The present invention relates to the component system de¬ fined in the preamble of Claim 1 and to the components defined in the preambles of Claims 17-21. The system is made up of prefabricated concrete parts which are assembled and fastened to each other in a suitable manner to form ground-bearing stairways, platforms, terraces, and similar structures in pedestrian areas and in the surroundings of buildings, for example in connection with entrances.

The use of various so-called landscape concrete products is rapidly increasing in Europe and also in Finland. This in¬ crease is due to the general trend in the building industry to shift to the factory as large a proportion as possible of the work done, to the diversification of the range of concrete products, and to the reusability of the concrete products as compared with in situ building.

Nowadays, short flights of stairs or a few ground-bearing steps are most commonly assembled from concrete products manufactured for other purposes, such as rectangular slab and block pavings and curbstones. There is often the dis¬ advantage of unsuitable dimensioning, inferior appearance, and, as a factor detracting from safety, the fact that the parts cannot be fastened to each other in a durable manner. This has inhibited the construction of long, steep but safe heavy-use flights of stairs from separate parts.

For this reason, ground-bearing stairways are today mostly cast in situ as a continuous structure. The disadvantages of in-situ casting include high cost, especially in winter conditions, a low quality of the visible surfaces, and the difficulty of achieving sufficient resistance to freezing

temperatures as regards the concrete. In factory condi¬ tions, control is more thorough, ensuring higher quality. Attempts are often made to improve the outer appearance by cementing concrete slabs to the steps, which for its part complicates the work.

Simple separate step components and retaining-wall compo¬ nents, as well as curbstones, have been available on the market. However, owing to dimensional and shape incompati¬ bility and to differences in color, it is impossible to assemble these separate parts into a neat structure.

The accompanying figures I-V depict the ground-bearing stairway components currently used. They have a great dis¬ advantage in that they cannot be fastened to each other to form framework structures. The ground underneath will serve as the loadbearing structure. Their installation is diffi¬ cult and slow. In addition, the structure is subject to ground shifts, for example to frost heave.

It is. the object of the present invention to overcome the disadvantages mentioned above and to provide a component system which fulfills the functional and production- technique requirements listed below:

Because of the risk of shifts in the sub-base it must be possible to fasten the parts to each other and to overlap them. This is both a structural durability requirement and the user's safety requirement. The fastening points must remain hidden in the completed structure; the visible surfaces must be acceptable in terms of quali¬ ty, and, in particular, the surfaces to be walked on must not be slippery; the concrete must be resistant to freezing temperatures and to road salt; it must be possible to construct ground-bearing stairways,

platforms, intermediate landings, ramps, and inner and outer corners from only a few basic parts of different shapes; in terms of production technology, the design of the prod¬ ucts must be such that the molds required are single-part molds in order that the products can be cast like "sand cakes" from zero-slump concrete. In addition, the visible surfaces must be cast against the mold in order to achieve a high-standard outer appearance.

All these objectives are achieved using the component sys¬ tem according to the invention, the main characteristics of which are given in the characterizing clause of Claim 1, and using the components belonging to it, the main charac¬ teristics of which are given in the characterizing clauses of Claims 17-21.

The idea of the component system according to the invention is thus that, in one and the same layer of the component structure, either the upright supports of a single slab component, possibly the only upright support of the slab component together with the surrounding ground, or the up¬ right supports of two adjacent slab components constitute at least two support and fastening surfaces for a slab component in the next higher layer. Exceptionally, two adjacent slab components form three support and fastening surfaces for a slab component in the next higher layer. The component which is disposed on top is fastened to these support and fastening surfaces by nailing, for example shooting, by means of a wedge bolt, or by a corresponding method based on drilling a hole, or by cementing. The fas¬ tening point will be concealed by the slab component to be placed on top. Cementing is possible especially in the edge slabs of the top landing and in intermediate landings, where the fastening must not be visible.

The upright support of a slab component preferably consists of a ridge parallel to its front and rear edges. The ridge preferably extends across the entire slab component.

According to a preferred embodiment of the component sys¬ tem, all of the components have the same width.

According to a preferred embodiment of the slab component, its dimensioning is such that the width of the slab com¬ ponent, i.e. its dimension in the direction of, for exam¬ ple, the width of the stairs, is twice the tread of the structure, i.e. the overlap of the structure in the direc¬ tion of depth. This is necessary in order to achieve the structure of the outer and inner corners of stairways and platforms in such a way that the same pitch and overlap continue at an angle of 90° in relation to the original direction of the tread.

Instead of an upright support in the form of a straight ridge, the corner components have an upright support which forms a corner.

The width of the slab components which are to be placed at the edges of the structure is the same as the width of the αther slab components, or half of it. The edge components have edges having the height of the upright support in order to produce a closed wall structure.

All of the mutually opposite upright surfaces of a slab component, i.e. all the side walls of the upright supports and of the slab component itself, are preferably beveled upwards and inwards. Thus such cants are obtained in the upright surfaces that it is possible to use single-part casting molds. This means that the mold need not be opened in connection with demolding; inverting the mold or pushing the casting through the mold will suffice.

In connection with the casting it is possible to produce an anti-slip roughening, either in the mold itself or by using negative surface retarders, i.e. so-called "exposed-aggre¬ gate finish". When exposed-aggregate finish is used, the products must be allowed to harden in the mold.

The component system according to the invention preferably comprises basic components of two different types, i.e. step components and inner components. At one end of the step component there is an upright support at the end of the step distance, i.e. the tread, and the step component to be placed on top of this component will end at it. Ver¬ tically successive step components will form the steps in the structure and will be located at the front of the structure. The inner component has two upright supports fitted symmetrically in relation to the center line of the inner component, and the length of the inner component is twice the tread, i.e. the step length. Since the width of the components is preferably twice the tread of the struc¬ ture, the inner component is thus preferably square. The inner part of the structure is built using inner compo¬ nents, and they are thus disposed next to the components closest to the edge, which are either step components or other edge components. Inner components are preferably used turned 90° about their vertical axis in vertically succes¬ sive layers, whereby a considerably more advantageous dis¬ tribution of loads will be obtained.

There are preferably two different types of step compo¬ nents. One has the same length as has the inner component, i.e. twice the tread, and the other has 1.5 times the length of the inner component, i.e. three times the tread. The former has only one upright support and the other one has two, one of the upright supports being located at or close to the rear end of the component. By selecting the depths of the step components so as to correspond to 2 or 3

times the tread, various adjusting pieces in the edges of the structure, in the intermediate landings and in the ramps are avoided. Even shorter step components can be used.

In addition, the component system according to the inven¬ tion includes ramp components for forming ramps between the various height levels. There are preferably two types of ramp components. One is a single-part component and has the same length as the inner component and forms a steep ramp. The other has two or more parts and has a total length which is a multiple of that of the inner component, and it forms a gently sloping ramp. The steep ramp ^' component has a shoulder serving as an upright support at the tread dis¬ tance from the front edge. The part between the shoulder and the front edge forms a sloped surface which runs from the bottom level of the slab to the shoulder, to a level slightly higher than the shoulder, corresponding to the step level of the component to be placed on top. The parts of the gently sloping ramp component have the length of the inner component, and the highest part has a shoulder serv¬ ing as an upright support at the tread distance from its front edge. The ramp parts together form a continuous sloped surface which runs from the front edge at the bottom level of the slab, to the shoulder, to a level somewhat higher than the shoulder, corresponding to the step level σf the component to be placed on top. The upright walls of the ramp components are beveled upwards and inwards, as are the other components, and they are cast in the same manner in single-part casting molds. The visible sloped surface is formed against the wall of the casting mold and is thus in accordance with the mold, and neat.

The components may be made heatable so that it will be pos¬ sible in the winter to melt ice from their surface. The heating may be carried out, for example, by using electric

resistors placed between those upright supports of the step components which are closest to the edge. In the case of a flat structure made from the components, all of the compo¬ nents may be heatable by electric resistors placed under them.

To supplement the components mentioned above there are needed flat surface slabs the width and length of which correspond to the dimensioning of the inner components and the edge components.

Prior-art concrete ground-bearing stairway components, as well as preferred embodiments according to the present invention, are described below with reference to the accom¬ panying figures, in which

Figures I-V depict the prior-art concrete ground-bearing stairway components which were already described above, Figure la depicts a step component provided with two up¬ right supports,

Figure lb depicts a step component provided with one up¬ right support,

Figure lc depicts an inner component,

Figure 2a depicts an edge component corresponding to the inner component,

Figure 2b depicts a half of an edge component, Figure 3a depicts a steep ramp component,

Figure 3b depicts ^' a gently sloping two-part ramp component, Figure 4a depicts a vertical section of an inner corner component,

Figure 4b depicts a plan view of an inner corner component, Figure 4c depicts an inner corner component in a stairway corner structure,

Figure 5a depicts a vertical section of an outer corner component, Figure 5b depicts a plan view an outer corner component,

Figure 5c depicts an outer corner component in a stairway corner structure,

Figures 6-8 depict ground-bearing stairways constructed by using the various components,

Figure 9 depicts a ground-bearing intermediate landing, Figure 10 depicts a ground-bearing ramp structure, Figure 11 depicts a platform,

Figure 12 depicts another embodiment of the platform according to Figure 11,

Figure 13 depicts a section, through A-A, of the platform according to Figure 12,

Figure 14 is a perspective representation of a flight of stairs embedded in the ground and trimmed using edge compo¬ nents _r

Figure 15 is a perspective representation of a planting platform and platform stairs constructed in connection with it.

In the figures, the same parts are indicated with the same reference numerals. A step component provided with two up¬ right supports is indicated by reference numeral 1, a step component provided with one upright support with numeral 2, an inner component with numeral 3, an inner component hav¬ ing an edge with numeral 4, an inner-component half with an edge with numeral 5, a steep ramp component with numeral 6, the support part of a gently sloping two-part ramp compo¬ nent with numeral 7, and its extension part with numeral 8, an inner corner component with numeral 9, and an outer corner component with numeral 10.

Figures 1-3 show clearly the shapes of the individual basic components and their mutual dimensional proportions. All * of the upright surfaces are beveled upwards and inwards, which enables the components to be cast in single-part molds, inverted with respect to the figures. The cast prod-

ucts will detach from the molds owing to their cants when the molds are inverted. This considerably simplifies the manufacture of the components.

Owing to this manufacturing method, all the visible sur¬ f ces, such as the step surfaces and the ramp surfaces, are smooth and provided with the desired roughening pattern, since they are formed against the walls of the casting molds. In connection with the casting there is obtained, in addition to the roughening, also any desired rounding of the noses of the step surfaces and possibly other edges. The rounding of the nose is the most visible of them. The rounding of the lower edges can, when so desired, be done in connection with the casting. If the anti-slip roughening is produced by using surface retarders, i.e. by using ex¬ posed-aggregate finish, as mentioned above, the components must be allowed to harden in the molds. Since the casting of the components takes place indoors under controlled conditions, their quality will be maximally high.

When stairways are built, the rise and the tread of a step depend from each other and they have clear practical limit values. The higher the rise, the shorter can the tread be. Each selected rise-tread combination thus has its own di¬ mensional series of all components.

The dimension series depicted in the figures illustrates a preferred rise to ^' tread ratio, in which the tread is 400 mm and the rise 150 mm. The depth of the step, which is the same as the tread, is thus 400 mm, and the width of the components is a multiple of the tread, preferably twice the tread, i.e. 800 mm. To produce corner structures, the width must be twice the tread in order that the same pitch and overlap can continue at an angle of 90° to the original direction of the tread. The depth of the inner component is twice the tread, i.e. 800 mm, and the same as the depth of

the step component provided with one upright support. The depth of the step component provided with two upright sup¬ ports is 1200 mm. The thickness of the upright supports in the depth direction of the component is approximately 70 mm, and their mutual distance in the inner component is 170 mm and distance from the edges 245 mm. The thickness of the slab is approximately 50 mm. With this dimensioning, the weight of each component is less than 150 kg, and they are thus capable of being handled manually by using suitable auxiliary tools.

Figures 4 and 5 show the structure of stairway corners. Figure 4c depicts an inner stairway corner and Figure 5c and outer stairway corner.

The width of the step components is the same as twice the tread, i.e. the same as their depth. To form straight stairway edges there are additionally needed halves of step components, i.e. components of half the width dimension.

Figures 6-8 depict different solutions for ground-bearing stairways. Figure 6 depicts a structure on a gently sloping terrain. Figure 7 on a slightly steeper terrain, and Figure 8 on a steep terrain. All the stairways have been con¬ structed using the same basic components, i.e. with the same rise to tread ratio.

In the gently sloping structure, nothing other than step components 1 with two upright supports have been used. The sub-base used for the components is gravel, which is com¬ pacted under the components. The figure shows that each component is supported at two points, i.e. at the upright" supports of the component underneath. The lowest component is ground-bearing. Vertically successive components are fastened to each other at the upright supports (a black triangle indicates a fastening point) . The top landing as

well as the paving in front of the stairs are made from ordinary concrete slabs. The slab fitted on top of the step component is fastened by cementing to the upper surface of the upright supports. Thus also the fastening of the top slab will be invisible. The adhesive used may be conven¬ tional concrete adhesive such as cement, bitumen cement or epoxy cement.

The stairway constructed on a terrain steeper than the above has been made from step components 2 provided with one upright support and from inner components 3. Located symmetrically in relation to the center line of the compo¬ nent, the upright supports of the inner component 3 each support a separate upper component, i.e. in the case shown in the figure the step component 2 and the inner component 3. In the lowest layer of components and in the middle layer there are two components adjacently, whereas the top layer has only one step component. The top layer does not require two adjacent components, since the load in it is small. Since the question is of a stairway structure, the leading component is always a step component. Each compo¬ nent is again supported at two upright supports underneath and is thus firmly in place. The fastening is done, for example, by nailing at concealed points or by cementing at visible points. At the foot of the stairway and at its upper end there are conventional slabs.

According to Figure 8, the stairway constructed on a steep terrain has been formed from three different basic compo¬ nents 1, 2 and 3. The only component 1 of the middle step is exceptionally supported at three points. The top step layer again has, because of the small load, only one step component 2, provided with one upright support. If more steps were needed, the construction could be continued inwards in order to provide sufficient support for the structure. An inner component 3 would be suitable as a

continuation of the component 3 in the lowest layer and as the continuation of the component 1 in the middle layer. In this case the step component 2 of the topmost layer should be replaced by a step component 1. A step component 2 would again be suitable as the topmost additional step.

The three basic components described thus suffice for the construction of ground-bearing stairways of any shape.

Figure 9 depicts a simple intermediate-landing structure and Figure 10 a ramp structure applied to a slight rise of terrain,. Since the ramp components 6, 7 and 8 have the same basic dimensioning as do the step component having one upright support and the inner component, they can be used in any top layer of the structure, side by side with step components and flat slabs. The ramp components differ from the other basic components in that they have an even, sloped surface. In the parts 6 and 7 this surface extends sufficiently higher than the upright support so that the top surface is at the same level as the step level of the next component layer. Thus the ramp surface forms a smooth cross-over bridge between two components at different levels. The sloped upper surface ends at the front edge of the upright support and thus forms a shoulder on which the component of the next. layer will bear. The continuation part 8 of the two-part ramp component does not have the said shoulder; the continuation part joins its front part 7 so that the sloped surfaces of both form a continuous smooth sloped surface.

Figure 11 depicts the structure of a platform. The only building components used are inner components 3 and edge components 4 and 5, of two lengths.

Figure 12 depicts a platform according to another embodi¬ ment, which is built from inner components 3 and edge com-

ponents 4 and 5, and in which the components of the middle inner component layer are turned 90° horizontally. This provides for a substantially more advantageous distribution of loads and, furthermore, reduces the need for different edge parts.

Figure 13 depicts the platform according to Figure 12 in a section through A-A. It illustrates the more advantageous distribution of loads by means of upright supports serving as beams.

Figure 14 depicts a stairway embedded in the ground; its edge components are provided with upright edges which form a retainer for a lawn, for example.

Figure 15 is a perspective representation of a planting platform and platform steps. All of the edge components have been provided with upright edges to form a closed wall.

The embodiments described and depicted above are only exam¬ ples of how the component system according to the invention can be applied. It is possible to design and produce in a simple manner strong, safe and neat ground-bearing struc¬ tures of the desired shape by using the basic components described, together with additional components complying with the same dimensioning, such as slabs, edge components, rounded components, etc.