GB1559831A

GB1559831A - Sheet piling

Info

Publication number: GB1559831A
Application number: GB14769/75A
Authority: GB
Original assignee: Charcon Composites Ltd
Current assignee: Charcon Composites Ltd
Priority date: 1975-04-10
Filing date: 1975-04-10
Publication date: 1980-01-30
Also published as: BE840654A; NL7603736A; DE2615239A1; SE7604232L; DK168576A; FR2307086A1

Description

(54) IMPROVEMENTS IN AND RELATING TO SHEET PILING (71) We CHARCON COMPOSITES LIMITED, a British Company, of Porter Lane, Middleton-by-Wirksworth, Derbyshire, formerly of 83 Friar Gate, Derby, and prior to that of 11, Vernon Street, Derby, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment: The invention relates to the production sheet piling.

Sheet piling may be used, for example, to retain river or canal banks, and is commonly constructed from thin steel sheet or concrete reinforced with steel bars.

It has also been proposed to construct sheet piling from asbestos cement. The disadvantage of steel is that rapid corrosion can occur, particularly in sea water, concrete piles are heavy and more difficult to drive into position, and asbestos cement sheet is brittle.

It has now been found possible to manufacture a thin cementitious sheet pile without the use of steel reinforcement and to drive this satisfactorily, with the advantage that it is very much lighter in weight than conventional concrete piles, does not corrode like steel and has higher impact resistance than asbestos cement sheets.

According to one aspect of the present invention there is provided a method of manufacturing a sheet pile, comprising depositing a layer of material, formed of 90-98% of cementitious material and 2-10% of glass fibres substantially uniformly dispersed in the cementitious material on a support which is substantially plantar and deforming the layer before hardening thereof by changing the profile of the support surface to correspond to the desired profile of the sheet pile.

The present invention also provides a sheet pile comprising from 90-98 % of cementitious material and from 2-10% of glass fibres substantially uniformly dispersed in the cementitious material and formed by the method described in the preceding paragraph. The pile may include fillers, such as sand, crushed limestone or pulverised fuel ash, plasticisers, workability agents and other additives compatible with the cement. Such piles can be manufactured to provide different properties for specific applications, and are preferably of shaped cross-section to obtain adequate stiffness. The thickness of the pile may be varied but it is preferably between 4mm. and 25mm.

Embodiments of the invention will now be described, by way of example only, and partly with reference to the accompanying diagrammatic drawings, in which: Fig. 1 is a perspective view of a sheet pile; Fig. 2 is a perspective view of apparatus for use in producing a sheet pile; and Figs. 3 to 5 show cross-sections through a deformable mould or former in different positions.

In one embodiment of the invention a slurry consisting of a suitable hydraulic cement or water, with or without fillers, is sprayed on to a support member in the form of a fiat table simultaneously with chopped glass fibre so that the fibre is uniformly distributed throughout the slurry on the table. By varying the rate of application of the glass fibre and slurry, the proportion of fibre expressed as a percentage of the weight of slurry can be varied.

The proportion is preferably between 2% and 10%, although for most applications between 5% and 6% of fibre is satisfactory.

The fibre length is preferably between 12mm. and 50mm., a length of approximately 37mm. being particularly suitable for most applications. The thickness of the mixture of fibre and slurry is controlled by varying the rate of application on to the table. The glass fibre acts as a rein forcement for the cement matrix and the final properties of the sheet pile depend on accurate control of the fibrelslurry ratio, the thickness of the layer of fibre cement slurry, and the profile of the finished pile. The pile is preferably of a profile such as that shown in Fig. 1. Suit able fillers which may be incorporated in clude silica sand and pulverised fuel ash.

In the former case the percentage of sand is preferably between 25% and 200% by weight of cement, the preferred percentage being 50%. In the case of pulverised fuel ash this is preferably also present in an amount of between 25% and 200% by weight of cement the preferred percentage being 40%.

The fibre/cement can be deposited on the table by means of a hand operated spray gun by which the operator sprays uniformly over a surface of the table, or by mechanical means. One form of appa ratus for this purpose is shown in Fig. 2 and comprises a spray head 10 mounted at a fixed distance above the table 11 on a track 12 and arranged to be mechanic ally propelled backwards and forwards along the track. The table 11 is mounted on a conveyor 12 which travels in a direc tion at 90" to the direction of movement of the spray head. The head has outlets for the fibre and for the cement slurry which are thus sprayed on to - the table in the form of "bands" which overlap and form a uniform thickness.The finished thickness of the pile is determined bv the rate of pumping of the fibre and the slurry and the speed of travel of the conveyor, means (not shown) being provided for vary ing both these factors.

The wet material is then compacted to ensure a thorough mix between the fibre and slurry and to remove any air which has become entrained. Compaction may be effected by hand or mechanical rolling of the top surface or by applying a vacuum to the top or bottom surface thus removing any surplus water and allowing atmos pheric pressure to compact the mix.

After compaction it is necessary for the uncured material to be formed to the desired profile and then allowed to harden prior to being removed from its former and stored to develop to full strength.

Shaping the mixture to its final form may be carried out in a number of different ways. For example the compacted material may be transferred from the table to a former having a support surface of suit able shape and worked on to the shaped former by hand. Alternatively the compacted material may be transferred to a flexible former which consists of a number of members connected by hinges which permit sections to fold relative to each other, thus shaping the still wet fibre slurry mixture to a pre-determined profile. The movement of the flexible former can be carried out by hand, or by hand operated mechanical means or automatically.

The table may itself comprise a flexible former which is shaped after the spraying process is completed. Alternatively the table may be of hollow section with a perforated top covered by suitable filter medium on to which the material is sprayed. When spraying is complete a vacuum or partial vacuum is created in the hollow table and the resulting pressure on the top of the fibre/slurry mix removes excess water and air and compacts the mix.

A further arrangement is shown in Figs.

3 to 5 of the drawings in which the table consists of a series of hollow boxes 15 hinged together at 16 so that they may be mechanically moved relative to each other to form the desired profile. Fig. 3 shows the arrangement in its initial flat condition in which the fibres and slurry are applied, Fig. 4 shows an intermediate position, and Fig. 5 shows the final position in which the material is allowed to harden. The upper surfaces of the boxes 15 are perforated and covered by a filter paper 17, vacuum being applied to the boxes after spraying is complete to assist in compac- tion and drying of the mix. After hardening the pile is removed from the former by a vacuum lifting pad 18 (Fig. 5).

The techniques described above make possible the production of pre-shaped sheet piles of cement and glass fibre having high impact resistance and high resistance to transverse tensile stresses. Piles of different lengths may be produced without requiring separate moulds. The use of a former which is separate from the spraying apparatus enables piles to be Droduced on a continuous production cycle. Relatively simple production techniques are involved and the disadvantages of sheet piles of conventional form are reduced or eliminated. Various modifications in the manufacturing methods and apparatus and in the composition of the piles may be made without departing from the invention.

WHAT WE CLAIM IS: 1. A method of manufacturing a sheet pile comprising depositing a layer of material formed of from 90-98% of cementitious material and 2-10% of glass fibres substantially uniformly dispersed in the cementitious material on a support surface

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

for most applications. The thickness of the mixture of fibre and slurry is controlled by varying the rate of application on to the table. The glass fibre acts as a rein forcement for the cement matrix and the final properties of the sheet pile depend on accurate control of the fibrelslurry ratio, the thickness of the layer of fibre cement slurry, and the profile of the finished pile. The pile is preferably of a profile such as that shown in Fig. 1. Suit able fillers which may be incorporated in clude silica sand and pulverised fuel ash.

In the former case the percentage of sand is preferably between 25% and 200% by weight of cement, the preferred percentage being 50%. In the case of pulverised fuel ash this is preferably also present in an amount of between 25% and 200% by weight of cement the preferred percentage being 40%.

The fibre/cement can be deposited on the table by means of a hand operated spray gun by which the operator sprays uniformly over a surface of the table, or by mechanical means. One form of appa ratus for this purpose is shown in Fig. 2 and comprises a spray head 10 mounted at a fixed distance above the table 11 on a track 12 and arranged to be mechanic ally propelled backwards and forwards along the track. The table 11 is mounted on a conveyor 12 which travels in a direc tion at 90" to the direction of movement of the spray head. The head has outlets for the fibre and for the cement slurry which are thus sprayed on to - the table in the form of "bands" which overlap and form a uniform thickness.The finished thickness of the pile is determined bv the rate of pumping of the fibre and the slurry and the speed of travel of the conveyor, means (not shown) being provided for vary ing both these factors.

The wet material is then compacted to ensure a thorough mix between the fibre and slurry and to remove any air which has become entrained. Compaction may be effected by hand or mechanical rolling of the top surface or by applying a vacuum to the top or bottom surface thus removing any surplus water and allowing atmos pheric pressure to compact the mix.

After compaction it is necessary for the uncured material to be formed to the desired profile and then allowed to harden prior to being removed from its former and stored to develop to full strength.

Shaping the mixture to its final form may be carried out in a number of different ways. For example the compacted material may be transferred from the table to a former having a support surface of suit able shape and worked on to the shaped former by hand. Alternatively the compacted material may be transferred to a flexible former which consists of a number of members connected by hinges which permit sections to fold relative to each other, thus shaping the still wet fibre slurry mixture to a pre-determined profile. The movement of the flexible former can be carried out by hand, or by hand operated mechanical means or automatically.

The table may itself comprise a flexible former which is shaped after the spraying process is completed. Alternatively the table may be of hollow section with a perforated top covered by suitable filter medium on to which the material is sprayed. When spraying is complete a vacuum or partial vacuum is created in the hollow table and the resulting pressure on the top of the fibre/slurry mix removes excess water and air and compacts the mix.

A further arrangement is shown in Figs.

3 to 5 of the drawings in which the table consists of a series of hollow boxes 15 hinged together at 16 so that they may be mechanically moved relative to each other to form the desired profile. Fig. 3 shows the arrangement in its initial flat condition in which the fibres and slurry are applied, Fig. 4 shows an intermediate position, and Fig. 5 shows the final position in which the material is allowed to harden. The upper surfaces of the boxes 15 are perforated and covered by a filter paper 17, vacuum being applied to the boxes after spraying is complete to assist in compac- tion and drying of the mix. After hardening the pile is removed from the former by a vacuum lifting pad 18 (Fig. 5).

The techniques described above make possible the production of pre-shaped sheet piles of cement and glass fibre having high impact resistance and high resistance to transverse tensile stresses. Piles of different lengths may be produced without requiring separate moulds. The use of a former which is separate from the spraying apparatus enables piles to be Droduced on a continuous production cycle. Relatively simple production techniques are involved and the disadvantages of sheet piles of conventional form are reduced or eliminated. Various modifications in the manufacturing methods and apparatus and in the composition of the piles may be made without departing from the invention.

WHAT WE CLAIM IS: 1. A method of manufacturing a sheet pile comprising depositing a layer of material formed of from 90-98% of cementitious material and 2-10% of glass fibres substantially uniformly dispersed in the cementitious material on a support surface

which is substantially planar, and deforming the layer before hardening thereof by changing the profile of the support surface to correspond to the desired profile of the article.
2. A method according to claim 1 wherein the cement is a hydraulic cement and is deposited in the form of an aqueous slurry.
3. A method according to any of claims 1 and 2 wherein the material is compacted after depositing but before hardening.
4. A method according to any of the preceding claims wherein the material is de-watered after depositing but before hardening.
5. A method according to any of the preceding claims wherein the material is deposited on the support surface by spraying.
6. A method according to claim 5, wherein spraying is effected while effecting relative movement between the support surface and the spraying means whereby to form a homogeneous cementitious layer of a desired variable length and thickness dependent on the extent and rate of relative movement.
7. A method according to any of the preceding claims wherein the layer is removed to a separate former for hardening, whereby production of a further sheet may be commenced immediately thereafter.
8. A method according to claim 7, wherein said support surface is removed along with the layer and replaced by a further support surface to receive the next layer.
9. A method according to claim 7 or 8, wherein deforming of the layer is effected after removal for hardening but before hardening.
10. A method according to claim 7 or 8, wherein deforming of the layer is effected before removal from the support surface.
11. A method of manufacturing a profiled article substantially as hereinbefore described.
12. A profiled article in the form of a sheet pile manufactured by the method according to any of the preceding claims, comprising from 90-98% of cement and from 2-10% of glass fibres substantially uniformly dispersed in the cement.
13. A sheet pile according to claim 12 wherein the glass fibres are between 12mm.

and 50mm. in length.
14. A sheet pile according to claim 12 or 13, including one or more additives selected from fillers, plasticisers and workability agents.
15. A sheet pile according to claim 12, including sand, crushed limestone or pulverised fuel ash as filler.
16. A sheet pile according to claim 15, wherein the filler comprises silica sand or pulverises fuel ash and is present in an amount between 25% and 200% by weight of cement.
17. A sheet pile according to any of claims 12 to 16. which is between 4mm.

and 25mm. in thickness.
18. A sheet pile substantially as hereinbefore described with reference to Fig.

1 of the accompanying drawings.