GB2035433A

GB2035433A - Concrete container for liquid

Info

Publication number: GB2035433A
Application number: GB7936266A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-10-25
Filing date: 1979-10-18
Publication date: 1980-06-18

Abstract

A swimming pool, reservoir or other container for liquid, comprising ing pre-cast reinforced concrete sections (1,2) held together by post- tensioning means (4). O-ring seals and mastic sealant is disposed between adjacent sections. Post-tensioning is effected by jacks acting against wedge abutment means, in Fig. 3 (not shown). <IMAGE>

Description

SPECIFICATION Concrete container for liquid The present invention relates to a concrete container for liquid.

It has already been proposed to build a concrete swimming pool structure by forming a wire framework where the walls of the structure are intended to be, and then blasting concrete at the framework so that it becomes encased in the concrete and reinforces the latter when set.

It has also been proposed to build a concrete swimming pool structure by successively casting reinforced blocks in situ.

These methods of building swimming pool structures both have a disadvantage in that they require the mixing of concrete on site, necessitating the presence of equipment for doing this and involving much time spent at the site.

An aim of the present invention is to avoid this disadvantage. With this aim in view, the present invention is directed in one of its aspects to a swimming pool, reservoir or other container for liquid, comprising pre-cast concrete sections held together by post-tensioning means.

With the same aim in view, the present invention is directed in another of its aspects to a method of making a swimming pool, reservoir or other container for liquid, in which pre-cast concrete sections are positioned adjacent to one another and post-tensioning means are applied to the sections to hold them together.

The number of different components involved can be reduced if the sections abut one another directly.

Advantageously, intermediate sections are U-shaped, abutting one another laterally to form a channel which is closed by end sections.

Manufacture of the sections is simplified if two end sections of the container are mutually identical, and also if all intermediate sections are mutually identical.

Preferably, the sections are made waterproof by virtue of the mix being such as to make the material of the section itself waterproof. Such a mix is one part cement, one and a half parts sand, and three parts stone.

A convenient form of post-tensioning means comprises steel rods, bars or wire passing through all the sections from one end of the container to an opposite end thereof.

An example of a swimming pool in accordance with the present invention is illustrated in the accompanying diagrammatic drawings, in which: Figure 1 is a exploded perspective view of part of the swimming pool; Figure la shows, on a different scale, a side view of part of the swimming pool with mastic sealant between sections; Figure 2 is a cross-sectional view of part of one section of the swimming pool shown in Fig. 1; and Figure 3 is an axial sectional view of an achorage device for a tendon of the swimming pool structure.

Fig. 1 shows two pre-cast concrete end sections or modules 1 between which are arranged a number of intermediate pre-cast concrete U-shaped sections or modules 2. The thickness of the vertical side wall portions of the U-shaped sections tapers towards their tops. The end sections are mutually identical, and the intermediate sections are mutually identical. Each section is formed with a plurality of holes or bores 5 extending through the concrete transversely in relation to each section, and centrally in relation to the thickness of the concrete. The holes or bores of all the sections are in register with one another so that a plurality of continuous bores extends right the way from one end of the structure to the other. Respective steel bar, rod or wire tendons 4 extend through these bores so that each tendon 4 is threaded through all the sections.Each tendon 4 is held under tension, being anchored at its two opposite ends at the ends of the bores 3 on the main outer faces of the end sections 1. It will be appreciated in this respect that, whilst the sections are shown spaced apart in Fig. 1 for the sake of clarity, they do in fact abut one another. Thus the tendons 4 hold the sections firmly together under tension. Along each abutment side of each section there is formed a groove 1 2 (shown only in one section for clarity) of Vshaped cross-section, so that adjacent grooves of abutting sections register with one another.

An O-ring 1 3 is squashed within adjacent grooves to form a seal between the sections.

The seal between adjacent sections is improved by means of a mastic sealant 1 4 (see Fig. 1 a). The concrete of the section is itself waterproof, being made from a one part concrete, one and a half part sand, three parts stone mix, so the whole structure is water retaining. An additive may be included in the mix to improve the water-proof properties of the concrete.

Fig. 2 shows reinforcing rods 6 to 10 encased within the concrete of one of the intermediate sections 2. All the sections are reinforced in the same manner. A main reinforcement comprises vertical rods 7 and 8 in the upright portions of the section, and horizontal rods 9 and 10 in the base portion of the section, these rods being spaced apart in pairs through the depth of the section at intervals of 1 50 centimeters. Each part of vertical rods 7 and 8 is linked at the top by an inverted U-shaped rod 11. A secondary reinforcement comprises horizontal rods 6, perpendicular to the rods of the main reinforcement, and spaced apart in pairs at inter vals of 300 centimeters. The reinforcing rods are of Y1 0. Thus the reinforcement is a twin layer of high tensile steel rod.

The dimensions of the sections are given by the following: depth : 1 metre width : 5 metres height : 2.15 metres thickness of ver tical wall : 75 millimetres at top 1 50 millimetres at bottom thickness of base : 1 50 millimetres The concrete provides a cover of 20 millimetres to the secondary reinforcement.

The weight of an intermediate section 2 with these dimensions is 2.94 metric tons.

The sections are manufactured by positioning the reinforcing rods in the manner in which they will finally adopt, tie wire being used at the crossings for this purpose. These rods are arranged in a steel mould, the space defined by the mould being the shape of an inverted U-section. The height of the U-section can be reduced simply by filling in a bottom portion of the mould prior to casting.

Once set, the section has a fair faced smooth steel mould finish.

The required pre-cast sections are transported to the site. After an appropriately sized hole has been dug in the ground, a reinforced concrete slab may be laid as a foundation for the swimming pool. Alternatively, the sections may be laid on level compacted fill. The precast sections are then positioned so as to abut one another, with O-ring seals between adjacent sections and mastic sealant applied to the faces of the sections which will abut one another. The length of the swimming pool is determined by the number of intermediate sections 2 placed between the end sections 1.

Thus the length may be selectively chosen to be any integral number of metres. With the bores 5 of all the sections in registration with one another, tendons 4 are threaded through.

One end of each tendon 4 is anchored to the main side wall of one of the end sections 1 by a wedge anchorage, and the other is pulled by means of an hydraulic jack until the desired post-tensioning is obtained. Another wedge anchorage is used to maintain this stress after release from the jack. The space in the bores 5 which is not taken up by the tendons 4 is then filled by pressure groating.

The tendons 4 may be 1/2 inch (12.7 millimetres) steel wire rods that can be tensioned up to 4 metric tons, and will allow a small degree of flexing. Alternatively, the tendons may be 7/16 inch (11.2 millimetres) five strand cable.

Once in place, the twin layer of reinforcing rod acts to prevent cracking of the concrete by pressure in either direction. For example, if the swimming pool is above ground and filled with water, the outer rods 8 will prevent cracking on the outside of the concrete owing to the pressure of water. Conversely, if the swimming pool is sunk into the ground and empty, inner rods 7 will prevent cracking of the concrete on the inside owing to soil pressure.

As an alternative to the O-ring seals between sections, there may be grout duct seals.

The material of the sections may be concrete Grade 30 and the tendons may be Steel, Hot rolled high yeld (410).

Fig. 3 shows a collet type anchorage device which can be used to grip the ends of the tendons 4, to keep the tendons under tension.

A main body 31 has an externally screwthreaded portion 32 engaged by an internally screwthreaded nut 33. The body 31 is formed with a bore 36 along its axis, which widens out towards the end of the body which is further from the screwthreaded portion 32.

The widening part of the bore 36 receives wedges 34 held together by a ring 37, for example a circlip, and provided with toothed inside surfaces 35. The device abuts a portion 38 of an end section 1 shown in Fig. 1, through the intermediary of washers 39. The tendon 4 extends through the bore 36, and is tensioned by means of a jack (not shown).

As the pull of the jack on the tendon is reduced, the teeth on the inner surfaces 35 of the wedges 34 bite into the tendon which draws the wedges further into the main body 31. This causes the wedges to be jammed tight between the main body and the tendon, which is thereby gripped firmly by the device.

Using a jack, the tension of the tendon can be subsequently adjusted by appropriate rotation of the nut 33.

Claims

1. A swimming pool, reservoir or other container for liquid, comprising pre-cast concrete sections held together by post-tensioning means.

2. A container according to claim 1, in which the sections abut one another directly.

3. A container according to claim 1 or claim 2, comprising end sections and at least one U-shaped intermediate section.

4. A container according to claim 3, in which there are a plurality of U-shaped intermediate sections abutting one another laterally to form a channel which is closed by the end sections.

5. A container according to any preceding claim, having mutually identical end sections and mutually identical intermediate sections.

6. A container according to any preceding claim, in which the concrete sections are water-proof by virture of the mix from which the sections have been made making the material of the sections itself waterproof.

7. A container according to claim 6, the mix being one part cement, one and a half parts sand, and three parts stone.

8. A container according to any preceding claim, in which the thickness of walls of the container tapers towards the top.

9. A container according to any preceding claim, in which seals are formed between adjacent sections by means of O-rings fitting in grooves formed in the sections.

10. A container according to any one of claims 1-8, in which grout duct seals are formed between adjacent sections.

11. A container according to any preceding claim, in which a mastic sealant is used to form or improve a seal between adjacent sections.

1 2. A container according to any preceding claim, in which the concrete sections have a twin layer reinforcement of high tensile steel rod.

1 3. A container according to any preceding claim, in which the concrete sections have a fair faced smooth steel mould finish.

14. A container according to any preceding claim, in which the post-tensioning means comprise rods, bars, wire or other elongate members passing through all the sections from one end of the container to an opposite end thereof.

1 5. A container according to claim 14, in which the ends of the elongate members project outwardly of the end sections, and gripping means grip those ends whilst abutting outer surfaces of the end sections to hold the elongate members under tension.

1 6. A container according to claim 15, in which the gripping means comprise wedge anchorages.

1 7. A swimming pool substantially as described herein with reference to the accompanying drawings.

1 8. A method of making a container as claimed in any preceding claim, in which precast concrete sections are positioned adjacent to one another and post-tensioning means are applied to the sections to hold them together.