US3217075A - Method for making stressed lightweight concrete products - Google Patents

Method for making stressed lightweight concrete products Download PDF

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Publication number
US3217075A
US3217075A US221913A US22191362A US3217075A US 3217075 A US3217075 A US 3217075A US 221913 A US221913 A US 221913A US 22191362 A US22191362 A US 22191362A US 3217075 A US3217075 A US 3217075A
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United States
Prior art keywords
inforcement
light concrete
concrete
moisture
iron
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Expired - Lifetime
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US221913A
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English (en)
Inventor
Kjell-Berger Olof
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Skovde Gasbetong AB
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Skovde Gasbetong AB
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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
    • 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
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • 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
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
    • B28B23/046—Post treatment to obtain pre-stressed articles
    • 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
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
    • B28B23/06—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed for the production of elongated articles
    • 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
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/18—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members for the production of elongated articles
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
    • E04C2/04—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres
    • E04C2/044—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres of concrete
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/20—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members
    • E04C3/26—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members prestressed
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/08—Members specially adapted to be used in prestressed constructions
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/12—Mounting of reinforcing inserts; Prestressing

Definitions

  • the present invention refers to a method for the production of a re-inforced light concrete plate.
  • the invention also refers to a light concrete plate, produced according to said method.
  • the prior art shows placing in the mould before the ready-making and before the raising of the light concrete mass a re-inforcement crate or re-inforcement mat.
  • the raising takes place by adding to the light concrete mass a gas development means, for instance aluminum, said metal reacting with the lime contained in the raw material for forming the light concrete thereby forming hydrogen.
  • a gas development means for instance aluminum
  • the bulk volume of the mass has increased, so that its upper surface has raised as by dough raising, but the re-inforceinent construction has still remained in its initial place in the mould.
  • the concrete mass is thin fluid, when it is first poured into the mould, but simultaneously with its raising a thickening or plastification of the mass starts, and at least during the later phase of the abovementioned displacement movement between the mass and the re-inforcement, the mass is plastic and thickened to such a degree, that it has no longer the same power of filling out the space.
  • the consequence thereof has been, that an empty space is formed above the re-inforcement means running in a horizontal direction, and the mass thereby only adheres to the lower side portions of the re-inforcement bars, but not to the upper side, where a moon-sickle like space forms between the upper side of the re-inforcement bar and the corresponding lower side of the mass.
  • this re-inforcing means did not give the rigidity which was expected according to theoretical calculations.
  • the light concrete when it is removed from the autoclave after steam curing, has a content of moisture of between 25% and 30%.
  • this moisture is readily evaporated, i.e. the surface moisture, but due to the light concrete having another highly estimated property, i.e. an utterly low hygroscopicity, the evaporation of the interior moisture takes place only slowly.
  • the light concrete had often a remaining moisture, which could amount to approximately 25
  • the piece of light concrete is thereafter mounted and will get into contact with mortar, plaster and so on, the surface moisture is re-instated, and the total moisture again increases.
  • the invention is based upon the understanding that the said shrinkage causes a relaxation of the tension of the re-inforceinent in the re-inforcement irons which have been mounted in the moist state of the plate, this is believed to be the reason for the loss of strength in the above mentioned prior art structure.
  • the light concrete is dried out before the joining of the light concrete structure or its parts with the re-inforcement bars, whereafter the re-inforcement bars are applied under a suitable bias tension in the dried out light concrete.
  • This may per se be rather weak, and during mounting, transportation and so on the light concrete may thereafter assume moisture and swell, which will only increase the bias tension, be-
  • the invention can be used successfully on an undivided piece in the form of a plate of light concrete, in which one drills holes or previously arranges holes during molding, for inserting the re-inforcement means.
  • the invention is not dependent upon the plate being undivided or composed by a plurality of pieces, the reinforcement can be applied in the plate after it has been dried out, and it is tensioned in such a way, that the plate in the building, were it is also subjected to a drying out of eventually added moisture after the re-inforcement is applied, will remain as stably re-inforced as at the production.
  • the horizontal axis indicates in logarithmic division the shrinkage of a light concrete plate in millimeters per meter of length dependent upon the content of moisture indicated along the vertical axis.
  • the content of moisture is indicated along the vertical axis in percent.
  • the diagram according to FIG. 1 is based from the assumption that normal moisture immediately after steam curing of the piece of light concrete is about 30%. It is then evident from the diagram, that when the moisture has decreased to half of normal moisture after steam curing, that means to only minute shrinkage has taken place, i.e. 0.15 millimeter per meter. Thereafter, however, the rate and magnitude of the shrinkage rather quickly increases. At a remaining moisture of 5% a shrinkage from the initial state has taken place of 0.4 millimeter per meter, and when the content of moisture has decreased to zero value the shrinkage has increased to 5 millimeters per meter. If the environmental climate change takes place changing from dry to moist, the effect will be the contrary one expanding the block.
  • FIG. 2 shows a perspective drawing of a light concrete body, which has been re-inforced according to the present invention.
  • the proper light concrete body 10 has either already when moulded been provided with channels or after moulding by drilling or in another suitable way been provided with channels, intended to house the re-inforcement irons 11.
  • These re-inforcement irons are inserted through a pressure distribution plate 12 or 13 respectively at each end of the body 10, said plate being provided with holes, corresponding to the channels 14 in the light concrete body.
  • the ends of the re-inforcement irons 14 are secured by means 15 so that a suitable bias tension is obtained to lock the re-inforcement iron in position.
  • the light concrete body should be dried out before securing the re-inforcement irons so that none or only unessential remaining moisture exists, and only thereafter the re-inforcement irons 11 should be introduced through the pressure plates 12 and 13 and the channels 14 provided in the light concrete body 10.
  • the bias tension in the re-inforcement irons is thereby adapted by means of the nuts 15 in such a way, that the bias tension will still remain at a given value, after the light concrete has been fully dried out with the shrinkage following therefrom.
  • the iron used for the re-inforcement as a rule is hot drawn or cold drawn iron with a lower allowable stretching limit between 13 and 20 kg./mm
  • This re-inforcement iron takes up practically all of the strain, to which the light concrete plate is subjected, and in order that it shall get the desirable rigidity in many a case a rather essential quantity or iron is required. Thereby the product will be inconveniently heavy. Further it will conduct sound as well as heat to a rather high degree. Also that iron has a very great tendency of rusting, after it has been applied as a re-inforcement in concrete, especially light concrete. The tendency of the re-inforcement irons to rust has been decreased by protection by some suitable means, which makes the production of the final product more expensive.
  • a further developement of the present invention is based upon an investigation of the suitability of other materials concerned. It has been found that plastic bars, preferably glass-fiber re-inforced bars of plastics, are preferred over an iron-re-inforcement.
  • glass-fiber re-inforced plastic bars The specific properties of glass-fiber re-inforced plastic bars, are that the bars have a very high security against breakage when subjected to drawing as there is no stretching limit. Therefore, one would assume that the glassfiber re-inforcement plastic bars would, as a re-inforcement in light concrete products be too dumb, and would not allow for normal extension procedures before they break, which the iron will do. It has also been found, that light concrete products, which have been re-inforced by means of iron bars, have different characteristics than those which have been re-inforced by glass-fibers.
  • Plastic a material which forms the main part of glassfiber re-inforced plastic bars, which should according to the present invention be used for re-inforcement in light concrete products, has a very low power of conducting heat, whereas iron has a high power of conducting heat.
  • the glass-fiber reinforced plastic is not normally substituted, per se, in the process for making the concrete plate because then the plastic would be together with the light concrete product at the high temperature of between 180 and 200 C., which exists in the autoclave during the steam curing. Plastic cannot withstand this temperature, because the plastic will at this temperature be subjected to interior atomic changes, decreasing the rigidity, and the glass-fiber will melt at this temperature, and therefore its re-inforcing activity will get fully lost.
  • glass-fiber re-inforced plastic in the form of bars therefore is subject to the method in which the moulded light concrete product after having been steam cured in its non-re-inforced state, is dried to none or only unessential remaining moisture, and the re-inforcement is thereafter introduced under a mechanical bias strain so adapted that it will increase to a suitable value after the light concrete has been moisture-conditioned and consequently has expanded.
  • glassfiber re-inforced plastic bars as re-inforcement material
  • these bars must necessarily have such a form as the traditional re-inforcement irons, that means substantially circular cross-section area, but any extended form of the re-inforcement should be regarded as a bar.
  • the tensioning preferably takes place by securing the extending ends of the glass-fiber re-inforced plastic bar by providing a greater cross-section area than the cross-section area of the hole through which the re-inforcement extends.
  • the thickness of the bar should be at the ends be greater than the thickness of the bar at its middle part.
  • the thickened part could be conically made or it could be split end formed.
  • the glass-fiber re-inforced plastic bars which should form the re-inforcement in the light concrete products
  • plastic is preferable to add plastic to the bundle of glass fibers at the ends of the bars after the mounting of the re-inforcement bar into the light concrete product, so that one can connect to these ends the anchoring means which are suitably placed.
  • the fluid plastic which includes the required curing means and also acceleration means, whereafter this is allowed to solidify in place.
  • the drying of the light concrete plate or the parts forming the light concrete plate can take place either by storing in a dry atmosphere or in artificial Way, for example in a drying oven.
  • a method for making light weight, reinforced concrete structures comprising the steps of providing longitudinal, through openings in the concrete structure for the insertion of reinforcing means, curing the structure with steam under pressure; drying the cured structure until substantially all of the free moisture is removed from the concrete, inserting reinforcing means in said openings, locking the ends of said reinforcing means to hold said reinforcing means stationary relative to movement of said structure and placing said structure in a normal humidity environment, whereby the reinforcing means is subjected to a bias tension when the light concrete structure expands under normal humidity conditions.
  • reinforcing means are glass-fiber-reinforced plastic formed by inserting glass fibers into the openings and inserting a mould- References Cited by the Examiner UNITED STATES PATENTS 10/33 Hutteman et a1.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
  • Rod-Shaped Construction Members (AREA)
US221913A 1961-09-14 1962-09-06 Method for making stressed lightweight concrete products Expired - Lifetime US3217075A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE914861 1961-09-14
SE897562 1962-08-17

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US3217075A true US3217075A (en) 1965-11-09

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US (1) US3217075A (US07282526-20071016-C00003.png)
BE (1) BE622483A (US07282526-20071016-C00003.png)
DE (1) DE1207845B (US07282526-20071016-C00003.png)
DK (1) DK114927B (US07282526-20071016-C00003.png)
GB (1) GB1013264A (US07282526-20071016-C00003.png)
LU (1) LU42352A1 (US07282526-20071016-C00003.png)
NL (1) NL283229A (US07282526-20071016-C00003.png)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0197236A2 (en) * 1985-01-29 1986-10-15 National House Industrial Co., Ltd. Reinforced glazed cement product and method for its manufacture
US5046778A (en) * 1990-06-29 1991-09-10 The Standard Products Company Reduced weight vehicle door pillar
US5168008A (en) * 1985-01-29 1992-12-01 National House Industrial Co., Ltd. Glazed cement product and method for manufacturing thereof
US20090152430A1 (en) * 2005-08-17 2009-06-18 Kyoto University Brace

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3817831A1 (de) * 1988-05-26 1989-11-30 Sicowa Verfahrenstech Verfahren zur herstellung von bloecken

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1932971A (en) * 1932-04-15 1933-10-31 Frederick O Anderegg Method of making light weight blocks
US2234663A (en) * 1935-09-21 1941-03-11 Frederick O Anderegg Method of reinforcing building units
US2413990A (en) * 1943-01-25 1947-01-07 Eric P Muntz Process of making prestressed reinforced concrete
US2686963A (en) * 1948-04-27 1954-08-24 Freyssinet Eugene Method of anchoring reinforcements
US2871554A (en) * 1954-06-16 1959-02-03 Losinger Ag Method for post-tensioning the reinforcing of a prestressed concrete structure
US2921463A (en) * 1952-08-20 1960-01-19 Goldfein Solomon Concrete structural element reinforced with glass fibers

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE384754C (de) * 1922-07-14 1923-11-24 Ernst Heinkel Leicht loesbare Tragflaechenbefestigung fuer Flugzeuge

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1932971A (en) * 1932-04-15 1933-10-31 Frederick O Anderegg Method of making light weight blocks
US2234663A (en) * 1935-09-21 1941-03-11 Frederick O Anderegg Method of reinforcing building units
US2413990A (en) * 1943-01-25 1947-01-07 Eric P Muntz Process of making prestressed reinforced concrete
US2686963A (en) * 1948-04-27 1954-08-24 Freyssinet Eugene Method of anchoring reinforcements
US2921463A (en) * 1952-08-20 1960-01-19 Goldfein Solomon Concrete structural element reinforced with glass fibers
US2871554A (en) * 1954-06-16 1959-02-03 Losinger Ag Method for post-tensioning the reinforcing of a prestressed concrete structure

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0197236A2 (en) * 1985-01-29 1986-10-15 National House Industrial Co., Ltd. Reinforced glazed cement product and method for its manufacture
EP0197236A3 (en) * 1985-01-29 1988-12-14 National House Industrial Co., Ltd. Reinforced glazed cement product and method for its manufacture
US5168008A (en) * 1985-01-29 1992-12-01 National House Industrial Co., Ltd. Glazed cement product and method for manufacturing thereof
US5046778A (en) * 1990-06-29 1991-09-10 The Standard Products Company Reduced weight vehicle door pillar
US20090152430A1 (en) * 2005-08-17 2009-06-18 Kyoto University Brace

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BE622483A (US07282526-20071016-C00003.png)
NL283229A (US07282526-20071016-C00003.png)
DK114927B (da) 1969-08-18
GB1013264A (en) 1965-12-15
LU42352A1 (US07282526-20071016-C00003.png) 1962-11-13
DE1207845B (de) 1965-12-23

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