IE990834A1

IE990834A1 - Apparatus for Making Foamed Concrete, Vehicle Comprising an Apparatus for Making Foamed Concrete and Method for Making Foamed Concrete

Info

Publication number: IE990834A1
Application number: IE990834A
Authority: IE
Inventors: Brian Alan Frost
Original assignee: Est Ltd
Priority date: 1998-10-08
Filing date: 1999-10-07
Publication date: 2000-11-15
Also published as: GB2344296B; GB9821830D0; GB2344296A; GB9923622D0

Abstract

An apparatus for making foamed concrete comprising first water supply means, air entrapment agent supply means and air supply means, to supply water, air entrapment agent and air respectively to a first mixing means, said first mixing means comprising foaming means such that said water, air and air entrapment agent form a foam, and a second mixing means to which said foam is supplied, the apparatus further comprising cement supply means, aggregate supply means, sand supply means and second water supply means, to supply cement, sand, aggregate and water to said second mixing means.

Description

Title: Apparatus for Making Foamed Concrete, Vehicle Comprising an ί Apparatus for Making Foamed Concrete and Method of Making Foamed ΐ j Concrete ι Description of Invention I ] This invention relates to an apparatus for making foamed concrete, a vehicle comprising an apparatus for making foamed concrete and a method of making foamed concrete. s Foamed concrete is conventionally made by mixing aggregate, sand, ί ί cement and water together with an air entrapment agent. The presence of the air entrapment agent traps air in the mix such that the density of the concrete I j produced is much lower than if no air entrapment agent is used.

Conventionally aggregate, sand, cement, water and the air entrapment agent are mixed in a static batching plant to form the foamed concrete. After mixing in the static hatching plant, the mixture is fed from the static batching plant to a conventional “drum mixer” type vehicle in which a rotating drum is mounted on the rear of the vehicle. The vehicle is then driven to the location where it is desired to use the foamed concrete, whereat the foamed concrete is discharged from the drum in conventional manner.

One disadvantage of this method is that the foamed concrete can increase in volume as it is transported from the static batching plant to the location at which it is to be used. This can lead to foamed concrete leaking from the vehicle. It is also necessary in such a method to mix the concrete sufficiently to provide the desired degree of foaming.

An aim of the invention is to provide a new or improved method and apparatus for making foamed concrete.

According to a first aspect of the present invention, we provide an apparatus for making foamed concrete comprising first water supply means and air entrapment agent supply means, to supply water and air entrapment agent to a first mixing means, said first mixing means comprising foaming means such that said water and air entrapment agent forms a foam, and a second mixing means to which said foam is supplied, the apparatus further comprising cement supply means, aggregate supply means and sand supply means to supply cement, aggregate and sand to said second mixing means.

The apparatus thus comprises means to mix water and an air entrapment agent in the first mixing means to form a foam, and then means to mix the foam with the cement, sand and aggregate, hereinafter referred to as the loose ingredients, in the second mixing means to form a foamed concrete.

The apparatus may comprise air supply means to supply air to said first mixing means.

The apparatus may comprise second water supply means to supply water to said second mixing means.

The sand supply means and aggregate supply means may be separate, or a combined supply means may be provided to supply both sand and aggregate to the second mixing means.

The apparatus may comprise storage means for at least one of sand, cement and aggregate. A combined storage means may be provided in which a mixture of sand and aggregate is stored.

At least one of the cement supply means, the sand supply means and the aggregate supply means may be provided with metering means wherein a desired amount of cement, sand or aggregate may be supplied to the second mixing means.

The metering means for the sand supply means and/or aggregate supply means may comprise a gate at an outlet of the storage means to control the amount of sand and/or aggregate carried by the supply means.

The metering means of the cement supply means may comprise a revolving discharge head. •Ε 990834 At least one of the air supply means, the first water supply means, the air entrapment agent supply means and the second water supply means may be provided with further metering means wherein a desired amount of air, water or air entrapment agent may be supplied to the first mixing means or a desired amount of water supplied to the second mixing means.

The further metering means of the second water supply means may comprise a water flow meter and a valve to control the flow of water in accordance with the water flow meter.

The further metering means of at least one of the first water supply means, the air entrapment agent supply means and the air supply means may comprise a peristaltic pump.

The apparatus may comprise storage means for at least one of water and air entrapment agent.

Further ingredient supply means may be provided to supply one or more further ingredients to the first mixing means and/or the second mixing means as desired. A further ingredient may for example comprise a quick setting agent, a colouring agent or any other suitable ingredient as desired.

According to a second aspect of the invention we provide a vehicle comprising an apparatus for making foamed concrete comprising means to mix ingredients comprising water, air entrapment agent, air, cement, sand and aggregate.

The means to mix air, water, air entrapment agent, air, cement, sand and aggregate may be arranged such that the ingredients are mixed at or immediately before discharge from the apparatus.

The vehicle may comprise storage means for water, air entrapment agent and cement comprising separate containers and storage means for sand and aggregate comprising separate containers or a single common container.

The apparatus may comprise an apparatus according to a first aspect of the invention.

The vehicle may be located at a desired site for the foamed concrete prior to making said foamed concrete.

According to a third aspect of the invention we provide a method of making foamed concrete comprising the steps of mixing water, air and an air entrapment agent and causing said mixture to form a foam, and then mixing said foam with sand, cement, aggregate and water to form a foamed concrete.

According to a fourth aspect of the invention we provide a method of making foamed concrete at a desired site comprising the steps of transporting aggregate, sand, cement, water and air entrapment agent to the site, mixing said ingredients in an apparatus for making foamed concrete wherein the ingredients are mixed immediately at or before discharge from the apparatus.

In the fourth aspect of the invention, the ingredients may be mixed by a method according to the third aspect of the invention.

The mixing may be carried out in an apparatus according to the first aspect of the invention.

The apparatus may be provided on a vehicle according to the second aspect of the invention.

The invention will now be described by way of example with reference to the accompanying drawings, wherein Figure 1 is a side view of a vehicle embodying an apparatus according to the first aspect of the present invention, and Figure 2 is a perspective view of the vehicle of Figure 1.

Referring now to the Figures, a vehicle provided with an apparatus according to the present invention is shown generally at 10. The vehicle comprises ground engaging means in the form of wheels 11 mounted on a chassis 12. Mounted on the chassis 12 is a platform 13. In the present example, the vehicle further comprises a cab 13a and an engine (not shown), although it will be appreciated that any suitable vehicle may be provided, for example a trailer having wheels but no engine. Alternatively, the apparatus may be provided as a static batching plant.

Disposed on the platform 13 is a water storage means in the form of a water tank 14, a combined sand and aggregate storage means in the form of a container 15 and cement storage means in the form of a cement hopper 16. The container 15 is here shown as a single container in which a mixture 17 of sand and aggregate is stored, although if desired the container 15 may be subdivided, for example longitudinally, or a second container provided to provide separate storage means for sand and aggregate. A tank to provide air entrapment agent storage means is shown at 18. Further ingredient storage means provided at 19a, 19b for any other ingredients that may be desired, such as a quick setting agent, a colouring agent or any other suitable ingredient. The hopper 16 is provided with struts 20 to hold it in a desired position, whilst the sand and aggregate storage container 15 is provided with side reinforcements 21.

A first mixing means is shown at 22, comprising an elongate tube provided at its lower end with foaming means 23. The foaming means may comprise tangled filaments made of nylon or some other desired material. A second mixing means is provided in the form of a funnel 24 and a mixing auger 25. The mixing auger 25 comprises an elongate channel 26 having an outlet 26a. Disposed within the channel 26 is an Archimedes screw 27. A motor 28 is provided to drive the Archimedes screw.

The mixing auger 25 is pivotally connected by a pivot 29 to the chassis 12 and is moveable between its lower, operating position as shown in the Figures and a raised position for when the vehicle is in transit. The mixing auger is moveable by raising means comprising a fluid operated ram 30. The mixing auger 25 is also pivotable about a generally vertical axis so that it can be slewed from one side of the vehicle 10 to the other.

A first water supply means 31 in the form of a pipe is provided leading from the water tank 14 to the first mixing means 22. A second water supply means 32 is provided to supply water from the tank 14 to the funnel 24 of the second mixing means. Alternatively, the first water supply means 31 and second water supply means 32 may supply water from separate water tanks to the respective mixing means.

Air entrapment agent supply means are provided (not shown) to supply air entrapment agent from the air entrapment agent storage means 18 to the first mixing means 22. Air supply means (not shown) may be provided to supply air to the first mixing means 22, or may alternatively be supplied by air being drawn into the first mixing means 22 as water and air entrapment agent are supplied. If desired, the air entrapment agent may be supplied to the second mixing means by introducing air entrapment agent into the second water supply means 32 or by any other suitable supply means. Where air entrapment agent is supplied solely through the second water supply means, the reduction in density of the concrete is up to around 10%. The air entrapment agent may be supplied solely to one of the first or second mixing means or to both the first and second mixing means.

Sand and aggregate supply means in the form of a single conveyor belt 33, in the preferred embodiment, driven by suitable drive means (not shown) is provided to supply sand and aggregate from the container 15 to the funnel 24. In die alternative arrangement where sand and aggregate are provided with separate storage means, a single conveyor belt could be provided to supply sand and aggregate from both storage means, or separate conveyor belts could be provided to supply sand and aggregate separately. For example, where the container 15 is subdivided longitudinally, separate conveyor belts may be provided disposed in a side-by-side configuration.

A cement supply means 34 is provided to supply cement to the funnel 24. A motor 35 is provided to operate the cement supply means 34. Alternatively, the cement supply means could be driven by the motor 28 or by the conveyor belt drive means via a suitable drive, for example a chain drive.

This enables a predetermined volume of cement to be supplied for a given rotation of the Archimedes screw or operation of the conveyor belt and hence control the ratio of cement to sand and aggregate.

The sand and aggregate supply means and the cement supply means are provided with metering means (not shown) whereby a desired amount of sand and/or aggregate and/or cement is supplied to the second mixing means. Where separate sand supply means and aggregate supply means are provided, or where a combined sand and aggregate supply means is provided as in the present example, the metering means may comprise a gate disposed at an outlet to the sand and/or aggregate storage means to regulate the amount of sand and/or aggregate carried by the supply means. In the present example, with a combined sand and aggregate storage container 15 and combined sand and aggregate supply means in the form of a conveyor belt 33, the gate may be moveable to vary its height above the conveyor belt 33 to restrict the amount of sand and aggregate carried by the conveyor belt 33.

At least one of the air entrapment agent supply means, the first water supply means, the air supply means, and the second water supply means is provided with further metering means to supply a required amount of air entrapment agent and/or water and/or air to the first mixing means 22, or water to the funnel 24 or the second mixing means. The further metering means for at least one of the air entrapment agent supply means, the first water supply means or the air supply means preferably comprises a peristaltic pump (not shown). The further metering means for the second water supply means preferably comprises a flow metre and a valve controllable in response to the flow metre to vary the flow of water.

The metering means of the cement supply means 34 comprises a revolving discharge head which supplies a metered amount of cement to the funnel 24. Alternatively the metering means may comprise an Archimedes screw.

A colouring agent may be supplied from the further storage means 19b by any suitable means, for example via the air entrapment supply means, or by introduction into the first water supply means 31, or could be fed into the first mixing means 22 directly, into the funnel 24 or directly into the mixing auger 25 as desired. The colouring agent is preferably supplied by a peristaltic pump (not shown), although any means may be used as desired to supply and control the rate of supply of the colouring agent. One or more colouring agents may be supplied in one or more separate containers, or alternatively a mix of colouring agents could be supplied in a single container, and may be in either powder or liquid form as desired.

Using suitable colouring agents, it is possible to produce coloured foam concrete for the purpose of, for example, indicating the presence and nature of a pipe, cable or other service contained within or buried beneath the concrete. The colours may be selected as desired.

In use, the vehicle 10 is driven to a location where the cement hopper 16, the sand and aggregate container 15 and the water tank 14 are filled. The relative volumes of the water storage tank 14, the sand and aggregate container 15, the cement hopper 16 and the air entrapment agent storage tank 18 may be such that each hold sufficient of its respective ingredient to provide a given volume of concrete. In an alternative preferred arrangement, the sand and aggregate container has a volume sufficient to hold enough sand and aggregate to form a given volume of concrete, like the water storage tank 14, cement hopper 16 and air entrapment agent storage tank 18 hold sufficient of their respective ingredients to form twice the given volume of concrete. Thus, when the given volume of concrete has been made, the vehicle need only be refilled with sand and aggregate to enable a second given volume of concrete to be made.

When the vehicle 10 has been driven to the location at which the concrete is desired, the mixing auger 25 is lowered using the fluid operated ram to the position shown in Figures 1 and 2. Water supply means 31, air entrapment agent supply means, and air supply means are operated to supply the respective ingredients to the first mixing means 22, the proportions being controlled by the respective further metering means where present. The foaming means 23 causes the mixture to foam, and the resulting foam enters the funnel 24. The cement is supplied to the funnel 24 of the second mixing means from the cement hopper 16 by the cement supply means 34, and sand and aggregate are supplied to the funnel 24 by operating the conveyor belt 33. Water is supplied to the funnel 24 by the further water supply means 32. The proportions of cement, sand and aggregate are controlled by the respective metering means where present. The foam, sand, aggregate, cement and water are fed into the funnel 24, and are directed into the mixing auger 25. As the Archimedes screw 27 is rotated by the motor 28, in such a direction that the ingredients are moved along the channel 26 towards the outlet 26a, the ingredients are mixed to produce a foamed concrete having a desired volume of entrapped air. The outlet 26a and the channel 26 may be positioned to pour the concrete at a desired position.

Typically, 100 kilograms of cement are mixed with 1400 kilograms of aggregate and 90 litres of water. Without the addition of a foaming agent, concrete produced by such a method has a density of around 2250 kilograms per cubic metre. When a foaming agent and air are added the resulting concrete has a density of around 1300 kilograms per cubic meter. The proportions of cement, sand, aggregate, water, air entrapment agent, air and further ingredients may be varied to produce concrete with the desired features and/or density required.

The aggregate may comprise recycled or conventional aggregate. Where recycled aggregate is used, a supply of sand may not be necessary due to the presence of particulate materials in the recycled aggregate.

Although it is preferred to make the foam first and then mix the foam with the sand, aggregate, cement and water, if desired the ingredients of the foam and the concrete may all be mixed together at the same time. Mixing the foam first and subsequently mixing the foam with the sand, aggregate, cement and water however avoids the potential difficulties of introducing air into a mix of sand, aggregate, cement and water to produce a desired density of foamed concrete, and particularly the difficulties in introducing air into a mixing auger as shown in the present example.

Although it is also preferred to mix the foamed concrete in an apparatus provided on a vehicle, it may if desired be mixed by a static batching plant.

Where the foam is made first, it is preferred that the concrete is mixed at the desired site in an apparatus provided on a vehicle, although if desired the foamed concrete could be mixed in a static batching plant and carried to the site in a suitable vehicle.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. An apparatus for making foamed concrete comprising first water supply means and air entrapment agent supply means, to supply water and air entrapment agent to a first mixing means, said first mixing means comprising foaming means such that said water and air entrapment agent form a foam, and a second mixing means to which said foam is supplied, the apparatus further comprising cement supply means, aggregate supply means and sand supply means, to supply cement, sand and aggregate to said second mixing means.

2. An apparatus according to claim 1 comprising air supply means to supply air to said first mixing means.

3. An apparatus according to claim 1 or claim 2 comprising second water supply means to supply water to said second mixing means.

4. An apparatus according to any one of claims 1 to 3 wherein the sand supply means and aggregate supply means are separate

5. An apparatus according to any one of claims 1 to 3 wherein a combined supply means is provided to supply both sand and aggregate to the second mixing means.

6. An apparatus according to any one of the preceding claims wherein the apparatus comprises storage means for at least one of sand, cement and aggregate.

7. An apparatus according to claim 6 wherein a combined storage means is provided in which a mixture of sand and aggregate is stored.

8. An apparatus according to any one of the preceding claims wherein at least one of the cement supply means, the sand supply means and the aggregate supply means is provided with metering means wherein a desired amount of cement, sand or aggregate may be supplied to the second mixing means.

9. An apparatus according to claim 8 where dependent on claim 6 or claim 7 wherein the metering means for the sand supply means and/or the aggregate supply means comprises a gate at an outlet of the storage means to control the amount of sand and/or aggregate carried by the supply means.

10. An apparatus according to claim 8 or claim 9 wherein the metering means of the cement supply means comprises a revolving discharge head.

11. An apparatus according to any one of the preceding claims wherein at least one of the air supply means, the first water supply means, the air entrapment agent supply means and the second water supply means is provided with further metering means wherein a desired amount of air, water or air entrapment agent may be supplied to the first mixing means or a desired amount of water supplied'to the second mixing means.

12. An apparatus according to claim 11 wherein the further metering means of the second water supply means comprises a water flow meter and a valve to control the flow of water in accordance with the water flow meter.

13. An apparatus according to claim 11 or claim 12 wherein the further metering means of at least one of the first water supply means, the air entrapment agent supply means and the air supply means comprises a peristaltic pump.

14. An apparatus according to any one of the preceding claims wherein the apparatus comprises storage means for at least one of water and air entrapment agent.

15. An apparatus according to any one of the preceding claims comprising further ingredient supply means to supply one or more further ingredients to the second mixing means and/or the first mixing means as desired.

16. An apparatus according to claim 15 wherein said one or more further ingredients comprises at least one of a quick setting agent and a colouring agent.

17. An apparatus as disclosed herein with reference to the accompanying drawings

18. A vehicle comprising an apparatus for making foamed concrete comprising means to mix water, air entrapment agent, air, cement, sand and aggregate.

19. A vehicle according to claim 18 wherein the means to mix air, water, air entrapment agent, air, cement, sand and aggregate are arranged such that the ingredients are mixed at or immediately before discharge from the apparatus.

20. A vehicle according to claim 18 or claim 19 comprising storage means for water, air entrapment agent and cement comprising separate containers, and storage means for sand and aggregate comprising separate containers or a single common container.

21. A vehicle according to any one of claims 18 to 20 wherein the apparatus comprises an apparatus according to any one of claims 1 to 7.

22. A vehicle according to any one of claims 19 to 21 wherein the vehicle is located at a desired site for the foamed concrete prior to mixing said foamed concrete.

23. A vehicle as disclosed herein with reference to the accompanying drawings.

24. A method of making foamed concrete comprising the steps of mixing water and air entrapment agent together with air to provide a mixture, causing said mixture to form a foam, and mixing said foam with sand, cement, aggregate and water to form a foamed concrete.

25. A method of making foamed concrete at a desired site comprising the steps of transporting ingredients comprising aggregate, sand, cement, water and air entrapment agent to the site and mixing said ingredients in an apparatus for making foamed concrete, wherein the ingredients are mixed at or immediately before discharge from the apparatus.

26. A method according to claim 25 wherein the ingredients are mixed according to the method of claim 24.

27. A method according to claim 25 or claim 26 wherein the mixing is carried out in an apparatus according to any one of claims 1 to 17.

28. A method according to claim 27 wherein the apparatus is provided on a vehicle according to any one of claims 18 to 23.

29. Any novel feature or combination of features described herein and or in the accompanying drawings.