CA1264590A - Groundcovering element, especially (concrete) slab - Google Patents

Abstract

Groundcovering element, especially (concrete) slab Abstract.
(in conjunction with Figure 4) Known groundcovering elements (44) consist of three basic shaped slabs which are connected to form a unit and which are delimited from one another by at least two dummy joints (stem dummy joint 74 and middle dummy joint 81), the peripheral surface having projections (67, 68, 79) and depressions (69, 70, 80) along an (imag-inary) base line to form a toothing. To improve the sta-bility and laying of such groundcovering elements (44), it is proposed to make these T-shaped by means of a half-size stem (13) formed approximately centrally on an elong-ate crossbar (12). When rhombi (45 - 47) are used as the basic shaped slab, the groundcovering element (44) has the form of an inclined "T".

Description

59(~

Groundcovering element, especially ~concrete) slab Description:

The invention relates to a groundcovering ele-ment, especially a (concrete) slab, according to the pre-characterizing clause of claim 1.
A kno~n groundcovering element of this type (German Patent Specification 1,459,739), if the projec-tions and depressions are imagined as being omitted, has the form of a cuboid. The bonding e~fect of this known groundcovering element with adjacent groundcoverlng ele-ments is obtained as a result of intermeshing by means of the projections and depressions in conjunction with the particular offset in the laying pattern. ~ecause of its elon~ate shape, th;s known groundcovering element has a pr~ferred bonding direction, namely in the direction of its longitudinal extension.
To avoid this disadvantage, a further known groundcovering element (German Patent Specification 3,116,~40) represents an angular design of the ground-covering element known from German Patent Specification 1,459,739. The angular shape of the groundcovering ele-ment is intended, in conjunction with the projections and depressions, to achieve an improved bonding effect with groundcovering elements laid next to it, since the shape itself contribu~es to the bonding effect, and moreover a meshing length greater than that of the

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essentially cuboid ground element is obtained.
However~ the disadvantage of the angular shape of the groundcovering element known -from German Patent Specification 3,116,540 is that the part sur~aces forming the angle~ as seen in a plan view, are at d;fferent d;s-tances from one another, thus result;ng ;n a correspond-ingly irregular transm;ss;on of loads into the bed and uneven edge pressure ~hen longitudinal and transverse forces are exerted. If the load direct;on ;s unfavour-able~ there ;s even the danger that the slab w;ll tilt,that ;s to say come loose from the bonded structure.
Th;s is usually assoc;ated w;th cracks or the l;ke, hence destruction of the slab.
The object on which the invent;on is based ;s, therefore~ to prov;de a covering element of the type ment;oned in the introduction, wh;ch is dist;ngu;shed by an ;ncreased and, above all, un;form bond;ng effect for cohesion during laying by means of convent;onal laying equipment and when laid.
~his object is ach1eved in a surpris;ngly simp~e way by means of the characteriz;ng features of patent claim 1, because the T-shaped form, as seen in a plan view, is obta;ned by attach;ng the stem centrally to the crossbar and by an approximately congruent des;gn-of the basic shaped slabs forming the groundcovering ele~ent.
Consequently, when a load is exerted on the groundcover-ing element ;n the long;tudinal and transverse direc-tions, an approximately uniform load transmission into the bed is obtained. Edge pressures no longer arise.
There is no longer the danger that the groundcovering element, in particular the concrete slab, will tilt, that is to say come loose from the bonded structure.
The danger of fracture is also reduced to a minimum as result.
The dummy joints div;de the groundcover;ng ele-ment visually, in such a way that ;t is v;rtually ;mpos-s;ble to detect in the la;d surfaces the T-shaped form which is often considered ugly. The middle dummy jo;nt ~ 3 - ~26~
extending approximately centrally and transversely through the crossbar and the transverse dummy joint mark;ng the stem in relation to the crossbar divide each groundcover-ing element into three approximately equal part surfaces to the onlooker, with the result that, because of an appropriate relative arrangement of the groundcovering elements according to the invention, a mult;plicity of laying patterns is possible~ without the alignment of the individual groundcovering elements being detectable in the composite structure.
In one embodiment of the invention~ the corners of the groundcovering element coincide with the corners of a base line bounding three ~imaginary) squares ar-ranged in a T-shaped formation relative to one another.
The prsjections extend beyond this alternately, while the depressions are set back from it, thus forming an approx-imately zigzag-shaped, meander-shaped or corrugated side face.
In a further especially advantageous embodiment of the invention, the groundcovering element is composed of three (imaginary) rhombi of equal size, which form a base line producing an inclined "T". At the same time, the amount of inclination of the rhombi is preferably selected so that the 1nclination corresponds to half the length of a side face of the rhomb;. This produces, in one direction of the groundcovering made from the ground~
cover;ng elements accord;ng to the invention, diagonally directed joints which are particularly well suited to absorbing the traffic loads exerted in a longitudinal and transverse direction of the groundcovering. Moreover, the groundcovering element according to the invention can be laid particularly easily in laying units, since, because of the rhombic shape of the base line, there is "bonding toothing" in one direction~ while an "open"
toothing is obtained in the other (oblique) direction.
Consequently, the transverse, free ends of the laying units have a uniform toothing converging outwards~
without any undercuts~ The laying un;ts consisting of ~ 6~

the groundcovering elements according to the invention can thus be laid successively in a simple way, without the otherwise customary need to thread in the laying units to be joined together, which requires a certain skill.
Finally, the groundcovering elements designed according to the invent;on, because of their rhombic shape, present the observer with a pattern of great vari-ety since the joints or dummy joints do not extend at right angles to one another.
Several preferred exemplary embodiments of a groundcovering element according to the invention are explained in more detail below with reference to the drawings. In these:
Figure 1 shows a plan view of a first exemplary embod;-ment of a groundcovering element, with projections and depressions formed by sloping faces and with a T-shaped form, Figure 2 shows a plan viPw of a groundcovering element of Figure 1, but with a modified run of the projections and depressions, Figure 3 shows a plan view of a groundcovering element corresponding to that of Figure 1, but with rounded pro-jections and depressions, Figure 4 shows a plan view of a second exemplary embodi-ment of the groundcovering element, with project;ons and depress;ons formed by sloping faces and with a shaPe corresponding to an inclined l'T", Figure 5 shows a plan view of a plurality of ground-covering elements according to F;gure 4 which are laidtogether, Figure 6 shows a plan view of a laying unit consisting of groundcovering elements according to Figure 4, and Figure 7 shows a plan view of the insertion of a laying unit according to Figure 6 into laying units already laid.
Figure 1 illustrates a groundcovering element 10 which has a peripheral surface with projections 37 and 5~
~ - 5 -depressions 38 for m0sh;ng with groundcover;ng elements 10 of the same type laid next to it. As seen in a plan view, the groundcovering element 10 has the basic form of a letter "T" and comprises a crossbar 12 and stem 13 attached perpendicularly relative to the latter, the stem 13 being joined to the crossbar 12 centrally. The cor-ners 26 to 33 of the groundcovering element 10 are the corners of a base line 34 which bounds three squares 11, 24, 25 and relative to which alternately the above-mentioned projections 37 project and ~he~depress;ons 38are set back, thus forming a zigzag-shaped peripheral surface. The peripheral surface of the crossbar 12 is defined by a longitud;nal side face 20 extending in a longitudinal direction of the latter, two longitudinal side portions 18 and 19 extending parallel to this, and two parallel transversely directed transverse side faces 15 and 16. The peripheral faces of the stem 13 are a ~short) longitudinal side face 21 extending in a longi-tudinal direction of the crossbar 12 and two transverse side faces 22 and 23 directed transversely relative to this. The crossbar 12, as seen in a plan view, comprises two (imaginary) squares 24, 25 of equal size, which each correspond to an ~imaginary) square 11 of the stem 13, as seen in a plan view. The longitudinal extension of the ~short) edge portions 35 adjoining the corners 26 to 33 each correspond to half the longitudinal extension oF the remaining edge portions 36 of equal length, which limit the projections 37 and depressions 38, and in the exem-plary embodiment illustrated the longitudinal side face 2~ of the crossbar 12 facing away from the stem 13 has t t'hree ~long) edge portions 36. Consequently', ~hen the stem 13 is attached centrally to the crossbar 12, this produces a respectively symmetrical pattern of the longi-tudinal side portions 18 and 19 of the crossbar 12 which adjoin the two ~inner-angle~ corners 16 and 17 between the crossbar 12 and the stem 13. Furthermore, the tshort) edge portions 35 limiting the (inner-angle) corners 16, 17 are then each of the same length, with a correspondingly IL5~

equal supporting effect in the reg;on of the (inner-angle) corners 16, 17 when the groundcover;ng element 10 is subjected to loads in the longitudinal and transverse directisns.
The (short) edge portions 35 limiting the corners 16 to 23 each form a right angle, whereas all the other (long~ edge portions 36 each form an obtuse, preferably constantly o~tuse angle with one another and with the respective adjoining (short) edge portions 35 located in the region of the corners 16 to 23~
Figure 1 also shows three center points 39, 40 and 41 of the three (imaginary) squares 11, 24 and 25 de-fining the T-shaped base line of the groundcovering ele-ment 10, these center points being connected by dot-and-dash lines. It emerges from this that the center points39, 40 and 41 of the three squares 11, 24 and 25 of the groundcovering element 10 are each located at an equal distance from one another. This means that, when a load is exerted on the groundcovering element 10, the load transmission into the bed is of equal amount both in the longitudinal direction and in the transverse direction.
This reduces considerabLy the danger that the ground-covering elements 10~ when laid, will tilt and come loose from the composite covering structure under Loads exerted on the edge re~ions~ for example wheeL loads from vehicles driving over them.
In the exemplary embodiment of Figure 2, the per-ipheral surfaces of the groundcovering element 10 have a larg0r number of (longer) edge portions 36. In particu-lar, here, the longitudinal side face 20 has seven edgeportions 36, while the (short) longitudinal-side face 21 of the stem 13 and the transverse side faces 15, 16 and 22, 23 each have three edge portions 36. In the ground-covering element 10 according to Figure 2, the longitudi-~
nal side portions 18 and 19 also each have a (long) edgeportion 36.
In this embodiment, the transverse side faces 22, 23 of the stem 13 extend parallel to the transverse S9~

side faces 15, 16 of the crossbar 12. Such a parallel run is not possible, nor is it provided, in the rema;n-ing exemplary embodiments.
Moreover, Figure 2 alSO shOws the run of the S dummy joints, in particular a middle dummy jo;nt 14 and a stem dummy joint 17 on the top side of the groundcover-ing element 10.
The stem 13 is set off visually from the cross-bar 12 by the stem dummy joint 17, and the stem dummy joint 17 continues the run of the longitudinal side por-tions 18, 19 of the crossbar 12, which laterally adjoin the stem 13 and the two ~inner angle) corners 26, 27 be-tween the crossbar 12 and the stem 13, thus forming a continuous run corresponding to the opposite longitudinal side face 20 of the crossbar 12~
In contrast to this, the middle dummy joint 14 extends on the top side of the crossbar 12 transversely to the longitudinal direction of the latter and has a run which corresponds exactly to the contour of the transverse side faces 15 and 16 of the crossbar 12 which extend parallel to it. The middle dummy joint 14 there-by divides the crossbar 12 visually into two equal halves correspond;ng to the squares 14 and 15 marking the base line. The dimension and shape of the peripheral surface of the halves of the crossbar 12 which are formed by the middle dummy jo;nt 14 correspond to those of the stem 13.
As result, as seen in a plan view, the two halves of the crossbar 12 are congruent relative to the surface of the stem 13.
In principle, it is possible to arrange several dummy joints corresponding to the middle dummy joint 14 on the top side of the crossbar~ in such a way that the crossbar 12 has, on its top side 2, dummy joints which extend transversely relative to its long;tudinal direc-tion and which, starting from the two (inner-angle) cor-ners 26, 27 between the crossbar 12 and the stem 13, each continue exactly or substantially the run of the two transverse side faces 22 and 23 of the stem 13 wh;ch ~6~S9~
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respectively adjoin the two corners 16, 17.
In a way known per se, the depth of the dummy joints (middle dummy joint 14 and stem dummy joint 17) ;s approximately 10 - 30% of the thickness of the ground-S covering element 10. Furthermore, the upper edges of theper;pheral faces ~transverse side faces 15, 16, longitudi-nal s;de portions 18, 19, longitudinal side face 20, 21 and transverse side face 22, 23) are preferably provided with a continuous chamfer 43 shown in Figure 2. Accord-ingly, the cross-section of the dumMy joints ~middle dummy joint 14 and stem dummy joint 17) is made approxi-mately Y-shaped in a corresponding way.
In a simiLar way to the illustration shown in Figure 2, the groundcovering element 10 according to Figure 1 can also be provided w;th a middle dummy jo;nt and a stem dummy joint, but with a run matching the di-mensions and toothing of the peripheral faces.
The e~bodiment according to Figure 3 corresponds essentially to that according to Figure 1, but with the difference that the run of the peripheral faces of the groundcovering element 1Q is made corrugated, specifi-cally preferably sinusoidal. The same applies to the m;ddle dummy joint 14 and the stem dummy joint 17 which are matched to the run of the peripheral faces. The tshort) edge portions 35 arranged in the regions of the corners 26 to 33 and the (longer) edge portions 36 ar-ranged between them are set off from one another by aux-;l;ary lines 4Z in Figure 3. Of course, these auxiliary lines 42 are not present in the groundcovering elements 10 according to Figure 3 which are actually producedn T`hey are merely intended to show that, even in the em-bodiment illustrated in this Figure, the same basic prin-ciple is used as in the embod;ments according to Figures 1 and 2 as regards the dimensions and ~ormation of the peripheral lines and du~my jo;nts. In order to illus-trate the auxil;ary func$ion of the auxiliary lines 42, these are not marked at all the possible points in Figure

3.

lL~64L~
_ 9 Of course, as regards the number of corrugated projections 37 and depress;ons 38, the exemplary embodi-ment according to Figure 3 can have a design correspond-ing to that of the exemplary embodiment according to Figure 2, specifically with a shorter corrugation length.
To that extent, the possibility of variation is not re-stricted to the groundcovering elements 10 described.
In the embodiments illustrated, all the particu-lar transverse side faces 15, 16 and 22, 23 arranged op-posite one another, the middle dummy jo;nt 14, thelongitudinal side faces 20 and 21, the longitudinal side portion 18 and 19 and the stem dummy joint 17 can be made to overlap one another by shifting them in parallel.
As result, a v;sually uniform impression is given in the bonded structure.
Figures 4 - 7 show a groundcovering element 44 which represents a further embodiment of the invention with particularly favourable bonding and handling prop-erties.
The groundcovering element 44 is also composed of three basic shaped slabs which are grouped together in a T-shaped formation. However, the most important dif-ference between this exemplary embodiment and the preced-ing ones is that the T shape is not obtained from three (imaginary) squares joined together, but from three equal rhombi 45, 46, 47. In this exemplary embodiment, these are combined in such a way that they form an ;nclined T .
Here, the perirheral faces of the groundcovering element 44 have a toothing consisting of alternately successive projections and depressions. The projections and depressisns of this exemplary embodiment are formed in a similar way to those of the exemplary embodiments of Figures 1 and 2, in particular from edge portions 51 -54 converging at an obtuse angle or at right angles.Gonsequently, the peripheral faces of the groundcovering element 44 extend both inside and outside the (imaginary) rhombi 45 - 47.

S~
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In co~parison with the embodiments described above, the edge portions S0, etcetera, have a more com-plex run with few regularities. ~ccording to the inven-tion, this run conforms to an interrelationship which can S be described simplest by two further (enveloping) rhombi, in particul3r an inner rhombus 55 and an outer rhombus 56. The inner rhombus 55 is obtained by a (subsidiary) connection of all the vertices 57 of the depressions of each basic shaped slab. In contrast to this, the outer rhombus is obta;ned by a subsid;ary connection of all the tips 58 of the projections of each basic shaped slab which are formed on the peripheral face of the ground-covering element 44. The outer rhombi 56 and inner rhombi S5 are likewise inclined, that is to say their re-spect;ve side faces located opposite one another extendparallel to one another and are at the same distance from one another all round.
In comparison w;th the inner rhombus 55 and the outer rhombus 56, the rhombi 45 - 47 have a larger en-closed acute angl~, preferably an angle of 60 in com-parison with an angle of 50 for the inner rhombus 55 and the outer rhombus 56. As a result, two diagonally oppo-site corners of the rhombi 45 - 47 are located outs;de the region of the outer rhombus 56, while the other two corners of -the rhombi 45 - 47, likewise located apposite one another, come to rest in the region between the outer rhombus 56 and the inner rhombus 55. In spite of these different enclosed acute angles, all the rhombi ~rhombus 45 - 47, inner rhombus 55 and outer rhombus 56) meet at a common point, in particular the center points 59, ~0 and 61 of the basic shaped slabs of the groundcovering ele-ment 44.
If the three center points 50 ... 61 of the indi vidual basic shaped slabs of the groundcovering element 44 are connected by means of (imaginary) auxiliary lines 62, a right-angled triangle with one leg extending longi-tudinally and one leg extending transversely relative to the longitudinal direction of the crossbar 12 is formedu Accordingly~ the hypotenuse of th;s (aux;l;ary) tr;anyle ;s at approx;mately 45 to the long;tud;nal direct;on of the groundcovering element 44.
The actual run of the peripheral faces of the groundcover;ng element of this exemplary embodiment ex-hib;ts two bas;c mesh;ng princ;ples. Accord;ng to these, the longitudinal side face 63 extending in the longitudi-nal d;rect;on of the crossbar 12, the opposite longitud;-nal side portions 64 and 65 interrupted by the stem 13, and a short longitudinal side face 66 each have a syn-chronic toothing composed of a trapezo;dal projection 67 and a triangular projection 68. Between the different projections 67 and 68 are formed correspond;ng depres-sions 69 and 70. Here, the trapezoidal projection 67 has a short edge portion 50 and a longer, but ~latter edge portion 51. The triangular projection 68 is composed of edge portions 50 and 51 of the same size and directed at the same angle. In the present exemplary embodiment, the (long) longitudinal side face 63 of the crossbar 12 has two trapezoidal projections 67 and two triangular projec-tions in alternating sequence. At the same time, the corners 71, 72 and 73, to which a trapezoidal projection 67 is assigned, are each preceded, between the respective corners 71 - 73 and projections 67, by a tplane) edge portion 52 in the longitudinal direction of the crossbar 12. This corresponds in length to the likewise plane, short base of the trapezoidal projection 67.
In the ~ay described above, a stem dummy joint 74 also present in this exemplary embodiment is formed to delimit the stem 13 from the crossbar 12. As result, the stem dummy jo;nt 74 visually continues the run of the longitudinal side portions 64, 65 or connects the two, in such a way that a toothing ma~ching the outer longitudinal toothing of ~he crossbar 12 is obtained on the surface of the groundcovering element 44 to an observer. The tooth-ing direction between the longitudinal side of the cross-bar 12 directed away from the stem 13 and the toothing formed by the longitudinal side portions 64, 65 or the 6~S~3~

stem dummy joint 74 are oppos;te to one another here. In contrast to this, the toothing on the short longitudinal side face 66 of the stem 13 is again designed so that it can be made to overlap with the toothing directed towards the stem 13 and located on the crossbar 12 by being shifted in parallel.
In the present exemplary embodiment, the toothing on the transverse peripheral faces, in particular the transverse side faces 75 and 76 of the crossbar 12 and the transverse side faces 77 and 78 of the stem 13, con-sists solely of triangular projections 79 and correspond-ing depressions 80 located between them. At the same t;me, as here, three projections 79 and two depressions 80 located between them can be arranged on each trans-verse side face 75 - 78. Here, the projections 79 are each composed of a short edge portion 53 and a long edge port;on 54 of lower inclination. Altogether, each trans-verse side face 75 - 78 has three short edge portions 53 and t~o long edge portions 54.
The run of the toothing formed from ~he edge por-tions 53 and 54 on the transverse side faces 75 - 78 ex-tends in the same direction here, that is to say trans-verse side faces 75 or 76 and 77 or 78 located opposite one another can be made to overlap.
The crossbar 12 composed of two rhombi 46 and 47 is divided here (centrally) by a middle dummy jo;nt 81, the run of which corresponds to that of the edge portions 53 and 54 on the transverse side faces 75 - 78. This gives the observer the impression that the groundcovering element 44 is composed of three lozenge-shaped basic slabs of equal size.
At the corners 71 - 73, two short edge portions 52 and 53 meet or,e another at right angles, specifically in a longitudinal and transverse direction relative to the longitudinal direction of the crossbar 12. Two (chort) edge portions 52 and 53 also meet at right angles at each of two (inner) corners 82 and 83, as regards the corner 83 these be;ng the edge port;ons 52 and 53 of the ~L~6~

m;ddle dummy jo;nt 81 and stem dummy joint 74 wh;ch meet at r;ght angles.
Because of the special design of the toothing as described above, the corners 71 - 73 and 82, 83 already mentioned do not coincide with the corresponding corners of the imaginary rhombi 45 - 47. The same applies to the remaining corners 84 - 87, which are likewise located outside the base line formed by the rhombi 45 - 47, that is to say are not located at the corners of this base line. However, the particular corners 71, 83; 72, 88;
73, 82 located diagonally opposite one another coincide ~ith corresponding corners of the inner rhombi 55, which is not true of the remaining corners 84, 85 and 86.
Figure 5 illustrates seven assembled ground ele-ments 44, their middle dummy jointS 81 and stem dummyjoints 74 being represented by broken lines~ Conse-quently, the peripheral faces of the individual ground-covering elements 44 can be dis~inguished clearly from the corresponding dummy joints (stem dummy joints 74 and middle dummy joints 81). In th;s Figure, a system of coordinate axes 89 marks the main load directions running at right angles to one another. It emerges clearly from this that, particularly because of the transverse side faces 75 - 77 extending obliquely relative to the system of coordinate axes 89, the forces exerted in the two ma;n load directions are absorbed in the most effective way possible. For example, equal loads can thereby be trans-mitted by the ~oothing of the groundcovering elements 44 both in the long;tudinal direction and in the transverse direction~
Figure 6 illustrates a laying unit consisting of a plurality of groundcovering elements 44 of Figure 4.
The laying unit 90 is obtained in one production cycle in a slab forming machine, with maximum utilization of a conventional board as a base. Such a laying unit 90, in order to be laid by means of a laying machine, is grasped on the longitudinal sides by an appropriately designed clamp or clamping jaws and is both transported - 14 - lZ64S9O
and la;d as a unit~
Since it is not possible to compose from the groundcovering elements accord;ng to the invention a lay-ing uni~ 90 which is as close to the rectangular form as S it should be the gaps 91 arising as a result of the T
shape of the individual groundcovering elements are filled with individual slabs 92 having the base surface of a basic shaped slab or else by double slabs 93 correspond-;ng approximately to a crossbar 12. This results, on the longitudinal sides 94 of the laying un;t 90, in a surface merely interrupted by individual depressions 69 or 70 which offer sufficient engaging surfaces for c~amps or the like of the laying equipment.
As a result of the special design according to the invention of the toothing, the end transverse edges 95 of the lay;ng unit 90 have mouth-shaped outward-converg~
ing recesses 96 on the groundcovering elements 44, spe-cifically both in the longitud;nal direct;on and in the transverse direction of these, bet~een basic shaped slabs lying next to one another. At these recesses 96, the cdge portions 53 are directed transversely and the edge portions 52 are directed longitudinally. In contrast, the rema;ning edge portions 51 and 54 are inclined in the recess 96, specifically in a direct;on opening outwards.
Thus, the recess 96 does not have any undercuts, so that it is possible to join individual laying units 90 to one another easiLy.
Figure 7 shows clearly how a laying unit 90 can be pushed ;nto a corner already formed by three la;d units, without having to be threaded in. According to this, the lay;ng un;t 90, at a short distance from the long;tudinal sid8s of the already laid un;ts, ;s f;rst moved towards the front laying unit, until the edges of the front transverse edge portions 53 approximately touch one another, that is to say the laying unit to be laid half extends into the recesses 96. Subsequently, the laying unit 90, as result of a superimposed longitudinal movement and transverse movement, with its longitudinal 5~

edge 94 and its transverse edge 95 is pushed up aga;nst the already laid laying units "unt;l ;t stops".

Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A groundcovering element (10, 44), especially a (concrete) slab, consisting of three basic shaped slabs which are connected to one another to form a T-shaped basic form, whereby the basic form is composed of a crossbar (12) formed by two equiaxially arranged basic shaped slabs and of a stem (13) arranged centrally and transversely relative to said crossbar (12) and composed of a single basic shaped slab, and the basic shaped slabs are delimited from one another by two dummy joints (stem dummy joint 17, 74); middle dummy joint (14, 81), characterized in that the peripheral faces of the basic shaped slabs have alternate depressions (38) and projections (37) from consecutive edge portions (35, 36) to form a toothing and that the edge portions (35) adjoining at corners (26..33) of the basic shaped slabs, have approximately half the length of the edge portions (36) located between them.

2. A groundcovering element as claimed in claim 1, wherein the basic shaped slabs are delimited from one another by two dummy joints, wherein a dummy joint (17, 74) between the stem (13) and crossbar (12) has a run matching the peripheral face (longitudinal side face 20, 63) located opposite the stem (13), and wherein a middle dummy joint (14, 81) passing approximately centrally through the crossbar (12) extends parallel to the longitudinal direction of the crossbar (12).

3. A groundcovering element as claimed in claim 1, wherein there are three (imaginary) squares (11, 24, 25) of equal size, which are arranged in a T-shaped formation and the base line of which coincides with the corners (26-33) of the peripheral faces, the projections (37) and depressions (38) extending alternately on both sides of the base line of the squares (11, 24, 25) in a zigzag-shaped, corrugated and/or meander-shaped manner.

4. A groundcovering element according to claim 3, characterized in that the longitudinal side faces (20, 21), extending in the longitudinal direction of the crossbar (12), have an odd number of (long) edge portions (36).

5. A groundcovering element as claimed in claim 3 or 4, wherein the (short) edge portions (35) limiting each of the corners form a right angle, while all the other edge portions (36) each form an obtuse, preferably constantly obtuse angle with one another and with the respective adjoining (corner) edge portions (36).

6. A groundcovering element as claimed in claim 2, wherein the middle dummy joint (14) and the stem dummy joint (17) extend parallel to the respective opposite peripheral faces of the stem (13) and of the crossbar (12), to form three basic shaped slabs of identical design as seen in a plan view.

7. A groundcovering element as claimed in claim 6 and one or more of the remaining claims, wherein all the opposing longitudinal side faces (20, 21), longitudinal side portions (18, 19), transverse side faces (15, 16, 22, 23) and dummy joints (middle dummy joint 14 and stem dummy joint 17) extend parallel to one another.

8. A groundcovering element as claimed in claim 1 wherein three (imaginary) rhombi (45, 46, 47) of equal size are arranged in a T-shaped formation in such a way that they produce an inclined "T".

9. A groundcovering element as claimed in claim 8, wherein the amount of inclination of the rhombi (45, 46, 47) corresponds approximately to half the side length of the latter.

10. A groundcovering element as claimed in claim 8 wherein the toothing formed by the depressions (69, 70, 80) and projections (67, 68, 79) extends in opposite directions on peripheral faces located opposite one another.

11. A groundcovering element as claimed in claim 8 wherein all the tips (58) of the projections (67, 68, 79) are located on a common (imaginary) outer rhombus (56), and all the vertices (57) of the depressions (69, 70, 80) are located on a common (imaginary) inner rhombus (55), the particular base sides facing one another of the inner rhombus (55) and of the outer rhombus (56) extending parallel to and at the same distance from one another, and the diagonals of all the imaginary rhombi (rhombus 45-47, inner rhombus 55 and outer rhombus 56) intersecting approximately at a common center point (59, 60, 61) in each basic shaped slab.

12. A groundcovering element as claimed in claim 11, wherein a center of gravity approximately coincides with the common center points (59-61) of the (imaginary) rhombi (rhombus 45-47, inner rhombus 55 and outer rhombus 56) as a result of appropriately designed depressions (69, 70, 80) and projections (67, 68, 79).

13. A groundcovering element as claimed in claims 11 and 12, wherein the inner rhombi (55) and the outer rhombi (56) are inclined to a greater extent than the rhombi (45-47), preferably having acute angles of 50, while the rhombi (45-47) have an acute angle of 60.

14. A groundcovering element as claimed in claim 8, claim 9 or claim 10, wherein outer corners (71, 72, 73, 84, 85, 86) are offset relative to the corners of the (imaginary) rhombi (45-47).

15. A groundcovering element as claimed in claim 8, claim 9 or claim 10, wherein the transverse side faces (75-78) of the crossbar (12) and of the stem (13) and the middle dummy joint (81) are of identical design and have six edge portions (53, 54) forming three triangular projections (79) and two triangular depressions (80), preferably four edge portions (53) being shorter than the remaining two edge portions (54) located between them.

16. A groundcovering element as claimed in claim 8, claim 9 or claim 10, wherein the longitudinal side faces (63, 68) and the stem dummy joint (74) are each formed from a trapezoidal and a triangular projection (67, 68) succeeding one another alternately and corresponding depressions (69, 70), these each having a longer and a shorter edge portion (50, 51), and the shorter edge portions (50) extending parallel to one another are inclined to a greater extent than the likewise parallel longer edge portions (51).

17. A laying unit according to claim 1, wherein there are several rows arranged next to one another of groundcovering elements (10, 44) which are offset by the length of their stems (13) and which are arranged alternately with stems (13) located at the top and bottom in relation to the crossbar (12), and edge gaps (91) arising thereby are filled with individual slabs (92) , to form continuous edges, especially longitudinal edges (94).

18. A laying unit as claimed in claim 17, wherein, when groundcovering elements (44) are used, the transverse edges (96) have recesses (96) opening outwards in the manner of a mouth, without undercuts, in the direction in which the laying units (90) are pushed together.