Field of invention

The present invention relates generally to an apparatus and method for producing concrete products and more precisely on an apparatus and method for producing concrete products using a mould comprising a non-rigid sheet for forming the surface of the concrete product according to the preambles of the independent claims 1, 2, 11 and 12 and according to the preambles of the dependent claims. Still more precisely the invention is related to the production of surface-patterned concrete elements where the patterns seem to continue from one element to another without noticeable discontinuity.

Background of the invention

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 being defined by cast surfaces inside a mould whereto the concrete is poured to mould 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 admixtures, additives, colour pigments, etc., added during a concrete mix preparation, each have their impact to the appearance, such as colour, of the surface. Further, different surface treatment methods, applied either to a cured concrete structure or while the concrete is curing, create different surface textures. Also surfaces, against which the concrete is poured in the mould may be provided with different 3-dimensional shapes, or a structured material, like a pattern transfer mat disclosed in US 5330694 Tokai Rubber Industries, Ltd., Jul.19, 1994, to create a 3-dimensional surface for a concrete structure. The pattern transfer mat has a transfer surface having three-dimensional irregularities and carrying a multiplicity of grains to be transferred to the substrate concrete. Concrete is cast against the transfer surface of the mat and cured in situ and the mat is then detached.

Finnish patent Fl 127621 B, Jakowleff, Renata Noemi, describes a method for creating a 3-dimensional concrete surface to a concrete structure includes using a rigid mould, an auxiliary mould and a non-rigid sheet. The non-rigid sheet is to be placed between an upper surface of concrete poured to the rigid mould and the auxiliary mould that is at least partly to be pressed into the concrete, the non-rigid sheet being placed before pressing the auxiliary mould.

Fl 127621 B comprises examples on manufacturing 3-dimensional concrete surface and examples of the methods described in Fl 127621 B can be applied in the present invention too. However, Fl 127621 B, leads to a method which may generate visually independent non-continuous surface pattern thus 3D- pattern structure not reaching close to the edges of rigid mould and is thus less useful in producing continuous structures, like walls, facades etc. In other words, mould and method described in Fl 127621 B is more useful in producing individual elements that producing elements for continuing structures.

Brief description of the invention

The aim of the present invention is to remove or at least remarkably reduce problems found in the prior art by an apparatus and method which provides concrete elements without essentially noticeable discontinuity from one casted concrete element to another. The invention is related to the production of 3D- surface-patterned concrete elements where the patterns seem to continue from one element to another without noticeable discontinuity. This requires optimal treatment of the auxiliary mould to mould a uniform visual outline for the motif regardless of the distance of the pattern details to the edge of the rigid mould. The depression of the tool shaping the upper surface of the concrete element, is different when the pattern approaches the edge area of the rigid mould in comparison to the middle part of the element, where the pattern depression can occur without the limitation of the edges of the rigid mould.

The parts of the auxiliary mould shape the depression of the pattern and, when pressing, shape the form of the displaced concrete.

The invented method comprises pouring concrete to a mould comprising at least a closed rigid frame, placing a non-rigid sheet and an auxiliary mould above the upper surface of the concrete that is not covered by the mould, the non-rigid sheet being between the upper surface of concrete and the auxiliary mould, the non-rigid sheet covering at least partly the upper surface of concrete that is not covered by the mould. To be able to press the auxiliary for into the concrete, the cross-sectional area of the auxiliary mould that faces the sheet is smaller than the upper surface area of concrete covered by the sheet.

The auxiliary mould is pressed into concrete, i.e., into the mould to a predetermined depth. Pressing causes at least part of a sheet facing surface of the auxiliary mould with corresponding one or more sheet fins, which the at least part of the sheet facing surface of the auxiliary mould contacts during pressing, to enter into concrete by displacing some of concrete, the displacing causing the upper surface of concrete to move upwards and press against the sheet in areas that are not in contact with the at least part of the sheet facing surface of the auxiliary mould.

Concrete is at least partly cured before removing the auxiliary mould.

Text above is valid also for Fl 127621 B. What is characteristic for the present invention is to place a rigid edge band with open area B similar, within manufacturing tolerances, to the open area A restricted by the rigid mould, between the upper surface of concrete and the non-rigid sheet before pressing the auxiliary mould to the rigid mould.

Another characteristic feature of the present invention is that the bottom face of the auxiliary mould which is facing the concrete and the bottom face of the fins which are necessary for producing a three-dimensional structure on the surface of the concrete element, deviates at least at some parts from a straightangled edge. The bottom face may be rounded with a radius larger than typical manufacturing rounding (typically up to 2 mm radius) or it can be a bevel (which is rounding with infinite radius). The actual dimension of rounding or bevel dimensions depends on the construction of the mould, depth of concrete, concrete composition, etc. Essential in the present invention is that rounding, or bevel is such that it allows the surface structure to propagate to the edge of concrete due to optimal concrete flow in pressing due to rounding or bevel. Such manufacturing produces 3-d surface structures with essentially continuous surface patterns from one element to another.

In one embodiment of the present invention an auxiliary mould 130 comprising fins 131 is pressed into concrete 140. The edge 133 of the bottom face of the auxiliary mould 130 as well as the edge 133 of the fins 131, which are facing concrete 140 and which are pressed into concrete 140, deviate from the part which is next to the inner surface of mould 100 in the direction of fin 131 from a straight-angled edge (see Figure 1).

In one embodiment of the method of the present invention the auxiliary mould is pressed into the mould and concrete in a stepwise way. The auxiliary mould is also removed from the mould in a stepwise way. Inserting or removing the auxiliary mould in a stepwise way improves concrete flow and makes the surface more uniform especially with some concrete mixes.

The non-rigid sheet used in the invented method may be removed at the same time as the auxiliary mould, or later than the auxiliary mould.

To form the required pattern and be able to press the auxiliary for into the concrete, the cross-sectional area of the auxiliary mould that faces the sheet needs to be smaller than the upper surface area of concrete covered by the non-rigid sheet. However, the continuing visuality of the pattern requires the inner size of the rigid mould and outer edge of the auxiliary mould to become close to other's taking into consideration the qualities and strength of the non- rigid sheet. To the pattern to create a continuously advancing visuality, the outer edge of auxiliary mould and its bevel must be formed according to the visual requirements of the motif to be shaped. As well the distances of the details of the pattern in relation to each other needs to be considered in designing the shape of the bevel. The close one pattern details also require consideration of the bevel versus the qualities of non-rigid sheet, such as maximum elasticity, to be considered precisely to create required visually continuous pattern for the precast elements.

When the auxiliary mould making outlines of the pattern is pressed into concrete i.e., into the mould to a predetermined depth of the pattern, the bevel needs to be able to be pressed close to the edge of rigid mould so that the optimal amount of concrete will be displaced to the sides of the auxiliary mould parts. The displacing of the concrete need to cause the upper surface of concrete to move upwards in a manner that supports the correct forming the pattern. The form of bevel and it's distances of the form to the edge of the rigid mould, define the shape that the displaced concrete will take. In addition, the forming of bevel requires consideration of the concrete material qualities, such as material particle sizes, particle size distribution and viscosity of the concrete.

Brief description of the figures

In the following the invention will be described in greater detail, in connection with preferred embodiments, with reference to the attached drawing, in which:

Figure 1 shows a schematic drawing of the mould arrangement 100 (A) from the side and (B) from the front (direction S). From direction S one can see the shaped edges of the fins 131;

Figure 2 shows a schematic drawing of the mould arrangement 100 situation where the auxiliary form 130 has entered mould 110 and the concrete 140;

Figure 3 shows a schematic drawing of the shape of the edge 133 of a fin in embodiments where the edge 133 forms a bevel;

Figure 4 shows a schematic drawing of the shape of the edge 133 of a fin in embodiments where the edge 133 forms a rounding. Figure 5 and 6 show an embodiment for a method for forming a concrete product 501 with pattern 503; and

Figure 7 shows an embodiment where fin 131 is rounded with several different rounding.

For the avoidance of doubt, it is noted that the shown embodiments are only shown as examples, and they may be combined to the same apparatus of the present invention.

Detailed description of the invention

The invention is next described in detail referring to the figures listed above.

Figure 1 shows the schematic drawing of the invented mould arrangement 100 with Figure 1A showing the side view which reveals the structure of the auxiliary mould 130 which shows fins 131a, 131b and 131c which give the characteristic structure when they are at least partly pressed to concrete 140 in the mould 110 defined by a rigid frame 111 and bottom 112 which bottom 112 may also be e.g. top of the casting table on which the rigid frame 111 is placed.

The mould arrangement 100 comprises the mould 110 which further comprises a closed rigid frame 111 which defines first area A (the symbol is not shown in the figures). The mould arrangement 100 further comprises a non-rigid sheet 120, which is placeable on the top of the mould 110 and dimensioned to cover at least part of the first area A. The auxiliary mould 130 is placeable on the sheet 120 and at least partly pressable to the mould 110 with the sheet 120. The cross-sectional area of the part of the auxiliary mould 130 that is pressable to the mould 110 is smaller than the first area A that is covered by the non-rigid sheet 120. The non-rigid sheet 120 is in one embodiment of the present invention pressed between a rigid edge 550 and the mould 110 and the structure edge-sheet-form, 550-120-110 is locked together with means 551 which may e.g., be suitable bolts. The rigid edge band 550 may be manufactured from suitable, essentially rigid material.

In one embodiment of the present invention, edge 133 of the bottom face of at least one fin 131, which are facing concrete 140, deviates from a straightangled edge from the part which is next to the inner surface of mould 110 in the direction of the fin 131. In other words, at least the fin 131 which is pressable into concrete 140 is either rounded or comprises a bevel at edge 133 in the long direction of the fin 131, i.e. parallel to a fin 131. Edge 133 is situated next to the inner surface of the mould 110. Such arrangement ensures smooth flow of concrete 140 ending up with continuous surface structure of adjacent, cured concrete elements.

The open area of the mould 110 is within manufacturing tolerances same as the open area determined by the rigid edge band 550.

Essential to the present invention is that an edge 133 of the bottom face at least one fin 131, which is facing concrete 140, deviates at least at some parts from a straight-angled edge. This is shown schematically in Figure IB which shows the mould arrangement 100 in the direction S marked in Figures 1A and IB.

Figure 2 shows the mould arrangement 100 in a situation where auxiliary mould 130 is pressed inside mould 110 and concrete 140. Fins 131a, 131b and 131c enter concrete 140 and stretch the non-rigid sheet 120 which essentially follows the forms of fins 131a, 131b and 131c. The fins entering concrete 140 lift the upper surface of concrete 140 so that the shape of the concrete 140 volume changes although the volume is essentially unchanged.

Shape of the edge 133 of the at least one fin 131 ensures that concrete in mould arrangement 100 flows in such a way that the surface structure of different casted concrete elements form a continuous structure when the elements are joined together. Joining may be done with or without fixtures as long as the elements are placed close together so that the continuous surface structure can be noted.

Figure 3 shows some embodiments of the at least one fin 131. These embodiments show a bevel in edge 133 and are meant for examples only and any edge form deviating from a straight angle may work.

Figure 3A shows a bevel of a mould arrangement 100. The edge of the bottom face of the fin 131 which is facing concrete 140, comprises a bevel between the essentially horizontal bottom border X and essentially the top corner 553 of the auxiliary mould 130 which is next to the mould's 110 inner surface when auxiliary mould 130 is pressed to the maximum depth inside mould 110. The upper point 553 of the bevel may also situate in another point in the Y- direction.

Figure 3B shows a bevel of a mould arrangement 100. The edge of the bottom face of the fin 131 which is facing concrete 140, comprises a bevel in an angle a.

Figure 4 shows an embodiment of the mould arrangement 100 where the edge 133 of the bottom face of the fins 131 which is facing concrete 140 is rounded with radius larger than conventional edge rounding radius, typically corner is rounded with higher than 2 mm radius.

Radius of rounding the edge 133 depends on the mould dimensions, concrete layer depth, properties of the concrete mixture, etc. In some embodiments of the present invention the mould parameters are shown in Table I.

Table I parameters of the mould arrangement 100 in some embodiments with edge 133 radius

Figure 3B shows another embodiment of the mould arrangement where the edge 133 of the bottom face of the auxiliary mould 130 which is facing concrete 140 forms a bevel which shows an angle a between the horizontal line X and vertical line Y of the auxiliary mould 130. The bevel deviates from normal bevel used in manufacturing and distance d between the essentially vertical border Y and the point where the bevel starts in the essentially horizontal bottom border X is at least five (5) millimetres. Angle a, which is the angle between the essentially horizontal bottom border X of the auxiliary mould 130 and the bevel line 135 is preferably 10-70 degrees, more preferably 15-65 degrees and most preferably 20-60 degrees which has been examined to ensure good flow of the concrete mix 140. The same as described for the auxiliary mould 130 in the chapter above, is also valid for fins 131 although for simplicity only the auxiliary mould 130 is discussed.

The auxiliary mould is pressed to the concrete and the straight bottom face of the auxiliary mould reaches concrete material. The depression of the auxiliary mould displaces concrete material evenly to the sides of the auxiliary mould.

The auxiliary mould is pressed deeper into the material and the bevel part reaches concrete surface. Displacing of concrete continuous to be even on the area of straight bottom area of the auxiliary mould. In the material in the area where the bevel sinks into the concrete, the direction of the concrete displacement starts to be affected by the proximity of the edges of the rigid mould. The concrete displacement is limited by at the wall of the rigid mould and partly the material displacement occurs away from the edges of the rigid mould.

The auxiliary mould is pressed towards the desired depth point and the edge of the auxiliary mould reaches the upper part of the rigid mould. The encounter of the mould shapes the outline shape of the patten entering to the edge of element.

The final displacement of the concrete takes the shape accordingly the shape of the bevel, the proximity of the edge of the rigid mould in each point of the dept vs. the distance to the edge of the rigid mould, the mutual distances between the mould parts of the auxiliary mould and the elongation of the non-rigid sheet to length- and width wise. In one embodiment of the present invention shown in Figures 5 and 6, the method for producing patterned concrete elements 501 with at least one visually continuous pattern 503 from one element 501 to another comprises: a. pouring concrete mixture to a mould 110 comprising a closed rigid frame; b. placing a non-rigid sheet 120 on the top of the mould 110; c. pressing an auxiliary mould 130 with at least one fin 131 to the mould 110; d. lifting the auxiliary mould 130 from the mould 110; and e. curing the produced concrete element 501.

Essential to the present invented method is that it is characterized by pressing auxiliary mould 130 to the mould 110 with at least one fin 131 pointing out from auxiliary mould 131. The edge of the bottom face of the fin 131, which is facing concrete 140, is deviating from a straight-angled edge from the part which is next to the inner surface of mould 100 in the direction of fin 131. Essentially the edge of the fin 131 which is facing concrete 140 is rounded with radius larger than conventional edge rounding radius which makes concrete 140 to flow evenly to the sides of the fin 131 creating at least one pattern 503 which continues evenly to the edge of the concrete element 501 and produces concrete elements 501 with at least one visually continuous pattern 503 from one element 501 to another.

In another embodiment of the present invention, the method for producing patterned concrete elements 501 with at least one visually continuous pattern 503 from one element 501 to another comprises: f. pouring concrete mixture to a mould 110 comprising a closed rigid frame; g. placing a non-rigid sheet 120 on the top of the mould 110; h. pressing an auxiliary mould 130 with at least one fin 131 to the mould 110; i. lifting the auxiliary mould 130 from the mould 110; and j. curing the produced concrete element 501.

Essential to the embodiment is that it is characterized by pressing auxiliary mould 130 to the mould 110, with at least one fin 131 facing concrete 140. The edge of the fin 131 which is facing concrete 140, is deviating from a straight-angled edge from the part which is next to the inner surface of mould 100 in the direction of fin 131 in a way that the edge of the fin 131 which is facing concrete 140 comprises a bevel between the x- and y-directions of the auxiliary mould 130, which makes concrete 140 to flow evenly to the sides of the fin 131, creating a pattern 503 which continues evenly to the edge of the concrete element 501 and produces concrete elements 501 with at least one visually continuous pattern 503 from one element 501 to another.

When the method used rounded edges rather than a bevel, the radius of rounding of the bottom face of the fin 131 is preferably larger than 2 millimetres, more preferably larger than 5 millimetres and most preferably larger than 10 millimetres. The edge of the fin 131 may also be shaped so that is comprises more than one radius of rounding. Such multi-rounding arrangement of fin 131 improves creating a visually continuous pattern 503 with some mixtures of concrete 140. Example of such fin is shown in Figure 7.

In another embodiment of the present invented method, a bevel rather than rounding of the edge of fin 131 is used. The embodiment is characterized in that distance (d) between the essentially vertical border (y) and the point where the bevel starts in the essentially horizontal bottom border (x) is at least five (5) millimetres. In yet another embodiment of the present invention, the fin 131 used for in the method is characterized in that angle a, which is the angle between the essentially horizontal bottom border (x) of the auxiliary mould 130 and the bevel line 135, is 10-70 degrees

It is also possible to use an embodiment where at least one fin 131 has bevel shape and rounding combined.

Specifications for concrete to be used in manufacture of concrete element 501 are examples the following: strength class according to the European Concrete Standard EN-206 should be C30/37 or C35/45, fresh concrete class according to the European Concrete Standard EN-206 should be S3 or S4 and maximum grain size of aggregate is 12 mm. Typical other specifications for the concrete structure are: exposure class according to the European Concrete Standard EN-206 XC3 or XC4 and additionally if freeze-thaw stress is anticipated, such as in Nordic Counties, also classes XF1 or XF3. Realizing that there are various concrete mixtures which can be used to produce element 501 makes the requirement of different shapes of fin 131 obvious.

It is apparent to a person skilled in the art that as technology advanced, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.