EP0183805A4

EP0183805A4 - Building system and portable masonry plant suitable therefor.

Info

Publication number: EP0183805A4
Application number: EP19850902932
Authority: EP
Inventors: Alan Charles Atkins; Colin Donald Campbell
Original assignee: Austpac Housing Corp Pty Ltd
Current assignee: Austpac Housing Corp Pty Ltd
Priority date: 1984-06-08
Filing date: 1985-06-07
Publication date: 1987-08-10
Also published as: EP0183805A1; AU4434685A; ZA854349B; BR8506822A; WO1986000043A1

Abstract

A portable plant (1) for the manufacture of shaped building products, such as masonry blocks for wall construction, comprises a motorized mixer (2) and an adjacent moulding machine (4) mounted on a rigid platform (3) for transportation of the plant. A skip bucket (5) is adapted to charge the mixer (2) with raw materials to be mixed, and conveyor means (10) are disposed beneath the mixer to convey the mixture discharge from the mixer moulding machine (4). Masonry blocks so manufactured are used for walled building construction wherein are constructed without mortar, with rows of such building blocks (35) clamped between upper (46) and lower (26) elongate reinforced members with spaced apart metal rods (32) extending between the upper and lower reinforced members and extending vertically through the adjacent rows of building blocks. A masonry wall and a method of making such a masonry wall are also disclosed.

Description

BUILDING SYSTEM AND PORTABLE MASONRY PLANT SUITABLE THEREFOR

TECHNICAL FIELD The present invention relates to a mobile plant for the manufacture of masonry building products, such as masonry blocks, and to the construction of walls and other building structures using such building products, without the use of mortar.

BACKGROUND ART Masonry block has for a long time been attributed as one of the best building materials available for building construction, especially in tropical and sub-tropical zones. Masonry buildings, however, appear expensive when compared to other forms of construction. This is not only due to the fact that the base material requires energy usage in its product but also that there is a high degree of skill required in the assembly and construction of buildings using masonry block.

Throughout recent times numerous systems have been designed and marketed in various countries of the world in an attempt to provide cheaper building construction and/or to reduce construction time. However, previously known systems have had limited success in achieving these aims, and many of these systems have not attained universal acceptance because of factors limiting their applicability to one country or one region; when attempts have been made to apply these systems in other parts of the world, a great deal of their domestic advantage is lost. Most require very high capital investment in plant and machinery, the training of operators in tasks with which they are unfamiliar and usually the importing of large quantities of materials at a high cost in foreign exchange.

There is a need for mobile plants for the manufacture of shaped masonry building products which can be located and/or re-located at various sites according to the availability of raw materials, and/or according to the needs of the community e.g., sites for new housing construction. Transport costs for finished building products can be quite high, and where long-distance transport is required the costs can be prohibitive. The most commonly known method for masonry wall construction comprises the laying of masonry building blocks in a series of courses or rows inter-spaced with mortar, or cement, which adheres the bricks or masonry blocks one to the other and forms a wall. The blocks are maintained in position by their own weight or the compressive force of the load supported by the wall. Such walls are not very strong when subjected to transverse forces.

In addition, conventional brick or block wall construction requires skilled labour or expertise for the preparation of the correct mortar mix and for brick/block laying. This prevents the use of relatively low cost unskilled workers and is a significant disadvantage in regions where skilled tradesmen are unavailable.

Further, not only must the cost of mortar be met but also water must be provided on site and this is a particular disadvantage in regions of dry climate.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a building system which has both low energy requirements and a low requirement for skills of personnel required to operate the system.

It is a further object of this invention to provide a building system that is not only constructionally superior to conventional building construction systems, but which also allows a more efficient utilisation of capital; to provide a system which is less expensive in terms of both material and labour costs, and which requires less time for construction.

It is another object of the present invention to provide a mobile plant for the manufacture of shaped building products. It is yet a further object of the present invention to provide a method of masonry wall construction in which there is no mortar required between adjacent rows or courses of the wall to secure the masonry blocks, or bricks, one to another. It is yet another object of the present invention to provide a method of masonry wall construction, and means for producing shaped building products to be used therein which simplify and improve the efficiency of building construction and minimize the requirements for skilled tradesmen. According to one aspect of the present invention there is provided a mobile plant for the manufacture of shaped building products, comprising a motorised mixer for mixing a batch of sand, aggregate and cement, a skip container associated with said mixer for receiving predetermined amounts of materials and discharging the materials into the mixer, means for discharging mixed concrete from the mixer, conveyor means so disposed in relation to said mixer for receiving concrete discharged from said mixer and for conveying same to a hopper adjacent to said mixer, and mould means disposed below said hopper for receiving a charge of concrete from the hopper and adapted to mould said charge of concrete into a predetermined shape, wherein the component parts of said plant are mounted on a rigid platform whereby the plant is adapted for transportation from one site to another as required.

According to another aspect of the present invention there is provided a method of construction of a masonry wall, said method comprising the steps of:-

1. laying an elongate reinforced foundation including a lower elongate member;

2. positioning a plurality of rods extending vertically from said lower elongate member at each of a plurality of predetermined locations;

3. laying, without mortar, a plurality of rows of masonry blocks one above the other with the bottom one of said rows being laid on said foundation, said blocks having openings therein for threading onto said rods at predetermined locations;

4. locating an upper elongate member on the upper one of said rows, and

5. tensioning said rods to clamp said blocks between said members.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to some non-limiting embodiments thereof as illustrated in the drawings, in which:-

Fig. 1 is a perspective view of a platform-mounted mobile masonry block plant;

Fig. 2 is a side elevation view of the plant of Fig. 1; Fig. 3 is a plan view of the plant;

Fig. 4 is an end elevation view of the plant taken from the mixer end;

Fig. 5 is an end elevation view of the plant taken from the hopper/block moulding end; Figs. 6-8, inclusive, illustrates some of the masonry blocks manufactured by the mobile plant and utilized in mortarless building construction according to the method disclosed herein;

Fig. 19 represents a cross-section taken through the foundation and part of a vertical wall of a building structure constructed in accordance with one embodiment of the invention.

Fig. 20 represents a cross-section similar to Fig. 18 showing starter bar reinforcements extending from the wall into the floor slab.

Fig. 21 represents a perspective view of the formation of reinforced beam or foundation blocks;

Figs. 22, 23 and 24 represent perspective views of a wall under construction, laying courses of masonry blocks without mortar one above the other; Fig. 25 represents a perspective view of the completed wall structure with the top reinforced trough beam partly cut away;

Fig. 26 represents a perspective view of a building structure with the roof frame attached;

Fig. 27 is a cross-sectional view through an embodiment of a vertical wall of a single storey structure constructed in accordance with the invention; and

Fig. 28 is a cross-sectional view through vertical walls of another embodiment of the invention, being a two storey building structure.

MODE FOR CARRYING OUT THE INVENTION

Referring to Fig. 1 the mobile masonry block plant 1 comprises a motor-driven concrete mixer 2 mounted on a platform 3 with an adjacent block-moulding machine 4. A skip bucket 5 is mounted on rails 6 and 7 to one side of the mixer

2 and is adapted to receive a charge of raw materials for concrete mixing (sand, concrete and/or aggregate) and is hoisted up the rails by either mechanical or motor-driven means 8 to discharge its contents into the mixer 2.

The skip bucket 5 is lowered to its lowest point for the filling operation. This is preset according to requirements; in some embodiments the skip 5 is adapted to be lowered to a point lower than the platform 3 of the plant (as depicted in phantom in Figs. 2-4), whereby the open top of the skip 5 is at ground level for ease of filling. In one preferred embodiment, the skip 5 is designed with a capacity of 0.4m³, but can be varied as required.

The cam-operated gate 9 on the bottom outlet of the mixer is closed, and with the skip bucket hoisted to its highest point the aggregate mix is discharged from the skip 5 into the mixer 2 and then mixing operations are commenced.

Water and any other additives are added to the mix according to predetermined requirements; the actual amounts required are determined by separate testing procedures. Upon completion of the mixing operation, the bottom cam-operated gate 9 is opened and the gate is moved to one side of the outlet. The concrete mixture is discharged from the mixer onto the conveyor 10 disposed beneath the mixer outlet and the mixture is then conveyed to the conical-shaped hopper 11 above the block moulding machine 12. In the preferred embodiment the hopper 11 is designed to be of a capacity similar to that of the skip 5 (e.g. 0.4m³).

The block moulding machine 12 is designed to manufacture concrete blocks 13 in accordance with local requirements or standards, e.g. in Australia blocks are preferably manufactured in accordance with Australian Standard 1500-1974, or the equivalent thereof. Prior to manufacture in any one location, analysis is carried out on the locally available materials (e.g. aggregates and cements) to allow a mix to be formulated that will satisfy the abovementioned standards.

The block moulding machine 12, by means of simultaneous unilateral vibration and compression produces blocks 13 of an accuracy of plus or minus 1mm.

At the start of moulding, the mould box 14 is up, the pressure plate is inside the mould box, and the scraper frame is forward. A wooden pallet is placed and positioned on the vibration plate. In the preferred embodiment, the mould box 14 is lowered onto the pallet using pneumatic or hydraulic means, such as a pneumatic double-acting cylinder 15 and 16. The scraper frame is then pushed back as far as possible.

Concrete mix is then discharged from the hopper 11 into the mould box 14, which is simultaneously vibrated to facilitate settlement of the mix. When the mould box is full, the scraper frame is pulled forward so that the pressure plate is above the mould box; this clears all excess material from above the mould box.

The pressure plate is then lowered while the mould box 14 is vibrated until the block is compacted and moulded to a predetermined vertical size. The mould box 14 is then raised, by pneumatic or hydraulic means in the preferred apparatus, and the manufactured block remains on the timber pallet. The block and pallet are then removed and the blocks are stacked for curing.

The blocks are allowed to cure by natural processes for about 14-21 days, during which time they are preferably covered with plastic and kept moist to slow hydration. Alternatively, the blocks can be cured by either low or high-pressure steam curing to reduce the curing time.

The mobile plant 1 is preferably of dimensions which make it adaptable (i.e. when partly disassembled) to transport in a standard sized container. A preferred plant has dimensions of about 5.4 metres (length) x 2.2 metres (width) x 3.7 metres (height). Disassembled, it is possible to fit two such plants into a standard sized container.

In order to construct a dwelling a number of block types are produced. Normally, there are four main types of blocks which will be described below with reference to the drawings and to non-limiting examples in terms of both size and shape, as follows:- 1. Straight Run Blocks (Stretchers)

These blocks 17 are shown in Figs. 6, 10-12 and 18 designed with a projecting nib 18 at one end and an inverted nib 19 at the other. Some of these blocks are designed with an inverted nib 19 at each end as in Figs. 10 and 12. This allows horizontal tying to take place. The blocks are mostly of hollow construction with a rectangular hole or cavity 20 therethrough, but at the projecting end of the block a solid fill is inherent through which a vertical hole 21 of just over 10mm diameter passes. This is to allow vertical reinforcement to pass through while eliminating concrete filling of cores. The laid size of the preferred block of this embodiment is 400mm long x 200mm high x 150mm wide. 2. Corner Blocks Embodiments of corner blocks 22 are illustrated in Figs. 13, 14, 16 and 17. Although most embodiments are basically a hollow block they have provisions close to each nib to allow a steel bar to be passed through in the same manner as the stretcher.

The dimensions of one embodiment of a corner block are as follows:

Main face: 400mm long x 200mm high x 150mm wide Second face: 200mm long x 200mm high x 150mm wide 3. End Blocks

These blocks 23 are illustrated in Figs. 7, 8 and 9 and are designed in both 'male' and 'female' mode. These blocks are used at every opening and each has a rod passing through every block. The end of the block has a groove 24 which will allow the flashing nib at the side of the window to slide into it. The nib is held firm using a clip. The following dimensions for end blocks are given by way of example only: 400mm long x 200mm high x 150mm wide 200mm long x 200mm high x 150mm wide. 4. Beam Blocks

Beam blocks 25 are illustrated in Figs. 19, 20, 21 and 25. Beam blocks are preferably "trough" blocks 26 and are used both below (Figs. 19-21) and above the wall (Fig. 25). They may also be used below any opening. They are designed to allow reinforcement steel to be laid into their trough and be concrete filled. In some embodiments the troughs 26 have performed holes to allow the passage of 10mm steel rod from below. The following dimensions of one embodiment are given by way of example only. 400mm long x 200mm high x 150mm wide 200mm long x 200mm high x 150mm wide.

The invention will be further described with reference to a preferred non-limiting form of construction of a building, illustrated with reference to Figs. 19 to 28 utilizing concrete blocks manufactured on a mobile masonry plant of the above described type. (a) FOUNDATION

A trench 27 is excavated to expose sub strata 28 of even load bearing material. The trench bottom is levelled as accurately as possible and lined with damp-proof course plastic sheeting.

Using a spirit level for levelling the 200mm wide beam blocks 26 are laid butting along the line of the foundations. At corners 29, the blocks overlap and the obstructing side is chipped away to allow steel reinforcement to directly follow the foundation line.

Two 12mm reinforcement rods 30 are laid into the blocks trough spaced at a minimum about 40mm apart. Overlapping at joins should be a minimum of about 600mm and wired with 10 gauge wire.

In embodiments where construction is off a footing and not from a slab, starter bars 31 are wired to these rods and left vertically protruding from the trough; see Figs. 19 and 21 . These starter bars are intended to provide the first section of a vertical tie rod 32 to tie together vertical courses of blocks forming the wall (as illustrated in Figs. 19 and 22-28), or to provide a tie from the wall 33 for the floor slab 34 (as illustrated in Fig. 20). They should therefore project sufficiently to allow them to be bent at right angles at the estimated floor height and to project into the floor slab a minimum of 300mm.

The troughs 26 are then progressively filled with concrete, care being taken to lift the reinforcement through the concrete to allow full bonding between the rods and the concrete fill. (.b) WALLS

In one method of construction, while the concrete is still in a very plastic state, the first course of stretchers 35 are laid on it (see Fig. 22). At 800mm intervals the stretchers have had inserted in the reinforcement hole a starting rod and concrete anchor. As these blocks are laid, the anchor is firmly pressed into the plastic concrete and manouvered to ensure that concrete has surrounded the splay. This starting rod is threaded and is of sufficient length to finish at least 300mm above the top of the beam block. Each starter block is individually levelled and is kept at equal level to its immediate blocks. The blocks are laid against a string line to ensure straightness.

Once the concrete in the foundation beam has set, blocks are laid in normal staggered bond (see Figs. 23 and 24). Prior to the second course being laid it is necessary to extend the starter rods. The starter rod is threaded, and a joining collar 36 is screwed on for half of its length and a galvanised threaded steel rod of suitable length is screwed into the other side of the collar. Laying of the second course 37 can now commence. At corner positions each block is alternately long side 38, short side 39 , so providing the correct spacing of the other blocks in normal bond. When the wall 33 is two or three blocks above the anticipated finished floor level, laying is stopped and the rods 32 are temporarily tensioned by applying a nut and washer to each, using a shim for levelling the block if necessary, and tightened down.

At the mid level of the floor slab 34, the reinforcement rods 31 are bent at right angles and a chip taken out of the side of the blocks (as at 40 in Fig. 20) to allow passage of the rods to proceed without affecting the level sitting of the block above. The blocks through which these reinforcement rods pass are concrete filled 41 when the floor slab 34 is being poured.

The temporary tensioning is released and laying is continued as previously described. In some embodiments, at openings such as below windows etc., the blocks are stopped one course below and the beam blocks are laid in their stead. These beam blocks will have reinforcement rods laid in them and be concrete filled. Prior to the concrete filling however, tension will be applied to the rods as described below.

Upon completion of each day's laying the projecting rods 32 have a temporary tension applied to them to ensure overnight stability of the wall. Once the wall is one course from the top, use of the stretcher block ceases and a beam block 46 is laid around the wall, as in Fig. 25. Where openings are encountered, the beam block is allowed to pass over the opening by using temporary formwork. The beam blocks 46 have holes in their base which allow the rods 32 to pass through. It is necessary for sufficient rod to be available to allow it to project a minimum of 100m above the top of the beam block. Nuts and washers 47 are then run down the threaded rod until the bottom of the trough of the beam block is reached. Each of these nuts are tightened using a socket spanner and applying maximum force permissable with a lever handle. Notwithstanding the fact that there is no mortar between the blocks, the blocks are rigidly held together to form the wall. A wall so formed is structurally a beam and is in fact very much stronger than a conventional masonry wall. If during the process of laying, the wall has tended to move out of line either vertically, or horizontally, this is corrected by tapping the blocks into position using a rubber mallet prior to the full tightening process.

Once all the rods have been tightened two 12mm reinforcement rods 48 are laid all around the beam block trough as for the foundation block. The trough is then concrete filled, again lifting the rod off the bottom of the trough as at 49. When the concrete has set the wall is complete, (c) FLOOR

In one method of construction, the floor is laid quite early in the construction process. There are a number of reasons for this:

(i) Easy access for filling material and concrete. (ii) Easy access for steel reinforcement rods of maximum length. (iii) The floor provides a firm platform for the use of trestles, enabling laying to be undertaken from the inside and thereby eliminating costly scaffolding. Using blockwork as formwork, filling material is loaded into the perimeter of the dwelling until a position 50mm below the proposed underside of the floor is reached. The filling is well compacted by laying it in layers of not more than 150mm and then compacting. The final 50mm is achieved by using sand.

Reinforcement rods are then laid in a grid pattern. The rods are wired together at every intersection and the rods that line up with the starter bars are allowed to overlap these bars by a minimum of 300mm and are then firmly wired thereto.

Concrete is then laid to the required thickness with the 'mesh' of reinforcement being raised through it to approximately 50mm from the bottom. This slab is well tamped and kept level. If a wet area has outside access then it is permissable to leave a slight slope towards the door in this area only in lieu of a floor drain. (d) WINDOWS

If windows are specified as having fins at each side, then these are inserted during the construction of the wall. If, however, the windows do not have side nibs, these may be inserted in a later period in the manner recommended by the manufacturer. (e) DOORS

Doors are installed in the normal manner of fixing jambs direct to the block openings. The jambs fully cover the groove in the end blocks. (f) ROOF FRAMING At the commencement of the roof framing a wall plate (e.g. 100mm x 38mm) is run around the top of the walls 33, as shown at 50 in Fig. 26. At positions where the block threaded reinforcement rod 32 is projecting, the plate 50 is drilled to allow the rod to pass through. A nut and washer 51 is run down and tightened, this now ties the wall plate directly through to the foundation.

Roof trusses 52 are preferred although conventional roofing can be constructed according to local requirements and/or specifications.

Eaves are prepared for lining in the conventional manner. (g) INTERNAL WALLS

It is recommended that some internal walls, especially the bathroom area, be of the system. Using the system selectively internally will substantially increase the structural strength of the house and provide safe shelter for the occupants in the event of a cyclone. However, some walls may be treated as partition walls. If, as recommended, roof trusses are used, then the internal walls are entirely non-load-bearing. In this instance, timber frames, either prefabricated or constructed in situ, may be masonry nailed to the floors. When fixing to the trusses however, it should be noted that the bottom chord of an engineered truss must be able to flex. Brackets with slotted nail holes should be used in this instance. (h) WALL FINISHING

Because the blocks are accurately manufactured and the walls are laid without mortar, the resulting wall is very accurate in plumb. Very little render is therefore required and it is recommended that a render be applied as a 2mm or 3mm bagging rather than in the traditional manner. Render should then be painted with a water repellent paint.

Fig. 27 is a cross-section through a vertical wall 33 of a single storey dwelling illustrating that the wall comprises a plurality of rows of blocks rigidly held between top and bottom beam blocks 26 and 46. Notwithstanding the fact that there is no mortar between the blocks, the blocks are rigidly held together to form the wall 33. A wall so formed is structurally a beam and is in fact very much stronger than a conventional masonry wall.

The construction method of the present invention is not limited to single storey dwellings, and it is in fact readily adaptable to the construction of multi-storey buildings of two or more floors. By way of example only, Fig. 28 illustrates the principal of construction of the present invention when applied to a two storey building. In this embodiment the ground floor comprises a concrete raft or slab 53 which is rebated around its peripheral edge to provide a seat for the bottom beam or bond block 26 on a bed of mortar 54. The blocks are then laid in a plurality of rows to provide a mortarless wall as described above. At the required height of the first floor, an intermediate bond beam or beam block 55 is laid and the intermediate rows of blocks forming the external walls 33 are clamped between bond beam blocks 26 and 55. Galvanized steel saddles are attached to the inside edge of the intermediate bond beam to provide support for the first floor joists 57.

The external walls of the second storey of the building are then built up from first floor bond beam 55 in the previously described manner, with the first floor bond beam being reinforced with steel rods and concrete filled for extra rigidity. Subsequent rows of blocks are threaded onto the vertically extending rods as previously described until the walls of the second storey reach the required height. This wall is held rigidly in place by the addition of the top beam block 46 in the manner as previously described. The plate 50 is then secured in position and the roof structure 52 is added.

Internal walls 58 are built straight on to the concrete raft 53 with the vertical rods 59 onto which the blocks of the internal wall are threaded being secured to the raft by means of chemical anchors or by any other suitable means. In summary, the building construction system of the present invention has the following advantages: 1. Elimination of filling a foundation trench with concrete. Trenches vary in width. The deeper one excavates by hand, the wider the trench. In conventional construction, the sides of the trench are used as formwork and therefore far more concrete than is useful is poured to cater for this.

2. Eliminates some foundation steel. Most conventional building demands a minimum of six steel bars in the foundation together with the stirrups and separator bars. In some embodiments, the system of the present invention may require only two bars.

3. No mortar is used in the laying of the blocks. Because some currently available blocks, are of dubious size and because the skill of some masons are of unknown or dubious quality, the mortar used in conventional building can be excessive.

4. Horizontal bars are eliminated. Horizontal bars are normally used to prevent the cracking of convention walls caused by stress, vibration, expansion etc. Because the system of the present inventon does not use mortar, each and every block is capable of expanding or contracting, taking shocks, vibrations etc., in its own right without causing stress to its neighbouring block and without finding the weakest point of the structure to release its energy. 5. Thinner render. Because the walls in the system of the present invention are so accurate, very little render is required. 6. No scaffolding. Blocks are laid from within the house using the floor as a base for easily moved trestles. This eliminates costly scaffolding. Although the invention has been described above with reference to preferred embodiments and drawings, it will be appreciated that numerous variations, modifications or alternatives may be substituted for specifically described features without departing from the spirit or scope of the invention as broadly described.

Claims

AMENDED CLAIMS

[received by the International Bureau on 08 November 1985 (08.11.85); original claims 1-10 replaced by new claims 11-23]

11. (new) A masonry wall made from masonry blocks comprising:

Upper and lower elongated rigid channel form members; a plurality of rows of masonry blocks laid row upon row without mortar between said upper and lower rigid channel form members, said blocks including at least one hole adapted to receive a vertical rod; a plurality of rods, extending vertically from said lower elongate channel form member to said upper elongate channel form member and passing through said holes in said blocks; the lower elongate channel form member havinq being filled with a hard setable substance to anchor the said rods therein. and means associated with said rods and said elongated channel form members to tension said rods causing at least some of said blocks to be in compression.

12. (new) A masonary wall as claimed in claim 11 in which the upper elongate channel form member was filled with a hard setable substance after the rods had been tensioned.

13. (new) A masonry wall as claimed in claim 11 or claim 12 wherein one of said elongated channel section rigid members is formed of a plurality of masonry blocks laid in end to end arrangement, contains at least one elongated reinforcing member and having been filled with a hard setable substance.

14. (new) A masonry wall as claimed in any one of claims 11 to 13 wherein both of said elongated rigid members are formed of a plurality of channel section masonry blocks laid in end to end arrangement, each of said elongated rigid members containing at least one elongated reinforcing member and having been filled with a hard setable substance.

15. (new) A wall as claimed in any one of claims 11 to 14 wherein said rods comprise two or more lengths of rod joined together in end to end relationship. 16. (new) A wall as claimed in any one of claims 11 to 15, wherein each rod includes a threaded end which is threadably engaged with nut means which bear against the upper elongate channel form member to cause the said rod to be tensioned

17. (new) A wall as claimed in any one of claims 11 to 16 wherein some of said masonry blocks have one or more projecting tongues and/or one or more tongue-receiving grooves on opposite end faces to facilitate horizontal tying of the blocks.

18. (new) A wall according to claim 13 or claim 14 wherein the rods extending between the upper and lower channel form members are tied to one of said one or more reinforcing members.

19. (new) A method of construction of a masonry wall of the type as defined in any one of claim 11 to 17, said method comprising the steps of :-

a. laying an elongate reinforced foundation comprising a lower elongate channel form member formed of a plurality of channel section masonry blocks laid in end to end array and containing at least one elongate reinforcement member; b. positioning a plurality of rods extending vertically from said lower trough at each of a plurality of predertermined locations and filling the trough with concrete or another hard setable material; c. laying, without mortar, a plurality of rows of masonry blocks one above the other with the bottom one of said rows being laid on said foundation, said blocks having openings therein for threading onto said rods at predetermined locations; d. locating an upper elongate channel form member formed of a plurality of channel section masonry blocks laid in end to end arrangement, on the upper one of said rows; e. tensioning said rods to clamp said blocks between the upper and lower elongate members and to cause at least same of said blocks to be in compression and f. filling the upper elongate channel form member with concrete or another hard setable material,

20. (new) A mobile plant to manufacture mortar blocks from cement and aggregate comprising:

(a) a motorised mixer for mixing a batch of said cement and aggregate with water;

(b) a skip container associated with said mixer for receiving predetermined amounts of said cement and aggregate and discharging said materials into the mixer;

(c) conveyor means so disposed in relation to said mixer for receiving concrete discharged from said mixer and for conveying same to;

(d) a hopper adjacent to said mixer and;

(e) a block forming means further comprising;

(i)a mould adapted to produce a plurality of blocks having an open top for receiving loose concrete from said hopper and a closed bottom,

(ii)vibration means adapted to cause alternating displacement and acceleration of said mould in a vertical direction, a pressure plate forced into said mould by a ramming means to compact concrete placed therein in conjuction with said vibration means, and

(iv)a switch means to activate said ramming means to release said pressure plate after same has reached a predeterminded distance from the bottom of said mould All of the component parts of said plant are mounted on a rigid platform for transportation of said plant 21. (new) A mobile plant as in claim 20, wherein the skip container is mounted on running rails upon which the skip container is adapted to be raised from a first position substantially adjacent to the platform to a second position adjacent to the top of the mixer. 22. (new) A mobile plant as in claim 21, wherein the running rails extend below the platform such that in the said first position the top edge of the skip can be aligned substantially adjacent to the platform. 23. (new) A mobile plant according to any one of claims 20 to 22 adapted to be assembled on site and to be disassembled for transport or for storage.