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Circular prestressed concrete tanks
have been in various stages of development and perfecting for decades. Early
systems used in the United States called for the use of cast-in-place
concrete in the core wall of the tank and steel rods
with turnbuckles as the prestressing elements. Although theoretically this
approach to circumferentially prestressed concrete tanks was sound,
deficiencies in the placement of concrete together with insufficient
residual compression in the corewall brought about modifications and
improvements
In the early
1930's, the matter was fully understood when J. M. Crom, Sr. began the
development of what was later to become the COMPOSITE system of tank wall
construction, using a steel shell cylinder with shotcrete encasement for the
core wall, and high strength wire for the prestressing elements.
Successors
to Mr. Crom have over the years improved and perfected the COMPOSITE system
for tank wall construction. These improvements have included the selection
of better construction materials, together with ever improving design and
construction procedures. Consideration was given to:
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Ready-mixed concrete and pneumatically
applied shotcrete in combination with a steel shell diaphragm. |
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Prestressing rods, cables, and
high-strength wire. |
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Emulsion type sealants, polysulphides,
polyurethanes, and epoxies for sealing the steel shell membrane. |
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Wall base joints using conventional
waterstops, special bearing pad and waterstop combinations, and monolithic
floor-wall joint connections. |
Emerging from all of these was the
development of the prestressed COMPOSITE system:
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The steel shell diaphragm was found to
be the most foolproof means for making the core wall watertight. |
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Shotcrete with its high cement factor
and low water/cement ratio had greater corrosion inhibition, impermeability
and strength than conventional concrete. |
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High-strength wire could be used to
more accurately apply prestressing forces and could be better protected from
corrosion and mechanical damage. |
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In the early 1950's, J.M. Crom,
Sr. and three associates, Ted Crom, Jack Crom, Jr., and Frank Bertie,
established The Crom Corporation, with headquarters in Gainesville, Florida,
for the prime purpose of perfecting the design and construction techniques
for COMPOSITE tanks. Since then, their successors have continued the
tradition of excellence initiated by the company's founders. The company has
constructed in its own name and with its own forces over 2,600 circular and
elongated prestressed COMPOSITE tanks. |
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