GB2453395A

GB2453395A - Organic aggregate based masonry unit production machine

Info

Publication number: GB2453395A
Application number: GB0801134A
Authority: GB
Inventors: Christopher Aidan Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-04
Filing date: 2008-01-22
Publication date: 2009-04-08
Also published as: GB0801134D0; GB0719290D0

Abstract

The invention relates to a machine for the production of organic aggregate based masonry units. The machine comprises a mould box 3, in which a mixture comprising an organic aggregate and a binder material is filled in use. A compressive member 4 is applied through an opening provided in the mould box 3 to compress the mixture within the mould box 3 by at least 15% and form the masonry units. A feed cart 5 moves from a delivery position to a position above the box 3 to deposit the mixture into the box 3. Combination of movement of cart 5 and vibration due to a vibrating table helps the mixture into the box 3. A cylindrical component 6, which may be rotatable, serves to smooth and suppress the mixture in the mould box 3. A delivery system may comprise a reservoir, hopper etc with a movable floor which is able to drag or drop out the mixture into the cart in a controlled manner.

Description

AN ORGANIC AGGREGATE BASED MASONRY UNIT PRODUCTION MACHINE

The invention relates to a machine for the production of organic aggregate based masonry units; particularly, but not exclusively, masonry building units suitable for carbon capture through the process of photosynthesis used by the organic aggregates during their life cycle. The invention also relates and a method of manufacturing these masonry building units, and to the building units.

The levels of carbon dioxide (002) in the atmosphere are having an effect upon the Earth's climate. It is beneficial if CO2 can be captured and stored to reduce atmospheric CO2 levels.

There are many suggested industrial ways of carbon capture and storage. One natural way that results in a secondary benefit, is that of carbon sequestration through the action of photosynthesis performed by plants. During photosynthesis, plants absorb CO2 from the atmosphere and convert it into carbohydrates such as cellulose. The carbon is, essentially, stored in the cellulose until it is released either in the process of decomposition or combustion of the plant based material, if, instead of burning the plant based material as a fuel or allowing it to decay, the plant cellulose is used as a raw material (an organic aggregate) in the built environment; the carbon can be captured and stored. This captured carbon can then be retained within the fabric of a building. This sequestration of atmospheric CO2 offers an exciting opportunity to grow and produce sustainable, renewable organic aggregate construction materials.

The idea of using renewable organic aggregates, mixed with a range of binders, as a carbon capture tool in on site in-situ monolithic construction is not new. There are, however, several problems associated with this method of construction. Hydrated lime is required to stabilize and preserve the organic aggregates in association with other additives and/or other cement binders that cause a chemical setting process through hydrolysis and hydration. The result for those involved within the construction process is that the material is messy and caustic to work with. Furthermore, the organic aggregate and binder mix also possesses a long curing time and can take months to dry properly, making the construction process costly and time consuming. Thus, when compared to conventional construction methods and materials, this method of construction is costly, slow and hazardous to human health. These disadvantages mean that the method is unlikely to be used in the mainstream construction industry, so the aforementioned method of carbon sequestration will have little effect on global CO2 levels.

The above problems would be overcome if the organic aggregate were able to be provided --in pre-cast masonry blocks or units. These masonry units could be manufactured off site, and would be cured and dried before being transported to site. The said masonry blocks/units could then be used in a conventional block laying construction method.

The manufacturing of organic aggregate based masonry units would remove all the time and safety problems, and thus costs issues, associated with the use of lime and organic aggregate within on site in-situ monolithic construction. By overcoming these drawbacks, the uptake of this material in mainstream construction should increase, facilitating greater carbon sequestration within the built environment.

It is common in the manufacture of concrete units to use a combination of pressure and vibration (vibro-press). Two methods of manufacture, full or partial compaction, may be used. Where durability and/or surface finish are key concerns, such as in paving blocks and fair faced units, the units are produced to virtually full compaction. The height of the block is set by the volume of material in the mould box since the concrete is compressed until a pressure head can fall no further. Alternatively, for the manufacture of conventional concrete masonry blocks, a partial compaction method is used. The pressure head is only allowed to descend a minimal distance into the mould box. This distance, and hence the block size, is not governed by the volume of concrete in the mould box, but by some mechanical means setting a limit upon the distance the pressure head is allowed to fall.

The above methods have, however, proved unsatisfactory in the manufacture of organic aggregate based masonry blocks. A specialist machine is required to produce a product that is able to conform to the building specifications to which conventional masonry blocks conform.

It is an object of the present invention to provide a means of producing masonry units or blocks, incorporating an organic aggregate, for use in the construction industry.

According to the present invention there is provided an organic aggregate based masonry unit production machine comprising a mould box which is, in use, filled with a mixture comprising an organic aggregate and a binder material, and a compressive member which is, in use, applied through an opening provided in the mould box to compress the mixture within the mould box by at least 15% and form the masonry units. The compressive member is preferably hydraulic, and the degree of penetration of the compressive member into the mould box may be controlled by mechanical means.

A higher ratio of mould box depth to block height is required to facilitate high compressive strength units when compared to that of a mould box in a conventional masonry unit production machine. Conventional stone or synthetic aggregates do not require the mould depth to block height ratio to be greater than 1.18:1 (equivalent to a compression of 15%) to achieve compressive strengths which comply with building standards for masonry units.

The minimum depth of compression produces a product that is able to conform to the building specifications to which conventional masonry blocks conform.

The figure of 15% is based on the requirements to manufacture a block of sufficient quality. Research showed that to produce a block of 215mm, from a dense mix design (high proportion of stone aggregate relative to organic aggregate), it was necessary to start with a mould box 255mm deep and compress the contents by 40mm. This corresponds to a box height to block height ratio of 1.18:1, or a linear compression of 15%, which can be used as a standard for this type of mix. Since the width and depth of the block are constrained by the mould box, this also represents a volumetric compression of 15%.

The compression required will vary depending on the type and size of aggregate particles used in the mix. For example, less dense mixes, with higher percentages of organic aggregate, will require a greater degree of compression. Greater degrees of compression will also give rise to stronger finished masonry units.

The mould box may have two opposing substantially parallel sides, each of which preferably comprises an opening. One of said openings may be closed by a pallet when a masonry unit is being formed by the machine. For example, the mould box may comprise a substantiallyrectangular sleeve which rests on a moveable pallet to form an open box, into which the mixture may be poured. The compressive member may then move vertically, from a position above the mould box, to compress the mixture.

Preferably, one of the mould box and pallet is moveable relative to the other of the mould box and pallet. The open box may be formed by the mould box and the pallet moving together.

The mould box may be vertically movable, preferably independently of the compressive member, to allow the mould box to be lifted away from the masonry unit once formed.

Alternatively, the mould box may be stationary and the pallet may be movable vertically.

In this case, the mould box would remain stationary after formation of the masonry unit, and the pallet could then be lowered to allow removal of the masonry unit.

The machine may further comprise a vibrating table on which, in use, the mould box is positioned. The vibrating table may be vibrated by a vibrating motor. Vibrations have a number of advantages, including ensuring a good degree of compression of, and consistency in, the mixture.

A movable feed cart is preferably provided to receive the mixture from a delivery system and transfer it to the mould box. The delivery system comprises a movable floor which is able to drag or drop out the material into the cart in a controlled consistent manner. Due to the inclusion of straw, flakes or chips of cellulose the mixture has a tendency to bridge' (brace itself against vertical or angled sides of a bottomless container). The problem of bridging is worse in the case of organic aggregates than for conventional concrete, since cellulose particles have a tendancy to interlock with one another. The result is uneven or non existent movement of the material from the container or hopper. The provision of a movable floor on the reservoir, hopper or pre cart container allows an even and consistent fill of the cart.

The feed cart may also comprise a plurality of internal dividers to ensure an even fill of the mould box, and should move in a direction at right angles to the direction of movement of the compressive member. Preferably, the feed cart moves horizontally, and has a range of motion from a position below the delivery system, to a position directly above the mould box from where the mixture is deposited into the mould box. Where vibrations are applied to the system these can help to ensure that the mixture passes smoothly and evenly into the mould box. The feed cart may also comprise a stationary or rotatable smoothing element on a surface which contacts the mould box during movement of the feed cart.

The smoothing element is preferably at least substantially cylindrical.

In low scale/low cost applications, it is likely that the degree of compression will be monitored by a user and controlled manually. However, the machine may further comprise a Programmable Logic Controller (PLC) and one or more switches to control various aspects of the machine operation. For example, a limit switch or micro switch could be configured such that it is contacted by the compressive member when the 15% compression point has been reached. The PLC would then prevent any further compression of the mixture. This would greatly simplify higher capacity manufacture.

Switches could also be applied to control various other aspects of the machine such as, for example, the filling and/or movement of the feed cart, the hopper, the movement of the pallets through the machine and so on. Switches including, but not limited to limit switches, micro switches, photo sensitive cells and weight cells could be used as the particular application requires.

The machine according to the invention has the capability to manufacture organic aggregate based masonry units of uniform density and dimensions, with a high quality of finish. The machine has been specifically designed to be able to handle the organic aggregate based material and feed it in a uniform and regular fashion into its moulding area. Manufacture of the units is efficient, allowing low cost and low scale production or high capital and high capacity manufacture.

A further aspect of the present invention provides a method of forming an organic aggregate based masonry unit comprising the steps of filling the mould box of a machineS as previously described with a mixture comprising an organic aggregate and a binder material, and compressing the mixture with a compressive member, wherein the compressive member is moved into the mould box to compress the mixture by at least 15%.

The organic aggregate may comprise cellulose in any number of particle dimensions, including, but not limited to, chip, straw, flake or dust; and the binder material is preferably a thixotropic paste. Further materials, such as hydraulic cements and/or hydrated lime and/or chemical additives and/or sand/gravel or crushed rock and/or sintered pulverised fuel ash or alternative light-weight aggregates may also be incorporated into the mixture.

The step of transferring the mixture from a delivery system to the mould box is preferably accomplished by using a movable feed cart, which also preferably serves to retain and smooth the mixture in the mould box as it moves across the top surface. To help to achieve this, a low friction smoothing element may be provided on a surface of the mould box.

Vibration may be selectively applied to the mould box during the formation of the masonry unit. Where the binder material used in the mixture is thixotropic, this vibration encourages the mixture to liquefy and form menisci with the aggregate particles while the masonry unit is being formed. When compression is complete, the vibration may be ceased to allow the thixotropic binder material to solidify or gel' and provide a stable block for handling.

Once the masonry unit has been formed, the mould box may be removed, for example vertically, to leave the masonry unit on a pallet. The masonry unit may then be removed from the machine to allow the masonry unit to dry and cure, and a further pallet inserted in its place.

Alternatively, the mould box may be left in position and the pallet moved relative to the mould box to allow removal of the masonry unit.

The present invention further provides an organic aggregate based masonry unit formed as described above.

A better understanding of the present invention will be obtained from the following detailed description of a preferred embodiment. The description is given by way of example only and makes reference to the accompanying drawing in which: Figure 1 is a schematic view of a masonry unit production machine according to the present invention.

The components an operation of a particular embodiment of a machine for producing organic aggregate based masonry units will now be described with reference to Figure 1.

The machine comprises a vibrating table 1 which has, in this case, a vibrating motor 8 attached below. On top of the vibrating table 1 is a pallet 2 upon which the masonry units will be made. The pallet 2 shown in Figure 1 is one of many that are cyclically positioned by the machine to allow the handling and transportation of each finished masonry unit to the curing area. Each pallet 2 in turn is located between the vibrating table 1 and a mould box 3. The mould box 3 determines the shape of the block to be produced, and in this instance is a substantially rectangular container, open at both top and bottom ends, and movable vertically in a controlled manner on a plurality of slides 7. In use, the bottom of the mould box 3 is closed by the pallet 2 positioned on the vibrating table 1. The vertical movement of the mould box 3 facilitates the deposit of the masonry unit upon the pallet 2.

A hydraulic pressure plunger, or pressure head, 4 is located above the pallet 2 and the mould box 3 and is also able to move vertically, in a controlled manner, on the slides 7.

When not in use, as shown in Figure 1, the pressure head 4 is spaced vertically from the mould box 3 so as to allow free movement of the a feed cart 5 from a delivery position to a position directly above the mould box 3.

The feed cart 5 serves to transport the raw material, which comprises an organic aggregate (usually in conjunction with a typical stone aggregate) and a binder material, from the delivery system (not shown) to the mould box 3. The delivery system may comprise a reservoir, hopper or similar container with a movable floor which is able to drag or drop out the material into the feed cart 5 in a controlled consistent manner. The schematic view of Figure 1 shows the feed cart 5 in the delivery position to one side of (to the left as shown), and above, the mould box 3. In the delivery position shown, the feed cart 5 is charged with the aggregate and binder material through a first opening provided in the top of the feed cart 5. In use, the feed cart 5 then moves horizontally to a position directly above the mould box 3, where it is able to deposit the material into the mould box 3 through a second opening provided in the bottom of the feed cart 5. The material passes into the mould box 3 through a first opening provided in the top of the mould box 3.

The combination of the movement of the feed cart 5 and vibration caused by the vibrating table 1 helps the material into the mould box 3 until it is completely full. Internal dividers (not shown) are provided within the feed cart 5 to allow the material to be evenly dispersed into all areas of the mould box 3, and thereby ensure that each finished block has even surfaces and a uniform density.

Having deposited the organic aggregate based material, the feed cart 5 then returns to its delivery position so as to allow the pressure head 4 to descend and apply pressure to the material within the mould box 3. As the feed cart 5 is returned to the delivery position shown in Figure 1, a cylindrical, or similar shaped, component 6 at one end of the feed cart smoothes the top surface of the material in the mould box 3 as the feed cart 5 is drawn back across it. The cylindrical component 6 is of a durable material and has a low friction surface which prevents material from being removed from the mould box 3 by the motion of the feed cart 5 as it is in withdrawn to the delivery position. The cylinder is mounted on the base of the feed cart 5at right angles to the direction of movement of the feed cart 5 from its delivery position to its position above the mould box 3, along one edge of the feed cart 5 which is distal from the delivery position. Accordingly, in the process of the movement of the feed cart 5, the cylindrical component 6 moves across the entire upper surface of the mould box 3 as the feed cart 5 moves both from and to its delivery position as shown in Figure 1. This prevents the movement of the feed cart 5 across the top of the full mould box 3 from dragging material out of the mould box 3, and also serves to smooth and suppress the mixture in the mould box 3, enabling quality mortar beds and uniform densities to be achieved. The cylindrical component 6 shown in the drawing is static, but it may be rotatable if desired.

Once the feed cart 5 has been fully withdrawn, the pressure head 4 moves vertically downwards, being guided by the slides 7 to apply pressure to the material in the mould box 3. The range of movement of the pressure head 4 is not determined by the volume of material in the mould box. 3, but is controlled such that an appropriate degree of compression is applied to the material. In order to produce organic aggregate based masonry units with compressive strengths which comply with building standards, this has been found to be in the region of 15% or more. In the embodiment shown, a limit switch (not shown) is engaged by the pressure head 4 when the appropriate level of compression has been reached. This sends a signal to a Programmable Logic Controller (not shown) which closes a solenoid valve on the hydraulic ram driving the pressure head 4 so that no further compression is applied. In simpler variants, the degree of compression could simply be monitored and controlled by a user.

Depending on the percentage of organic aggregate in the mix, different degrees of compression will be require to produce a suitable unit, but 15% is considered the minimum -10 -compression required to produce a masonry unit from a mix containing a relatively low proportion of organic aggregate. The greater the degree of compression, the greater will be the compressive strength of the finished masonry unit. A high degree of compression is also important in ensuring that the finished units obtain a uniform finish; without protrusion of the aggregate, and uniform dimensions so as to not require trimming or shaping after production.

While the pressure is applied by the pressure head 4, the vibrating motor 8 continues to cause vibration of the vibrating table 1. This vibration serves to increase the compression of the material in the mould box 3, and thereby increase the density of the masonry units produced. Furthermore, the vibrations force the binder paste in the material, which is thixotropic, to liquefy and flow to form menisci at the points of contact of the organic aggregate particles and bond them like properly soldered joints.

After a predetermined time and/or after the desired degree of compression has been achieved, the vibration is stopped and the mould box 3 is moved vertically away from the pallet 2 along the slides 7. When the compaction and vibration stops, the thixotropic binder paste gels' or becomes virtually solid and the whole masonry unit quickly becomes firm enough to be handled. The pressure head 4 is retained in place on top of the newly formed unit, so that the vertical movement of the mould box 3 strips the mould box 3 and deposits a formed masonry unit on the pallet 2. Once the mould box 3 has been stripped, the pressure head 4 is withdrawn vertically, back to the position shown in Figure 1, to allow the pallet 2 to be removed from the machine along with the masonry unit, which is taken away for drying/curing. A further pallet 2 can then be positioned and the mould box 3 returned to the position shown in Figure 1, ready for the machine to be used again.

The organic aggregate based masonry block/unit production machine has the technical capability to manufacture building regulation compatible masonry blocks/units with organic aggregates, allowing carbon to be captured within the built environment. This carbon sequestration helps to fight climate change. -11 -

The invention is not considered to be limited to the specific configurations described above. Various aspects of the design, for example the shape of the mould box, may differ from that disclosed, and the various components may be guided in their movement by means other than slides.

The described embodiment relates to a machine suitable for high capacity manufacture.

The various moving parts of the machine may be moved by hydraulic andlor pneumatic rams and motors, electric motors or the like. All may be controlled by way of the incorporated PLC, and switches. Where a machine is to be used for smaller scale production such a high degree of automation is not required, and it should be clear that the principles of the invention are also applicable where the various parts of the machine are moved by hand, or by other mechanical means. -12-

Claims

CLAIMS: 1. An organic aggregate based masonry unit production machine comprising a mould box which is, in use, filled with a mixture comprising an organic aggregate nd a binder material, and a compressive member which is, in use, applied through an opening provided in the mould box to compress the mixture within the mould box by at least 15% and form the masonry units.
2. A machine according to claim 1, wherein the mould box has two opposing substantially parallel sides.
3. A machine according to claim 2, wherein each of said opposing sides comprises an opening.
4. A machine according to claim 3, wherein one of said openings is closed by a pallet when a masonry unit is being formed.
5. A machine according to claim 4, wherein the pallet is movable relative to the mould box.
6. A machine according to claim 4, wherein the mould box is movable relative to the pallet.
7. A machine according to any of the preceding claims, wherein the compressive member moves vertically, from a position above the mould box, to compress the mixture in the mould box.
8. A machine according to claim 7, wherein the mould box is vertically movable, independently of the compressive member.
9. A machine according to any of the preceding claims, further comprising a vibrating table on which, in use, the mould box s positioned.
1O.A machine according to claim 9, wherein the vibrating table is vibrated by a vibrating motor.
11.A machine according to any of the preceding claims, further comprising a movable feed cart to receive the mixture from a delivery system and transfer it to the mould box.
12. A machine according to claim 11, wherein the delivery system comprises a movable floor.
13.A machine according to claim 11 or 12, wherein the feed cart comprises a plurality of internal dividers.
14.A machine according to any of claims 11 to 13, wherein the feed cart moves in a direction at right angles to the direction of movement of the compressive member.
15.A machine according to claim 14, wherein the feed cart has a range of motion from a position below the delivery system, to a position directly above the mould box.
16.A machine according to any of claims 11 to 15, wherein the feed cart comprises a smoothing element on a surface which contacts the mould box during movement of the feed cart.
17.A machine according to claim 16, wherein the smoothing element is substantially cylindrical.
18.A machine according to claim 17, wherein the smoothing element is rotatable.

-14 -
19.A machine according to any of the preceding claims, wherein movement of the compressive member is controlled by mechanical means.
20.A machine according to any of the preceding claims, further comprising a Programmable Logic Controller (PLC).
21.A machine according to claim 20, further comprising at least one switch in communication with the Programmable Logic Controller (PLC).
22.A machine according to claim 21, wherein at least one switch is contactable by the compressive member at the end of its movement.
23.A machine according to claim 22, wherein said at least one switch is a limit switch.
24.A machine according to claim 22, wherein said at least one switch is a micro switch.
25.A machine according to any of the preceding claims, wherein the compressive member is hydraulic.
26.A method of forming an organic aggregate based masonry unit comprising the steps of filling the mould box of a machine according to any of the preceding claims with a mixture comprising an organic aggregate and a binder material, and compressing the mixture with a compressive member, wherein the compressive member is moved into the mould box to compress the mixture by at least 15%.
27.A method according to claim 26, wherein the organic aggregate comprises cellulose.
28.A method according to claim 26 or 27, wherein the binder material is a thixotropic paste.
29.A method according to any of claims 26 to 28, further comprising the step of transferring the mixture from a delivery system to the mould box using a movable feed cart.
30.A method according to claim 29, wherein movement of the feed cart serves to retain and smooth the mixture in the mould box.
31.A method according to any of claims 26 to 30, further comprising the steps of selectively applying vibration to the mould box during the formation of the masonry unit.
32.A method according to any of claims 26 to 31, further comprising the steps of removing the mould box once the masonry unit has been formed to leave the masonry unit on a pallet, and removing the pallet and masonry unit from the machine to allow the masonry unit to dry and cure.
33.An organic aggregate based masonry unit formed as claimed in any of claims 26 to 32.
34.An organic aggregate based masonry unit production machine substantially as herein described with reference to the accompanying drawing.