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) This invention relates to the building industry and in particular to the construction of masonry walls.

In conventional masonry wall construction masonry blocks 5 comprised of a mixture of cement and aggregates of varying sizes are used. Such masonry is heavy and is porous. In addition the fact that the blocks are cast makes it very difficult to maintain accurate dimension tolerances. An attempt has been made to overcome the weight problem by 10 using fly ash from the combustion of coal as the aggregate, and to some extent that has been successful. The problems of water absorption and size variation have remained.

Another form of light weight masonry block has been recently developed and is called AAC in the trade, the letters AAC

15 stand for Autoclaved Aerated Concrete. AAC blocks are formed by mixing together sand, lime and cement and a gas forming agent which reacts with alkali in the cement to produce hydrogen gas. The result is a gas expanded semi-hard mass which is wire cut to provide very accurately

20 sized blocks. The "green" blocks are then autoclaved for several hours at about 180 degrees C to provide light weight water impervious masonry blocks which are about 20 the weight of convention masonry blocks of the same size.

The size and squareness accuracy of AAC blocks is such that they can be laid without bonding medium, such as mortar or glue, a procedure termed 'dry stacking ¹ in the building industry. If a level undersupport is used a dry stacked wall which is substantially vertical can be erected by workers with very little experience in masonry wall construction. As will be understood this is a big step in the building industry.

One consideration with any masonry wall is its ability to withstand lateral force, such as wind pressure. Where conventional hollow masonry blocks are used for wall construction the ability of the wall to resist lateral forces is a function of the bond between the masonry blocks resulting from the keying effect of the mortar in the apertures in the blocks. Sometimes additional strength is provided by means of reinforcing rods which are passed through the apertures of the blocks in the courses and encased in a cement slurry. This serves to tie the blocks of a wall together but does not anchor the wall to the support on which the wall stands. In the case of solid masonry blocks the resistance to lateral force is a function of the weight of the blocks and the bond between the mortar and the block surfaces.

The use of dry stacked AAC masonry blocks to form walls where they are likely to be subjected to lateral load conditions has been under review and the present invention has been devised with that application for AAC masonry blocks in view.

Broadly stated the present invention comprises a method of masonry wail construction comprising the steps of providing an undersupport, forming a wall comprised of a plurality of rows of masonry block elements αf substantially rectangular configuration with apertures therethrough which will lie in the plane of the erected wall and which are modular with respect to their positioning in said block elements (as herein defined) so as to provide columns of apertures extending from the top of the wall to the undersupport and applying compressive force to the wall in the plane of the wall by means of tensionable anchoring means respectively located in columns of apertures and connecting the top of the wall to the undersupport.

Several aspects of a presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

Fig.l is an exploded pictorial view showing a corner at the intersection of two walls constructed according to the

invention .

Fig.2 is a perspective view of a stretcher block for use in the method of the invention,

Fig.3 is a perspective view of one form of closing block for use in the method of the invention.

Fig.4 is a perspective view of a second form of closing block for use in the method of the invention.

Fig.5 is a perspective view of form of corner block for use in the method of the invention, Fig.6 is a perspective view of a second form of corner block for use in the method of the invention,

Fig.7 is a perspective view of one form of half block for use in the method of the invention, and

Fig.8 is a perspective view of a second form of half block for use in the method of the invention.

Referring to the illustration Fig.l, there is shown an undersupport 1 in the form of a concrete slab, but it is to be understood that strip footings or steel beams or like members can provide a suitable undersupport and can be used as an alternative to a slab. Anchored in the slab 1 at predetermined spacings at the positions identified 2 there are rods 3 which extend vertically. The rods 3 can be anchored in any suitable manner at their lower ends, as for example by known mechanical locking members inserted into the slab 1 and threadably engaged by the ends of the lower

ends of the rods, or by known gluing techniques as are used in the mining industry under the general name of chemical anchors.

The masonry blocks used in the wall construction are preferably of the AAC type (as hereinbefore described) although this is not essential. The blocks can be of several forms as is required for laying blocks in a known bonding manner in a course and to provide wall ends and openings in walls. The blocks allow walls with and without corners to be assembled in a dry stack manner by selecting blocks as required from the range provided.

The blocks are all of rectangular shape and the longest block in a range is a stretcher block as illustrated in Fig.2 and identified 4. It has a centrally positioned vertical tongue 5 at one end and a centrally positioned vertical groove 6 at the other end. In one form the stretcher block is 600mm long. The length is the block body length excluding the tongue and herein lengths of tongued blocks when given will refer to the body length of the block without the upstanding height of the tongue included) . A block height is 200mm and its thickness is 150mm.

The next block in the range is a closing block which is

identified 7 and 8 in Figs.3 and 4 respectively. This block is used where a wall is terminated with a full length block, that is a block of 600mm length. It will be noted that the closing blocks of Figs.3 and 4 are provided with one only of the tongue and groove of the stretcher block.

The next block in the range is a corner block as illustrated in Figs.5 and 6 where tongued and grooved forms of the corner block are illustrated and identified 9 and 10. The corner block is used where corners in the wall are to be constructed and they have the same thickness and height as a stretcher and closing block.

The next block in the range is the half block and the tongued and grooved forms of this block are illustrated in Figs.7 and 8 and are identified 11 and 12.

Other blocks can be added to the range to facilitate the construction of wall configurations but those blocks identified above are the basic blocks in the range and with those blocks most wall construction can be achieved.

It is to be noted that in each of the blocks in the range there is a through hole or holes 13.

The dimensions of the blocks and the positioning of the

holes 13 are on a modular pattern so that when blocks are aligned in a running bond manner in courses in a wall the holes will be aligned through all of the courses. Likewise when a corner is constructed the holes in the blocks extending in each direction from the corner in a course will still be in a running bond pattern and the holes in the blocks in superimposed courses will still be aligned. This is easily seen in Fig.l where the wall construction of several courses has been illustrated and a corner has been included.

The Fig.l arrangement shows the bars 2 anchored in the slab 1 to be of a relatively short length and it is envisaged that the rods will be threaded bars of, say, 1.5 meter length. Threaded joining bushes 14 are provided to allow the bars to be extended to the wall height required. It is to be understood that where joining bushes 14 are to be used the holes 13 need to be of a size to receive a joining bush.

When the wall has attained the required height a top plate 15 as shown in Fig.l is placed over the blocks in the top course and the bars 2 are passed through holes 16 in the top plate. Nuts 17 and washers 18 are applied to the bars extending above the top plate and are tightened onto the top plate 15 to create a compressive force thereby to lock the masonry in the wall together and to the floor slab 1. The

result is that the blocks, which have a high crushing strength and can withstand compressive force, are unified within the wall and with the concrete slab 1.

The result of the method proposed by this invention is the provision of a single masonry wall which has the following qualities. Because of the anchoring means provided the wall in substance becomes a monolithic vertical beam which is very strong in resisting loads in the vertical plane. Because it is anchored to the floor slab it has great resistance to lateral loads, such as wind loads. Where the AAC form of masonry block is used it has very good insulation properties due to the gas pockets within the blocks. The water imperviousness which results from the manner of manufacture of AAC blocks makes the conventional cavity wall arrangement unnecessary. The light weight of AAC blocks makes the load on the floor slab (or other undersupport) substantially less than that for brick or masonry walls and thus a saving is possible on thickness and/or reinforcing needed in the floor slab from that which is required for a conventional brick or masonry wall construction.

The foregoing is the preferred embodiment of the invention. It is to be understood that the sizes given for the blocks can be varied provided a modular relationship between blocks

in a range as described is followed. It is also possibl to use blocks without end tongues and grooves and still perform the invention.

The form of top plate may be varied from that disclosed if desired and the use of nuts and washers with threaded bars is to be understood as illustrative. Other means for applying permanent compressive load on ήt locks in a wall whilst passing through columns of aligned holes in the courses of the wall are to be considered as within the inventive concept herein set forth. As an example, collet type gripping means using captive wedges, of known form, could be used to grip the rods and maintain a compressive force on the wall, the collet type gripping means being applied during the temporary application of a compressive force to the wall.

It is also within the scope of the invention to provide substantially inextensible cables, e.g. steel cables, in place of the rods 3 hereinbefore disclosed. The foregoing collet type gripping means is especially suitable for cables used as the means for applying the compressive force to the wall.