Paving block arrangement for laying a paving-set arc assembly

An arcuate paving block assembly comprising two outer transitional blocks (1) with four arcuate sides, wherein two adjacent sides (10, 18) are curved inwards and the other two sides (19, 20) are curved outwards in order to form a continuous transition from one arc to another; adjacent thereto on both sides an equal number of arc blocks (2, 3, 4; 2a, 3a, 4a) constructed to be mirror images of each other and symmetrical or mirror image shaped keystones of apex blocks (5, 6, 5a, 6a; 7, 7a, 8) which together make up the entire length of an arc, the whole being such that when laid the two outer edges (10) of the transitional blocks (1) enclose an angle of 90.degree. and the height (H) of all the blocks measured at right angles to an imaginary baseline (S) through the lower corner of the transitional blocks (1) is the same. Herein the blocks have a lower portion remote from the top tread surface which extends further in the horizontal direction and an upper portion of less extent in the horizontal direction, wherein the lower portion of the radial sides (21) of the arc blocks and crown blocks and the outwardly curved sides (19, 20) of the transitional blocks (1) are provided with vertical or perpendicular projections (14, 15) and the edging of the upper portion has lateral surfaces which are irregularly formed in the same way as a natural stone.

The present invention relates to a combination of manufactured paving 
blocks or sets which are arrangeable into arcuate combinations. 
The arrangement of arcs of paving stones or sets with natural stone has 
been known for a long time, but requires specialist personnel in order to 
lay such, and in addition to this such arrangements are very expensive 
because the individual stones have to be cut by hand. Although natural 
stone arc arrangements are aesthetically very effective and attractive, 
their sometimes very uneven surfaces are not appreciated by everybody, in 
particular not by women. Efforts have therefore been made for a long time 
to provide paving stones or paving stone units, by means of which arc 
arrangements can be formed cheaply and with a more even surface. Thus, for 
example, an arc shaped paving member unit for the formation of an arc 
arrangement is known from DE-A-31 51 876 in which the units are subdivided 
into individual stones by means of non-penetrating separating channels or 
grooves--these units being cheaper to manufacture and easier to lay than 
natural stone sets. However, as a result of their construction these units 
have a regular and readily identifiable texture, whereas the manufacture 
of arc-shaped relatively large units of conventional rectangular shape is 
rather uneconomic. 
The object of this invention is therefore to provide a combination of 
paving stones or blocks for laying in an arc or arcs which blocks on the 
one hand can be manufactured rationally and on the other hand can be laid 
easily, and in addition to this have an attractive appearance 
approximating to that of natural stone arc sets or blocks. Also these 
paving blocks should be compatible with other paving blocks which can be 
laid in straight courses. This objective is achieved by means of a paving 
as described in the claims. 
In particular, according to the present invention there is provided a 
combination of paving blocks for forming arcuate paving arrangements 
comprising outer bridging blocks each with four arcuate sides, wherein two 
adjacent sides are curved inwards and the other two sides are curved 
outwards in order in use to form a continuous transition from one arc to 
another; adjacent thereto an equal number of arc-forming paving blocks 
disposable on opposite sides of an arc and shaped to form mirror images of 
each other and adjacent to said arc-forming paving blocks, symmetrical or 
mirror image shaped apex or crown paving blocks which blocks together make 
up the entire length of the arc arrangement, the whole being in such a 
form that when laid the two outer edges of the bridging blocks include an 
angle of 90.degree. and the height (H) of all the blocks measured at right 
angles to an imaginary baseline (S) through the bottom corner of the 
bridging blocks is the same.

In FIG. 1 there are illustrated two arcuate courses of pre-formed discrete 
paving stones or blocks in accordance with the invention in arcuate 
arrangement. The lower of the two courses has at each end an identical 
transition of bridging stones or blocks 1 and then, inwardly thereof has 
three arch stones or blocks 2, 3, 4 and three correspondingly mirror-image 
arc stones or blocks 2a, 3a and 4a. 
The blocks 1 each have upper and lower faces or sides and four curved or 
arcuate sides wherein two adjacent sides 10, 18 are concave or curved 
inwards and the other two sides 19, 20 are convex or curved outwards such 
as to enable a continuous transition to be formed from one arc to the 
next. 
In this arc arrangement, or arc forming unit, the mentioned blocks are 
supplemented by two apex stones or crown block 5 and 5a and two crown 
blocks 6 and 6a, making four crown blocks in all and where also the two 
crown blocks 5a and 6a are mirror images of the two crown blocks 5 and 6. 
The upper course likewise includes the two bridging blocks 1 and the two 
groups of three arc blocks 2, 3, 4 and 3a, 4a and 5a respectively. Instead 
of the four apex or crown blocks of the lower course 5, 5a and 6, 6a, the 
upper course has two apex or crown blocks 7 and 7a which are likewise 
mirror images of each other, and a keystone or middle or top block 8. The 
length of arc of the four crown blocks 5, 5a and 6, 6a of the lower course 
is the same as that of the three blocks 7, 7a and 8 of the upper course so 
that these blocks can be inserted at will. 
In the development of the paving block arrangements the fundamental premise 
was that its appearance should match that of known paving stone 
arrangements in order to provide an even transition to normal pavings and 
to achieve a certain standardisation. In the preferred embodiment the 
starting point for the rectangular normal unit is a paving unit known by 
the name of CITY K which is described in detail in EP-B-0060 961 and is 
indicated by the number 9 in the variant embodiment illustrated in FIG. 4. 
This square paving unit has an edge length of 180 mm so that the grid in 
FIG. 1, i.e. the distance between centres or the diagonals of transitional 
blocks 1, is likewise 180 mm. If one assumes the normal width for a 
passageway, i.e. 1250 mm, as the span width S on which an arc or curve is 
based, and applies the condition that the outer edges 10 of the 
transitional blocks should include an angle of 90.degree., then the radius 
r of the centre line M of the circular arc r=S/.sqroot.2=883.9 mm. As is 
usual in the case of arc pavings, the arc drawn at right angles to the 
baseline S always has the same height H of 180 mm. These figures and 
dimensions are purely by way of example and largely relate to the 
specification or selection of the particular paving unit used as a basis. 
Obviously another grid dimension can be used as a basis so that there is a 
larger or a smaller number of units in a course. It is important however 
that the two transitional blocks at the ends are identical and that the 
number of blocks on both sides is the same and that these are mirror 
images of each other. 
However, not only have the dimensions of the known paving unit 9 been used 
as a basis, but also its appearance and shape. Thus it is a characteristic 
of the known paving unit that in thickness it has two different portions, 
i.e. as seen in a vertical direction the lower portion is provided with a 
wider projection and the upper portion is constructed independently of 
this projection in such a way that on the one hand the lower projection 
cannot be seen when located and on the other hand the surface has the 
appearance of a natural stone. This means that the side surfaces of the 
upper part are irregular. As shown in FIG. 5, all the units in the course 
have a lower portion 11, which extends further in horizontal 
cross-section, and an upper portion 12 with irregular side surfaces, while 
upper surface 13 is slightly wavy as in the example given and thus is slip 
resistant. All the blocks in the course with the exception of the two 
transitional blocks 1 have projections on the lower portion 11 of radial 
sides 21 which differ as shown in FIG. 1. Projections 14 and 15 of the 
adjacent sides of the two crown blocks 6 and 6a in the lower course 
correspond with the projections of the normal facing unit 9, see FIG. 4, 
and each have three projections 16 by means of which, as shown in FIG. 4, 
they can if necessary pass without discontinuity into normal paving. In 
this example therefore only one projection is present in the radial 
direction. This obviously also applies for the transitional blocks in 
which the projection is of course found on the two adjacent sides. 
FIG. 1 shows that with the exception of the projection just described on 
crown blocks 6 and 6a, the projections on the various blocks are not 
identical. Starting from the keystones or crown blocks it will be seen 
that the projections located at the centre points of the blocks are always 
directed outwards, i.e. towards the bridging blocks 1, and that there is a 
recess which corresponds to these. It may also be seen from FIG. 1 that 
the distance from the outer edge of a block to the edge of the projection 
is always the same, so that the length of the projection decreases from 
the centre towards the transitional blocks. The transitional blocks always 
have a recess in the middle of the two adjacent sides in order to engage 
the projections on the next arc block. 
FIG. 3 shows most clearly that all four sides of the bridging blocks are of 
an arcuate shape, in such a way that there is a continuous transition from 
one arc to the next, as may clearly be seen in the transitional position 
illustrated in FIG. 3. Here the two adjacent sides 18 are concave or 
curved inwards and the two other sides 19 are convex or curved outwards. 
Obviously arcuate sides 22 of the other blocks are also constructed in 
this way so that the desired circular arc can be achieved, while the 
radial sides, with the exception of the sides bounding the first arc 
blocks 2 and 2a on the transitional blocks, are straight. As a result 
there is a continuous transition from one arc to another without any 
visibly obvious discontinuities. 
As the paving blocks or units are delivered on pallets and each unit in a 
course has its specific place, the individual units in a course must be 
marked or identified. In the example provided this is achieved by means of 
a specific number of marking or identification grooves 17 on each block, 
as is shown in FIG. 1. Transitional blocks 1, which differ from the other 
blocks in that they have indentations or no indentations on two adjacent 
sides must not be marked. The first two arc blocks 2 and 2a can be 
identified by the fact that they have no markings, while the subsequent 
blocks have 1, 2 or 3 grooves, and the two upper or crown blocks 6 and 6a 
and keystone or crown block 8 each have one or two grooves. As the two 
crown blocks 6 and 6a have another projection on their sides in addition 
to those on the other blocks these blocks can readily be identified. The 
same applies for crown block 8, which is the only one to have projections 
on two opposite sides. FIG. 1 also shows that the individual grooves are 
always placed on the blocks in such a way that they are always at right 
angles to each other when laid, in relation to the baseline S. In this way 
these grooves can be used as a guide when laying individual courses. 
In addition to the different possible dimensions of the paving blocks 
already mentioned, all known materials and colouring agents may be used 
for the manufacture of these blocks in order to match these paving blocks 
with standard facing units or to produce a deliberate difference. 
It will be seen from the description that these arc paving blocks can be 
manufactured using the same machine as is used for other paving blocks, 
but obviously using different moulds.