AU2002248956A1

AU2002248956A1 - Building material

Info

Publication number: AU2002248956A1
Application number: AU2002248956A
Authority: AU
Inventors: Leon Kruss
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-22
Filing date: 2002-02-22
Publication date: 2002-09-04

Description

BUILDING MATERIAL

Field of the Invention

The present invention relates to a building material. In particular the invention relates to a cement-based building material comprising a polyvinyl alcohol (PVA) bonding agent, one or more fillers selected from coated fly ash and elastomeric beads, and optionally further additives. The invention also relates to a method for the manufacture of said building material.

Background of the Invention

The building materials and construction elements currently used in the building industry include cementitious based panels, walls, sheets, planks, bricks and the like. These building materials are formulated depending on their intended application to have good acoustic and fire resistant properties, strength, durability, and/or good workability.

A requirement accordingly exists for building materials which have one or more of the following qualities; strength; substantially non-flammable; workable; strong; durable; sound and head insulating; easily handled and worked; relatively light weight; and able to be plastered, painted or rendered. A further requirement exists for new or improved materials for use in the building industry, or at least materials which provide a suitable alternative for those presently known or in the market.

Disclosure of the Invention

The present inventor has developed a strong, highly workable building material suitable for use as a panel or sheet for internal or external use. The building material meets the requirement for new or improved construction elements and materials for use in the building industry. The building materials of the present invention exhibit advantages over other materials known in the art. Thus, according to aspect of the present invention there is provided a building material comprising a cementitious material, a polyvinyl alcohol (PVA) bonding agent, one or more fillers selected from coated fly ash and elastomeric beads, and optionally at least one other additive.

The present invention also provides a method for producing a building material comprising: a) mixing a cementitious material, a PVA bonding agent, one or more fillers selected from coated fly ash and elastomeric beads, and optionally at least one other additive with water to form a slurry; and b) allowing the slurry to hydrate and set.

The invention also relates to building materials produced by the above method of the invention.

The terms "cement" and "cementitious material" are used herein in their broadest sense to generally refer to a mixture of clay and limestone that hardens and fastens on setting.

The cementitious material can be any cement but preferably is high strength cement such as Portland cement. High strength cement differs from normal cement in that it is a finer grind which causes it to cure more quickly and have a higher strength when set. When high strength cement is not used it is preferable to add lime to this cement to increase the strength when set. The cementitious material is typically present in an amount from 180- 300 kilograms per cubic meter (kg/m³), more preferably 220-260 kg/m³, and most preferably about 240 kg/m³.

The polyvinyl alcohol (PVA) bonding agent is a modified PVA containing a resin additive which provides good bond strength and sealant qualities. An example of a suitable PVA bonding agent is that sold under the trade name Bondcrete™ available from Bondall Building & Renovating Products (Western Australia). The PVA bonding agent functions as an adhesive and sealant, and further assists in the workability, strength and durability of the building material and product. The PVA bonding agent is preferably present in an amount from 5-30 kg/m³, more preferably 8-20 kg/m³, and most preferably about 13 kg/m³.

The coated fly ash used in the present invention is required to be coated with silicone, glass or the like to assist in the setting of the slurry in the formation of the building material. The inclusion of the coated fly ash in the final product also typically yields less dense yet higher strength products. Many types of fly ash are suitable. One source of fly ash results from the burning of coal in electrical generating facilities. More preferably it is naturally occurring volcanic fly ash, which is purified and ground as a white, finely divided powder. The fly ash is required to be coated with silicone, glass or similar type materials. The fly ash once coated significantly enhances the quality of the building products prepared therefrom. Uncoated fly ash is not preferred as it absorbs large amounts of water from the wetted slurries and composition. Coated fly ash may be obtained from various sources including Harborlite of La Porte, Texas who market the product under the Trade name Microfϊl Grade F-2. The coated fly ash is typically present in an amount from 3-30 kg/m³, preferably 6-15 kg/m³, more preferably about 9 kg/m³.

The elastomeric beads are preferably polystyrene beads. The elastomeric beads are desirably smaller than 0.25 mm but can have a size of up to 2 mm. The elastomeric beads are typically present in an amount from 10-35 kg/m³, preferably 15-25 kg/m³, more preferably about 19 kg/m³.

Other fillers in addition to the coated fly ash and elastomeric beads may be incorporated in the building material of the invention. Such other fillers may include sand, rock powder and aggregates as well known in the art.

It will be appreciated that the present invention is not limited to these additives and may include other additives used in the art. Other additives may include fibre reinforcement, for example, cellulose fibre or chopped fibreglass and/or light weight filler, for example, water proof perlite. Typically the additives are present in an amount from 0-50 kg/m³. The building materials of the present invention may also optionally contain other additives including various dies, oxides and pigments if a coloured product is desired. The building material can also be plastered, painted, sealed or rendered if required.

Water used in the formation of the building material should be clean, and preferably be used at a temperature in the range from 10-25°C for good results.

In preparing the building materials of the invention, the amount of water required to be added to form the slurry depends on the nature and amount of ingredients used as can be readily determined by those skilled in the art. Ideally the slurries should be fluid enough to be able to be poured without too much difficulty, yet not too fluid to compromise the setting time or strength of the final building material product. Typically the amount of water added in preparing the slurry for use in making the building material is 90-150 litres, preferably 105-135 litres, more preferably about 120 litres, per cubic meter of final building material product.

In the method of producing the building material of the present invention the ingredients may be mixed in any order to prepare the slurry, however in a particularly preferred embodiment the PVA bonding agent is first diluted with the water in a ratio of about 1 :9 prior to being mixed with the remaining ingredients to form the slurry. It will be understood that variations in the mixing order are possible as maybe readily determined by those skilled in the art.

The building material is preferably set in the shape of a sheet panel or wall, however other shapes and construction elements such as blocks, statues, ceiling roses, paving stones and the like maybe contemplated.

The building product is preferably a sheet or panel for internal or external use. Thus in a preferred embodiment of the invention the slurry is cast or poured into a flat mould, allowed to set and harden and then removed from the mould. In another embodiment of the invention the slurry is sandwiched between two boards and allowed to harden. A suitable board is sold under the trade name Villaboard™ available from James Hardy & Co. Pty Limited. Another suitable board is Masonite™ which is available from CSR Limited.

The slurry rapidly sets to form the building material of the present invention in about 30-60 minutes. The building product then continues to set and harden to full strength in about from 6-12 hours to 1 day. The time taken to set and harden the building material of the present invention will vary significantly depending on the quantities of ingredients used to form the slurry, and in particular will greatly depend on the amount of water used, its temperature and the relative humidity of the space in which the product is left to cure. When the slurry sets and hardens to form the building material there is typically only minimal shrinkage. No heating is required during the setting or hardening of the building material, however it will be understood that slightly higher ambient or room temperatures, or lower levels of humidity in the surrounding air, are likely to increase the setting time.

In a particularly preferred embodiment of the invention the building material comprises 220-260 kg of cementitious material; 8-20 kg of a PVA bonding agent; one or more fillers selected from 6-15 kg of coated fly ash and 15-25 kg of elastomeric beads; and optionally 0-50 kg of at least one other additive.

In a further preferred embodiment of the invention there is provided a building material prepared by the steps comprising: a) diluting 8-20 kg of a PVA bonding agent with 90-150 L of water to form a solution b) mixing in any order 220-260 kg of a cementitious material; one or more fillers selected from 6-15 kg coated fly ash and 15-25 kg of elastomeric beads; and 0-50 kg of at least one other additive with the solution to form a slurry; and c) allowing the slurry to set.

The building material may also be produced by a continuous process whereby the slurry is discharged into a layer or layers of paper, fabric or other material by methods well known in the art, and the slurry is then allowed to set. After the building material has set, the board is then cut into desired lengths.

When formed into sheets or panels, the building material may be used as internal or external walls. Due to the addition of the PVA bonding agent, the building material is generally not required to be sealed.

The invention is further described in and illustrated by the following examples. The examples are not to be construed as limiting the invention in anyway.

EXAMPLES 1 - 5. Building Material and Composition

General Method The PVA bonding agent is diluted with the water in a ratio of about 1 :9, and the resultant solution is mixed with the remaining ingredients to form a slurry. The slurry is poured into a mould, allowed to harden and then removed from the mould. Alternatively, the slurry is sandwiched between two boards and allowed to harden.

The building materials of the present invention shows good workability, being able to be cut, sawn, nailed, screwed and bolted whilst maintaining an acceptable strength and integrity for their weight. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour.

In the above description, embodiments of this invention have been described, but it will also be understood by those skilled in the art that the invention is capable of other functions. Also, it should be understood that the desirable properties of the building material of the present invention are intended to be generic and should not be regarded as necessarily limiting.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification individually or collectively, and any and all combinations of any two or more of said steps or features.

Claims

Claims:

1. A building material comprising a cementitious material, a polyvinyl alcohol (PVA) bonding agent, one or more fillers selected from coated fly ash and elastomeric beads, and optionally at least one other additive.

2. A building material according to claim 1 comprising: (i) 180-300 kg of cementitious material;

(ii) 5-30 kg of a PVA bonding agent;

(iii) 3-30 kg of coated fly ash; and

(iv) 0-50 kg of at least one other additive.

3. A building material according to claim 1 comprising: (i) 180-300 kg of cementitious material;

(ii) 5-30 kg of a PVA bonding agent; (iii) 10-35 kg of elastomeric beads; and (iv) 0-50 kg of at least one other additive.

4. A building material according to any one of claims 1-3 comprising: (i) 220-260 kg of cementitious material;

(ii) 8-20 kg of a PVA bonding agent;

(iii) one or more fillers selected from 6-15 kg of coated fly ash and 15-25 kg of elastomeric beads; and

(iv) 0-50 kg of at least one other additive.

5. A building material according to claim 3 or claim 4, wherein the elastomeric beads are polystyrene beads.

6. A method for producing a building material comprising the steps: a) mixing a cementitious material, a PVA bonding agent, one or more fillers selected from coated fly ash and elastomeric beads, and-optionally at least one other additive with water to form a s rrry; and b) allowing the slurry to hydrate and set.

7. A method according to claim 6, wherein the cementitious material is in an amount of 180-300 kg, the PVA bonding agent is in an amount of 5-30 kg, the coated fly ash where present is in an amount of 3-30 kg, the elastomeric beads where present are polystyrene beads in an amount of 10-35 kg, the at least one other additive is in an amount of 0-50 kg and the water is in an amount of 90-150 L.

8. A building material prepared according to a method of claim 6 or claim 7.

9. A building material prepared by a method comprising the steps: a) diluting 8-20 kg of a PVA bonding agent with 90-150 L of water to form a solution; b) mixing in any order 220-260 kg of a cementitious material; one or more fillers selected from 6-15 kg coated fly ash and 15-25 kg of elastomeric beads; and 0-50 kg of at least one other additive with the solution to form a slurry; and c) allowing the slurry to set.

10. A building material according to any one of Examples 1 to 5.