Classifications

• • 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
  • E04C2/26—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials composed of materials covered by two or more of groups E04C2/04, E04C2/08, E04C2/10 or of materials covered by one of these groups with a material not specified in one of the groups
• • 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
  • B28B19/00—Machines or methods for applying the material to surfaces to form a permanent layer thereon
  • B28B19/0053—Machines or methods for applying the material to surfaces to form a permanent layer thereon to tiles, bricks or the like
• • 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

Definitions

• the present invention involves a combined natural stone and concrete slab intended for use as face material in accordance with the caption of Claim 1.
• This element consists of a face layer of natural stone and of a base layer of concrete which lies against the natural stone layer.
• the invention involves, in accordance with the caption of Claim 14, the manufacture of the combined natural stone and concrete slabs.
• concrete is cast on one side of the natural stone slab which then provides the casting bed for the concrete and, if required, the concrete is fitted with reinforcement, and is then allowed to set and harden .
• the invention also involves the way of making natural stone slabs, especially face slabs of natural stone, more water repellent .
• the aim of the invention is to provide a remedy for the difficulties relating to the state of the art and to offer a combined natural stone and concrete slab of a whole new type which can be used as face material .
• the invention is based on the idea that natural stone, for example marble, is cast together with a reinforced concrete slab to form a face element.
• the natural stone slab is bent, so that the surface upon which the concrete for the concrete slab is cast becomes convex and shows a bending of about 0.1 to 10 mm per metre. Since the cast concrete shrinks during setting and hardening, the natural stone slab straightens out of the firm concrete thereupon, and this takes place during the setting and hardening process.
• the surface of the natural stone must be made water repellent prior to casting, preferably by a treatment with a polymerized resin. It is an advantage if the concrete contains a part of crushed natural stone which is able to bind water.
• the bent natural stone slab straightens out of the concrete during the setting and hardening process, which means that the tension or stress is taken up by the concrete reinforcements.
• a continuing (undesirable) bending of the natural stone slab is prevented by both the concrete and its reinforcement, which means that such bending in natural stone, for example in marble, that would otherwise cause breaking due to weathering can be avoided.
• the bond between the natural stone and the concrete is excellent: tests have shown that the slab breaks in the concrete layer rather than at the junction between the natural stone slab and concrete.
• the crushed natural stone serves in the concrete as a water reservoir, which means that we achieve a controlled setting of the cast concrete, while water is prevented from escaping out of the natural stone slab, which would weaken the bond.
• Figure 2 gives a front view of the slab.
• Figure 4 gives a sectional view 2-2.
• Figure 5 shows in more detail the construction of the slab, with the concrete protraction (4) (section A-A) and the suspension rod (5) (section B-B) .
• the reinforcement (7) is laid across the middle of the concrete layer (3), to produce a mesh reinforcement which increases the concrete layer's tensile strength in the long direction and in the direction of the breadth.
• a suitable diametre for the reinforcing irons is from 2 to 6 mm, for example about 4 mm, for a slab with a 10 mm layer of marble and a 30 mm layer of concrete.
• double reinforcement can be used to make the construction extra strong.
• the edge of the natural stone slab (2), along the concrete protraction (4), is provided with a longitudinal groove (8).
• a U-shaped fixing iron (9) which is cast in under the transverse reinforcing iron is bent twice, so that it first runs over the longitudinal reinforcing iron and then bends in with the end of the U-shaped iron in the groove (8).
• a second flat U-shaped fixing iron is fitted in the concrete layer with the U-iron's end cast in the concrete protraction (4).
• the fixing iron is made of spring steel.
• a natural stone slab which consists of a stone type that is suited for use as face material.
• Such natural stones are, for example, oxide and hydroxide minerals as well as carbonate minerals.
• suitable natural stones for example, marble and other calcium and calcium-magnesium-carbonate based minerals (for example limestone), as well as granite, quartz and quartzites, labradorite and other similar silicate based minerals.
• marble or granite Preferably we use marble or granite.
• the natural stone slab is bent approximately 1 to 4 mm per metre.
• the bending is calculated as the distance from a point in the middle of the slab to an assumed straight line which unites the edges of the slab.
• the required bending is achieved by sand blasting the inner surface of the natural stone slab.
• sand blasting we use preferably sand which is OK 50 to 90, most suitably OK 70 that contains nickel slag.
• the pressure reaches in general 5 to 20 kg/cm.2, preferably about 10 to 12 kg/cm2.
• the slab can also be bent in a different way, for example mechanically by applying pressure on the middle of the slab.
• the cast concrete which after setting forms one part of the combined element, contains a hydraulic binder (i.e. a binder that hardens when water is added to it), fillers and suitable additives.
• the binder can be, for example, Portland cement, rapid cement or slag cement but we prefer to use cement with a high bond strength, such as white cement.
• the suitable fineness of the cement is up to 100 to 800 m2/g, preferably 200 to 600 m2/g.
• the fillers for the concrete may be sand, polymeric compounds and fibrous materials. We preferably use sand with a particle size of up to 3 mm. According to a preferred procedure, we use sand of two different particle sizes.
• the concrete can also contain fibrous fillers, such as natural and synthetic fibres. As examples we may mention cellulose based fibres, glassfibre, carbon fibres and plastic fibres.
• the concrete may contain known additives, such as fluidizers, accelerators or retardants, pore-forming agents for frost resistance and corrosion protection.
• the concrete layer is most suitably provided with the above mentioned reinforcement, which takes up tensile stresses acting on the slab, as well as with the above mentioned fixing irons and suspension rods.
• the combined slab is allowed to dry and set.
• the bending of the natural stone layer reverts as the concrete dries and shrinks.
• the bending stress is carried on to the concrete layer and taken up by the reinforcement.
• the marble slab was laid down in a form lined with a plastic sheet, and the treated side was turned up and used as the casting bed for the concrete mixed according to the following formmula:
• the bond strength of the combined marble and concrete slabs (25 x 35 cm), manufactured according to the above description, have been tested in the Laboratory for Structural Engineering at the Technical Research Centre of Finland (VTT).
• the slabs contained crushed granite, limestone or quartz.
• the frost resistance of the slabs as well as the bond strength between the marble layer and the concrete layer were determined in the testing.
• the tensile strength of the slabs after a freezing/melting process was determined according SFS 5445. The first inspection showed that the treatment had not caused any visible damage to the slabs.
• the tensile strength of the slabs was at least 88 per cent of that of the reference slabs, and was up to 2.8 MPa for slabs containing crushed granite, 2.5 MPa for slabs with limestone and 2.9 MPa for slabs with quartz. Since a facade construction is considered to be frost resistant if after 100 cycles of freezing and melting its strength is not below 2/3 of the reference, it was found that the slabs according to the invention obviously well fulfil the criteria of the standards.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Finishing Walls (AREA)

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Publications (1)

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• 1996
  • 1996-10-15 FI FI964148A patent/FI110494B/sv active
• 1997
  • 1997-10-14 WO PCT/FI1997/000626 patent/WO1998016358A1/sv not_active Application Discontinuation
  • 1997-10-14 AU AU46257/97A patent/AU4625797A/en not_active Abandoned
  • 1997-10-14 EP EP97944915A patent/EP0932484A1/en not_active Withdrawn

Non-Patent Citations (1)

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