Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
  • C04B24/24—Macromolecular compounds
  • C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C04B24/2641—Polyacrylates; Polymethacrylates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/10—Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
  • C04B2111/12—Absence of mineral fibres, e.g. asbestos

Definitions

• the present invention relates to building articles form from cementitious materials and more particularly to building articles in the form of sheets formed from such materials.
• the invention further relates to a process for the formation of such building articles.
• the present invention consists in a building article comprising from 50 to 200 parts by weight of cement, from 50 to 150 parts by weight of a filler, from 5 to 20 parts by weight of an acrylic modifier on a dry weight basis and from 27 to 30 percent by weight of the cement of water, including any water present in the modifier, which materials have been mixed, formed, into a desired shape, compressed at a pressure of at least 1200 p.s.i., and cured.
• the present invention further consists in a process for forming a building article comprising mixing together from 50 to 200 parts by weight of cement, from 50 to 150 parts by weight of a filler, from 5 to 20 parts by weight of an acrylic modifier on a dry weight basis and from 27 to 30 percent by weight of the cement of water, including any water present in the modifier, forming the mixture into a desired shape, compressing the mixture at a pressure of at least 1200 p.s.i. and curing the compressed mixture.
• the building articles according to the present invention may comprise sheets or panels, blocks or formed shapes for use as guttering, ducting or the like. It is however in the area of sheets and panels in which the present articles have particular applicability due to the high flexural strength exhibited by these articles when made by the process according to this invention. Sheets having a thickness of from 1/4" to 1 1/2" for use as flooring materials are paticularly advantageously made from the present materials.
• the cement used in the present invention is preferably conventional Portland cement.
• the cement should constitute from 50 to 200 parts by weight of the articles and preferably 80 to 120 parts by weight.
• the cement content is most preferably 100 parts by weight.
• the filler preferably comprises a crystalline or non crystalline silicate such as sand or crushed glass however other fine fillers such as fly ash, rice hull ash, crushed quartz and the like could equally well be used.
• a preferred filler is a crushed naturally ocurring volcanic glass known as perlite.
• the filler may all be fine grade material, however, it is preferable to use a mixture of fine filler and coarser material.
• Advantageously 75 parts of fine material to 25 parts of 6/10 mesh material is used.
• the filler should be present in an amount of from 50 to 150 parts by weight, preferably from 75 to 125 parts by weight. It is most preferable that the filler comprises 100 parts by weight.
• the acrylic modifier is one of a range of commercially available cement additives which constitutes powders or emulsions of acrylic acid polymers and copolymers. These modifiers increase the impact and flexural strength of cement as well as improving its adhesion to a variety of substrates.
• Preferred examples of acrylic modifiers are the products MC76 and B60A sold by Rohm and Haas.
• the modifier is present in the article in an amount of 5 to 20 parts by weight of modifier solids. If the modifier is an emulsion the water content is included in the total water content in the articles. More preferably the modifier is present in an amount of 8 to 14 parts by weight and most preferably 11 part by weight.
• the amount of water in the mixture used to form the articles according to this invention should be from 27 to 30 percent by weight of the cement, including any water present in the acrylic modifier.
• the amount of water is sufficiently low that no water will be exuded when the mixture is compressed while being sufficient to bring about the appropriate hydration reaction involved in the setting of the cement content of the article.
• the articles according to this invention may advantageously include a reinforcing material such as a metal or plastic mesh or fibrous material such as fibres of cellulose or glass. This reinforcing material is preferably applied as a layer between two layers of the ceme ntitious mixture prior to the formed article being compressed.
• the process according to the invention is preferably carried out by mixing the filler with from 20 to 50% of the total water content and at least a proportion of the acrylic modifier and then adding the cement to form an almost "dry" granular mixture which is flowable.
• Half of this flowable mixture is then put into a suitable mould and levelled.
• a reinforcing mesh of steel wire is preferably laid on this layer of cementitious mixture and half of the remaining water sprayed in a fine spray evenly over the layer.
• the remaining mixture is then placed over the reinforcing mesh and levelled.
• the remaining water is then sprayed onto the top of the mixture and the whole mould passed into a press which compresses the formed mixture at a pressure of at least 1200 p.s.i.
• the wire mesh may be supported in a suitable mould and all of the granular cementitious mixture added to the mould and vibrated down through the wire mesh into a uniform screeded condition. The remaining water is then added and the material pressed as described above. In tliis embodiment of the invention it is desirable to add a surfactant to the water to assist in wetting the cementitious material. After the article has been formed and compressed it must be cured. The article will generally have acquired sufficient green strength for the mould to be removed in a matter of hours, however, a period of from seven to twenty eight days is required for sheets formed by the present process to acquire sufficient strength to be freely handled.
• Panels formed by the process according to this invention have been found to be flame resistant and non-flamable, to have a very low moisture absorbtion after initial curing and to have a high flexural strength.
• a flooring sheet was formed from the following materials:
• Fine sand - 75 parts by weight Fine sand - 75 parts by weight.
• Acrylic modifier (MC-76 Rohm and Haas) (dry weight basis) 11 parts by weight.
• the acrylic modifier was measured out and mixed with 20% of the total water requirement.
• a reinforcing mesh of steel 4 ram. wires having a grid spacing of 200 mm. and a size of 1100 ⁇ 2300 mm was placed on the levelled layer of mixture. 7. 50% of the remaining water was sprayed on the mixture in the mould in a fine spray evenly applied over the whole layer.
• the mould was introduced into an hydraulic press and the mixture in the mould compressed at a pressure of 2000 p.s.i. for one minute.
• the sheets so formed showed a water absorption of only 5% by weight after 72 hours immersion in water.
• the cured sheets had a density of 2.32 grams/c.c. and a mass of 32.5 kg per square metre.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=3768894

Family Applications (1)

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Cited By (1)

Families Citing this family (4)

Family Cites Families (7)

• 1980
  • 1980-12-22 AU AU78794/81A patent/AU7879481A/en not_active Abandoned
• 1981
  • 1981-12-22 EP EP19820900082 patent/EP0067183A1/de not_active Withdrawn
  • 1981-12-22 WO PCT/AU1981/000192 patent/WO1982002195A1/en unknown

Non-Patent Citations (1)

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