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GB1581396A - Waterproofing plaster materials - Google Patents

Waterproofing plaster materials Download PDF

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Publication number
GB1581396A
GB1581396A GB37259/77A GB3725977A GB1581396A GB 1581396 A GB1581396 A GB 1581396A GB 37259/77 A GB37259/77 A GB 37259/77A GB 3725977 A GB3725977 A GB 3725977A GB 1581396 A GB1581396 A GB 1581396A
Authority
GB
United Kingdom
Prior art keywords
polyhydrogenomethylsiloxane
plaster
parts
water
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB37259/77A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAMBERT IND
Original Assignee
LAMBERT IND
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LAMBERT IND filed Critical LAMBERT IND
Publication of GB1581396A publication Critical patent/GB1581396A/en
Expired legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B24/00Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/40Compounds containing silicon, titanium or zirconium or other organo-metallic compounds; Organo-clays; Organo-inorganic complexes
    • C04B24/42Organo-silicon compounds

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Materials Applied To Surfaces To Minimize Adherence Of Mist Or Water (AREA)

Abstract

Water repellency of plaster structures is obtained by mixing less than 0.5 parts of a liquid polyhydromethylsiloxane consisting of units of formula <IMAGE> itself not sufficiently water-repellent but being converted into a water-repellent material in the course of the process, with 100 parts of plaster powder which comprises CaSO4 semihydrate, anhydrite III and overburnt plaster, mixing water is then added and the structure is coated with this mixture.

Description

(54) WATERPROOFING PLASTER MATERIALS (71) We, LAMBERT INDUSTRIES, a French body corporate, of 105 Route d'Argenteuil, 95240 Cormeilles-en-parisis, France, do 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: Plaster is naturally hydrophilic. Liquid water can impregnate material made from plaster and can migrate to the core of the material. It would be very desirable to waterproof such material but hitherto it has only been possible to do this at high cost.
Various products used for waterproofing powders are known. One of them is a polyhydrogenomethylsiloxane having monomeric units of the formula -SiHCH-O-. This product is marketed in France as Dow Corning Fluid 1107 at a cost of about 28,000 French francs per tonne and the directions for its use are to distribute it in a proportion of 0.5 to 1.5 parts by weight of product to 100 parts by weight of powder, by mixing it into the powder to be waterproofed in the presence of a suitable catalyst. Fol!owing these directions for use with plaster powder means relatively high waterproofing costs and renders the plaster powder unfit for the uses for which it is usually intended; mixing the waterproofed plaster powder with water is difficult and the paste which is obtained expands very greatly, thereby deleteriously affecting the strength of the product.
British Patent Specification No. 952,522 describes a plaster bandage in which calcium sulphate hemihydrate is intimately admixed with from 0.1 to about 10% by weight of a hydroxide of an alkali metal or of an oxide or hydroxide of an alkaline earth metal and from 0.1 to about 10% by weight of a finely-divided water-repellent solid which may be a solid organopolysilooxaneor a liquid organopolysiloxane coated on an inert material.
According to the present invention, a composition which is substantially free of water has been formed by mixing powdered calcium sulphate hemihydrate, powdered insoluble anhydrite (obtained by baking plaster at more than 300"C), polyhydrogenomethylsiloxane and, optionally, soluble anhydrite (anhydrite III: obtained by baking plaster at about 200"C), in which the polyhydrogenomethylsiloxane has been added in liquid form, without any solid adjuvants, the amount of the polyhydrogenomethylsiloxane being less than 0.5 parts by weight per 100 parts by weight of the said powdered materials. Such a composition is satisfactorily hydrophobic.
The composition of the invention can be mixed with water to form a plaster material.
Alternatively, a plaster material may be formed directly by mixing powered calcium sulphate hemihydrate, powdered insoluble anhydrite, a polyhydrogenomethylsiloxane and, optionally, soluble anhydrite, the polyhydrogenomethylsiloxane being added in liquid form, without any solid adjuvants, and in an amount which is less than 0.5 parts by weight per 100 parts of the said powdered materials.
It is preferred that from 0.05 to 0.4, e.g. about 0.15 parts, by weight of the polyhydrogenomethylsiloxane should be used per 100 parts by weight of the powdered materials. The anhydrous compositions of the invention are preferably, but not necessarily, formed by mixing the polyhydrogenomethylsiloxane with calcium sulphate hemihydrate and subsequently mixing in insoluble anhydrite and any soluble anhydrite. In any of the embodiments of the invention, it may be appropriate to dilute the polyhydrogenomethylsiloxane in a compatible liquid before mixing.
It is preferred that soluble anhydrite should be present in the compositions and methods of this invention. It has been observed that good preservation of the plaster powder containing the waterproofing agent requires the presence of soluble anhydrite, which is the variety of calcium sulphate obtained by dehydration of gypsum at moderate temperature beyond the hemihydrate and which is converted spontaneously into the hemihydrate on contact with air, by absorption of water vapour contained in air. This is why, if it is desired to ensure the preservation of the waterproofing capacity, it is also necessary to protect the powder containing the waterproofing agent against the action of water vapour in the air.
Plaster materials made in accordance with the invention are especially sultable for use in buildings or other external surfaces. Their strength is not effected in the manner described in relation to the prior art where the proportion of the polyhydrogenomethylsiloxane is too high. Plaster materials can be formed in accordance with the invention without the need for a catalyst, and there is no difficulty in forming the material either by hand or by using known casting machines. The paste which is obtained in the presence of water does not expand to any great extent, and because of the low proportion of polyhydrogenomethylsiloxane, the waterproofing cost is kept relatively low.
It is to be understood that the present invention is not limited to particular forms of plaster powders, but the following Examples illustrates how the invention can be used.
Example To a plaster powder containing 94.5% of calcium sulphates (comprising calcium sulphate hemihydrate, insoluble anhydrite and about 20% of soluble anhydrite), 5% of impurities, and about 0.5% of delaying products and thickener, 1.5 kg of waterproofing polymer per tonne of plaster powder was mixed in. A paste was obtained from the powder mixture by mixing in water mechanically in a casting machine. After 7 days of hydration, drying and moulding, prisms (4 x 4 x 16 cm) gave the following results: Bending strength 56 bars Compressive strength 212 bars BRINELL hardness 335 bars Dynamic modules of elasticity 91,900 bars Weight per unit volume 1,260 kg per m3 Water absorption (24 hrs total immersion) 1.75 % WHAT WE CLAIM IS: 1.A composition which is substantially free of water and which has been formed by mixing powdered calcium sulphate hemihydrate, powdered insoluble anhydrite, a polyhydrogenomethylsiloxane and, optionally, soluble anhydrite, in which the polyhydrogenomethylsiloxane has been added in liquid form, without any solid adjuvants, and in which the amount of the polyhydrogenomethylsiloxane is less than 0.5 parts by weight per 100 parts by weight of the said powdered materials.
2. A composition according to claim 1 which comprises soluble anhydrite.
3. A composition according to claim 1 or claim 2 which comprises 0.05 to 0.4 parts by weight of the polyhydrogenomethylsiloxane per 100 parts by weight of the said powdered materials.
4. A composition according to any preceding claim which has been formed by mixing the polyhydrogenomethylsiloxane with the calcium sulphate hemihydrate and subsequently mixing in the soluble anhydrite and any soluble anhydrite.
5. A composition according to claim 1 substantially as herein described with reference to the Example.
6. A method for forming a plaster material which comprises adding water to a composition according to any preceding claim 7. A method for forming a plaster material which comprises mixing water, powdered calcium sulphate hemihydrate, powdered insoluble anhydrite, a polyhydrogenomethylsiloxane and, optionally, soluble anhydrite, in which the polyhydrogenomethylsiloxane is added in liquid form, without any solid adjuvants, and in which the amount of the polyhydrogenomethylsiloxane is less than 0.5 parts by weight per 100 parts by weight of the said powdered materials.
8. A method according to claim 7 in which soluble anhydrite is used.
9. A method according to claim 7 or claim 8 in which the amount of the polyhydrogenomethylsiloxane is from 0.05 to 0.4 parts by weight per 100 parts by weight of the said powdered materials.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    containing the waterproofing agent requires the presence of soluble anhydrite, which is the variety of calcium sulphate obtained by dehydration of gypsum at moderate temperature beyond the hemihydrate and which is converted spontaneously into the hemihydrate on contact with air, by absorption of water vapour contained in air. This is why, if it is desired to ensure the preservation of the waterproofing capacity, it is also necessary to protect the powder containing the waterproofing agent against the action of water vapour in the air.
    Plaster materials made in accordance with the invention are especially sultable for use in buildings or other external surfaces. Their strength is not effected in the manner described in relation to the prior art where the proportion of the polyhydrogenomethylsiloxane is too high. Plaster materials can be formed in accordance with the invention without the need for a catalyst, and there is no difficulty in forming the material either by hand or by using known casting machines. The paste which is obtained in the presence of water does not expand to any great extent, and because of the low proportion of polyhydrogenomethylsiloxane, the waterproofing cost is kept relatively low.
    It is to be understood that the present invention is not limited to particular forms of plaster powders, but the following Examples illustrates how the invention can be used.
    Example To a plaster powder containing 94.5% of calcium sulphates (comprising calcium sulphate hemihydrate, insoluble anhydrite and about 20% of soluble anhydrite), 5% of impurities, and about 0.5% of delaying products and thickener, 1.5 kg of waterproofing polymer per tonne of plaster powder was mixed in. A paste was obtained from the powder mixture by mixing in water mechanically in a casting machine. After 7 days of hydration, drying and moulding, prisms (4 x 4 x 16 cm) gave the following results: Bending strength 56 bars Compressive strength 212 bars BRINELL hardness 335 bars Dynamic modules of elasticity 91,900 bars Weight per unit volume 1,260 kg per m3 Water absorption (24 hrs total immersion) 1.75 % WHAT WE CLAIM IS: 1.A composition which is substantially free of water and which has been formed by mixing powdered calcium sulphate hemihydrate, powdered insoluble anhydrite, a polyhydrogenomethylsiloxane and, optionally, soluble anhydrite, in which the polyhydrogenomethylsiloxane has been added in liquid form, without any solid adjuvants, and in which the amount of the polyhydrogenomethylsiloxane is less than 0.5 parts by weight per
    100 parts by weight of the said powdered materials.
  2. 2. A composition according to claim 1 which comprises soluble anhydrite.
  3. 3. A composition according to claim 1 or claim 2 which comprises 0.05 to 0.4 parts by weight of the polyhydrogenomethylsiloxane per 100 parts by weight of the said powdered materials.
  4. 4. A composition according to any preceding claim which has been formed by mixing the polyhydrogenomethylsiloxane with the calcium sulphate hemihydrate and subsequently mixing in the soluble anhydrite and any soluble anhydrite.
  5. 5. A composition according to claim 1 substantially as herein described with reference to the Example.
  6. 6. A method for forming a plaster material which comprises adding water to a composition according to any preceding claim
  7. 7. A method for forming a plaster material which comprises mixing water, powdered calcium sulphate hemihydrate, powdered insoluble anhydrite, a polyhydrogenomethylsiloxane and, optionally, soluble anhydrite, in which the polyhydrogenomethylsiloxane is added in liquid form, without any solid adjuvants, and in which the amount of the polyhydrogenomethylsiloxane is less than 0.5 parts by weight per 100 parts by weight of the said powdered materials.
  8. 8. A method according to claim 7 in which soluble anhydrite is used.
  9. 9. A method according to claim 7 or claim 8 in which the amount of the polyhydrogenomethylsiloxane is from 0.05 to 0.4 parts by weight per 100 parts by weight of the said powdered materials.
  10. 10. A plaster material when formed by a method according to any of claims 6 to 9.
GB37259/77A 1976-09-07 1977-09-07 Waterproofing plaster materials Expired GB1581396A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7626882A FR2363532A1 (en) 1976-09-07 1976-09-07 PROCESS FOR HYDROFUGATION OF PLASTER ARTICLES

Publications (1)

Publication Number Publication Date
GB1581396A true GB1581396A (en) 1980-12-10

Family

ID=9177437

Family Applications (1)

Application Number Title Priority Date Filing Date
GB37259/77A Expired GB1581396A (en) 1976-09-07 1977-09-07 Waterproofing plaster materials

Country Status (14)

Country Link
JP (1) JPS5363431A (en)
AR (1) AR217445A1 (en)
AU (1) AU512195B2 (en)
BE (1) BE858468A (en)
BR (1) BR7705937A (en)
CH (1) CH624651A5 (en)
DE (1) DE2740049A1 (en)
EG (1) EG12807A (en)
FR (1) FR2363532A1 (en)
GB (1) GB1581396A (en)
GR (1) GR63625B (en)
IL (1) IL52829A (en)
IT (1) IT1085699B (en)
PT (1) PT66896B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1120384A1 (en) 2000-01-27 2001-08-01 Wacker Polymer Systems GmbH & Co. KG Water repellant agent for hydrophobing building materials with gypsum binder
US8070895B2 (en) 2007-02-12 2011-12-06 United States Gypsum Company Water resistant cementitious article and method for preparing same
US8329308B2 (en) 2009-03-31 2012-12-11 United States Gypsum Company Cementitious article and method for preparing the same

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5654263A (en) * 1979-10-02 1981-05-14 Kurashiki Boseki Kk Waterrresistant gypsum formed body
DE3429311C1 (en) 1984-08-09 1985-12-05 Bayer Ag, 5090 Leverkusen Process for the production of water-repellent porous molded body from plaster
DE3704439A1 (en) * 1987-02-12 1988-08-25 Wacker Chemie Gmbh METHOD FOR PRODUCING WATER-REPELLENT OBJECTS FROM PLASTER AND HYDROPHOBIC AGENTS CONTAINING PLASTER POWDER

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1120384A1 (en) 2000-01-27 2001-08-01 Wacker Polymer Systems GmbH & Co. KG Water repellant agent for hydrophobing building materials with gypsum binder
US6547874B2 (en) 2000-01-27 2003-04-15 Wacker Polymer Systems Gmbh & Co. Kg Hydrophobicizing agents for hydrophobicizing gypsum-plaster-bound construction materials
US8070895B2 (en) 2007-02-12 2011-12-06 United States Gypsum Company Water resistant cementitious article and method for preparing same
US8568544B2 (en) 2007-02-12 2013-10-29 United States Gypsum Company Water resistant cementitious article and method for preparing same
US8329308B2 (en) 2009-03-31 2012-12-11 United States Gypsum Company Cementitious article and method for preparing the same

Also Published As

Publication number Publication date
PT66896A (en) 1977-09-01
AR217445A1 (en) 1980-03-31
IT1085699B (en) 1985-05-28
BR7705937A (en) 1978-07-18
EG12807A (en) 1979-12-31
BE858468A (en) 1978-03-07
GR63625B (en) 1979-11-27
PT66896B (en) 1979-01-26
IL52829A (en) 1981-11-30
CH624651A5 (en) 1981-08-14
IL52829A0 (en) 1977-10-31
AU2859277A (en) 1979-05-03
FR2363532B1 (en) 1982-08-27
JPS5363431A (en) 1978-06-06
DE2740049A1 (en) 1978-03-09
FR2363532A1 (en) 1978-03-31
AU512195B2 (en) 1980-09-25

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee