WO2001034357A1

WO2001034357A1 - A mixer and mixing method

Info

Publication number: WO2001034357A1
Application number: PCT/SG2000/000158
Authority: WO
Inventors: Eng Hock Goh; Eng Soon Goh
Original assignee: Sky Technology Pte Ltd
Priority date: 1999-11-12
Filing date: 2000-09-28
Publication date: 2001-05-17
Also published as: WO2001034358A1; AU3690200A; AU7698400A

Abstract

A method of providing a concrete mix at a construction site including the steps of: (a) at a remote site loading into a mixing drum of a mixer one or more initial ingredients selected from the group consisting of: and, granite and cement, each being in a quantity to satisfy a required ration, (b) using a cover to close the mixer drum to substantially prevent unwanted entry of water into the mixer drum and to prevent accidental discharge from the mixer drum of the one or more ingredients; (c) transporting the mixer front the remote site to the construction site, (d) when the concrete mix is required, adding to the one or more ingredients required, adding to the one or more ingredients one or more final ingredients to form the concrete mix; (e) mixing the concrete mix into the mixer; and a mixer for mixing the concrete mix in accordance with the method is also disclosed.

Description

A MIXER AND METHOD

Field of the invention

The present invention relates to a mixer. In particular, the present invention relates to a mixer of a type that is suitable for mixing fluid and particulate materials such as dry flowable particulate matter mixtures, slurries of particular matters in liquids, and liquids. Example of these materials include dry/wet concrete mixtures, mortars, screeds, cement, sand, dry/wet animal feed, chemicals, coffee mix, beans and soft drink mixtures.

Background to the invention

A number of designs for mixers suitable for mixing particulate and fluid materials are known. One of the best known mixers is a ready mix concrete mixing truck having a cylindrical or tapering drum mounted on top. This mixing truck is used to transport "ready mixed concrete" in the form produced in a batching plant and to discharge the ready mix concrete at the customer's location.

In the ready mix concrete industry, when concrete is required to be delivered to a specific location, the ready mix concrete is produced at the batching plant and charged into the ready mix concrete mixing truck. The mixing truck is driven to the delivery destination at which point the ready mix concrete is discharged from the mixing truck.

A number of constraints are place on the suppliers of ready mix concrete as a result of the requirement that the ready mix concrete be produced and distributed from the batching plant. Firstly, if a great volume of ready mix concrete is ordered by one or more parties at the same time, the batching plant production capacity will limit the ability of the ready mix concrete company to deliver the quantities of concrete ordered to the required destinations. In addition, the nature of wet ready mix concrete does not allow pre-production in readiness for such times of high activity since the concrete may set and harden in the time between production and the placement of an order for the concrete. There are also times when concrete cannot be delivered to customers requiring the concrete outside normal operating hours for the concrete producer. In an attempt to address the difficulties associated with the production and delivery of wet ready mix concrete, a dry mix concrete has been introduced into the industry. However, ineffective storage problems still exist because the truck-type mixers in the prior art do not enable effective storage of the dry mix therein. The only method of storage of dry mix concrete being delivered by such trucks is by lining the trucks up one by one. This is not however a feasible option for the efficient storage of the dry mix concrete due to high capital investment of the prime movers and trucks, and inefficient usage of land.

Also, existing mixer drums have an infill funnel at the rear opening. The infill funnel obstructs the opening thus preventing an effective cover of surprise design from being placed over the opening.

Ready mix concrete production - in wet or dry mix - is a pollutive industry. It is therefore preferred for it to be located away from major cities or other areas of high population density, and to be located in areas of low population density and/ or of low cost and readily available land. For example, have the plant in Indonesia to supply Singapore.

The present systems require the cement to be transferred from a processing plant and/ or temporary storage silo to a transport container of appropriate form. During that transference large quantities cement dust are released into the atmosphere. When the container arrives at the ready mix concrete plant in or near a major city, the cement is transferred to the concrete production plant. Again, large quantities of cement dust are released into this atmosphere. This highly polluting, and to have such a high level of pollution in a close to a major city is undesirable.

Similar problems exist with the granite and sand used in concrete production.

Accordingly, it is an object of the present invention to provide an improved mixer design which alleviates the problems associated with the storage and/ or transportation of such products and/ or semi- prepared products prior to use.

Summary of the invention According to the present invention there is provided a method of providing a concrete mix for a construction site including the steps of:

(a) loading into a mixing drum of a mixer one or more initial ingredients selected from the group consisting of : sand, granite, water, chemicals and cement, each being in a quantity to satisfy a required ratio, the loading being at or adjacent a production site of the one or more initial ingredients;

(b) using a cover to close the mixer drum to substantially prevent

unwanted entry of water into the mixer drum and to prevent accidental discharge from the mixer drum of the one or more ingredients;

(c) transporting the mixer from the production site to the

construction site so that when the concrete mix is required, to

the one or more ingredients can be added one or more final

ingredients to form the concrete mix thus enabling the concrete

mix to be mixed in the mixer drum. Preferably, the final ingredients are sand and/ or granite and/ or cement and/ or water and/ or chemicals. Also, the transporting steps may by sea and/ or rail and /or road. Advantageously, during the transporting step the mixer undergoes storage in a storage yard. The storage may be a freight container stacking yard, and the storage may be in stacks. The stacks may include at least one freight container. One or more of the final ingredients may be added to the mixer drum when in the storage yard. There may be a storage sub-yard which may be located relatively close to the construction site. At the sub-yard one or more final ingredients may be added. Upon all final ingredients being added, the mixer may be transported to the construction site, and be operated during transport. Transport to the storage yard and /or the sub-yard may be during times of reduced traffic flow. The cover should be able to substantially prevent the unwanted entry of water during storage and transport, including a storm at sea. The production site may be at or adjacent the production source of one or more of the initial ingredients.

The invention also provides a mixer for mixing a concrete mix, the mixer including a mixing drum and an outer framework; the mixing drum being adapted to receive, store and transport therein one or more initial ingredients for the concrete mix; the mixing drum having a cover to substantially sealingly cover an opening in the mixer drum through which the one or more initial ingredients are able to be charged into the mixer drum and for the concrete mix to be able to be

discharged from the mixing drum; the cover being able to substantially prevent unwanted entry of water and /or other materials into the mixing drum, and to substantially prevent accidental discharge of the one or more initial ingredients from the mixing drum. In this form, the mixer drum will not have an infill funnel.

Preferably, the outer framework defines the outer limits of all components of the mixer so that the mixer is fully stackable with normal freight containers. The outer framework may have a first end and a second end remote from the first end, the first end having a handle attached thereto and located within the outer limits of the framework; and the second end having at least one ground engaging means attached thereto for movement between a first position where the at least one ground engaging means is within the outer limits of the outer framework, and a second position where the at least one ground engaging means extents generally downwardly from and beyond the outer limits of the outer framework.

The outer framework may have two sides, there being one of the at least one ground engaging means adjacent each of the sites. The at least one ground engaging means may be at least one roller, at least one wheel, or at least one skid. The handle may be moveable between a retracted position where it is within the outer limits of the outer

framework, and an extended position where it extends outwardly from the first end and beyond the outer limits of the outer framework. The

movement of the ground engaging means may be a pivoting movement

or a sliding movement. The movement of the handle may be a pivoting movement, or a sliding movement.

Alternatively, the present invention may provide a mixer for mixing a

concrete mix, the mixer including a mixing drum and an outer framework; the mixing drum being adapted to receive, store and

transport therein one or more initial ingredients for the concrete mix; the outer framework defining the outer limits of the mixer so that the mixer is fully stackable with normal freight containers, wherein the outer framework having a first end and a second end remote from the first end, the first end having a handle attached thereto, the handle being moveable between a retracted position where it is within the outer limits of the outer framework, and an extended position where it extends outwardly from the first end and beyond the outer limits of the outer framework; and the second end having at least one ground engaging means attached thereto for movement between a first position where the at least one ground engaging means is within the outer limits of the outer framework, and a second position where the at least one ground engaging means extents generally downwardly from and beyond the outer limits of the outer framework.

The outer framework may be solid- sided, with a top opening for charging material into the mixer drum, and a lower opening for discharging material from the mixer drum. The openings may have doors to sealingly close them.

Preferably, the outer framework has two sides, there being one of the

at least one ground engaging means adjacent each of the sites the at

least one ground engaging means may be at least one roller, at least one wheel, or at least one skid.

The movement of the ground engaging means may be a pivoting movement, or a sliding movement. The movement of the handle may be a pivoting movement, or a sliding movement.

More preferably, the mixing drum has a cover to substantially sealingly cover an opening in the mixer drum through which the one or more initial ingredients are able to be charged into the mixer drum; the cover being able to substantially prevent unwanted entry of water and/ or other material into the mixing drum, and to substantially prevent accidental discharge of the one or more initial ingredients from the mixing drum. In this case the mixer will not have an infill funnel.

Description of the drawings

The present invention will now be described in further detail with reference to the following figures which illustrate various preferred embodiments of the invention, and in which:

Figure 1 is a rear perspective view of a mixer of the present invention;

Figure 2 is a side view of the mixer of Figure 1 ; Figure 3 is a rear perspective view of a second form of mixer of the present invention;

Figure 4 is a side view of the mixer of Figure 3;

Figure 5 is a side view of a third form of mixer of the present invention; Figure 6 is a rear perspective view of a fourth form of mixer of the present invention;

Figure 7 is a rear perspective of a fifth form of mixer of the present invention;

Figure 8 is a side view, in partial cross-section, of the mixer of Figure 7;

Figure 9 is a rear perspective view of a sixth form of mixer of the present invention;

Figure 10 is a rear perspective view of a seventh form of mixer of the present invention; Figure 1 1 is a side view, in partial cross-section, of the mixer of

Figure 10;

Figure 12 is a rear perspective view of an eighth form of mixer of the present invention;

Figure 13 is a perspective view of two mixers of two preferred embodiments of the invention stacked one on another;

Figure 14 is a schematic illustration of seven mixers of the present invention stacked one on the other in two columns;

Figure 15 is a schematic side illustration of a mixer of one preferred embodiment of the invention; Figure 16 is a schematic side illustration of a mixer of a second preferred embodiment of the invention;

Figure 17 is a schematic side illustration of a mixer of a third preferred embodiment of the invention;

Figure 18 is a schematic side illustration of the mounting means for the mixer illustrated in Figure 5; Figure 19 is a schematic side illustration of the mounting means for the mixer illustrated in Figure 6;

Figure 20 is a schematic side illustration of the mixer illustrated generally in Figure 16;

Figure 21 is a schematic side illustration of the mixer illustrated in Figure 16 being filled with material through side openings;

Figure 22 is a schematic side illustration of the mixer illustrated in Figure 16 being filled with material through an end opening;

Figure 23 is a schematic side illustrated of the mixer illustrated in Figure 15 placed on a trailer; Figure 24 is a schematic side illustration of the mixer illustrated in Figure 16 placed on a trailer;

Figure 25 is a schematic side illustration of two of the mixers illustrated in Figure 15 placed on the same trailer to be towed by a single truck or prime mover; Figure 26 is a schematic side illustration of the mixer on a trailer illustrated in Figure 24 being delivered by a prime mover;

Figure 27 is a schematic illustration of a series of mixers where bulk material can be fed into each mixer;

Figure 28 is a schematic side view of a first form of mixer with tanks fitted; and

Figure 29 is a schematic side view of a second form of mixer with tanks fitted.

Description of preferred embodiments To firstly refer to Figures 1 to 12, there is shown a mixer generally designated 20, and which is mounted within a frame 22.

Frame 22 has two generally rectangular, spaced-apart, parallel side frames 21 and two rectangular end frames 23 joining them.

Rectangular includes square. The frames 21 , 23 have four parallel, aligned corner posts 24; upper 26 and lower 28 side members; and upper 30 and lower 32 end members, the members 26, 28, 30 and 32 join the four posts 24. The posts 24 and members 26, 28, 30 and 32 are secured to each other by any suitable means such as, for example, welding. They may be made of any suitable materials such as, for example, steel. At each lower corner 34 a pad 36, or normal corner fittings 25, may be provided.

The corner fittings 25 are also at or adjacent each upper corner 38, to enable frame 22 and mixer 20 to be lifted by freight container handling equipment such as a crane using a spreader, for example, and/ or a container stacker. If rings 40 are provided they will also be required to be able to be removed, or to be retracted until they are within frame 22 to enable several frames 22 to be stacked one upon another in one or more vertical columns. By having rings 40, frame 22 (and thus mixer 20) can be lifted by any form of crane.

One or more skid or wheel assemblies 27 may be provided as a replacement for, or in addition to, one or more of the pads 36, > if desired. Any such skid or wheel assembly 27 should be able to be retracted into the frame 22 to enable the frames 22 to be vertically stackable in one or more vertical columns without the skid or wheel assemblies 27 causing interference vertically or horizontally. Retraction may be by pivotal movement, and /or vertical movement. This movement may be by use of one or more pneumatic or hydraulic rams 29 mounted on or to frame 27 and acting directly or indirectly on wheel assemblies 27. Alternatively, a manual lever action may be used, as may be a screw-action system; electric motor system; or any other suitable system for extending and retracting skid or wheel assemblies 27.

Alternatively, the skid or wheel assemblies 27 may be built into the frame 22 such that they extend downwardly by substantially the same extent as pads 36 and/or corner fittings 25. The corner fittings 25 of frame 22 allow the frame 22 to sit on the corner fittings of another container during stacking. The corner fittings 25 of frame 22 also allow the frame 22 to sit on and be locked onto the tray of a truck or trailer using twist locks commonly used when transporting freight containers. By having wheels 27, the mixer 20 and frame 22 can be loaded onto trucks and /or trailers in a rolling manner by use of a winch, ram, or the like - somewhat similarly to the way in which large bins are loaded onto trucks at present. The mixer 20 and frame 22 can also be moved, such as around a building site for example, without requiring a crane.

It is also preferred that the skids or wheels 27 be at one end of outer frame 22. At the opposite end there may be provided an eye 31 adapted to be engaged by a hook or the like (not shown) to move the mixer across the ground on the skid or wheel assemblies 27, as well as allowing the loading and unloading of the mixer 20 and frame 22 from a truck in the same manner as bins are at present. The eye 31 may be pivotally attached to the outer frame 22 so that during normal use it is within the outer boundaries of frame 22. This may be achieved in the same manner as for the wheel or skid assemblies 27 as described above, and may include a pneumatic a hydraulic ram 33, or the like.

The eye 31 may be located adjacent lower end member 32 (Figure 7 and 8), or adjacent upper end member 30 (Figure 9). Alternatively, eye 31 may be fixedly mounted to a beam 35 extending between and fixed to corner posts 24 of end frame 23 adjacent lower end member 32 (Figure 10 and 1 1); or upper end member 30 (Figure 12).

Frames 22 should be able to be stacked one on top of another in a vertical column, for example, in like manner to freight containers. Furthermore, they should be able to be moved, detachable from one another and transported on, for example, trucks and/ or trailers. This is somewhat like the way in which freight containers, bins, and other such products, are transported.

Mixer 20 has an infill funnel 1 1 , as is shown in Figures 1 and 2.

This may be delected, if desired, as is shown in Figures 3 to 12. This enables a cover 12 to be placed over opening 2 of mixer drum 1. The cover 12 may be a large, truncated cone which may have a relatively rigid side wall 16 and an end wall 17. It is preferably an interference fit over drum 1 adjacent opening 2 (Figure 3 et seq); or, as is shown in Figure 5, may be a flexible cover 13 of canvas, plasticized canvas, or the like and which is held over a rim 18 around opening 2 by use of an elastic material, draw string, or the like. Covers 12, 13 should be able to cover opening 2 to resist the ingress of water due to rain, storm, waves and/ or storms when at sea, and so forth.

Mixer 20 has a drum 1 and discharge system 6 including a chute 46. It may have a motor 42 and drive shaft 44, although these may be a separate component. The motor 42 may include a gear system, if desired. Alternatively, the mixer 20 may be driven by a power pack (not shown) fitted to the truck or prime mover; or may be driven by an independent power pack (not shown) which may be releasably mountable within or to frame 22, if desired. The controls for the power pack may be on the power pack or the mixer. The power pack may be an internal combination or diesel engine, electric motor, hydraulic motor, or otherwise, as desired.

This is generally illustrated in Figures 4 and 5 where, in Figure 5, a rim-drive system 37 is shown. Rim-drive system 37 a wheel 39 which presses against mixer drum 1. Wheel 39 is driven by a motor 41 which may be an electric, hydraulic or pneumatic motor. Motor 41 is mounted to frame 22. Alternatively, the motor may be a separate component (not shown) driving wheel 39 through a gear box 41. In Figure 4, there is a gear box 43 adapted to be driven by a drive (not shown). Gear box 43 drives shaft 44 by a gear system, pulley drive, wheel (rim drive) 45 or the like. Any other form of rim or other drive can be used including, for example, gear drive, worm gear drive, belt drive, function ring, roller drive, and so forth. Figure 13 illustrates mixers of two alternative embodiments of the invention stacked one on another. Each of the mixers includes a mixing drum 1. The mixing drum of a first embodiment of the invention which is illustrated on top of a tapered drum configuration and has a central longitudinal axis. The drum of the second embodiment of the invention which is underneath is generally cylindrical in shape with the axis of the drum extending longitudinally. Each of the mixers includes an axial end opening 2 through which material to be mixed can be charged into the drum 1 and through which mixed material can be discharged from drum 1. Specifically, fluid or particulate material can be charged into either of openings 2 and 5, and discharged from opening 2 and /or circumferential side openings (not illustrated in Figure 13). The mixers of each embodiment of the invention also include an outer structure in the form of a framework having dimensions which enable the mixers to be stackable, detachable and transportable.

The framework of the two mixers illustrated in Figure 13 is open-sided and includes outer frame components 3a which define the outer boundaries of the mixer, and inner frame components 3b which support the mixing drum. The framework of the preferred embodiments illustrated is formed from steel, and essentially defines a square or rectangle box which encases the mixer. An upper side of the outer frame component 3a defines a substantially horizontal surface upon which a lower side of the outer frame component 3a of a like mixer can be stacked. Nevertheless, it will be understood to persons skilled in the art of the invention that many other configurations of the outer framework would be possible.

Such alternative outer structures or outer frameworks may include closed-sided structures 7. Of course, in the case of a closed- sided outer structure, openings will be provided in the top, end and/ or side of the outer- structure to enable access to the or each opening in the mixing drum. In Figure 14 there is illustrated a series of alternative forms of mixer of the present invention having either open-sided (as indicated by the broken lines) or closed-sided (as indicated by solid lines) outer structures. If there is an upper opening in the top or at the top of a side or end, the upper opening could be used for charging ingredients into the mixer drum. A lower opening at the bottom of an end or side may be used as a discharge opening. In this case, an infill funnel could be aligned with the upper opening and the discharge chute aligned with the lower opening. The upper and lower openings may have openable and closeable doors which may have a relatively water-tight seal. The doors may be sliding, or hinged.

As illustrated in Figure 14, the mixers of the preferred embodiments of the invention may be layered in stacks a number of mixers high. The mixers illustrated in Figure 14 each include end openings 2 at the radially outer ends of the mixing drums 1. The mixers having cylindrical drums as indicated by the number 4 include side openings 5 in a circumferential side region of the drum 1. Each of the cylindrical drums illustrated in Figure 14 includes two side openings 5. The mixers of some of the preferred embodiments of the invention illustrated may include a filling funnel, and a discharge chute, collectively designated 6, adjacent to the end opening 2 of the mixing drum 1. The mixer of the first preferred embodiment of the invention illustrated in Figure 15 includes a mixing drum 1 which is tapered to each axial end, and a single opening 2 through which material to be mixed can be charged into the drum 1 and discharged from the drum 1. Openings throughout the drawings which are shaded indicate that the opening has been covered by a cover.

Unshaded ovals for openings indicate that the cover is not placed over the opening, such that the opening is in an open condition. For example, in Figure 16, one of the side openings 5 is in an open condition, and the second of the side openings 5 is in a closed condition with the cover placed over the opening. The end opening 2 is also covered.

As is illustrated in Figure 17, the mixer according to a third preferred embodiment of the invention is mounted within a closed- sided container 7 and is adapted to be moveable between a first position in which the mixer is located within the confines of the container, and a second position in which the mixing drum is located at least partially outside the confines of the closed-sided container 7. Movement between the first and second positions is in the direction indicated by arrow A. Any suitable mechanism known to persons skilled in the art of the invention for moving the mixing drum between the first and second positions may be utilised. A locking mechanism is also included to prevent unnecessary movement of the mixing drum. In mixers of the preferred embodiments of the invention illustrated, the mixing drum is rotatable. The tapered mixer of the first preferred embodiment of the present invention is mounted to support structures 8 (see Figure 18, for example) in such a way as to enable the mixing drum to be rotated or revolved to effect mixing of the contents. The mixer of the second preferred embodiment of the invention illustrated in Figure 19 is mounted within the framework 3 by means of a series of roller rings 9 which encircle the cylindrical drum and a series of corresponding rollers 10.

As will be understood to persons skilled in the art of the invention, the various mounting and support arrangements and the drive mechanisms by which rotation of the drum is achieved are flexible and an appropriate mechanism can be selected for any particular application. For example, rotation of the drum can be achieved by using hydraulic, pneumatic, mechanical, electrical drives and/ or any suitable combination. The drive mechanism can be by virtue of a direct or indirect drive mechanism or any suitable combination thereof.

It is preferred that there be a form of brake, or other locking mechanism, so that during transport, especially by sea in particular, the mixer drum will not unwantedly or unnecessarily rotate. As illustrated in Figure 20, the location of the mixing drum within the confines of the outer structure of the mixer contributes to the stability of the mixer as a whole during the filling, mixing, transportation and discharge processes. This is due to the fact the centre of gravity of the mixer is located close to the base of the container which itself forms a stable surface.

As illustrated in Figures 23 to 26, the mixer can be placed on a trailer 15 (either singly or in twos) for delivery to a site by a vehicle 14 such as a prime mover. Two mixers can be delivered either by stacking one on top of the other on a single trailer (not illustrated) or in a row as illustrated in Figure 25. The number of mixers able to be carried will depend upon the rules or regulations in each country. For example, in some countries they can be legally stacked two high on the tray of the trucks, and transported on public roads.

The operation of the mixer will now be described with reference to the following examples which relate to the mixing of components for forming ready mix concrete.

It is to be noted that the overall efficiency of any industry that involves large volumes in terms of storage, mixing, transportation and discharge of a product (such as the ready mix concrete industry) will be greatly affected by logistic operations. The ready mix concrete industry is characterised by large volume, "just in time" production and peak plant capacity. Therefore, an increase in the overall operation efficiency must take into account each of these characteristics.

Ready mix concrete is made from a mixture of materials including, principally, cement, sand, granite, chemicals and water. Once all of these components and other necessary components are mixed, the ready mix concrete will begin to harden or bond. In order to simplify the following descriptions, chemicals will not be referred to; and it is to be understood that the hardening and/ or bonding will only result after the cement has been mixed with water for some time. Accordingly, if it is desired to provide a mixture which can be stored for a prolonged period of time without hardening or bonding, the cement and water shall be separated. Instead, a mixture of the sand and granite may be stored in the mixer on site and, when the ready mix concrete is required, the final components (including, but not limited to, sand and water) are added to the mixer and mixed with the other components in the mixer to provide the required ready mix concrete.

Alternatively, the sand, granite and cement, or sand, granite and water, may be stored in mixer without hardening and/ or bonding problems.

According to a first example, granite and sand in the correct ratios are filled into the mixer via the side openings 5, or via the end opening 2. Thereafter, the cover 12, 13 are closed over the respective openings and the mixer is sent to store. The mixer may be stored at the location where the granite and sand are charged into the mixer, or may be transported to a location where ready mix concrete has been pre-ordered ready for use on site at any chosen time. The mixer may be stacked on top of other mixers at the delivery location. Accordingly, the mixer containing the granite and sand in the correct ratios can be stored efficiently.

When ready mix concrete is required to be laid, water and cement can be charged into the mixer through either the side opening(s) 5 or the end opening 2. Mixing of the contents of the mixer is achieved by any suitable means, for example, by way of the relative rotation between the mixing drum and its blade(s).

In an alternative version of the same example, the sand and granite is pre-mixed prior to charging in the required quantity into the mixer. Thereafter, again, the covers 12, 13 are closed and the mixer is delivered to the desired location for storage. When ready mix concrete is required, cement and water are charged into the mixer and mixing of the stored contents with the newly charged contents is achieved by a few rotations of the drum. Thereafter the concrete is ready for use.

Accordingly, to a second example, all components of the ready mix concrete except cement are charged into the mixer. Thereafter the filling covers 12, 13 are closed and the mixer is sent to storage at the desired location. When ready mix concrete is required, the cement is charged into the mixer, the contents of the mixer are mixed by the method described above. According to a third example, all of the dry components of the ready mix concrete are charged in the correct ratios in to the mixer. These components in the mixer can be sent to storage for a prolonged period. Again, the dry materials can be charged with the correct ratios either individually or together following pre-mixing. When ready mix concrete is required, the necessary quantity of water is added to the mix which can then be mixed by any one or more of the methods described above.

It is preferred that the changing into the mixer drum and the storage in the mixer drum of the dry materials, be they sand and/ or granite and/ or cement, commenced at a site remote from the construction site where the concrete is required. The remote site may be at or adjacent a plant where one or more of the sand and /or granite and/ or cement are produced. The initially-loaded dry materials may even be loaded in a different country to that where the concrete is to be laid. In this way the mixer, when charged at the source of the granite and/ or sand and/ or cement, can then be transported to the construction site. Therefore, the only material handling is to charge the mixer drum at the source of the initial ingredients, add the final ingredients at the construction site (normally cement and water), and the discharge the mixed concrete. Not only does this significantly reduce material handling, but it can also significantly reduce infrastructure costs, and reduce pollution due to less use of trucks, and less creation of dust.

By having the outer framework defining the outer limits of the mixer so that not even the eye 31 and rollers 27 extend beyond the outer limits (when in their retracted position), the mixer 20 may be moved, transported and stacked in the same manner as a freight container, and may be stacked with freight containers.

Therefore, the mixer 20, with its load of dry materials, can be moved by road and/ or rail and/ or sea in the same manner as a normal freight container. This can therefore result in the complex and expensive infrastructure required for the present systems for handling cement and/ or sand and /or granite being eliminated as the mixer can use the existing infrastructure for freight containers. During the transport from the remote site to the construction site, the mixer may undergo a period of storage. This may be in a stacking yard where the mixers can be stacked in the same manner as, and with, normal freight containers. Additionally or alternative storage locations may be a storage yard and /or the construction site. By being able to be stacked vertically, several mixers 20 can be stored in a relatively small area. In this way the mixer may be transported to the storage yard at a convenient time - during the night, for example, or at other times when interference with normal traffic flow may be minimized. The storage yard may be conveniently located for one or more construction sites so that the time taken to transport a mixer to a construction site will be low. The final ingredients may, if desired, be added to the mixer drum at the storage yard just prior to the mixer leaving the storage yard for the construction site. In this way the concrete mix can be mixed in the mixer drum during transport.

There may be storage sub-yards located quite close to one or more construction sites with a main storage yard being located nearby - such as the outskirts of the city. Transport from the main yard to the sub-yard may take place during low traffic times. Some or all of the final ingredients may be added at the sub-yard, and the ingredients may be mixed while the mixer is being transported to the construction site. Some or all of the dry mix ingredients (i.e no water) may also be mixed while the mixer is in the storage yard and/ or sub- yard.

Of course, the mixer of the present invention can be used in accordance with the standard protocol in which all ready mix concrete components are mixed together and delivered to the required destination ready for immediate use. Accordingly, the mixer of the present invention is versatile since it can used both for immediate mixture and delivery; or for storage purposes prior to it be used for mixture and delivery. As is stated above, the openings in the mixing drum are provided with water-tight covers. Alternatively, if the outer structure provides a water-tight encasement of the enclosed mixing drum, materials that are at risk of deteriorating on exposure to moisture, or others elements, can be stored for extended periods of time without risk of degradation. To now refer to Figure 27, there is shown two vertical stacks of mixers 20 similar to those of Figure 14. Any appropriate number of vertical stacks may be used. Here there is a main feeder 50 for supplying bulk material to all mixers in the stacks. This may be by way of initial charge, supplemental charge, or a new charge following discharge. For each mixer 20 there is a branch feeder 52 which may have an in-line container/ hopper 54. The main feeder 50 may use belt, screw, bucket or other form of conveyor or other device, for example, to lift the bulk material to the mixer 1 via the branch feeder 52, container/ hopper 54, and filling system 6. To maximise efficiency, one main feeder 50 may be used for one type of bulk material only. That bulk material may be any one or more of those described above. Therefore, there may be a number of main feeders 50, and each may have its array of branch feeders 52. Therefore, feeding of the different bulk materials can take place simultaneously, or at different times.

The container/ hopper 54 may be used to hold the bulk material before feeding it into the mixer. It can also be used to determine the correct volume of bulk material supplied - the volume of the container hopper 54 being known. Weighing and/ or scaling devices may be installed at an appropriate location to accurately determine the quantity of bulk supplied to each mixer, if desired.

After the ready mix concrete or other contents of the mixer have been discharged, the mixer can be cleaned by feeding water into the mixer, rotating the mixer a number of times with the water inside to rinse the interior of the mixer and thereafter discharging the wash water from the mixer. Any appropriate means of water supply can be used for this purpose. A water tank with or without a water pump or booster can be also integrated into a truck or other vehicle which is used to transport the mixer, for one example. After water cleaning of the mixing drum, the interior of the mixer can be left to dry either in a stationary position or on the journey back to the ready mix concrete plant. Alternatively, an air jet could be used to blow air into the mixer to speed up the drying process. Air injected into the drum may be at ambient temperature or may be preheated. Figures 28 and 29 show mixers 1 each fitted with a first tank 56 and a second tank 58. One of the tanks 56,58 may contain sufficient water for the dry mix inside mixer 1 so that a correctly mixed concrete can be made without requiring external water. The other of the tanks 56,58 may contain the required water for post-discharge cleaning. Alternatively, one or both of the tanks 56,58 may be used for the storage of cement and/ or tools. The number of tanks can be as required such as, for example, four.

The mixer of the present invention can be formed by retro-fitting a mixer having a mixing drum which is capable of mixing contents of the mixing drum, the mixing drum including an opening through which the material to be mixed can be charged into the drum in through which mixed material can discharged from the drum so as to be capable of being stackable, detachable and transportable. This retro-fitting operation involves forming an outer structure for the mixer. The required framework for the mixer can be constructed around the mixing drum in such a way that the mixing drum is mounted within this outer structure.

Many modifications may be made to the present invention without departing from the spirit and scope thereof. A number of these modifications have been discussed above in relation to the description of the preferred embodiment of the invention. However, it is to be understood that the modifications described above are not exhaustive.

Claims

THE CLAIMS:

1. A method of providing a concrete mix for a construction site including the steps of:

(a) loading into a mixing drum of a mixer one or more initial

ingredients selected from the group consisting of : sand, granite,

water, chemicals and cement, each being in a quantity to satisfy a required ratio, the loading being at or adjacent a production site of the one or more initial ingredients;

(b) using a cover to close the mixer drum to substantially prevent unwanted entry of water into the mixer drum and to prevent accidental discharge from the mixer drum of the one or more ingredients;

(c) transporting the mixer from the production site to the construction site so that when the concrete mix is required, to

the one or more initial ingredients can be added one or more final ingredients to form the concrete mix thus enabling the

concrete mix to be mixed in the mixer drum.

2. A method as claimed in claim 1, wherein the final ingredients

are selected from the group consisting of : sand, granite, cement, chemicals and water.

3. A method as claimed in claim 1 or claim 2, wherein the

transporting step is by a means selected from the group

consisting of: sea, rail, air, and road.

4. A method as claimed in any one of claims 1 to 3, wherein during

the transporting step the mixer undergoes storage.

5. A method as claimed in claim 3, wherein the cover can

substantially prevent the unwanted entry of water or other unwanted material during storage and a storm at sea.

6. A method as claimed in any one of claims 1 to 5, wherein the production site is at or adjacent a production source of one or more of the initial ingredients.

7. A method as claimed in claim 4, wherein the storage yard is a freight container stacking yard, and the storage is in stacks.

8. A method as claimed in claim 7, wherein the stacks include at least one freight container.

9. A method as claimed in any one of claims 4, 7 or 8, wherein one

or more of the final ingredients are added to the one or more initial ingredients when the mixer is in the storage yard.

10. A method as claimed in any one of claims 4, 7, 8 or 9, wherein

the mixer is transported to the storage yard during times of reduced traffic flow.

1 1. A method as claimed in any one of claims 7 to 10, wherein there

is a storage sub-yard located relatively close to the construction

site.

12. A method as claimed in claim 1 1 , wherein the mixer is

transported from the storage yard to the storage sub-yard

during times of reduced traffic flow.

13. A method as claimed in claim 1 1 or claim 12, wherein one of more of the final ingredients are added to the one or more initial ingredients when the mixer is in the storage sub-yard.

14. A method as claimed in any one of claims 9 to 13, wherein upon all final ingredients being added the mixer drum is operated to mix the concrete mix during transport to the construction site.

15. A mixer for mixing a concrete mix, the mixer including a mixing drum and an outer framework; the mixing drum being adapted to receive, store, mix and transport therein one or more initial ingredients for the concrete mix; the mixing drum having a

cover to substantially sealingly cover an opening in the mixer drum through which the one or more initial ingredients are able

to be charged into the mixer drum and for the concrete mix to

be able to be discharged from the mixing drum; the cover being

able to substantially prevent unwanted entry of water or other

unwanted material into the mixing drum, and to substantially prevent accidental discharge of the one or more initial

ingredients from the mixing drum.

16. A mixer as claimed in claim 15, wherein the outer framework

defines the outer limits of all components of the mixer so that the mixer is fully stackable with normal freight containers.

17. A mixer as claimed in claim 16, wherein the outer framework

has a first end and a second end remote from the first end, the first end having an eye attached thereto within the outer limits

of the outer framework; and the second end having at least one ground engaging means attached thereto for movement between a first position where the at least one ground engaging means is within the outer limits of the outer framework, and a second

position where the at least one ground engaging means extends generally downwardly from and beyond the outer limits of the outer framework.

18. A mixer as claimed in claim 17, wherein the outer framework

has two sides, there being one of the at least one ground engaging means adjacent each of the sides.

19. A mixer as claimed in claim 17 or claim 18, wherein the at least

one ground engaging means is selected from the group consisting of: at least one roller, at least one wheel, and at least

one skid.

20. A mixer as claimed in any one of claims 17 to 19, wherein the

eye is moveable between a retracted position where it is within

the outer limits of the outer framework, and an extended position where it extends outwardly from the first end and beyond the outer limits of the outer framework.

21. A mixer as claimed in any one of claims 17 to 20, wherein the

movement of the ground engaging means is a pivoting movement.

22. A mixer as claimed in any one of claims 17 to 20, wherein the movement of the ground engaging means is a sliding movement.

23. A mixer as claimed in any one of claims 20 to 22, wherein the movement of the handle is a pivoting movement.

24. A mixer as claimed in any one of claims 20 to 22, wherein the movement of the handle is a sliding movement.

25. A mixer as claimed in any one of claims 15 to 24, wherein the mixer does not have an infill funnel.

26. A mixer for mixing a concrete mix, the mixer including a mixing

drum and an outer framework, the outer framework defining the

outer limits of the mixer so that the mixer is fully stackable with

normal freight containers; the mixing drum being adapted to

receive, store, mix and transport therein one or more initial

ingredients for the concrete mix; outer framework having a first

end and a second end remote from the first end, the first end having an eye attached thereto moveable between a retracted

position where the eye is within the outer limits of the outer

framework, and an extended position where the handle extends outwardly from the first end and beyond the outer limits of the

outer framework; and the second end having at least one

ground engaging means attached thereto for movement between a first position where the at least one ground engaging means is

within the outer limits of the outer framework, and a second position where the at least one ground engaging means extends generally downwardly from and beyond the outer limits of the outer framework.

27. A mixer as claimed in claim 26, wherein the outer framework

28. A mixer as claimed in claim 26 or claim 27, wherein the at least one ground engaging means is selected from the group

consisting of: at least one roller, at least one wheel, and at least one skid.

29. A mixer as claimed in any one of claims 26 to 28, wherein the

movement of the ground engaging means is a pivoting

movement.

30. A mixer as claimed in any one of claims 26 to 28, wherein the

movement of the ground engaging means is a sliding movement.

31. A mixer as claimed in any one of claims 26 to 30, wherein the

movement of the eye is a pivoting movement.

32. A mixer as claimed in any one of claims 26 to 30, wherein the

movement of the eye is a sliding movement.

33. A mixer as claimed in any one of claims 26 to 32, wherein the

outer framework is a closed framework and has an upper opening through which the initial ingredients and the final

ingredients can be charged into the mixing drum; and a lower opening through which the concrete mix can be discharged.

34. A mixer as claimed in claim 33, wherein the upper opening and the lower opening each have a door which closes with a relatively water - tight seal.

35. A mixer as claimed in any one of claims 26 to 34, wherein the mixing drum has a cover to substantially sealingly cover an opening in the mixer drum through which the one or more

initial ingredients are able to be charged into the mixer drum; the cover being able to substantially prevent unwanted entry of

water or other unwanted material into the mixing drum, and to

substantially prevent accidental discharge of the one or more initial ingredients from the mixing drum.

36. A mixer as claimed in claim 35, wherein the mixer does not have an infill funnel.