GB2175326A - Constructional elements and method and apparatus for manufacture - Google Patents

Abstract

A constructional element such as a building block is made from an aerated cementitious material and has two major sides 10 and four minor sides. To enable a wall to be built without the need for mortar, keyways in the form of ridges 16 or channels 12 are formed along at least three of the minor sides or, in the case of a corner block along at least two minor sides and one major side. Each of the ridges 16 is shaped and dimensioned to fit into an channel 12 of another similar element. Moulds for making such constructional elements are also disclosed, together with a method of manufacture wherein partially formed blocks are cut before they harden. <IMAGE>

Description

SPECIFICATION Constructional elements and method and apparatus for manufacture This invention relates to constructional elements such as building blocks and in particular to blocks made from aerated cementitious materials. The invention also relates to a method and apparatus for producing such blocks.

Aerated cementitious materials have become increasingly popular in recent years in the manufacture of building blocks and the like.

These materials are generally made by mixing cement, fillers such as sand or pulverized fuel ash, water and a foaming agent. They can be made in mobile units such as those sold under the trademark AERCRETE. Constructional elements made with such materials have low weight and high insulating properties and can be easily worked on site, for example by sawing or drilling. They are also relatively cheap to make.

The present invention is based on the discovery that if a wet mix of aerated cementitious material is poured into a mould it can be cut, having passed its initial set and before final hardening, with a bladed tool such as a guillotine. According to a first aspect of the invention therefore there is provided a method of making constructional elements such as building blocks which comprises the steps of making an aerated cementitious material by mixing cement, a filler, a foaming agent and water, pouring a mixture into a mould, allowing the mixture to set sufficiently to retain its shape but not to harden, cutting the moulded mixture to the desired shape with a bladed tool, preferably a guillotine, while it is still soft and finally hardening the shaped product.

To enable the moulded mixture to be cut it should be free of stones or hard lumps of aggregate.

The process of the invention is particularly suited to the manufacture of building blocks having projecting and/or recessed keyways. In a preferred process in accordance with the invention, the cementitious material is moulded to form an elongate body of uniform crosssection with one or, more preferably, both of two opposite sides formed with a keyway in the form of an elongate ridge or channel.

These two sides form the top and bottom of the blocks. A guillotine is then used to cut the elongate body into blocks of the required length, the guillotine blade having a U-shaped central portion when viewed edge on, so that with each cut it forms a recessed channel or keyway in one block and a corresponding projecting ridge or keyway in the next.

Accordingly, the present invention also provides a constructional element such as a building block made of an aerated cementitious material having two major sides and four minor sides, elongate keyways in the form of ridges or channels being formed along each of the four minor sides, or along their minor sides and one major side, and each of the ridges being shaped and dimensioned to fit into a channel of another similar element.

The constructional element preferably has a top side with a ridge, a bottom side with a channel, an end face with a ridge and an opposite end face with a channel One course of such building blocks will comprise a line of blocks laid end to end with the end ridge of each block fitting into the end channel of the next, and forming a continuous ridge along the top. This top ridge is then accommodated in a continuous channel formed on the underside of the blocks of the next course laid above it.

Instead of the guillotining method described above, the constructional elements of the invention can also be made in moulds preferably of a type in which several blocks can be made at one time.

Accordingly, the invention also provides a mould for the manufacture of building blocks comprising an outer frame separable into at least two parts, and more preferably three or four parts, the outer frame comprising a pair of opposed elongate side portions and a pair of opposed end portions, and one or more dividing members extending across the outer frame between the two side portions and spaced from the two end portions, wherein one said side portion and one said end portion each have an inwardly facing moulding surface with a central longitudinal ridge flanked by a pair of longitudinal flat surfaces, wherein the other side portion and the other end portion each have an inwardly facing moulding surface with a central longitudinal channel flanked by a pair of longitudinal flat surfaces, and wherein the or each dividing member has a projecting central portion at one end to fit into the central channel of one side portion and a recessed central portion at the other end to accommodate the central ridge of the other side portion, the cross-section of the or each dividing member having a central Ushaped portion flanked on either side by straight portions.

The mould may have open top and bottom sides,being laid on a board or the like to be filled with cementitions material, preferably of the aerated type described above.

The mould should be separable into as many parts as may be necessary to allow removal of the moulded blocks. Each of the side and end portions of the outer frame may be a separate member. In another embodiment each end portion is integral with a respective side portion.

The dividing members are preferably separable, being located in position by means of pins or lugs on the inwardfacing moulding surfaces of the side portions of the outer frame.

By using a sufficient number of such pins or lugs, spaced at intervals along the length of the outer frame, the spacing between dividing members, and hence the size of the blocks, can be varied.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein: Figures 1 a, 1 b, 1 c and id show respectively a side elevation, an end elevation, a perspective view and a top plan view of a building block in accordance with the invention; Figures 2a, 2b and 2c show respectively a side elevation, an end elevation and a perspective view of a base block for use in conjunction with the blocks of Figure 1; Figures 3a, 3b, 3c and 3d show respectively a side elevation, an end elevation, a perspective view and a top plan view of a capping block for use in conjuction with the blocks of Figure 1;; Figures 4a, 4b, 4c and 4d show respectively a side elevation, an end elevation, a perspective view and a top plan view of a corner block in accordance with the invention; Figures 5a, 5b and Sc show respectively aside elevation of a corner block in accordance with another embodiment of the invention and an end elevation and top plan view of a corner block which is a mirror image of the block of Figure 5a; Figures 6a, 6b and 6c show respectively a side elevation, an end elevation and a top plan view of a corner block in accordance with a further embodiment of the invention; Figures 7a, 7b and 7c show respectively a side elevation of a corner block in accordance with a further embodiment of the invention and an end elevation and top plan view of a corner block which is a mirror image of the block of Figure 7a;; Figures 8a, 8b, 8c and 8d show respectively a side elevation, and end elevation, a perspective view and top plan view of a building block in accordance with the invention with a ridge at each end; Figures 9a, 9b and 9c show respectively a side elevation, an end elevation and a top plan view of a building block in accordance with the invention with a channel at each end; Figures 10a, 10b, 10c and 10d show respectively a side elevation, an end elevation, a perspective view and a top plan view of a half-length building block in accordance with a modified embodiment of the invention; Figure 11 shows perspective views of door and window jambs and sills for use with the building blocks of the invention; Figure 12 is a perspective view of a reinforced constructional element in accordance with the invention, in the form of a lintel;; Figure 13 shows a mould for casting constructional elements in accordance with the invention, prior to cutting to the desired shape; Figure 14 is a front view of guillotine for cutting a cast constructional element; Figure 15 is a cross-section on the line XV XV of Figure 14; Figure 16 is a plan view of a mould for casting complete building blocks in accordance with the invention; Figure 17 is a cross-section on the line XVII-XVII of Figure 16; and Figure 18 is a cross-section on the line XVIII-XVIII of Figure 16.

Referring first to Figure 1, a building block, preferably made of aerated cementitious material has plane rectangular major sides 10. On its top side is a keyway in the form of a ridge 11 between respective flat portions 15. The ridge has sloping sides 16 and a central flat top surface 17, giving it a trapezoidal crosssection. One end of the block (the left hand end in Figure 1a) has a keyway in the form of a vertical ridge 13, the cross-section of of which is identical to that of the ridge 11.

Ridge 13 also has a flat central surface flanked by sloping surfaces, with vertical flat surfaces 18 on either side, and a trapezoidal cross-section identical to that of the top ridge 11.

The underside of the block has a keyway in the form of a channel 12, the shape of the underside being complementary to that of the top side, similarly, at the opposite end of the block to ridge 13, shown in Figure 1b, there is formed on inwardly tapering vertical channel 14 with vertical side walls 19 angled inwardly towards a vertical central wall. the cross-section of channel 14 is identical to that of the bottom channel 12. The overall shape of this end of the block complements that of the other end so that a course of such blocks can be laid with the ridge 13 of each block fitting into the channel 14 of the next. There is thus formed a course of blocks with a continuous bottom channel and a continuous top ridge, the bottom channel accommodating the ridge of a similar course below and the top ridge fitting into the bottom channel of a similar course laid on top.

The blocks of the invention interlock in such a way that they can be laid dry without the use of mortar or other bonding agents. The blocks are thus ideal for fast, simple and cheap building.

The base block shown in Figure 2 is identical to that shown in Figure 1 except that it has a flat bottom surface with no channel. At the left hand end of the block as shown in Figure 2a, a keyway in the form of a ridge 23 of trapezoidal cross-section extends down to the bottom of the block, as does a channel 24, also of trapezoidal cross-section, at the opposite end of the block as shown in Figure 2b. The top plan view of this block will be identical to that shown in Figure 1 d.

The capping block shown in Figure 3, is similar to that of Figure 1 except that has a flat top surface 30 without a ridge and the keyways 33 and 34 at the ends of the block are cut off at the top as compared with the blocks of Figures 1 and 2, The corner block shown in Figure 4 is identical at one end (the right hand end in Figure 4a) to that of Figure 1, but its opposite end 43 is flat, without a ridged keyway. Its top ridge 41 is also cut off at one end. The fourth keyway in this case is at right angles to the other three, being in the form of a channel 45 formed in the major side wall 40 and top ridge 41. The shape of the bottom channel 42 essentially complements that of the top ridge 41, except that this channel merges into the vertical channel 45.

this corner block is designed to receive respective vertical ridges of two blocks of the type shown in Figure 1, at right angles to one another.

The corner block shown in Figure 5a is similar to that of Figure 4 except that instead of a vertical channel in one major side it has a projecting vertical ridge 55, the top ridge 51 and the bottom channel 52 being L-shaped in plan view. The block shown in Figures 5b and Sc is a mirror image of that shown in Figure 5a, so that while the end channel 54 is the same in each case, as seen in plan view in Figure Sc the ridge 55a and the shorter arm of top ridge 51a project to the right whereas in Figure 5a the corresponding ridges project to the left.

The two blocks of Figure 5 are designed to be laid one above the other, with the shorter arm of the top ridge of the lower block received in the longer arm of the bottom channel of the upper block and vice versa, allowing two courses of blocks in each direction to be laid in the usual staggered formation.

The corner block of Figure 6 is similar to that of Figure 4 except that in place of a vertical channel at one end it has a vertical ridge 64 into which top ridge 61 merges.

The corner blocks of Figure 7 are similar to those of Figure 5 except that in place of vertical end channels 54 they have ridges 74, 74a.

As in the case of Figure 5, the block of Figure 7a is a mirror image of that of Figures 7b, 7c and these blocks are designed to be laid one above the other in staggered formation.

The block of Figure 8 is similar to that of Figure 1 except that instead of having a vertical channel at one end it has a vertical ridge 83 at each end top ridge 81 merging into both vertical ridges.

The block of Figure 9 is similar to that of Figure 1 except that instead of having a vertical ridge at one end it has vertical channels 94 at each end. The blocks of Figures 8 and 9 are for bridging odd gaps where two courses meet with two vertical ridges or two vertical channels facing one another.

As in the conventional laying of bricks, breezeblocks andthe like, half length blocks are required to enable staggered courses of blocks to terminate at the same vertical line.

Such a block is shown in Figure 10. The major side surfaces 100 are square. Compared to the blocks described above, the keyways are modified in that top ridge 101 and end ridge 103 have respective shallow longitudinal grooves 108 and 109 formed centrally therein, while bottom channel 104 and end channel 106 have respective longitudinal central ribs 105, 107. These central ribs and grooved assist in aligning the blocks more precisely when they are laid.

Figure 11 shows two types of door or window jamb or sill, in the form of elongate sections the length of which can be determined as desired. These components are of male or female type, having a longitudinal keyway in the form of a ridge 113 or a channel 114, depending on the type of keyway around the door or window opening. Reinforcing rods 112 extend longitudinally through these components.

The lintel shown in Figure 12 is essentially an elongated version of the basic building block of Figure 1, having a top ridge 121, a bottom channel 122, a vertical ridge 123 at one end and a corresponding vertical channel at the other. To comply with building regulations, the lintel will normally be made of reinforced concrete, with reinforcing rods such as 126, 128 extend longitudinally through the lintel.

Figure 13 shows a mould in the form of a flat base 130, a male side member 131 with an inwardly facing ridge 132, an opposing female side member 133 with an inwardly facing channel 134 and a pair of flat end members 135, the nearer one of which is omitted from the drawing to show the inside of the mould more clearly.

The length of the mould of Figure 13 is a precise multiple of the height X of the major side 10 of the block of Figure 1. This height X will usually be 9' (approx.23cm), but may be varied depending on local requirements.

The mould of Figure 13 is separable into its component parts and can be used as follows to produce one base block as shown in Figure 2, one capping block as shown in Figure 3 and a number of blocks as shown in Figure 1, depending on the overall length of the mould.

An aerated cementitious mixture as described above is poured into the mould and allowed to set partially to produce a pre-form. When the pre-form has set sufficiently to be selfsupporting, the mould is turned through 90 onto its female side member and the base 130, male side member 131 and ends 135 are removed. The pre-form thus produced has flat ends and flat major sides, with a longitudinal channel formed along the top by the male mould member 131 and a longitudinal ridge along the bottom, still accommodated in the channel 134 of female mould member 133.

The pre-form and its supporting mould member are transported, for example on rollers, to a guillotine such as that shown in Figures 14 and 15. This comprises a base 143 on which are mounted a pair of uprights 140 connected together at the top by a cross piece 144. Vertical slots 150 are formed in each of the uprights, to receive the.outer portions of a shaped blade 141 made of steel or the like. The edges of the blade are provided with guide strips 142 to ensure that it slides straight up and down. As can best be seen in the cross-sectional view of Figure 15, the central part of the blade is bent to a trapezoidal shape corresponding to that of the keyways on the blocks to be cut. This central portion also extends downwardly, the elevation of this projection as seen in Figure 14 having the same trapezoidal profile.

The pre-form 146, the height X of which corresponds to the length of the blocks to be cut and its supporting mould element are pushed through the guillotine a distance corresponding to the desired value of X, and the blade 141 is brought down to cut the first block. If the preform is pushed through in the direction of the arrow in Figure 15, the first block to be cut will be a capping block as shown in Figure 3, with its flat top formed by the end of the mould and its bottom channel cut by the blade. In cutting this channel, the blade will also be cutting the top ridge of the next block.

The pre-form is then moved through the guillotine, each time by a distance X, cutting a series of blocks of the shape shown in Figure 1. The last block to be cut will be a flat bottomed base block as shown in Figure 2.

It can be seen in Figure 14 that the profile of the bottom of the blade 141 corresponds to the cross-sectional shape of the mould element 133, so that the lower extension 145 is received in the channel 134 to enable the cut to be completed.

When the blocks have been cut, their drying and hardening can be completed.

Instead of being made by guillotining, the blocks of the invention can be made by moulding alone, for example in a mould as shown in Figures 16 to 18. These figures show an open-sided mould for making five blocks of the type shown in Figure 1.

The mould comprises an outer frame made up of side frame members 160, 161, end members 162, 163 and four dividing members 164 spaced at intervals between the end members, the spacing corresponding to the desired height X of the blocks being made.

The dividing members are located by lugs 165, 166 spaced at intervals along the inwardly facing surfaces of the side frame members 160,161. More such lugs can be provided if it is desired to vary the number and spacing of the dividing members.

Each of the outer frame members 160-163 is made from sheet metal, bent to form on one side a moulding surface having the shape of one side of the blocks to be made. The cross-section of these members can be seen in Figures 17 and 18. In each case the sheet metal is bent back behind the moulding surface, the opposed edges being connected by cross-struts 171, 172, 180, 181. The four outer frame members are secured together by pairs of clamps 167, 168, 169, 170.

The cross-sectional shape of the dividing members can be seen in Figure 17, and their main profile in Figure 18. As can be seen from these figures, one block as shown in Figure 1 will be formed between each pair of adjacent dividing members, or between one of these members and an adjacent end frame member, the top and bottom keyways 11, 12 being formed by the respective mutually facing convex and concave surfaces of adjacent dividing members or end frame members and the end keyways 13, 14 being formed respectively by the mutually opposed concave and convex moulding surfaces of side frame members 160, 161. Replacing one of the dividers with a flat sheet enables a base block and a capping block (figures 2 and 3) to be moulded.

To mould the blocks, the assembled mould is laid on a flat surface such as a board with one of its open sides uppermost and a mixture of aerated cementious material is poured into each of the compartments within the mould. Excess moulding material is scraped off and the top side can then be covered with another flat board while the blocks set. When the blocks have set, the mould is dismantled by releasing the clamps 167-170.

It will be apparent that blocks of other shapes, for example the various corner blocks, can be made by using moulds of different shapes or by releasing the partially set blocks from the mould and cutting then to the final shape.

The invention thus provides a cheap and simple way of making, on site if desired, building blocks which are easy to use, do not require bonding and give high rigidity of construction. The blocks so produced can be formed into self aligning wails interlocking horizontally and vertically as to render professional brick laying unnecessary thus catering for amateur builders and the D.l.Y. market.

They are light enough to be easily usable by men and women, but at the same time provide immense strength, insulation and protection against frost, penetration of water and wind, and are rot proof, vermin proof, fire proof and capable of withstanding continuous cycles of 2,000 C and freezing alternately without injury to the surface. The aerated material being capable of accepting Thermal shock unlike some Ceramic and other refractory materials.

Claims (15)

1. A constructional element made from an aerated cementitious material and having two major sides and four minor sides, elongate keyways in the form of ridges or channels being formed along at least three of its minor sides, or along at least two minor sides, and one major side, and each of the ridges being shaped and dimensioned to fit into a channel of another similar element.

2. A constructional element according to claim 1 which has a top side with a ridge, a bottom side with a channel, an end face with a ridge and an opposite end face with a channel.

3. A constructional element according to claim 1 which is in the form of a base block having a flat bottom surface, a top surface with a ridge, an end face with a ridge and an opposite end face with a channel.

4. A constructional element according to claim 1 which is in the form of a capping block having a flat top surface, a bottom surface with a channel formed therein, an end face with a ridge and an opposite end face with a channel.

5. A constructional element according to claim 1 in the form of a corner block having a flat end face and a ridge or channel in the opposite end face, a vertical ridge or channel also being formed on one of the major sides of the block, offset towards said flat end face.

6. A constructional element according to any preceding claim, wherein each said ridge has a shallow longitudinal groove formed centrally therein, a corresponding central longitudinal rib being formed in each said channel.

7. A mould for the manufacture of building blocks comprising an outer frame separable into at least two parts, said outer frame comprising a pair of opposed elongate side portions and a pair of opposed end portions, and one or more dividing members extending across the outer frame between the two side portions and spaced from the two end portions wherein one said side portion and one said end portion each have an inwardly facing moulding surface with a central longitudinal ridge flanked by a pair of longitudinal flat surfaces, wherein the other side portion and the other end portion each have an inwardly facing moulding surface with a central longitudinal channel flanked by a pair of longitudinal flat surfaces, and wherein the or each dividing member has a projecting central portion at one end to fit into the central channel of one side portion and a recessed central portion at the other end to accommodate the central ridge of the other side portion, the cross-section of the or each dividing member having a central U-shaped portion flanked on either side by straight portions.

8. A mould according to claim 7 wherein the dividing members are separable from the outer frame parts.

9. A mould according to claim 8 wherein lugs or pins are provided on the inward-facing moulding surfaces of the side portions of the outer frame, for location of the dividing members.

10. A mould according to claim 9 wherein a plurality of sets of said pins or lugs are provided sufficient to enable the member and spacing of the dividing members to be varied.

11. A method of making constructional elements which comprises the steps of making an aerated comentitious material by mixing cement, a filler, a foaming agent and water, pouring a mixture into a mould, allowing the mixture to set sufficiently to retain its shape but not to harden, cutting the moulded mixture with a bladed tool and finally hardening the shaped product.

12. A method according to claim 11 wherein the bladed tool is a guillotine.

13. A method according to claim 11 or claim 12 wherein the cementitious material is moulded to form an elongate body of uniform cross-section with at least one longitudinal side formed with a keyway in the form of an elongate ridge or channel.

14. A method according to claim 13 wherein one said longitudinal side is formed with a ridge and the opposite longitudinal side is formed with a channel.

15. A method according to any one of claims 11 to 14 wherein the tool blade has a U-shaped central portion when viewed edge on, so that with each cut it forms a recessed channel or keyway in one block and a corresponding projecting ridge or keyway in the next.