GB2062079A - Precast Wall Unit for Silage Pit or Tank - Google Patents

Abstract

A precast concrete wall unit 100 for a tank or pit comprises a pair of spaced walls 11 and 12 which converge towards one another from the base of the unit to the top edge thereof, and which are connected together at least at the top edge of the unit by spaced bridging pieces 13 extending across the gap between the two walls. Preferably the bridging pieces 13 extend substantially the entire height of the unit, forming vertical channels 14. Each side edge of the unit 10 is preferably recessed at 15 to facilitate grouting between abutting units. <IMAGE>

Description

SPECIFICATION Precast Concrete Wall Unit The present invention relates to precast concrete wall units, for example for use in the construction of slurry tanks and silage pits. Such tanks and pits may be located above or below ground and are often of concrete construction.

According to the present invention there is provided a precast concrete wall unit comprising a pair of spaced walls which converge towards one another from the base of the unit to the top edge thereof and which are connected together at least at the top edge of the unit by spaced bridging pieces extending across the gap between the two walls.

The invention also provides a tank or pit in which the walls are constructed using units according to the above paragraph. The bottom of the tank or pit may be concrete slabbing supported on suitable foundations and the units themselves are advantageously supported by a concrete base.

Preferably the bridging pieces extend substantially the entire height of the wall unit to form substantially vertical channels in the units. In order to facilitate ease of assembly of the units into tank or pit walls, such channeled units may have substantially vertical recesses in each side edge of the unit that extend the height of the unit.

Adjacent units may then be set together by grouting.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates part of a silage tank constructed using embodiments of wall units according to the present invention; Figure 2 is a vertical section through one of the flat wall units of Figure 1; Figure 3 is a top view of two of the flat wall units of Figure 1 joined together; Figure 4 is a top view of the corner wall unit of Figure 1; Figure 5 is a top view of an embodiment of a single, smaller wall unit according to the invention; Figure 6 is a longitudinal cross-section of an alternative embodiment of flat wall unit; and Figure 7 illustrates the complete silage tank of which part is shown in Figure 1.

Referring first to Figures 1 to 4 of the drawings, a silage tank (Figure 1) comprises a plurality of generally flat wall units 10 and corner wall units 10' assembled edge to edge to form a complete four-sided rectangular tank, only part of two adjacent sides being shown in Figure 1.

Each flat wall unit 10 (Figures 2 and 3) is of precast concrete construction and comprises spaced outer and inner walls 11 and 12 respectively which converge towards one another from the base of the unit to the top edge thereof, the outer wall 11 being substantially vertical and the inner wall 12 being upwardly inclined towards the wall 1 The walls 11 and 12 are connected together by bridging pieces 13 integral with the walls and spaced apart at predetermined intervals along the top edge of the unit. The bridging pieces 13 preferably extend vertically parallel to one another substantially the entire height of the wail unit from the top edge to the base, so forming a number of longitudinal channels 14 between the pair of walls 11 and 12.However, some at least of the bridging pieces 1 3 may, if desired, be provided only at the top edge of the unit; thus they may terminate at the point shown by the broken line 13' in Figure 2.

The corner units 10' (Figure 4) are constructed in substantially the same manner as the flat units 10, except that the outer and inner walls 11 and 12 are right-angled in cross-section.

Where the bridging pieces extend the entire height of the wall unit, the walls 11 and 12 of the unit and the bridging pieces 13 at each convergent side edge of the unit form a respective semi-hexagonal recess 1 5 extending substantially the entire height of the unit. These recesses 1 5 form further channels 15' of hexagonal crosssection at the abutting edges of adjacent wall units 10 and/or 10', Figures 1 and 3, these further channels being grouted to seal the join between the units.

Typical dimensions of the units 10 are as follows. The gap between the walls 11 and 1 2 .decreases from 12" at the base of the unit to 4" at the top edge, the unit being 6'6" in height. The concrete thickness of each wall 11, 12 also decreases in the upward direction, being 3+" at the base and 2+" at the top edge. The overall thickness of the unit is therefore 19" at the base and 9" at the top edge. The bridging pieces 13 and 2+" in thickness, as measured in a direction parallel to the top edge of the unit, and are spaced apart by 10+" from one another as measured in the same direction.The recesses 1 5 are 2+" in depth, so that the overall width of each unit 10 shown in Figure 3, which comprises four 2+" bridging pieces 13, three 10+" channels 14, and two 2+" recesses 15, is 3' 10+".

The component parts of the corner unit 10' (Figure 4) have the same dimensions as the unit 10 where applicable, except that the width of each limb of the right angled outer wall 11 is 2'0if". In the case of both the flat and corner units 10 and 10' respectively, where a bridging piece does not extend through the full height of the unit, it may terminate at 13' (Figure 2) 4" below the top edge of the unit. Also, in both cases the units may be reinforced with steel in conventional manner.

It is of course to be understood that in order to be able to construct tanks or pits having a variety of overall dimensions, the precast concrete wall units themselves may be constructed in a variety of widths and heights. Thus Figure 5, for example, is a top view of a flat wall unit of similar dimensions to the unit 10 described above, with the exception that it has only three bridging pieces 13 and two 6+" channels 14. The width of the unit is therefore 2'2".

In an alternative form of the wall unit 10, shown in longitudinal cross-section in Figure 6, a steel bar 1 3a is housed in and supported by the bridging pieces 13, the bar 1 3a extending through the bridging pieces 13 adjacent the top edge of the unit and spanning the channels 14 in a direction generally perpendicular to the latter and parallel to the walls 11, 12. in this case, in order to provide adequate support to the bar 1 3a, the bridging pieces 13 are widened at their top end as shown. The bar; 1 3a may be used for lifting the unit during assembly of the tank.

The silage tank (Figures 1 and 7) is been formed using the units described by first forming foundations on undisturbed soil 16. The foundations comprise six inches of well consolidated hardcore 1 7, on top of which is laid a one inch layer of sand blinding 18. This is covered by a 1000 gauge "visqueen" 19. Around these foundations and enclosing the periphery thereof is a twelve inch deep concrete base 20 having an R.C. pad 21 near the bottom thereof.

The outer side of the concrete base has an upwardly extending flange 22 which is 6 inches high and 4 inches wide. The selected precast units (the required number of flat units 10 and four corner units 10') placed in position about 3 inches from the flange 22 with their inclined walls 12 facing towards the inside of the tank, and are grouted together, and 5 inch thick concrete floor slabs 30 are arranged inside the walls 12 extending across the foundations and, at the sides, resting on the concrete base 20. The gap between the flange 22 and the units is filled in with concrete to complete the fixing of the units.

The final floor level is designated 31 in Figure 2.

To complete the silage tank, columns 23 (Figure 7) are fitted in selected channels 14 or in the channels 15' between adjacent units, and a roof 24 is supported thereon in conventional fashion.

To form a beef tank, 2 foot wide slats are supported directly on the units. Where necessary, columns and beams are provided. A single 12 inch by 9 inch beam supported on 18 inch by 12 inch columns is necessary for a 71 foot by 21 foot by 9 inch tank.

A slurry tank 60 ft by 40 ft has also been designed, having a drive in ramp. The beef and slurry tanks may be provided with extra support for the units in the form of a wall surrounding the units, the width of which is very much greater at the bottom than the top.

The use of preformed units such as those described has many advantages, among which are speed, lack of skill required, and the ability to erect without steel shuttering and the extra excavation this would require. There will be no subsidence under the concrete as a result of backfilling, and as no plastering is necessary, the weather conditions are less important.

The units are suitable for surface or underground tanks and are designed to carry slats and animal weight on dairy and beef houses.

Claims (11)

Claims

1. A precast concrete wall unit comprising a pair of spaced walls which converge towards one another from the base of the unit to the top edge thereof and which are connected together at least at the top edge of the unit by spaced bridging pieces extending across the gap between the two walls.

2. A wall unit as claimed in claim 1, wherein the thickness of each individual wall decreases from the base to the top edge of the unit.

3. A wall unit as claimed in claim 1 or 2, wherein the bridging pieces extend substantially the entire height of the unit to form a plurality of longitudinal channels between the walls.

4. A wall unit as claimed in claim 3, further including a support bar which extends through the bridging pieces adjacent the top edge of the unit and which spans the channels in a direction generally perpendicular thereto and parallel to the walls.

5; A wall unit as claimed in 3 or 4, wherein the walls and bridging pieces at each convergent side edge of the unit form a respective recess extending substantially the entire height of the unit.

6. A tank or pit having walls formed by a plurality of wall units as claimed in any preceding claim and assembled edge to edge.

7. A tank or pit as claimed in claim 6, wherein the wall units are as claimed in claim 5 and are set together by grouting the further channel formed by the opposing recesses of adjacent wall unit edges.

8. A tank or pit as claimed in claim 6 or 7, wherein the wall units are supported on a concrete base.

9. A tank or pit as claimed in claim 8, wherein the floor of the tank or pit comprises concrete slabs laid on a foundation.

10. A precast concrete wall unit substantially as described herein with reference to Figure 3, 4, 5 or 6 of the accompanying drawings.

11. A tank substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings.