutions like the use of sand
stones, RCC covers have limitations, whereas the cast-iron
manhole covers are prone to 'pilferage', as reported by
the local authorities.
Acceptable
Technical Solution : The Developement of precast concrete
manhole covers/ frames based on plastic-fibre, reinforced
concrete(PRFC) - under the Rgistered trademark of 'POLYCRETE'
was pioneered by O.P. Ratra, a Plastics expert, in india
way back of during 1982. This indian development, has been
widely acclaimed in the country, and world-over having been
demonstrated at International Conferences / Seminars held
in Germany (1986), U.K.(1989 and 1992) and shaghal (China)
during 1990.
The
precast Polycrete-PFRC Manhole cover system was the first
organised attempt in india during 1982-83,a nd since than
it has been made available to user-departments all over
the country from kashmir to kanya-kumari, and over a period
of 20 years has instilled confidence with the local authorities.
The technical usefulness of this innovative manhole cover
system has also been apreciated in advanced countries.
TAILOR
MADE:
The precast Polycrete-PFRC Manhole cover system is tailor-made
meeting the technical requiements of the local autorities,
as also that of IS: 1726-1991, and 12592 (Part1 & 2
1998-1991 revised), complimenting various grades (LD-2.5,
MD-10, HD-20 and EHD-35 tonnes test loads) and other stipulations
like clear opening/shapes, depth and seatings.
NO
SCRAP VALUE:
Precast Plastic Fibre reinforced concrete (PFRC) Manhole
covers/cover assembly have no scrap value, thus will not
attract any pilferage commonly met with conventional CI
manhole covers system. Ths is one of the unique characteristics
of PFRC manhole covers/system, and this helps minimize extra
financial drain on the part of local authorities concerned
with maintenance of open or semicovered manholes in cities
and towns.
FIELD
EVALUATION:
During the period 1982-2002 Polycrete (PFRC) manhole covers/system
have been successfully tried, and evaluated by local authorities
/ Public Health Engineering Department / Municipal Corporations
/ Committees etc. in India, on busy city roads, and have
thus demonstrated that they can withstand impact load and
vibrations of vehicular traffic. Based on 10 tonne axle
load of vehicles, Polycrete (PFRC) manhole covers have been
successfully designed and rated as suitable for 15-35 tonnes
test load/ultimate breaking load, depending on the seating
/ depth of the frames corresponding to the thickness of
the covers, and certified for heavy - duty traffic.
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