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What We Do : Construction
The Crom Corporation provides a complete tank construction service. The company prefers no division of responsibility with respect to the tank structure itself. As a consequence, tanks are built totally by The Crom Corporation, including wall footings, floor slab, circular wall, dome roof, and other such appointments as are required for the structure. By avoiding a division of responsibility, the consulting engineer and the owner can proceed with confidence that the tank will be built expertly and the responsibility for its performance will be clearly shouldered by The Crom Corporation.

1. The floor of the prestressed tank is a heavily reinforced concrete slab. This view illustrates placement of floor concrete, reinforced with mild steel bars: a strong foundation.
2. The steel shell diaphragm is erected on a system of formwork especially designed for this purpose. The steel shell extends continuously the full height of the tank to insure watertightness. To avoid joint sealing problems, no horizontal splices are allowed in the diaphragm. Vertical joints in the steel shell panels are sealed watertight by epoxy injection.
3. Exterior encasement of the steel shell is accomplished with shotcrete, which is pneumatically placed concrete. The core wall of the tank is built up to its full thickness by successive layers of shotcrete.
4. The wall formwork has been removed and the inside face of the diaphragm is now encased with shotcrete. To insure good workmanship, all shotcrete nozzlemen are certified under guidelines adopted by the American Concrete Institute.
5. Vertical reinforcing bars are placed to design requirements and will later be encased in shotcrete. Once this encasement is complete, the tank wall is ready for epoxy injection of the vertical joints in the encased diaphragm.
6. Dome roof construction is undertaken with the aid of a system of forms made to the accurate curvature of the dome shell. Ordinarily, the dome has a rise from springline to apex of 1/10 the diameter of the tank.
7. Once the roof formwork is completed with an overlay of sheathing, reinforcement is placed.
8. The free-span dome roof is constructed of cast-in-place concrete. This view shows dome concrete being placed by the pumpcrete method.
9. Both the core wall and the free-span dome roof are circumferentially prestressed using high-strength steel wire wrapped around the tank in a continuous helix. Wall prestressing is designed to carry the tank's hydraulic load, while dome ring prestressing resists the horizontal forces of roof ive and dead loads.
10. To avoid over-stressing or under-stressing of the tank, the tension in the wire is accurately measured to within 2% accuracy by the use of a direct-reading electronic digital stressometer.
11. In order to afford complete protection for the prestressing elements, a shotcrete covercoat is placed over the wire, permanently bonding the wire to the tank wall. whenever two or more layers of prestressing steel are required, a flash coat of shotcrete separates the layers. Once the cover coat has been finished, the tank is structurally complete.
12. Final stage of construction involves the installation of accessories and painting of the exterior surfaces for decorative purposes.
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