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
  • B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
  • B28B17/0018—Separating articles from each other
• • 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
  • B28B7/00—Moulds; Cores; Mandrels
  • B28B7/0064—Moulds characterised by special surfaces for producing a desired surface of a moulded article, e.g. profiled or polished moulding surfaces
  • B28B7/007—Moulds characterised by special surfaces for producing a desired surface of a moulded article, e.g. profiled or polished moulding surfaces with moulding surfaces simulating natural effets, e.g. wood or stone
• • 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
  • B28B7/00—Moulds; Cores; Mandrels
  • B28B7/0088—Moulds in which at least one surface of the moulded article serves as mould surface, e.g. moulding articles on or against a previously shaped article, between previously shaped articles
• • 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
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/0009—Demolition agents based on cementitous or like materials

Definitions

• the present invention relates to a method for manufacturing split-faced concrete pieces, a split-faced concrete piece, and a means for applying the method.
• the invention particularly relates to concrete pieces that are the size of or bigger than garden slabs and similar.
• the concrete surface can also be broken, to reveal the coarser particles, such as stones, contained in the concrete.
• the simplest way to create such a surface structure is to use a so-called surface retardant, which retards the setting of the concrete, between the mould material and the concrete material being cast.
• the surface concrete is still plastic.
• the plastic surface concrete is then washed off, for example; using a water jet. This surface is calted exposed-aggregate concrete and is typified by the coarser aggregate particles, such as stones, in the concrete becoming fully visible in the surface of the concrete.
• Concrete surfaces can be mechanically broken, for example, by sand-blasting or chipping.
• Chemical means, such as acid washing, are also used, as are thermal treatments, such as flame treatment.
• the treatment of the surface is laborious; i.e. it demands work-time and energy and produces a great deal of waste. All of these methods are also characterized by a great need for labour, and a high consumption of material, such as water. They also create a great deal of sludge and other waste.
• Split-faced concrete products can also be manufactured by mechanically striking or bending the set concrete.
• Small concrete products like wall masonry, are manufactured by cracking set concrete slabs into two or more parts. This reveals the split-faced surface structure.
• This method is in widespread use and is disclosed in, for example, patents DE 2921432 and CH 595588. In practice, the method is limited to the manufacture of small surfaces, because cracking in large surfaces has been uncontrolled. As it has been impossible to make large surfaces, if extensive surfaces are required, it has been necessary to set several small split- surface pieces next to each other, for example, in retaining walls and in brick- faced units.
• the aggregate in the concrete may also react with alkali metal compounds in the concrete, to form an expanding layer between the aggregate particle and the hardened cement paste.
• alkali metal compounds in the concrete may also react with alkali metal compounds in the concrete, to form an expanding layer between the aggregate particle and the hardened cement paste.
• Desirable expansion is used in commercial applications, for example, to break stones and concrete pieces.
• the trade name of one product marketed in Finland is Betonamit.
• the material is mixed with water and used to fill a hole drilled in the stone or concrete. Within a few days, the material in the hole has expanded, causing a pressure that breaks the structure.
• the instructions for use state that the material contains lime (CaO).
• Such methods are typified by tending to break the concrete or stone piece into small pieces and by uncontrolled cracking.
• the present invention is intended to achieve such a method that can be also applied to large concrete pieces.
• the intention is also to achieve a method, by means of which large concrete pieces can be split controllably into two or more parts, so that the split faces can be used as such or processed for any purpose whatever, for which split-faced concrete has been traditionally used.
• the cracking is controlled and can be planned in advance and carried out repeatably.
• the method according to the invention permits the creation of large split-faced concrete products, which are cracked in a controlled manner.
• a significant part of the energy needed for cracking is produced by a reactive agent, which is placed during casting in the face to be split during casting, and which expands when it reacts. This expansion creates an internal pressure in the concrete, cracking the concrete along the boundary surface, in which the reactive agent has been placed.
• the reactive material can be manufactured to be such that expansion starts only once the concrete has achieved a sufficient strength. This achieves the advantage that the stones in the boundary surface will have adhered so tightly to the concrete, that they split when the concrete cracks.
• the split stones give the surface structure their own special character, which differs, -for example, from a plasterless concrete surface or other treated surfaces. Apart from the cracking being controllable, another significant difference is that the reactive material is introduced to the unset concrete, where it reacts with the aid of the moisture of the concrete material or with other compounds to cause cracking.
• a clear advantage of the method according to the invention over old methods of producing a concrete surface with large visible aggregate particles is that the method according to the invention can be used to split thick cast concrete into two or more thin units.
• the reactive material can be placed freely in the cast concrete, or it can be attached before casting to a mesh or other support structure, by means of which it is placed in the concrete structure. As it expands, it cracks the concrete surface from within.
• An application of this kind is especially beneficial in in-situ cast applications and in cases in which the aim is to have both the cast and the splitting boundary surface in a vertical position. It is also possible to make shaped split-shaped concrete structures, if the reactive material is attached to a sturdy support structure that can be shaped.
• Casting can also be arranged so that the first unit being cast is allowed to set, before casting the next unit.
• the surface of the first unit cast should be treated so that the concrete that is cast later will adhere to the concrete that is cast first.
• the surface that is cast first should contain raised aggregate particles that are split by the expanding material. The reactive material is placed before casting a second layer on top of the surface of the concrete that was cast first.
• facade concretes is ensured by using strong and dense concrete. This has been problematical, in that the retention of surfacings on the dense and smooth surface becomes uncertain. For example, slabs or rendering sprayed on the surface have often become detached.
• a split-faced unit manufactured according to the method eliminates this problem, as its good mechanical adhesion, also provides an excellent base for any surfacing materials used on the unit.
• the method according to the invention can be used to manufacture large split-faced concrete units meeting the requirement to adequately cover reinforcement.
• CaO quicklime
• Example 4 In one test investigating working techniques, four cardboard tubes containing the reactive material were placed parallel to each other at intervals of about half a metre on the surface of the cast concrete. The unit used was 2 m x 2 m, both cast layers being 20-cm thick. The concrete was the same grade as that used in tests 1 and 2. As the concrete set, the moisture travelled through the cardboard tube to start an expanding reaction, which broke the concrete along the row of tubes. This created a concrete surface that looked very much like a surface created in quarrying, i.e. the tubes left traces in the concrete looking like drill holes.
• the method according to the invention creates products with an very wide area of application. Concrete products created according to the invention can be used as such for many purposes, to create a lively and aesthetically pleasing surface. In addition, the products are very suitable for further processing, due, for example, to the excellent adhesion of surfacing materials to the surface created.
• the means developed to apply the method comprises a suitable support structure, such as a steel mesh, a mesh of a plastic material, or even a mesh of paper string, which is impregnated with the reactive substance or to which the reactive substance is attached using a generally known method.
• Glue-like materials for example, can be used for the attachment, which in certain cases can also rely " purely on the reactive material's own properties. Obviously, it is not necessary for the support material to be a mesh. As stated above, one embodiment was to put the reactive material inside a tube permeable by moisture. Many other applications can also be envisaged.
• the invention can also be applied to create curved or shaped surfaces.
• the invention is not limited to the above examples of embodiments, but is adaptable in many ways, while still remaining within the scope of the protection defined by the accompanying Claims and the inventive idea.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Aftertreatments Of Artificial And Natural Stones (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8555570

Family Applications (1)

Country Status (4)

Family Cites Families (4)

• 2000
  • 2000-11-06 EP EP00976098A patent/EP1237690A1/de not_active Withdrawn
  • 2000-11-06 WO PCT/FI2000/000970 patent/WO2001032379A1/en not_active Ceased
  • 2000-11-06 AU AU13989/01A patent/AU1398901A/en not_active Abandoned
• 2002
  • 2002-05-03 NO NO20022143A patent/NO20022143L/no unknown

Non-Patent Citations (1)

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