Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B1/00—Producing shaped prefabricated articles from the material
  • B28B1/50—Producing shaped prefabricated articles from the material specially adapted for producing articles of expanded material, e.g. cellular concrete
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/57—Processes of forming layered products

Definitions

• the present invention relates to an improved method of casting aerated concrete products, and particularly to an improved method of casting aerated concrete in two or more layers.
• Aerated concrete products are usually obtained by pouring an aerated concrete mass, chiefly consisting of a siliceous raw material, a limy binding agent, a porosityforming agent and water, into casting moulds of suitable dimensions.
• the siliceous material may be, for instance, a fine-ground sand, shale ash, fly ash or other materials with a high content of SiO
• the binding agent may be slaked and/ or unslaked lime or portland cement. Also some combinations of lime and cement may be advantageous.
• the porosity-forming agent preferably consists of aluminum powder, which, its surrounding milieu having been made alkaline by the binding agent, develops hydrogen gas in connection with the casting procedure, thus bringing-about the characteristic bubbles or porosity of the aerated concrete.
• the casting mould may advantageously measure 600 x 120 x 60 cm., the area of the mould bottom being 600 x 120 cm. and the form side walls of the mould 60 cm. high.
• the present invention relates to a casting method eliminating the above disadvantages of the casting in two or more steps.
• Characteristic of the method invented is that in the interval between the casting of two layers of mass there is applied to the upper surface of the first layer a film or covering which at least during the casting process remains essentially tight or retarding to the penetration of liquids.
• the film applied to the layer of mass in question is strongly adhesive to the aerated concrete even after the steam-curing. In that way the cohesion between the different layers is improved.
• the film to be applied may be produced in different ways and from different materials. It may, according to the invention, consist of or comprise plastic or rubber.
• plastic or rubber One possibility, for instance, is to use styrene-butadiene latex, which suitably may be kept dispersed in water at the applying occasions.
• polyvinyl alcohol as well as various sorts of acrylic plastic, such as polybutyl metacrylate, polymethyl acrylate or polyethyl acrylate.
• the thickness of films made from such plastics has been determined experimentally as corresponding to a quantity of plastic of 5-100, preferably 30-50, g./m. of solids at hand in the material.
• gluey materials such as ethyl-hydroxyethyl cellulose.
• inorganic additives for instance, portland cement or fine-ground materials containing SiO such as sand and sandstone.
• fine-ground lime or aerated concrete mass which has not yet been made porous, as this mass chiefly consists of a mixture of a siliceous raw material with a limy binding agent. It is possible also to make films or covering layers exclusively from one or more inorganic materials, i.e., not containing any plastic or rubber.
• the film perpendicularly to the plane of a building element to be taken from the cast block of mass may be done by applying the film to the upper surface of the first layer which surface is essentially horizontal and then dividing up the cast block by vertical cuts. It may be desired, for instance, to produce 6 elements 600 cm. long and 60 cm. wide from a mould of the dimensions 600 x 120 x 60 cm. It is possible then to cast a first layer of mass with a height, after completed porosity formation, of 30 cm. and to apply a film onto the horizontal upper surface of the same. on top of the first layer, then, a second layer of equal height is cast, i.e., the mould is filled up to its upper edge after completed porosity formation. After that, the block thus formed is, by five vertical cuts, divided into six elements of the dimensions 600 x 60 x 20 cm., the plane of the seam or the film thus becoming situated crosswise to the big surface or plane of the elements.
• the applying of the fihn can in practice be carried out by spraying the film-forming material with an optional spraying device.
• EXAMPLE 11 Instead of the styrene butadiene latex of Example I a film-forming material is-made from a mixture of 4 parts by weight of a 50% polymethyl metacrylate dispersion, 2 parts by weight of portland cement and 6 parts by weight of water. A quantity of 100 g./m. of this mixture is applied to a first layer of mass.
• Aerated concrete elements produced according to' the above examples show an even porosity on both sides of the seam and, besides, the cohesion between the layer cast-together is extraordinarily good.
• the invention offers considerable advantages as to the casting technique.
• great difiiculties exactly to choose the correct point of time for casting the second or subsequent layer. If it was applied to early, there was the risk of the first layer collapsing, if too late, too much water would pass between the layers causing faults in the aerated concrete nearest to the casting seam.
• For some raw material it has earlier been necessary to cast the second layer already 20-25 minutes after the first one to avoid the occurrence of unacceptable deficiencies around the casting seam. This has of course meant an imminent risk of the first layer crumpling down as that period is too short for the complete setting of the aerated concrete.
• a method of multilayer casting aerated concrete products comprising the steps of first casting one aerated concrete mass layer which is then brought to set or harden into a self-supporting consistency, then in at least one second step casting a further layer of aerated concrete mass on top of the preceding self-supporting layer and permitting said f urther layer to set or harden into a self-supporting consistency, and steam-curing the multilayer body, the improvement comprising improving the porous structure in the joint area between the two layers while promoting adhesion between the two layers by, in the interval between the casting of the two layers of mass, the step of applying to the upper surface of the first layer a solution or liquid dispersion of a film-forming polymeric material which, at least during the casting process, at least retards migration of water from said further layer to said first layer, and which promotes adhesion between the two layers after steam-curing.
• the filmforming material comprises styrene butadiene latex.
• a method according to claim 1 wherein the filmforming material comprises polyvinyl alcohol.
• the filmforming material comprises ethyl-hydroxyethyl cellulose.
• said filmforming material includes inorganic material additives selected from the group consisting of portland cement, finely-ground materials containing silicon dioxide, and finely-ground lime.
• a method according to claim 1 including the step of cutting the multi-layer body along planes normal to the film layer to form aerated concrete building elements containing said first and further layers adhered together at said joint.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=20302641

Family Applications (1)

Country Status (10)

Cited By (8)

Families Citing this family (1)

Family Cites Families (8)

• 1970
  • 1970-12-10 SE SE16709/70A patent/SE362237B/xx unknown
• 1971
  • 1971-09-14 DE DE2145819A patent/DE2145819C3/de not_active Expired
  • 1971-09-20 AT AT814971A patent/AT306612B/de not_active IP Right Cessation
  • 1971-11-03 CH CH1602871A patent/CH537345A/de not_active IP Right Cessation
  • 1971-12-03 IT IT32016/71A patent/IT943706B/it active
  • 1971-12-09 FR FR7144206A patent/FR2117579A5/fr not_active Expired
  • 1971-12-09 NO NO4544/71A patent/NO131124C/no unknown
  • 1971-12-10 JP JP46099592A patent/JPS5129178B1/ja active Pending
  • 1971-12-10 BE BE776561A patent/BE776561A/xx not_active IP Right Cessation
  • 1971-12-10 US US00206856A patent/US3808299A/en not_active Expired - Lifetime

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