NZ286191A - Manufacture of compressed bricks/pavers/blocks having a design compressed on a surface, made up of cement, soil and/or lime - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £86191 ^8 6 1 AMENDED under Section of the Patent Act 1953 from j3S»»»i)£»$i«wVW.«A..3..£l ASSISTANT COMMISSIONER OF PATENTS PATENTS FORM NO 5 Our Ref JM501358 NEW ZEALAND PATENTS ACT 1953 Complete After Provisional No 286191 Filed. 15 March 1996 COMPLETE SPECIFICATION COMPRESSED BRICKS/PAVERS AND A METHOD OF MANUFACTURE THEREOF We, EARTH BUILDING SYSTEMS LIMITED, a New Zealand company, of 8 Gurnard Road, Silverdale, Hibiscus Coast, New Zealand, hereby declare the invention, for which We pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement* JM VO PT0595282 REG070397031AHEflT 1 587IPAT FORM 5 -C60.00 REG0703970316HEAT 1 5871GST .3? 50 286191 This invention relates to building materials in the form of pavers or bricks, and in particular, pavers or bricks carrying a design and a method for their manufacture Conventional means of manufacturing pavers is by employing a wet mix in a mould A design may be applied to one surface of such pavers by incorporating that design into the mould. Earthen bricks are conventionally manufactured by cutting strips of the required material into the appropriate brick shape and then "firing" the bricks An alternative means of manufacturing earthen pavers or bricks is by compaction employing a hydraulic press However, using such processes there have been difficulties in producing a product with sufficient compressive strength particularly, in the manufacture of pavers. Further, it has not been possible to manufacture compressed pavers or bricks incorporating specific design features or patterns.

It is an object of the present invention to provide compressed bricks and pavers, and a method for their manufacture, which overcomes at least some of the above-mentioned problems, or which at least provides the public with a useful alternative Other objects of the invention may become apparent from the following description which is given by way of example only According to one aspect of the present invention there is provided a method of manufacture of a compressed block having a design on at least one 286191 surface Aaid method comprising preparing a composition of cement with soil and/or limeV comprising at least 5% cement, adjusting the moisture content to between 10% and 28% water, and compressing said composition on to a design surface m a press at a pressure above 2,000 psi, so that the design of the design surfaceus imprinted on the block formed during compression In one preferreo\form of the method of the present invention the design surface may be on a dieAPreferably the die may comprise a substantially flat and rigid sheet of material to which is adhered or on one surface of which is formed, a non-compressable material in the form of the required design.

Preferably said non-compressable material may be hard-setting silicon In a preferred form the method may further comprise separating said design surface from said composition during compression, with a membrane In a further preferred form of the methqd of the present invention the membrane may be adapted to take the shape orthe design surface under compression Preferably the membrane may be rubber or a flexible plastics material, preferably butynol rubber \ In a preferred method, the die may be removed frofcri the press with the compressed composition \ In one preferred form of the method of the present invention the block may comprise a paver adapted for use as a ground or floor cover, and wherein said composition may comprise a soil mix of substantially 90% sand,\nd 10% MOW AMENDED \ \ PAGE AS AMENDED surface, said method comprising preparing a composition of cement with soil and/or lime, comprising at least 5% cement, adjusting the moisture content to between 10% and 28% water, separating a design surface from the composition, in a press, with a membrane adapted to take the shape of the design surface under compression, and compressing said composition on to the design surface at a pressure above 2,000 psi, so that the design of the design surface is imprinted on the block formed during compression, the design surface comprising a pattern or design formed on a surface of a flat plate In one preferred form of the method of the present invention the design surface may be on a die Preferably the die may comprise a substantially flat and rigid sheet of material to which is adhered or on one surface of which is formed, a non-compressable material in the form of the required design Preferably said non-compressable material may be hard-setting silicon.

In a further preferred form of the method of the present invention the membrane may be adapted to take the shape of the design surface under compression Preferably the membrane may be rubber or a flexible plastics material, preferably butynol rubber In a preferred method, the die may be removed from the press with the compressed composition In one preferred form of the method of the present invention the block may comprise a paver adapted for use as a ground or floor cover, and wherein said composition may comprise a soil mix of substantially 90% sand, and 10% 1i FEB £ FTCCiVF 28 6 1 clay and silt, said soil mix mixed with cement in a ratio of substantially 5 to 1, respectively.

In an alternative preferred form of the method of the present invention the block may comprise a brick adapted for use in construction of buildings, and wherein said composition may comprise a soil mix of substantially 75% sand, 20% clay and 5% silt, said soil mix mixed with cement in a ratio of substantially 92 5% soil mix and 7 5% cement In a preferred form of the method of the present invention the composition may have a maximum particle size of substantially 8mm Preferably, substantially 80% of the composition may have a particle size of 3mm or less, with substantially 15% in the range 3 to 6mm and substantially 5% in the range 6 to 8mm According to a further aspect of the present invention there is provided a method of manufacture of a compressed block substantially as herein described and with reference to the accompanying examples According to a further aspect of the present invention there is provided a compressed brick or paver formed according to a method of the present invention Other aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying examples 28 6 1 9 The method of the present invention may employ a hydraulic press capable of producing a ram pressure of up to 3,000 psi.

The method may employ a stabilised soil cement mixture Soil (comprising a sand/silt/clay mix) is pulverised and sieved to an appropriate particle size and dried to the appropriate moisture content, namely between 10% and 28% moisture Cement is added to the soil to form a minimum content of about 10% The cement forms a surface coating on the particles of soil It is important therefore to exclude larger soil particles which might break up during compression producing weak spots or flaws in the end product Hence, the maximum soil particle size is about 8mm.

The soil/cement mixture is poured into a box-shaped structure the base of which is formed by the hydraulic press, a lid closed and secured and the press activated to a pressure of up to 3,000 psi to compress the soil/cement to about 60% of its original volume Compressive strength and durability of pavers may be improved by the addition of micro silica to the soil prior to mixing with cement For example, such that the soil may contain 10 to 20% micro silica In an alternative embodiment, the soil or a proportion of it may be replaced with limestone to produce a distinctive white product The colour of the limestone/cement may be varied by incorporation of small quantities of ochre in the precompressed mixture 2 8 6 1 9 In order to produce a required pattern or design on a compressed paver or brick a die is included in the press The die may constitute a flat plate of metal or plastics material corresponding with the shape of the ram of the hydraulic press and/or paver/brick to be formed A required pattern or design is formed on the upper surface of the flat plate by adhesion to it of a substantially non-compressable and/or resilient material, for example a hard setting silicon or bitumen produced products A thin membrane of a rubber or plastics material may be placed over the pattern on the upper surface of the flat plate, and optionally adhered to the plate This layer may be sufficiently thin to compress around the components of the pattern or design during the pressing process, and may also be nonadherent to the compressed soil/cement material The flat plate with its design and membrane uppermost is positioned on the ram of the hydraulic press, the material to be compressed is then poured on top of the membrane, the lid of the press secured, and the hydraulic press activated to compress the soil/cement mixture The membrane prevents adhesion of the mixture to the flat plate and its adhered design so that the design imprinted on the resulting paver or brick is not damaged when the product is removed from the press. It will be appreciated that the flat plate and design may be positioned on top of material in the press, beneath the lid, as opposed to the above configuration In this situation the membrane is still positioned between the material and the design 28 6 1 It will be appreciated that the required design could be formed or adhered directly on the surface of the ram of the press itself, although this would be a less practical and economic process It will also be appreciated that the method of producing designed pavers of the present invention may be employed to produce complex multi-paver designs or murals, where each paver is formed with a different design or a common design which forms an interlocking pattern or theme If the die is of metal, or includes a backing plate of sufficient rigidity, pavers may be produced down to a thickness of 15mm, since the die and/or backing plate may be removed from the press with the paver, providing support and preventing cracking or damage of the paver The die and/or plate may be removed once the paver has dried sufficiently Employing such a rigid, removable die or backing plate also enables pavers of larger dimensions to be produced Specific examples of the method of the present invention will now be described Example 1 This example is for the production of earthen compressed pavers of size 290 x 290 x 70mm, and a weight of 8 to 10 kilograms A required design is formed on a flat plate of hard plastics material or steel employing hard setting silicon The depth and shape of the silicon will form the required imprinted pattern on the final product A membrane of butynol rubber is placed over the 28 6 1 pattern and optionally adhered to the flat plate The flat plate with pattern and membrane uppermost is positioned on top of the hydraulic ram A soil mix comprising substantially 90% sand, 10% clay and silt is pulverised and sieved to produce a product in which the particle size is 80% under 3mm, 15% between 3 and 6mm and 5% between 6 and 8mm This soil is mixed with cement in a ratio of 5 to 1 (i e. 20% cement). The moisture content of the composition is adjusted to between 10% and 28% before the composition is poured into the press on top of the membrane-covered design The ram press is then activated to 2,500 psi to compress the soil/ cement composition to substantially 60% of its original volume and produce a compressed designer paver The compressive strength of the resulting paver is a minimum of 8 MPa and generally above 15 MPa The resulting compressed designer paver may be sealed with an acrylic slate and tile sealer, for example polyurethane Example 2 The process and method of Example 1 may be employed to produce earthen compressed bricks of size 290 x 290 x 120mm (± 30mm) and an average weight of about 17 kilograms However, the cement content of the composition is 7 5% to 10% and the soil mix has a higher proportion of clay (20%) and silt (5%), with only 75% sand The ram pressure applied is 3,000 28 6 1 psi and the compressive strength of the resulting compressed designer brick is about 6 5 MPa Where in the foregoing description reference has been made to specific components and integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth Although the invention has been described by way of examples, and with particular reference to preferred embodiments, it should be appreciated that variations and modifications may be made thereto, without departing from the scope of the invention as described in the accompanying claims JM vo CSPEC95000 JM501358 NOW AMENDED 28 6 1

Claims (4)

WHAT WE CLAIM IS

1 X A method of manufacture of a compressed block having a design on at le^st one surface, said method comprising areparing a composition of cement with soil and/or lime, comprising at least 5% cement, adjusting the moisture content to between 10% and 28% water, and compressin^Vsaid composition onto a design surface in a press at a pressure above>2,000 psi so that the design of the design surface is imprinted on the bltock formed during compression

2 A method according to ClaimSl, wherein the composition has a maximum particle size of substantially 8mm

3 A method according to Claim 2, wherein substantially 80% of the composition has a particle size of 3mm orsjess, substantially 15% is in the range 3 to 6mm, and substantially 5% is\n the range 6 to 8mm

4. A method according to any one of Claims 1 to 3, wherein said composition comprises a soil mix of substantially 90%\sand with 10% clay and/or silt, mixed with cement in a ratio of substantially five to one, respectively A method according to any one of Claims 1 to 3, wherein said composition comprises a soil mix of substantially 75% sand, 20% cla^ and 5% silt, mixed with cement in a ratio of substantially 92 5% soil mix and 7.5% cement