Abstract A hollow tank is formed by placing a hollow glass fiber reinforced inner container within a hollow rigid form comprising pieces assembled around the inner container and spaced from it to leave an air gap between the inner container and the inner wall of the assembled form. A suitable concrete material is introduced into the space between the inner container and the assembled form and is allowed to cure as a jacket of concrete integrally attached to and enclosing the inner container. The inner container may be formed by coating an inflated balloon with a thin layer of polyester resin and thereafter spraying on the glass fiber reinforced material to a thickness of a few mm. The concrete may be a standard flowable concrete or a polyester concrete, which is a resin-bonded gravel mixture. The concrete may be the outer layer formed as a jacket around the glass fiber reinforced inner container, or another glass fiber reinforced layer may be formed on the outer surface of the concrete. The buoyant upward force of regular concrete in fluid form is sufficiently cancelled by first introducing a certain quantity of water into the inner container. Thereafter the fluid concrete is introduced into the space between the inner container and the surrounding form to exert a buoyant force at least substantially overcoming the downward force of the water. Thereafter the inner container is filled with water and the remainder of the space between the inner container and the surrounding form is filled with the fluid concrete, which is allowed to set and thereafter is removed from the form.
The method of forming a substantially spherical tank using a closed mold of separable mold parts, said method comprising the steps of: inflating a spherical balloon; applying a coating of glass reinforced fiber material over the surface of said balloon; letting said glass rinforced fiber material harden to form a rigid inner container of limited strength, and removing it from said inner container; attaching a manhole cover to said inner container to render the inner container watertight; suspending said inner container from said cover; assembling a plurality of mold parts around said rigid inner container; the assembled mold being spaced from said rigid inner container; partially filling said inner container with water up to a predetermined level; adding fluid concrete into the space between said inner container and said mold at least substantially sufficient to provide buoyancy to overcome the weight of said inner container and said water area; the buoyancy counteracted by the rigidity of said inner container and said cover; then substantially filling said inner container completely with water; filling the remainder of the space between said inner container and said mold with concrete; allowing said concrete to set; and disassembling said mold to remove the resultant concrete jacketed inner container therefrom.
Claim 2
Independent Claim
204 words
The method of forming a substantially spherical tank using a closed mold of separable mold parts, said method comprising the steps of: inflating a spherical balloon; applying a coating of glass reinforced fiber material over the surface of said balloon; letting said glass rinforced fiber material harden to form a rigid inner container of limited strength, and removing it from said inner container; attaching a manhole cover to said inner container to render the inner container watertight; suspending said inner container from said cover; assembling a plurality of mold parts around said rigid inner container; the assembled mold being spaced from said rigid inner container; partially filling said inner container with water up to a predetermined level; adding fluid concrete into the space between said inner container and said mold at least substantially sufficient to provide buoyancy to overcome the weight of said inner container and said water area; the buoyancy counteracted by the rigidity of said inner container and said cover; then substantially filling said inner container completely with water; filling the remainder of the space between said inner container and said mold with concrete; allowing said concrete to set; and disassembling said mold to remove the resultant concrete jacketed inner container therefrom.
Claim 3
Dependent Claim
30 words
The method according to claim 1 comprising the additional step of spreading grit on the outer surface of said glass fiber reinforced inner container prior to assembling said form therearound.
Claim 4
Dependent Claim
50 words
The method according to claim 1 comprising the additional step of spraying glass fiber reinforced material over the outer surface of said concrete jacket to form, with said glass fiber reinforced inner container, a substantially vacuum tight enclosure integrally attached to the inner and outer surfaces of said concrete jacket.
Claim 5
Dependent Claim
61 words
The method according to claim 1 in which said glass fiber reinforced inner container is spaced from said mold by spacers that extend inwardly from said mold toward said container, said method comprising the additional steps of: removing said spacers prior to disassembling said mold; and substantially filling the voids in the concrete jacket left by the removal of said spacers.
Claim 6
Dependent Claim
19 words
The method according to claim 1 comprising the additional step of vibrating said mold while said concrete is hardening.