Concrete Water Houses As Powerhouses Through Prestressing

The sustainable environmental value and high protection level of concrete makes it the most demanded man made material for the construction of commercial tanks. Concrete is not all there is to a tank because unless the necessary strong reinforcement to stand the pressure of its load is provided, leaks can still happen.

If you want a concrete tank that is impervious to water, however, it needs to be. This is a way of strengthening the concrete tank by winding a continuous steel wire around the tank wall protected and passivized by the right mixture and thickness of concrete.

Ideally, is recommended for large commercial tanks that require hundreds of thousands of gallons in load while smaller tanks can be reinforced the conventional way. In order to be financially practicable, the concrete tank should have a minimum capacity of 250,000 gallons.

With continued innovations in tank design and construction, there is practically no limit to capacity as there are existing designs with loads of over 20 million gallons. Tank walls can be as high as 85 feet.

A relatively thin but sufficiently reinforced 4 inch layer of concrete slab serves as a strong and flexible tank floor. For earthquake prone areas, however, the tank floor should be designed and constructed to withstand seismic movements to maintain structural integrity. As a precautionary measure, reinforced footing must be laid around the wall base to protect deviations on the tank floor that may be caused by the combined weight of the wall and the roof.

Because the walls are in continuous compression, any cracks are firmly bonded together to disallow the passage of water through them. Since the concrete used is a special mixture of quality cement coupled with the constant dampness of the walls, cracks caused by drying are seldom and if ever they do happen, they easily close with time. Tank walls come in different styles and specifications.

The wall panels may be as thick or as thin according to the purpose for which the tank is built. For instance, it would be safe to provide panels of moderate thickness to a 3 meter high tank structure. According to some manufacturers, precast concrete does not degrade through exposure to the elements.

The precast wall panels must be made to the exact specifications of the tank design to conform to the expected construction load. The range of thickness of most tank panels run between 4 and 15 inches, depending on the height of the walls.

A vital component of the tank wall is the steel shell diaphragm sealed watertight with epoxy injection and embedded in shotcrete to make the walls impermeable. The tank wall takes its form from the steel diaphragm shells embedded in it. The diaphragm is further supported by upward steel ribs that are firmly bonded to the panels.

Along the perimeter is a spirally embedded steel wire that provides primary fortification of the tank. It sets the tank walls firmly in place to be able to carry the heaviest load. Naturally, the volume of wire strapped around the bottom of the walls is more than that at the top because of the greater weight at the bottom

A crucial element of a concrete tank is the point where the floor and walls meet. In order to prevent strain on the structure, a neoprene bearing pad acts as a cushion to let the wall base shift a little. In this case, steel and concrete are compactly compressed together, thus, there is no room for any further strain even if the tank is in full capacity.

Appropriate seismic cables are a must in tank construction because alone is not a foolproof guarantee against unpredictable seismic forces. Protection against leakage and allowance for movement are made possible by a PVC water stop firmly implanted on the floor and fixed into the walls. A small tank may be a losing proposition, but a million gallon commercial tank is a worthwhile investment.