EP3484680A1

EP3484680A1 - Method and form arrangement for 3-dimensional concrete surface

Info

Publication number: EP3484680A1
Application number: EP17751786.9A
Authority: EP
Inventors: Renáta JAKOWLEFF
Original assignee: Muotobetoni Oy
Current assignee: Muotobetoni Oy
Priority date: 2016-07-18
Filing date: 2017-07-11
Publication date: 2019-05-22
Anticipated expiration: 2037-07-11
Also published as: EA037594B1; FI127621B; EA201990113A1; CN109476036A; FI20165592A7; EP3484680B1; WO2018015614A1

Abstract

A method for creating a 3-dimensional concrete surface to a concrete structure includes using a rigid form (110), an auxiliary form (130) and a non-rigid sheet (120). The non-rigid sheet (120) is to be placed between an upper surface of concrete (140) poured to the rigid form (110) and the auxiliary form (130) that is at least partly to be pressed into the concrete (140), the non-rigid sheet (120) being placed before pressing the auxiliary form.

Description

METHOD AND FORM ARRANGEM ENT FOR 3-DIMEN30NALOONCRETESURFACE

FI ELD

The present invention relates to manufacturing one or more concrete structures. BACKGROUND ART

Concrete is one of the most durable building materials. In addition, the concrete, as a settable building material , offers a high level of design flexibility. Concrete structures may have many different shapes, a shape of a concrete structure bei ng defi ned by cast surfaces inside aform whereto the concrete is poured to form the concrete structure. There are several ways to affect to the appearance of a concrete structure. For example, basic materials of the concrete, i .e. cement, water and aggregates, and their proportional amounts, as well as possible ad mixtures, additives, colour pigments, etc., added during a concrete mix preparation, each have their i mpact to the appearance, such as colour, of the surface. Further, differ - ent surface treatment methods, applied either to a cured concrete structure or whiletheconcrete iscuring, createdifferent surfacetextures. Also surfaces, against which the concrete is poured in the form may be provided with different 3 di mensional shapes, or a structured material , like a pattern transfer mat disclosed in US 5330694, to create a 3-di mensional surface for a concrete structure. BRI EF DESCRI PTION

A general aspect of the invention is to provide a way to obtain a 3-dimensional concrete surface to a concrete structure by using a rigid form, an auxiliary form and a non-rigid sheet that is to be placed between an upper surface of concrete poured to the rigid form and the auxiliary form before pressing the auxil- iary form with the sheet at least partly into the concrete. The auxiliary form, together with the sheet, provide versatile possibilities to profile and/ or structure a surface of a concrete structure. Hence it is possible to create, and easy to manufacture, concrete structures with surfaces providing different visual , acoustic and/ or h apt i c ch ar act er i st i cs.

The invention is defined in a method and form arrangement, which are characterized by what is stated in the independent clai ms. The preferred embodi- ments of the invention aredisclosed in the dependent clai ms. BRI EF DESCRI PTI ON OF THE DRAWI NGS

In the following, exemplary embodi ments will be described in greater detail with reference to accompanying drawings, in which

Figures 1 and 2 illustrate an exemplified form arrangement; Figures3Aand 3B illustrateexemplified form arrangements from bird's eye view;

Figure4 is aflow chart illustrating an exemplary functionality;

Figure 5 is a block diagram illustrating an exemplary fastening means; and

Figures 6 and 7 areflow charts illustrating exemplary functionalities.

DETAI LED DESCRI PTI ON OF SOME EMBODI MENTS

The following embodi ments are exemplary. Although the specification may refer to "an", "one", or "some" embodi ment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodi ment. All words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodi ment. Sngle features of different embodi ments may also be combined to provide other embodi ments. Furthermore, words "comprising" and "including" should be understood as not limiting thedescribed embodi ments to consist of only those features that have been mentioned and such embodiments may contain also features structures that have not been specifically mentioned.

The present invention is applicable to a manufacturing process of any precast concrete element (structure) and any cast-in-place concrete structurethat uses a form in which at least part of an upper surface of a concrete poured to the form is not covered by the form. Below different examples are described using a form having an open upper surface, i .e. the upper surface of the concrete poured to the form is not at all covered by theform, without restricting the examplesto such a solution. It is a straightforward solution for one skilled in the art to i mplement the examples to a sol ution i n which the upper surface of the concrete is also partly covered by the form; the examples are applied to part(s) not covered by the form. Further, concrete means herein any mixture that comprises as raw materials at least aggregates, a paste of binder material, such as cement, and water, the mixture being fluid/ pourableto aform when the raw materials are mixed together, but the mixture hardening (curing) over ti me. The non-li miting examples include conventional concrete, light weight concrete, micro concrete, fiber reinforced concrete, steel reinforced concrete, and self-compacting concrete.

A cross section of an exemplified form arrangement is illustrated in Fig- ures l and 2, Figure 1 before the 3-di mensional upper pour surface is created and Figure 2 when it is created. It should be appreciated that the upper pour surface means herein a surface that is in the upper position when the concrete is poured, but once the concrete structure is in use the upper pour surface may be aside surface, upper surface or a bottom surface of the concrete structure.

Theexemplified form arrangement 100 is i I lustrated in Figure l in asit- uation in which concrete 140 has just been poured to a rigid form 1 10, the form 1 10 and the concrete is covered by a non-rigid sheet (membrane) 120, and an auxiliary form 130 is to be placed on the sheet 120.

In the illustrated example, the rigid form 1 10 comprises a frame, i .e. a frame part, illustrated by sidewalls 1 1 1 and 1 1 1 ', and a bottom 1 12, i .e. a bottom part. The form 1 10, also called a mould, or a for mwork, defines a space into which concrete is poured, and affects, in addition to the shape of the concrete structure, to the surfaces of the concrete structure that facetheform 1 10. Such surfaces may be called cast surfaces. To hold poured green (fresh) concretewithin theform 1 10, the frame needs be a closed frame, and to maintain the intended shape, the form 1 10 needs be rigid. Term rigid means herein capability to maintain the shape of the form as intended. That meansthat if pouring is planned to cause somedeformation of the shape, as is the case with fabric for mworks, that is allowed to happen, but not any unintended deformation of the shape. Another example of a form 1 10 in- eludes a casting on flat form. A casting on flat form may be used for concrete structures regardless of their size, and regardless of their final erection direction. For example, concrete wall elements, floor elements, columns, and beams, paving elements, concrete structures for furniture etc., may be manufactured using casting on flat forms.

Although in Figure 1 the frame and the bottom of theform 1 10 are integrated together that need not be the case; the frame and the bottom may be sepa- ratefrom each other, and of different material . Theform 1 10, or removable part of the form, may comprise only the frame; the bottom part may be any slab, such as a thin-shell slab, or a composite steel slab, or any material that will not be removed, i .e. that remains as part of the concrete structure or below the concrete structure in the final product. When concrete is poured to be directly in touch with a soil surface, the form 1 10 may comprise only the frame.

Although in the example illustrated in Figures 1 and 2 the bottom part 1 12 is even (flat) that needs not be the case. There are no restrictionsto the mate- rial and shape of the form, as long as the form, i .e. at least the bottom part, if such exists, and the frame part, is rigid enough to carry the load caused by the concrete and its pouring, and not to reshape when the auxiliary form with the sheet is pressed i nto the concrete, as wi 11 be descri bed i n detai I bel ow, and the shape of the form 1 10 has an upper opening to accommodate at least sheet contacting portions of the auxiliary form and displaced concrete. For example, the inner surface of the form 1 10 facing the concrete, or part of the inner surface of the form 1 10 may be covered, before the concrete 140 is poured to the form, by anything that creates a 3-di mensional structure to the concrete surface, or creates another kind of finishing to the concrete surface. For example, a pattern mat, a foil for graphic concrete, etc. may be used. Combining a form 1 10 providing a 3-di mensional surface with a 3-di mensional surface created by means of the sheet 120 and the auxiliary form 130 it ispossibleto manufacture concrete structures, such aswalls, that once cured have at least on oppositesides 3-di mensional surfaces not requiring additional finishing of the surfaces.

The non-rigid sheet 120 may be made of any material that allows adoption of theshapefrom ashape it was laid to cover the upper surfaceof theconcrete, illustrated in Figure 1 , to a 3-di mensional shape that may comprise one or more curvature portions and/ or one or more double-curvature portions and/ or one or more straight portions. An example of the 3-di mensional shape is a curvy-like shape illustrated in Figure 2. The non-rigid sheet 120 is preferably made of aflexi- ble/ ductile material , either plastic or elastic. If the non-rigid sheet is a single-use sheet, it may be made of a plastic material or elastic material , whereas a reusable non-rigid sheet may be made of an elastic material . However, even a non-flexible/ non-ductile material may be used, if thesheet 120 is sufficiently larger than the area of the upper surface of the concrete 140 facing the sheet 120 before pressing the auxiliary form. In such a case, in the situation illustrated in Figure 1 , a sheet made of a non-ductile material is in afolded (or folded-like) state, and in the situa- tion illustrated in Figure 2, in a non-folded (smooth/ less wrinkled) state.

Mini mum prerequisites for the sheet material includesthat its strength (resistance to tension or tensile breaking force) is big enough for the deformation so that tension caused by downward movement of the auxiliary form 130 stretching the sheet, or more precisely sheet portions having contact with the auxiliary form, and down and upward and sideward movement of displaced concrete stretching the sheet, or more precisely sheet portions having no contact with the auxiliary form, will not break the sheet 120. The tension caused, and hence the mini mum strength required, depends on characteristics of the concrete and characteristics of the 3-di mensional structure, which in turn depends on the bottom part design of the auxiliary form and how deep into the concrete the auxiliary form with thesheet is pressed. Thechar act eristics of theconcretedependson thechosen concrete type, its workability (plasticity), how long it will be allowed to cure, etc. Further, the roughness and coarseness of aggregate used in the concrete, as well as concrete batch size, may affect to the mini mum strength required. For example, if theform 1 10 is filled to its upper level (full to the pri m) with concrete, the tension caused to the sheet 120 may be bigger compared to a situation in which aconcrete batch size is a smaller than the pouring volume defined by the inner side of the form 1 10 when the sheet is placed on the upper level of the form. Naturally, if the surface is created by pressing the auxiliary form 1 10 even after the sheet 120 does not stretch any more, and hence does not provide space to the concrete 140, the sheet 120 has to be strength enough to carry in the stretched state forces caused by the concrete compacting against thesheet 120. It should be appreciated that any fabric used for fabric framework may be used as the sheet, but since the strength requirements are different, for example there is no need for the sheet to carry the weight of the poured concrete, fabrics not suitable for the fabric framework, may also be used.

In implementations in which the sheet is to be fastened to the form directly or indirectly and/ or to the auxiliary form, the sheet has to be fast enable.

One characteristic of the sheet that affects to the shape of the 3-di men- sional surface is the thickness of the sheet: a thinner the sheet is the more closely it follows the shapes of the portions of the bottom part of the auxiliary form that contact the sheet during pressing.

Water- and air permeability of the sheet material affects to thefinished surface of the concrete structure, for example to the amount of air bubbles (voids, blisters, blowholes), and to thewater-cement ratio near thesurface. With asuitable selection of the sheet material, concrete characteristics, bottom part design of the auxiliary form, and pressing depth a smooth surface without visible voids may be obtained. Further, with suitable water permeability of the sheet material , surface finishing fluids, such as surface retarding agents or colour pigments mixed with water, for example, may seep (pass) through the sheet to intended places, for example by adding them to specific spots in the bottom part of the auxiliary form before pressing the auxiliary form, or by adding them to cavities created to the sheet during the pressing. By varying thesefactorsdifferent appearances of surfaces will be obtained.

The texture of the sheet surface 120 that faces the concrete 140 affects to the texture of the concrete surface. This in turn increases the possibilities to design various concrete surface textures. Naturally the sheet surface facing the con- crete may be treated as if it were a surface in the form. For example, a special foil comprising areas with a surface retarder to create graphical concrete, may be placed on the sheet surface facing the concrete, or on the upper concrete surface, before the sheet is mounted on the fresh concrete. Further examples include providing the sheet 120 with one or more pigment dyes and/ or inlays and/ or sur- face retarder. It should be appreciated that any method to texture the surface may be used.

Examples of sheet materials that may be used include flexible non-adherent synthetic woven fabrics, like pol yam ide ( nylon) with weight of 65-70 g/ m2, and interlock polyester with weight of 1 10 g/ m2, and flexible non-woven fabrics, such as geotextiles. A fabric for a sheet, woven or non-woven, may comprise syn- theticfibers, natural fibers or both of them. The fabric may be surface treated with a release agent, if needed, to ensure that thefabricdoes not adhere to the concrete.

Although in the example illustrated in Figures 1 and 2, the sheet 120 is sol id, the sheet may comprise one or more holes (apertures) with sameor different shapes. That further enhancesappearancedesign possibilities. Still another feature enhancing appearance design possibilities is "stretchability" ratio of the sheet material ; if it is one, it stretches equally in each direction, if it is less or more than one, the sheet stretches differently in different directions.

It is also possible to use two or more sheets, with the same or different characteristics, instead of the one illustrated in Rgures i and 2. The two or more sheets may together form a kind of "combination sheet" that covers together the whole upper surface of the concrete (that is not covered by the form), and herein the term "sheet" also covers the "combination sheet" unless otherwise expressed. One or more of the two or more sheets may be an "additional sheet", i .e. a sheet placed over another sheet. The additional sheet may be smaller than the sheet over which is placed, and the additional sheet may be placed, for example, so that only proportion(s) of the sheet contacting portionsof theauxiliary form will contact the additional sheet. Having different sheet thicknesses obtained this way creates further variations in the shape of the concrete surface.

The auxiliary form 130 may be made of any material that is strong enough to cause displacement of the concrete 140, the required strength hence depending on concrete properties, like its consistency factor or value, also called workability. Preferably the material does not soften if the auxiliary form, or more precisely part(s) of the auxiliary form, come into contact with water. Further, the auxiliary form 130 needs to bear the pressing force it is exposed to. However, the pressing force may be only the gravity and the weight of the auxiliary form with a high-slump mix of concrete. In addition to that, to avoid unplanned colouring of the concrete surface, the material should be col our -proof.

The auxiliary form 130 may be one piece, as illustrated in the bird's eye views in Figure 3A, or comprise two or more pieces, as illustrated in the bird's eye view in Figure3B. More precisely, assuming that thesheet facing surface, or at least thesheet contacting portions when the auxiliary form is pressed into itsfinal position, of the auxiliary form 130 hastheshape illustrated in exampleof Figures l and 2, thethree protrusions 131 a, 131 b and 131 careconnected to each other by aplate in the example of Figure 3A and by a rodding 130' in the example of Figure 3B.

The sheet facing surface of the auxiliary form 130 may comprise one or more protrusions 131 a, 131 b, 131 c, as illustrated in Figures 1 and 2, and/ or one or more recesses (not illustrated in Figures 1 and 2), each protrusion/ recess having any outward extension length/ inward depth and shape, independent of each other. Naturally the surfacefacing thesheet (thesheet facing surface of the auxiliary form 130) may be smooth. In other words, there are no restrictions on the shape of the sheet facing surface of the auxiliary form 130. However, any di mension of the aux- iliary form that relate to the sheet contacting portions hasto be such that it is possible to press the auxiliary form with the sheet into the concrete. Hence, the only restriction relating to the shape of the auxiliary form 130 is for its size: the cross cut area of the sheet contacting portions should be smaller than the cross cut area of the concrete upper surface covered or cover able by the sheet, and each of the crosscut di mensions of thesheet contacting portionsshould be smaller than acor- responding di mension of the concrete upper surface covered or cover able by the sheet. I n other words, the area defined by the upper inside surfaces of the form, depicted by the rectangle 1 1 l a in Figures 3A and 3B has to be larger than the contact area of the auxiliary form 130, so that there are one or more auxiliary form - free areas 350, 350', 350" for the sheet to extend (stretch) upwards to occupy the displaced concrete, and the lengths of longer sides of the protrusions 131 a and 131 c i n Figure 3B haveto be smaller than the length of theshorter sidewallsof the frame. Otherwise the auxiliary form 130 may be shaped freely so that the sheet contacting portions, when in the final pressed position, creates with the sheet the desired 3-di mensional surface, or 3-di mensional figure to the concrete surface. Naturally, when the desired concrete surface is designed, one has to take into account different requirements that apply also to conventionally manufactured surfaces, such as a mini mum distance of reinforcement steel bars from the surface.

Further, although in Figures 3A and 3B also the upper part of the auxil- iary form is smaller than the upper inside surface of the form, that need not bethe case. There are no restrictionsto thesize of the upper part. For example, the upper part may be dimensioned so that it hasthesamesize astheform, or it may even be bigger.

The auxiliary form 130 may be used for manufacturing asingleconcrete structure or it may be repeatedly used for manufacturing si milar or in praxis iden- tical concrete structures, depending on the shape of the rigid form 1 10, and the reusability of the sheet 120 used with the auxiliary form, and naturally depending on pressing depth (different depth with other factors remaining the same creates another structure).

Figures 4 and 6 illustrate alternative functionality for a manufacturing phase and 7 illustrates different phase of the manufacturing: Figures 4 and 6 describing "adding" phase and Figure 7 "removal" phase.

In the example illustrated in Figure 4, it is assumed that preli minary preparations, including possible surfacetreatmentsto surfacesthat areto be faced with the concrete and protection of the form, or upper parts of the form, against splashed, if needed, have been performed.

Referringto Figure4, after fresh concrete is poured in step 401 to aform for a concrete structure, possible vibrated or otherwise handled, a sheet selected for the concrete structure is laid (mounted, spread) in step 402 to cover the upper surface of the concrete, and the sheet i s fastened i n step 403 to the for m. There are several ways to perform the laying and fastening. For example, the sheet may be rolled over the upper surface of the concrete and theform parts li miting the upper surface area of the concrete that is not covered by the form, and then the sheet, whose end portions may hang on the outer surfaces of the frame, isfastened to the form by fastening means that holds the sheet. Examples of fastening means include band, rope with tighter, and rivets. It should be appreciated that any fastening meansthat can hold the sheet in its place so that no unplanned flow of concreteout of theform duringthepressing (step 405) takes pi ace. In another examplethesheet is fastened to a framework (rack/ skeleton) that is di mensioned to fit either inside the upper surface area of the concrete that is not covered by the form, or outside the form, and by placing and fastening, separately if needed, the framework to the form the sheet is laid to cover the upper surface of the concrete and fastened to the form. Yet another example is illustrated in Figure 5, in which a fastening means 550, such as a balk, or joist, is attached to a sidewall 1 1 1 of the form once the con- crete 140 has been poured and the sheet laid to cover the concrete and extending at least between the sidewall 1 1 1 and the fastening means. The fastening means may be added to the form using screws or bolts, for example.

Then the auxiliary form is placed in step 404 on the sheet, on a predetermined position, so that the shape to be created will be created according to de- sign of the final concrete structure. It should appreciated that if the sheet is fastened to aframework, and the framework is also a support framework for theaux- iliary form, and/ or otherwise connected to the auxiliary form, so that the framework with the sheet and the auxiliary form are placeable on/ abovethe upper surface of the concrete pour, step 404 is integrated with steps 402 and 403, i .e. they all are placed in one go to cover the upper surface of the concrete pour.

When the auxiliary form is placed (step 404) on the sheet, it will be pressed i n step 405, accordi ng to a pressi ng di recti on, towards the f or m. Usi ng the example illustrated in Figures 1 and 2, the auxiliary form is pressed towards the bottom surface of the form. In other words, in the example of Figures 1 and 2, the pressing direction of the auxiliary form is vertical , i .e. the angle to a plane defined by the sheet before the auxiliary form touches the sheet is 90 degrees. However, any other pressing direction angle may be used, as long as it causes displacement of concrete when the auxiliary form is pressed with the sheet into the concrete.

Referring to Figure 5, assuming that the upper surface of the auxiliary form has such a size and shape that at least part of the upper surface will overlap with theform'sframewhen the auxiliary form is in its intended position, by di mensioning the fastening means 550 according to the intended pressing depth and dimensions of the auxiliary form, the fastening means may be used also as guide means for the intended pressed position of the auxiliary form: when the auxiliary form touches the upper part of the fastening means, the intended position is achieved. The pressing may be performed i mmediately, i .e. to the fresh concrete, or later to a concrete that has cured enough, for example cured a predetermined ti me, or determined other ways, as those currently used to determine for manual surface finishing when the concrete has cured enough. Further, the pressing may be performed in a step-wise way. For example, using the auxiliary form illustrated in Figures 1 and 2, the auxiliary form may be pressed down so that the protrusions denoted by 131 a and 131 c will cause, with corresponding sheet portions entering to the concrete, displacement of the concrete but the pressing is stopped beforethe protrusion denoted by 131 b will enter with the sheet to the concrete; and after a predetermined ti me, the pressing is continued so that the auxiliary form with the sheet will reach its intended penetration depth into the concrete.

The pressing of theauxiliary mold causes displacement of concrete: the sheet contacting portions of the auxiliary mold and corresponding portions of the sheet push the concrete away to have space for themselves. Naturally this stretches, or at least creates stretching forces, to the sheet portions contacting the auxiliary form, while they enter into the concrete. Further, the displaced concrete stretches, or at least creates stretching forces, that are in opposite direction than the pressing to sheet portions having no contact with the auxiliary form. Basically one can say that part of the sheet is pushed downwards by the auxiliary form and part of the sheet is pushed upwards and pressed (tightened) against the concrete by the pressure caused by the displaced concrete, creating thereby a curvy-like shape to the correspond! ng concrete surface.

If the sheet is made of water and air permeable material, tightening of the sheet against the concrete, for example in the situation illustrated in Figure 2, in which the upper surface of the concrete 140 is pressed against the sheet 120, air bubbles and water raising to the upper surface of the concrete 140 are pressed through the sheet 120 resulting to a more condensed, smoother, higher -quality concrete surface, as explained above. That has the advantage that it is possible to use the concrete structure without any further surface finishing, or only by mini- mum surface finishing, thereby reducing the ti me required to manufacture, and increasing productivity.

Figure 6 illustrates the same phase as Figure 4 but for a solution in which only part of the upper part of the concrete not covered by the form is designed to have the 3-di mensional structure, the other parts having a conventional structure, for example. Refer ring to Figure 6, after fresh concrete is poured in step 601 to aform for a concrete structure, possible vibrated or otherwise handled, a sheet selected and the auxiliary form are place in step 602 abovethe upper surfaceof the concrete pour, in the intended location so that the sheet is between the auxiliary form and the concrete. The sheet may be replaced separately, or with the auxiliary form, and the sheet may be fastened to portions of the auxiliary form that are to be entered into the concrete with the sheet. Once the sheet and the auxiliary form are place, the process is the same as in Figure4, i .e. the auxiliary form is pressed in step 603, according to apressing direction, towardstheform, step 603 corresponding to step 405 in Figure 4.

Referring to Figure 7, once the auxiliary form is pressed into its intended position, the concrete is let to cure (step 701 : no). Depending on the designed appearance of thesurface, theconcrete may be let to curetotally or partially before the form arrangement is touched. When the concrete is cured enough (step 701 : yes), the auxiliary form is removed in step 702. It should be appreciated that any removal method may beused. For example, the auxiliary form may be removed by lifting it up, or removing piece by piece. For example, using the structure illustrated in Figure 3B, each protrusion may be removed separately from each other. That facilitates creation of so called undercut shapes. The removal may also be per - formed in a step-like manner. Depending on the curing stage, the removal of the auxiliary form may or may not affect to the pressure with which the concrete is forced against the sheet.

In the example illustrated in Figure 7, the sheet is not in a rack moving in one go with the auxiliary form. Therefore, when the auxiliary form is removed, it is checked in step 703, whether the sheet is to be removed when the auxiliary form is removed. If yes (step 703: yes) , the sheet is removed i n step 704 at the same ti meastheauxiliary form. If not (step 703: no), it iswaited until it isti meto remove thesheet (step 703: yes), and the sheet is removed. For example, thesheet may act as a transport cover sheet that is to be removed only after the concrete structure has been erected. Another example include that the auxiliary form is removed when the concrete is partially cured, and the sheet when the concrete is cured, or at least more cured than when the auxiliary form is removed.

Naturally the concrete surface, after the sheet has been removed, may undergo afurther finishing, like polishing, sandblasting, painting, etc. to further af- feet the appearance. Although in the above examples it is assumed that the auxiliary form is pressed downwards, it should be appreciated that the auxiliary form may be pressed with the sheet into the concrete by moving the form, for example by lifting the form towards a stationary auxiliary form.

Although in the above examples it is assumed that one auxiliary form is used for one concrete structure/ one concrete upper surface, it should be appreciated that two or more separate auxiliary forms may be used and pressed, in the same manner or by different manners, to one concrete upper surface that is not covered by theform.

As is evident from the above, the auxiliary form, its sheet facing surface design, pressing angleand pressing depth, measured from the plane defined by the sheet towards the bottom surface of the fresh concrete, the pressing method, the selected sheet materials, or more precisely, selected sheet material characteristics, the removal ti me and removal method of the auxiliary form, the removal ti me of the sheet, possible sheet treatments, and characteristics of the fresh concrete, as well as materials used for the concrete mix, each affect to the appearance of the concrete surface, and hence provide in praxis li mitless possibilities to design and manufacture 3-di mensional structures. Thereby it is possible to design concrete structures with versatile haptic and/ or acoustic and/ or visual characteristics.

It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be i mplemented in various ways. The invention and its embodi ments are not li mited to theexamplesdescribed abovebut may vary within the scope of the clai ms.

Claims

CLAI MS

1 . A method comprising:

pouring (401 , 601 ) concrete to a form comprising at least aclosed rigid frame;

ch ar act er ! zed by

placing (402, 404, 602) a non-rigid sheet and an auxiliary form above the upper surface of the concrete that is not covered by the form, the non-rigid sheet being between the upper surface of the concrete and the auxiliary form, the non-rigid sheet covering the upper surface of the concrete that is not covered by the form;

fastening (403) the sheet to theform;

pressing (405, 603) the auxiliary form to the form to a predetermined depth, the pressing causing at least part of a sheet facing surface of the auxiliary form with corresponding one or more sheet portions, which the at least part of the sheet faci ng surface of the auxi I i ary form contacts duri ng pressi ng, to enter i nto the concrete by displacing some of the concrete, the displacing causing the upper surface of the concrete move upwards and pressing against the sheet in areas that are not i n contact wit h the at I east part of the sheet faci ng surface of the auxi I i ary for m ; and

curing (701 ) at least partly the concrete before removing (702) theaux- i Nary form.

2. A method as clai med in clai m 1 , wherein the pressing causes reshaping of the sheet.

3. A method as clai med in clai m 1 , further comprising at least one of the following:

pressing the auxiliary form to theform in astep-wiseway; and removing the auxiliary form in astep-wiseway.

4. A method as clai med in any preceding clai m, further comprising: removing (704) thesheet at the same ti me as the auxiliary form, or later than the auxiliary form.

5. A method as clai med in any preceding clai m, further comprising at least one of thefollowing:

treating the surface of the sheet that faces the concrete before placing the sheet on at least part of the upper surface of the concrete; and adding a surface finishing fluid on oneor morespotson thesheet on the side facing the auxiliary mold to let the surface finishing fluid to seep through the sheet onto the concrete surface.

6. A method as claimed in any preceding claim, further comprising at least one of thefollowing:

treating oneor moreinner surfaces of theform before pouring the con- creteto the form.

7. A form arrangement (100) for implementing a method according to any of the preceding claims, the form arrangement (100) comprising at least

aform (110) comprising at least aclosed rigid frame (111a) defining a first area;

anon-rigid sheet (120), layable on the top of theform (110) and dimensioned to cover at least thefirst area; and

an auxiliary form (130), placeableon thesheet (120) and at least partly pressabletotheform (110) with thesheet (120), a cross sectional area of the part of the auxiliary form (130) that is pressableto theform (110) being smaller than thefirst areathat iscovered by the non-rigid sheet (120).

8. Aform arrangement (100) as claimed in claim 7, wherein the part of the auxiliary form (130) that ispressableto theform comprises one or morepro- trusions(131a, 131b, 131c) extending from the surface facing the sheet.