CA2085933A1 - Interlocking slab element and ground surface cover - Google Patents

Abstract

INTERLOCKING SLAB ELEMENT AND
GROUND SURFACE COVER
Abstract of the Disclosure A integrally molded paving stone or slab element of ceramic material, and a ground cover made up of repeatable patterns of such elements wherein the slab elements include a hexagonal section having two 90° and four 135° angles and lateral and longitudinal sides and a square section with a side adjoining a side of the hexagon which is adjacent one of the 90°
angles. The lateral sides of the hexagon adjacent the 90° angles and the sides of the square are from 3.5"
to 5", approximately and the longitudinal sides of the hexagon section are such that there are approximately 9" to 11" from one 90° angle to the other. Such a paving stone provides superior support for standard dual wheel truck loads when assembled in a ground cover. For complementary lighter load bearing applications, the lateral sides are preferably from 2.5" to 3.5", and equal to more than half, but less than twice, the lengths of the longitudinal sides, with the overall dimensions of the stone not more than 160 x 240 mm.

Description

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INTERLOCKING SLAB ELEMENT AND
GROUND SURFACE COVER

Field of the Invention My invention is directed to uniquely shaped . :
slab elements for covering the ground or other like surfaces, and to surface coverings composed of config~
urations of such elements. Specifically, my invention is directed to such slab elements, or paving stones, which can be combined with other like slab elements in a variety of different orienta~ions to form stable load-carrying surfaces in a multiplicity of different patterns.
Backaround of the Invention The present invention is a new and improved slab element and ground surface cover arrangements of such elements. The invention provides many of the advantages of my previous inventi~n entitl.ed 2 ~ 3 3 INTERLOCKING SLAB ELEMENT FOR COVERING THE GROUND AND
THE LIKE disclosed in my U.S. Patent No. 4,544,305, and, in addition providing other desirable and unique advantages and characteristics. ~`
Slab elements of differing shapes have been employed in the construction of traffic-carrying surfaces such as roadways, footways, embankments and pool decks. Typically, the slab elements are made of concrete, formed in desired shape in molds, and cured under high pressure where the slab material is com~
pacted and hardened into the desired shape in the mold, and removed from the mold and exposed to ambient air to complete the curing cycle. The method by which such slab elements can be made are well known in the ~ -art and form no part of my invention. Hence, methods for making slab elements will not be addressed further except to note that the shape of the molds used to form prior art slab elements must be modified so as to conform to the shape of my slab elements.
To construct a surface employing slab elements, an under-surface is prepared in known fashion to provide a smooth flat surface upon which to place the slab elements. The slab elements are placed one at a time such that their vertlcal or peripheral walls or edge faces come into close contact. The gaps between edge faces may be filled either with mortar, concrete, or other such solidifying spacer element, 2~85~3~
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or, preferably, with sand which is simply poured into ~ ~ -the gaps in a known manner. My invention is ideally suited to the latter, less costly met:hod. The traffic load encountered by surfaces constructed in the above manner can vary from as light as pedestrian traffic to as heavy as several ton trucks and forklifts.
Slab elements employed for traffic surfaces have come in a wide variety of shapes from square and rectangular to multi-sided and irregular shaped surfaces, but a slab element's shape is known to affect the ground cover's load carrying capacity and durability. When viewed from the top, such slab elements generally fall into one of three basic categories.
The first category is a slab element which has a known and simple geometric shape, such as a rectangle, a square, a hexagon, or an octagon. From an aesthetic point of view, this cateqory of elements is highly desirable and has historically been in great demand. In other respects, this category has hereto-fore been less desirable than other categories herein-after discussed because such shapes preclude an interlock joint between adjacent slab elements.
Additionally, proper utilization can require greater material and care than other slab elements and are ~
often not satisfactory in use. For example, if such -slab elements were placed in the manner expected of my 2~8~3 :

~ , invention, i.e., with sand between them, the surface would not be stable because there is no interlock.
Furthermore, because there is no interlock, long, straight channels are more easily formed between the elements thus nermitting rain, for example, to wash away the sand further reducing the load carrying stability o~ the ground cover formed with those elements. Hence, such slab elements would typically require mortar or concrete between elements. Mortar or concrete are typically more expensive than sand and are more difficult to work with.
A second category of slab element is one wherein, from a top plan view, the slab element looks substantially rectangular but the edges are deformed in such a manner as to interlock when laid next to an adjacent, identical stone. Examples of second cate-gory slab elements are shown in U.S. Patent No.
2,919,634 and U.S. Patent No. 3,494,266. Also in-cluded in this category are certain multi-faced irregularly shaped slab elements such as those dis-closed in U.S. Paten~ No. Des. 82,970. The slab elements disclosed in the aforementioned patents overcome some of the drawbacks of slab elements discussed in the preceding paragraph because they may be interlocked. However, they are less attractive from an aesthetic standpoint. Moreover, the slab elements in this category generally may not be - :, .

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intermixed with other differently shaped second category slab elements as would be possible with first category slab elements to permit a wide variety of patterns to be created. -A third category of slab ~element, and the one with which my invention is concerned, overcomes the drawbacks of both first and second category slab elements. A third category slab element is comprised of two or more sections having the shape of first category slab elements which are combined into one integral slab element. An example of such a slab element is disclosed in U.S. Patent No. 4,128,357.
The slab element of that patent has a main section which is of a known octagonal shape, and a tail section which is of a known square shape, with the main and tail sections being formed as one slab element. The primary advantage of such an integral slab element is that it can interlock for durability and stability. A disadvantage, however, is that it is susceptible of only a few different interlocking patterns. ~
In German Patent No. 3/409,114 to Koelling, ~' a variety of patterns are provided with the use of ;
several individual stones of differing shapes, including squares and hexagons. ~ot only does such a combination of stones require plural stones of differ-ent shapes, which is un~esirable, but such combination .. . . .

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produces a surface which presents problems when subjected to heavy loads, particularly the loads of conventional large trucks, as for example, those having standard dual H-20 wheels.
In my Patent No. 4,544,305, I have disclosed a slab element for use Ln providing a ground cover particularly suited for use filling the joints with sand. In my prior patent, I have taught that the combined shapes of a square and hexagon could be used to form such a slab element when the hexagon has two pair of minor faces equal to those of the square, each pair joined by a right angle with the pair being joined together by two major faces each twice the length of a minor face, the square being joined.at a 15 minor face. ~ ;~
In integrating a paving surface pattern into an architectural or landscaping plan, certain designs call for surfaces with the more classical appearance ;~
of patterns which are built upon the more regular basic shapes of squares and hexagons. Such patterns are illus~rated in British patents of Crannis et al No. 9640 and Dodgson No. 610, German Patent No.
27-51-536. As I have pointed out in my previous U.S.
Patent ~Jo. 4,544,305, s.lab elements combining these shapes for use in a variety of interlocking patterns cannot be easily selected. Where an objective is, however, to provide an in-terlocking paving element of - . . .~, . .. .
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brittle ceramic material. such as concrete, certain other practical problems are presented.
In the art of roofing, for exampl.e, ~Ihere flexible materlals are employed, plural square or hexagon shapes can be joined in an i;ntegrated covering element with less concern for the st:ructural problems by joining brittle materials, for example, as shown in Abraham U.S. Patent D75,761. In arts requiring ceramic materials, particularly for the formation of thinner tile-like rather than thick block-like ele~
ments, the avoidance of thin elongated elements and elements with acute external or internal angles adds to the strength of the element, reduces the incidence K
of element breakage in manufacture, storage, handling, assembly and use, and enhances the ease of manufac- :
ture.
The usual applications for paving stones are :~
aesthetic. The working loads on such pavements are :
normally pedestrian or light wheel traffic, e.g., automobiles, and for this level the shapes, sizes, ;
colors and thicknesses (usually 60mm) can be as varied ;~
as the customer wishes and can afford. Most such applications are hand-laid, hence the stones are within the 4-6 kg weight and dimensional size that can be comfortably handled in manual placement. The stones specified in my U.S. Patent No. 4,544,305 and the above-mentioned German Koelling patent are ,.
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2 ~ 3 primarily designed for forming a wide variety of visually pleasing geometric patterns.
The paving stone of the present invention is an interlocking stone, which, when subjected to heavy truck wheel loadiny, is capable of retaining a contin-uous, smooth plane surface and withstands fracture forces. The stones of my U.S. Patent No. 4,544,305 and of the German Koelling patent, even thouqh super-ficially resembling, or producing patterns resembling, those of the present invention, are not satisfactorily capable of heavy truck wheel service. Further, these ;
stones cannot be made capable of satisfactorily withstanding such loads by mere enlarging or reducing the size of the stones, due to unobvious shortcomings in their geometries. , The stone of my U.S. Patent No. 4,54~,305 can create a very large number of varied patterns ~-using only a single style of s~one. Its elongated shape, however, limits its inherent load bearlng acceptability regardless of the size at which it is -~
made. The Koelling stone set requires several differ-ent shapes to create similar or equal patterns. Here too, regardless of the size of these stones, the mere differences in the sizes inhibits the load bearing adaptability of these stones.

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_9_ Summa.r~ of the Invention It is a primary objective of the p~esent invention to provide a tile-like interlocking paving element utilizing to a maximum extent the nearly regular appearing design shapes of hexagons and squares in an integrated slab element while preserving and extending, to the maximum extent possible, the advantages of my present invention of Patent No.

4,544,305. By regular, I refer to component shapes having equal sides and equal angles, or at least having sides and angles which are close enough in size so as to be perceived as equal or have the same aesthetic appearance as if they were equal. ~ :
It is another objective of the present 15 invention to provide such a paving element which ,~
avoids acute angles and elongated shapes, and which is shaped not only to provide the aesthetic requirements set forth above, but to avoid shape characteristics :
which undermine its strength and resistance to break-age. It is a further objective of the present inven-tion to provide such a paving element which can be arranged in a ground cover pattern which fully covers the surface without ~he use of irregular pieces and which is suitable for a wide range of designs and 2~ patterns using minimal irregular or multiple shaped elements.

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2 ~ 3 3 It is a more particular objective of the present invention to provide a paving which fully covers the ground with a stone of a single size and shape which provides pattern versatillty, an~ which S will support heavy vehicular loads, such as those imposed by trucks with standard dual H-20 wheels, while maintaining a level continuous, smooth surface, avoiding irregular vertical displacement or shifting, and without crackinq of the stones.
These objectives are accomplished by pro- ;
viding a seven sided tile-like paving integrated element having a hexagon portion which is virtually equilateral with a pair of opposed ~oo angles sep-arating the lateral sides of the hexagon, and having a -~
square portion adjacent one of the lateral sides. By virtually, equilateral, I mean with sides that will be perceived as equal in length to give the hexagon shape a regular rather than elongated appearance.
Another objective of my invention is to provide a slab element ~hich lends itself to forming a large number of different, attractive, interlocking patterns. This objective is accomplished by providing a slab element which has a main hexagonal section and one tail section integral therewith which are oriented substantially in one plane. The ~ain section has a first pair of adjoining lateral peripheral edges or faces and a second pair of adjoining lateral 2~i933 ~ 11 ~
peripheral ed~s o~ ~a~es ~ith the firs~ and second pairs of lateral peripheral edg~s o~ faces being opposi~ely disposed in spaced-apart relationship. The : ~
main section f~rther has a pair of spaced ap~rt, ; ~:' parallel longitudinal pexipheral edgles or faces interoonne~ing the ~irst and second pair5 of lateral pe~ipheral f~es. ~he ~ces of each pai~ are joine~ .
at right ~ngles. The tail section ha~ four lateral pe~ipheral faces or edges, with one o~ the fo~r ~:
lateral faces of the tail section being suhs~Antia~ly ~oextensive in ~ize and sh~pe and spacially coincident T~ith one o~ th~ late~al ~aces o~ the main section.
Each o~ the longitu~inal f~es is approximately equal to the length of t~e lateral faces, and ~he inter-~ection of eaah longitudihal Pace ~ith the adjoining ~t~ral face deflnes an angle o~ ~pprox~mately 135~ ~:
The lateral ~a~es o~ the tail se~tion define 6ub-stantially ~ square. ~he lateral face adjacen~ to the lat~ral fac~ at which the square tail ~ection i5 ~oined lie~ in the plane of one ~ide of the ~quare ~n~
with i~ fo~ms a single side o~ the ~lab elemen~.
According to on~ preferred embodiment of the pr~sen~ invention, the stone is formed of dn integral ~o~ded pieGe o~ ce~amic material such as concrete.
~he ~hape of the stone is defined by a hexagonal se tion and a square seation with the thickness of the s~one being less tha~ half o~ th~ g~eat~is~ dim~n~.ion 2 ~ 3 - 12 - :
of the stone. ~he hexagonal section has a p~riphery :
formed of six vertical faces, including four ldentical lateral faces and two identioal longitudin~1 face~.
The four la~eral ~aces are dispvseA ag two Opposing pair o~ adjacen~ lateral faces with ~he la~eral faces :~
of each pair fo~ming an internal angle of approximate- :
1~ 90 with the other.
~or hea-~y load application~, the lateral ~; :
faces have lengths which are of $ro~ approximately 3 1~ inches to approximately 5 inche~, preferably ~bout :-4 inch~s. The two longi~udinal faces each form, a~
opposite ends thereof, an angle of approximate~y 135 with one of the l~teral fa~e~ of each pair, ~o ~herePy -~
define a hexagon. ~he longitudinal and lateral sides h~ve length6 such that the hexagonal section, measured from one 90 angle to the other, is ~rom approximately :
g inohes to approximately 11 inches in length. With :
the lateral faoes 4 inches in length, the longitudinal faces ~re ~l~o pre~erably about 4 inches in length.
The square section has a periphe~y o~ foux verti~al :~
faces each havin~ a len~h equal to the length of the lat~ral faces of the hexagonal sec~ion. The s~u~re section has one of i~s ~er~ical ~aces l~i~g in the :~
pl~ne of one of the l~teral faces o~ the hexagonal section such ~h~ the vertical faces of the square section adjac~n~ the p}ane ~orm external angles of 2 ~ 3 3 - 12~ - :
135 and 180, respecti~ly, with the resp~ctive longitudinal and lateral ~aces of -the hexagon~l seotion ad~acent the plane.
The heavy du~y paving stone of the pre~ent invention is eapable o~ producing a ao~lplete ground co~er using only a single shape, but t~le stipulation that the longitudinal sides Pe les~ c~ o~her than twice the later~l sides considerably redu~es the n~mber of patterns that can be achieved, compared to that o~ ~ny U.S. Patent No. 4t544,305 and the }~oelling p~tent, which are their primary objec~ive~.
The heavy duty s~one of the present invention is capable of mai~taining a le~el ~nd con~inuou~ surface under heavy loads, particularly truck loads, such as th~ loads from ~he H-~0 wheel loading standard, wi~hout vertical displacement or, ~ .
al~erna~ively frac~ure of the sto~es. The stone of the presen~ invention is stxucturally supexior ~o the stones of my prior patent and the Ko~lling patent, and o~ s~ones large~ or smaller slze or differently proportioned, particul~rly i~ it~ ability to suppor~
heavy truck loads.
The heavy du~y ~tone of the present invention fulfills a need for areas subje~ed to ~he hea~iest H-20 truc~ e loads, which axe ~sually larg~ regularly shaped areas such as may be found ~, 2 ~ 3 3 - 13 - ;~
adjacent loading docks in retail shopping cenkers. In .
~u~h areas, it is ~enerally desirabl~ to ~ay -the pa~ing s~ones with maah.inery, prea~ranged on palettes.
~ n an integr~ted desi~n, such shipping areas will ~e adjoined by p~destridn areas or arPas exposed to passenger vehicles or othe~ lighter vehicular traffic. Such ar~as may have mo~e complex boundaxies to ~ccommodate ~andscaping or st~uc~ures~ As a result, the stones laid there px~erably are lighter :~:
and smaller t~ th~ heaYy du~y stones referred to ~ :
above, and more am~na~le to being laid by hand, : :~
preferably ao~orming ~o the Am~ri~an Society for ~esting and Materi~ls (AST~) Standard Sp~cifioation ~or Solid Concrete Interlockin~ Paving Units, which call~ ~or s~ones having maximum dimensions of ~-l/2 x~;
9-l/2 in~hes~ ~he stones ~or such areas must, howe~er, blend aesthetically with ~he heavy duty stone in the adj~cent truck ~oading areas.
X have ~ound that, in aGco~dance with further pri~ciples o~ my inventi4n, stones smaller than the h~av~ duty s~one can be use~ adjacent ~uch stones with~u~ appearing ~o be di~ferent in size or ::
~hape, and still suita~le ~or the loads to which they are exposeq~ Furthermora, such stones can be made within the AST~ speci~ication. Fo~ th.is application ~-2 ~ 3 3 - 13~ -of the i~vention, I prefer that ~he sto~e hav~ ~he same an~las as the heavy ~uty stone, and ~imilar lateral and longitudinal sides, but t:hat the later~l sides be ~rom approximatel~ 2~ to 3~ inches in length. Fur~her, ~ pre~er tha~ the ].ongitud~nal sides ~e perce1vably mo~e than one-half the length oE ~he l~teral sides bu~ perceivably less than twice the length of the lateral sides.
The ~atios of the la~eral side~ to the longitudinal side~ oan be ~elected ~or each appliaation, consider~ng the orientation ~f the stones with respe~t t~ th~ di~ections from which ~hey Will be viewed. P~eferably, the lengths of the sides are selected such th~t ~he overall leng~h and wid~h o the stone are e~al ~o or sligh~ly less than ~40mm and 160mm, r~speotively.
By mean~ of th~ ~ore~oing angular an~ l~ngth relationship~ of ~hat periphexal face, adjacent ~lab elements ~n be arranged in a wide variety of ~rien-tations relative to each other to provide many di~er-ent interlo~ing pattarns. In addition, and impor-tantly, ~he elements form ~ structurally skrong design particularly suitable for interlockiny paving elements of concrete or other ceramic makerial and present an appearance of a versatile hexagon and square design.
Brief Description of the_Drawinqs Fig. l is a front perspect:ive view of a first preferred embodiment of a slab element of my invention for covering the ground and the like.
Fig. 2 is a front elevational view of the slab element of Fig. 1.
Fig. 3 is a top plan view of the slab element of Fig. 1.
Fig. 4 is a bottom plan view of the slab element of Fig. l.
Fig~ 5 is a rear perspective view of the slab element of Fig. 1.
Fig. 6 is a top plan view similar to Fig. 3 -of a mirror image of the slab element of Fig. 1 and is another preferred embodiment of a slab element according to my invention. -Fig. 7 is a top plan view of a repeating -~
first closed pattern with the slab elements of Fig. 1.
Fig. 8 is a top plan view of a repeating second closed pattern with the slab elements of Fig. -1 . :
Fig. 9 is a top plan view of a repeating third closed pa~tern with the slab elements of Fig. l.

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Fig. 10 is a top plan view of a repeating fourth closed pattern with the slab elements of Fig. 1 and Fig. 6.
Fig. 11 is a top plan view of a repeating fifth closed pattern with the slab elemen~s of F'ig. 1 and Fig. 6.
Fig. 12 is a top plan view of a repeating first open pattern with the slab elements of Fig. 1 and Fig. 6.
Fig. 13 is a top plan view of a repeating third open pattern with the slab elements of Fig. 1.
Fig. 14 is a top plan view of a repeating fourth open pattern of slab elements of Fig. 6.
Detailed Description of the Preferred Embodiments With particular reference to Figs. 1 through 5, there is shown a slab element 1 comprised of a main hexagonal section 2 and an integral square tail section 3. The main hexagonal section 2 is comprised of four lateral and two longitudinal faces or edges 4 through 9 around the periphery thereof. First longi-tudinal face 4 adjoins a lateral face 5, which is internal, to form an included angle 14 of approx~
mately 135. First lateral face 5 adjoins a second lateral face 6, which is exposed, to define a~ in-cluded angle 15 of approximately 90. Second lateralface 6 adjoins a second longitudinal face 7, also exposed, to define an included angle 16 of ` `

2 ~ 3 3 ~ 16 -approximately 135~. S~cond longitudinal ~ace 7 adjoins ~hird exposed lateral ~ace 8 to de~ine an included angle 17 o~ approximately 1~ Third ~ ~:
lateral façe ~ adjoins ~ ~ourth exposed lateral ~e 9 to de~ine an inçluded angle 18 oE approxima~ely 90.
Four~h late~al face 9 ad~oins the first longitudinal face 4 to define an included angle 19 o~ approximately 135. Each of the lateral faces 5, 6, 8 ~nd 9 are, for the he~vy load stone, ~rom approxim~tely 3~5" to 5" in length, and pre~era~ly ahout 4" in length~ :
~on~itudinal, face~ 4 and 7 are equal in length. The overall le~gth of the ~exagonal section o~ ~he heavy load bearing stone is ~rom about g to abo~ 11 inches measured from the points o~ the go n angles. Tha~ is, th~ le~g~h of ~ lon~itudinal ~ide plus the length of ~he diayonal of the square section equals ~çt~een approx~ma~ly g" and approxi~ately 11". With the lateral sPction5 about 4" in len~th, the longit~inal sections are preferably also about 411 in leng~h and e~h equal ~o the leng~h of the lateral fa~e~ 5, 6, and 9. The ~a~e~ , 6, 7, 8, and ~ lie in planes which are su~ta~tially pe~pendi~ular to ~he plane~
oontainin~ the upper ~nd lower surface la a~d lb, re~pectively, o~ the slab elements, ~ he tail section 3 is çomprised o~ fo~r adjoining f~çes 10, 11, 12 ~nd 13 aro~nd the peripher~r thereo~, ~ach of whi~h is equal i~ length ~o ~hat o~

2~8e~33 the faces 4, 6, 8 and 9 of the hexagonal main section 2. The four tail sectlon faces 10, 11, 12 and 13 preferably define substantially a square when viewed from the top as in Fig. 3. Of faces lO, ll, 12 and 13, only face 10 is internal to the stone; the others are exposed.
The square or tail section 3, which is integral to hexagonal main section 2 to form the slab element l, adjoins at its lateral internal face 10 the hexagonal main section 2 along first lateral internal -~
face 5 thereof. Face 10 and first lateral face 5 are substantially coextensive in size and shape and ; ~-spatially coincident with each other such that no portion of either of those faces extends beyond the other. The vertical plane along which lateral face 10 and first lateral face 5 spatially coincide is indi- -cated by reference numeral 21. Face B joins face 4 to form an external 135 angle therewith. Faces ll and 6 ~-are adjacent and may be viewed as two faces joined at 180 angle along one edge forming a common face of the stone.
In my preferred embodiments, the upper edge of each face of each main and tail section is cham- ~ -fered as indicated by reference numerals 20, 20. The chamfer is preferably 6 mm. in height and 4 mm. in depth and, as shown in Fig. 2, starts inwardly from the outer wall of the face towards the interior of its :: , .: - .

2~5~33 respective main or tail section 2 or 3. When the slab element 1 is thus provided with chamfers 20, upper edge 21a of plane 21 may be viewed as a false joint in which case two identifiable polygons of known shape, namely, a hexagon and a square, are clearly discern-ible in slab element 1 as is especially shown in Fig.
3.
Alternately, slab element 1 need not be provided the chamfers 20 and would then appear as in the bottom plan view of Fig. 4.
As seen in Fig. 2, the slab element 1 is a tile-like slab with a width and length greater than its thickness, its thickness being preferably less than half the largest or longitudinal dimension of the element. This is in contrast to block-like elements as shown in Graham U.S. Patent No. 474,339 and Dodgson British No. 610.
In order to provide an even further variety of design from that available with the slab element 1 shown in Fig. 1, an alternative preferred embodiment generally depicted as 1' is provided as shown in top plan view in Fig. 6. Slab element 1' is identical in all respects to slab element 1 except it is a mirror image thereof. Alternatively, slab element 1' could be obtained by providing slab element 1 with chamfers 20 on both the upper edge as shown as well as along the bottom edge (not depicted) and turning slab 2~5~33 .

element 1 over. Providing a slab element 1 having chamfers 20 along the upper edge and the bottom edge eliminates the need for an alternative slab element 1', but is not generally desirable in that false joint 21 will be created on both the top and the bottom of ;~ ~
the slab element creating unnecessary stress concen- ~-trations and leavin~ less material to maintain the two sections as one integral element. Such weakening at the false joint is not desired in that the slab element could break more easily at the joint 21a under the stress of a heavy load, thereby losing the inter-lock feature sought by my invention. Moreover, having chamfers 20 along the bottom edge of slab element provides an opportunity for the sand between the slab elements to slowly fill the crevices left by the i~
chamfers on the bottom, causing the slab elements to `~h come loose or have less stability when they are i provided in an overall pattern to cover the ground as contemplated by my invention.
As more fully discussed hereinafter, a ground cover may be made by using any substantially L-shaped slab element comprised of two or more differ-ent integral sections of simple geometric shape which meet certain dimensional criteria. When such L-shaped sections are disposed in a common plane, adjacent slab elements are capable of having a wide variety of orientations with respect to each other and can result :~ -: . ~ . . . - , . .. . .. ~

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in ~ vast number of clif~erent interlockirlg pa~terns.
~owever, to satis~y ~he critaria o-f my in~rention, the :~
heavy duty sla}~ ele~nent must meet the ~ollowing dimen-sional ariteria with respect t:o include:d angles and length of faces:
(A) The slab element must be generally L-shaped and c:omprised o~ ~wo i.ntegral sectivns, one a hexagon and one a square;
(B) Each inc:luded angle of each sec:tion :
mu~t be either 135 or so o; ~C) The len~th o~ eaah face of each ~ection must ~e ~uS~h . ~ ~
~hat the lateral faces ar~ ~rom approximat~3ly 3 . 5" to 51- in length and, when mul~iplied by the squ~re root o~ 2 and added to the length of the longitudinal si~es, is between ~pproximately ~" ~nd ll"; (~) The internal spati~lly coincident ~ace~ of ad; oinin~ sections mu~t be coext~ensive in ~ize an~ hape ~E~ ~he square section musk ~djoin a side of the hexagon~l section which is adjacent a 90 ~ngle o~ the hexagon.
When th~se cri~eria are s~tis~ied, the resultin~
elemen~ 1 will ~e a ~evan i~ided :~igure, with two faces 4 and 1~ having merged in~o one coplanar surfa~e.
Figs. 7 through 14 show some o~ ~he man~
~faried patterns o~ ground c:overs whi~h ~an he obtained 2~933 ~::

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by using slab elements 1 and/or 1' of my invention.
The chamfers 20 and dummy joints 21a have been omitted to facilitate an understanding of the manner in which the patterns may be created, but it is to be under-stood that it is preferred that elements with such chamfers and dummy joints be employed. In the edgers 115 and 116, the main section 2 of a slab element 1 has been modified to main section 2a or 2b, respec-tively. It should be readily apparent that edger ~-elements may be useful to finish certain patterns and may be created by eliminating any part of a section along a line formed between two confronting face intersections. Also, preformed edges are preferable to breaking a complete slab element 1 as that could lead to frayed edges and weakened elements.
Typically, the slab elements of my invention will be employed to form one of two types of patterns which I refer to as closed or open pat~erns. Examples of closed patterns are shown in Figs. 7 through 11. I -~ -have used the term closed pattern to mean that there is no opening in the center or in any interior region of the pattern. Conversely, I have used the term open pattern to refer to patterns such as are shown in Figs. 12 through 14, in which t~ere is at least one opening in the interior of the patterns. Furthermore, a pattern is repeating where one or more repeaters, as hereinafter described, repeat in similar orientation. ;~
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2 ~ 3 3 As will be more fully understood by reference to the drawing figures, there are a number of basic "repeaters" which are employed in all of the above patterns whether open or closed. These repeaters consist of two of my slab elements 1 and/or 1' in a particular adjoining relationship. For example, a first repeater is indicated generally at 51 in Fig. 7.
First repeater 51 consists of two slab elements la and lb in a common plane wherein lateral faces lla and llb of tail sections 3a and 3b are located proximate to each other. Similarly, second repeater 52 consists of two slab elements la and lb in a common plane wherein lateral faces 9a and 9b of main sections 2a and 2b are located proximate to each other. As can readily be seen in Fig. 7, using a multiplicity of first repeaters 51 and second repeaters 52 results in the repeating first closed pattern 50. Upon further inspection, a third repeater 57 may be seen in Fig. 7.
Third repeater 57 consists of two slab elements la and lb in a common plane and in which longitudinal face 4a of slab element la is located proximate ~o longitudi-nal face 7b of slab element lb. Third repeater 57 may be employed as was done in Fig. 7 by making rows of third repeaters 57 which alternate between right side up and rotated 180. Similarly, rows of third repeaters 57 may be employed wherein all third repeaters have the same orientation as is shown in .

Fig. 8 as a repeating second closed pattern 55. Also shown in Fig. 8 is a fourth repeater 56 which consists of two slab elements la and lb in which lateral face ~a of main section 2a of slab element la is located proximate to lateral face llb of tail section 3b of ~ ~
slab elem~nt lb. A fifth repeater 61, shown in Fig. ~-9, consists of two slab elements la and lb in ~hich longitudinal faces 4a and 4b of slab elements la and lb, respectively, are located proximate to each other while their tail sections 3a and 3b are spaced away from each other.
Sixth repeater 66 is shown in Fig. 10 and, when employed in a repeating fourth closed pattern 65, also utilizes fourth repeaters 56 and 56'. Sixth repeater 66 consists of one slab element 1 and one slab element l' wherein the first longitudinal face 4 of slab element l is located proximate to second longitudinal face 7 of slab element 1'. Fourth repeater 56' is virtually identical to fourth repeater 56 except that the former is made with slab elements l' rather than slab elements 1.
As shown in Fig. 11, a fifth closed pattern 70 may consist o~ alternate repeaters 57 and the mirror image sla~ elements 1' as shown at 71. Other repeaters may be employed with my invention, but I
have chosen to illustrate only some of those repeaters for simplicity.

.: . , : .

.:

The varied patterns exemplified in Figs. 7 ~-through 13 employ a large number of slab elements disposed in a common plane with faces of each of most ~ -of those slab elements proximately located relative to faces of at least four other slab elements. That the above relationship is met is borne out by examination of any one of the several slab elements contained in the interior, as opposed to the periphery, of the above patterns and the proximate relationship had with the neighboring slab elements.
The slab element of the present invention does not lend itself to the same pattern variations of that disclosed in my prior Patent No. 4,544,305, but provides an element for forming other attractive designs, particularly those of the more classic type which have the appearance of comprising regular hexagons and squares. Even a pattern providing imbedded regular octagons as shown in Fig. 14 is possible. While actually the hexagon segments of my slab elements are not true regular hexagons, it has been found that use of an equilateral hexagon where ;~
the angles include 90' and 135 angles creates a perception of regular hexagons to most observers.
Additionally, making an opposed two of the angles of a regular hexagon equal to 90 and the othQr four equal to 135, with an integral square section adjacent one of the lateral sides forming the 90 angle provides 2~8~3~ ;`

fo~ clnsed ihtexlocking ~a~-~erns and for structural enhancement over the prior ar-t, which are ~mong the in~ended advantages set fo~th above. ~uch ~ pattern is one which is simple to cost of concrete or o~her such material and is one which is not as prone to ~reakage as other shapes.
Impor~ant f~atures of the stones o a preferred e~bodiment of the present in~ention are those tha~ make i~ capable of forming a ground cover which will support he~vy truck loads such as those to whiah it would be subjec~ed under with vehicles with ~tandard ~ dual tru~k whe.els. Pat~erns which b~st suppo~t such loads with are tho~e shown in Fiys. 7-11.
The patterns of Figs. 7-9 are, however, pre~erred beo~use the~ be ~ade with a stone of a single shape, where those o~ Figs. lO-ll require right and le~t handed versions of the same ~to~e. The pattern of ~ig. ~ i~ believed to be the best ~or heavy load ~earing pavement surfa~es.
It ~s generally understood th~ an H-20 dual -~
truck wheel must carry 1~000 lbs. o~ live load plus 30~ for impact Oh a dual wheel ~footprint~ 10" x 20"
(khown as the AASH~0 specific~t.ion~, i.e., a 41,~D~
lb, ~xle load. The tire trea~ on such whaels are 8~
wide with a 4" space betwee~ ~hem due to the sh~pe of the tire. The are~ in c~ntact with the pavement . .
.. . ~ -.
:-- . ~ .

2~93~

extends lO" front to back, so a loacl of 10,400 lbs. is incurred under each 8 x 10" tlre "footprlnt."
It is believed that the st:one of the present invention is superior to prlor art stones for the general reasons. A 10" x 20" tire footprint must support a loading of 130 lbs/sq. in., which exceeds the 30 psi bearing capacity of well compacted dry soil. Accordingly, a single paving stone placed directly on 30 psi soil would have to have an area of 347 sq. in. to carry the 10,400 lb. load without sinking into the soil. An 18.6+ inch square paving stone would have such area, but a stone of thickness normal to the trade would crack under H-20 wheel loading because of the uneven load by the rolling wheels. Furthermore, an 1806" square stone would have ~ ';
to carry nearly twice the load because its size permits two tires to bear on it simultaneously. The 18.6" square would weigh 97 lbs., too heavy for manual placement. By contrast, an 1,000 lb. automobile tire load can be carried on a 6x6 (36 sq. in) stone laid on 30 psi soil without significantly indenting the soil.
Unlike the large area of monolithic rein-forced concrete required to carry high volume truck traffic and have joints 50-60 ft. apart, a paving stone roadbed has many joints. Rainwater inevitably percolates through these joints and down through the gravel base to the soil. wet soil has far lower : -: . . ,, , . ~ :- , --- 20g~33 bearing capacity than dry soil, so that the assumption of a 4,000 psi soil load bearing capacity cannot be made in engineering design, but rather a value of 1500-2000 psf would be more realistic. The probabil-s ity that the stones will be fractured by the rolling wheel load is minimized where the ratio of length to breadth is close to the 8x20 ratio of the tire foot-print, because as the wheel comes on to the stone, it causes a rocking action that is countered by the interlocking action between stones, thereby creating severe tensile or fracture stress in the cross-section of the stone. ~ -When the 8" x 10" tire footprint is centered on the stones that comprise 80 sq. in. of bearing .: .- .
surface, the load is transmitted downward, and develops a pattern on the soil. As the full load of the tire reaches center on the stone cluster, the pressure driving the gravel into the soil sub-base is .
maximum at the edges of the vertical projection of the loaded stone pattern and the vertical surfaces of adjacent stonages cannot contribute support. The downward pressure exerted by the stones also has a lateral component on cohesionless material which causes the gravel around the perimeter of the loaded stones to bulge upward, much like a person's footprint in the sands of an ocean beach. This tends to raise the adjacent edges of the unloaded stones just prior - . . . . . : .. : . : :. -: . . . . .

2~8~g~3 to becoming loaded by the on-rolling tire footprint.
The result is a rocking action on the succession of stones the tire traverses. Though each traverse produces only a small displacement, t:he effect is cumulative. Stones sized and shaped to act as unity, and having as large an area on the vertical surfaces as possible, obtain maximum frictionaL resistance to displacement from the stones adjacent on the perimeter of the footprint load.
In addition to the above, the forces of the rolling load exert a tensile stress in the stones. As the vertical centerline of the tire comes to the edge of the stone, most of the wheel load is momentarily concentrated on the edge of the stone. This magnifies the tipping or rocking action which is resisted by the interlocking of the opposite edges of the stone with its neighboring stones. The result is a severe tensile stress developed just ahead of the leading edge of the tire. Accordingly, the larger the cross section of the stone and the shorter the lever arm resulting from the length of the stone, the more resistant it will be to tensile fracture.
Fig. 9 shows a pattern in which pairs of stones of the present invention arranqed matingly to form an irregular hexagon. The square section that forms the tail, or ~ shape, of the stone, is joined to the hexagonal section. Were the square and hexagonal - . ~ , ; :
.

20~3~

sections not integral, the square would be a separate element form the hexagon.
With separate sections, as an H-20 tire advances on the stone array across the longitudinal faces, a severe rotational or tipping action will develop on the first hexagon being traversed, and when the leading edge crosses the horizontal centerline of this hexagon, the 8'l side footprint will thereafter load only 2" of a stone with a 5.66l' diagonal dimen- -sion of each of the two cubes, for example, as it proceeds to the second hexagon. Thus, four stones will be contacted by the wheel and subjected to severe, eccentric loading. If the tire path is rotated 90~ to the longitudinal direction, so as to cover only one line of cubes, each cube will become disproportionately loaded when the tire reaches the centerline of the array causing it to depress more than the two hexagons and the stones of the adjacent identical array. This is because the 10,400 lb. load is not uniform over the entire 8" x 10" footprint, ~ -since tire shape is circular, as discussed and an- -alyzed above.
By contrast, the stone of the present invention has each cubical appendage integral with the hexagon to create a rigidity that resists the deflec-tion and rotational forces imposed by the tire at all times during the traverse.

Furthermore, with integral cubes and hexa-gons, when the direction of travel is longitudinal the ~-resulting forces on the line of cubes that is formed from a layout of this array will be even worse, for the tire footprint will engage the extending corner of each cube first, and when the footprint becomes centered over the centerline of the cubes, the higher load level will be born on just two cubes. Here again the integration of the cube appendages with the hexagons of the present invention, which at this point have become loaded, albeit eccentrical, provldes support and resistance to rotation.
With stones of my prior Patent No. 4,544,305 and the Koelling patent, when an H-20 tire traverses the stones in some directions, 2 to 3 times or more of a tire will extend onto adjacent stones than with stones of the present invention. While parts of 10,400 lb. load not being borne by two stones in each array are being carried by adjacent stones, the unit load, i.e., per sq. in., will be much lower than at the tire footprint centerline, but the small loads on these corners will nonetheless tend to produce the adverse side effects of initiating rotation in at least four of the neighboring stones.
When the dual wheel is considered in its entirety, i.e., two 8" x 10" footprints separated by a 4" space between, it can be seen that the stone of my prior patent would require f ive ~ton~s to carr~ the 20,800 l~s., even though only two are needed ~or a single tire. ~he Koelling patent~s separ~te s~uares and hexago~s ~ould have eig~t of ~he small ~q~ares depressing more ~han the companion ~exagons. Neither of these arran~ements would retain theilr horizo~al plane s~rfaces as well a~ the presen~ in~ention. : -~
If, to correct the ~ore~oin~ dia~repano .ies ~ ~ :
~he stones of my prior paten~ or of the Koellin~
patent are enlarg~d, ~he ~ide dimensions ~ould have ~o be increased such th~t the weigh~ of each stone would ~e s~bsta~tially inareased.
Accordingly, the present in~ention provides ~
a signific~n~ly more ~ta~le stone for heavy tr~ck ~:
wheçl loads. ~o stones can fully carry the foo~print of a single tire of ~ dual H-20 w~eel, ~hich the prior art stones cann~t do. This in turn insures long-te~m :
integrity of ~e horizontal plane surface ~s well as minimal ed~e and main ~ody frac~rin~. To achieve higher strength, t~e stones of prior art wo~ld have to be made mu~h heavier, sub~ti~u~ing one flaw for another.
In a~cordance with a fur~her embodiment of the inven~ion, the a paving stone similar to the heavy duty stone descri~ed above is p~o~ided for li~hter load appl.ications, partiaularly where ped~strian and ligh~er vehicular tr~f~ic ~reas are to be paved 2~933 _ 31A -adj acent the he~vy lo~d areas, whi~h can be laid easily hy hand. In such a s~one, such ~IS tha~
illustrated in Figs. 1-~, the lateral faces 5, 6, 8 and 9 are e~ual to from Z . 5" ~o ~ . 5" in length, Wi~h the length~ o~ the longitudinal sides equ~L1 to peroeptibly more than one half the length of the lateral sides and p~rceptibly le~s than twice ~he leng~h of the lateral sides.
Ideally, the overall dimen~;ions o:~ ~he stone are slightly less than about ~. 5" (or 240mm~ in length, and slig~tly le6s ~han abou~ 6~5" (or 160mm) in width . Irhese ariteria are sa~isf ied ~h~re ~he lateral and lon~itudinal side~ are es~2l1 in length, and e~ual to ;a~out 3 inches.
Having desc:ri~oed rny invention, wha~ is alaimed is:

Claims (21)

1. A paving stone capable of fully covering the ground or other like surface with a plurality of stones of a single identical shape and size to support heavy vehicular loads thereon, said paving stone comprising:
a hexagonal section and a square section integrally formed of a single piece of ceramic mate-rial having a thickness less than half of the greatest dimension of the stone;
said hexagonal section having a periphery formed of six vertical faces, said six faces including four identical lateral faces and two identical longi-tudinal faces;
said four lateral faces disposed as two opposing pair of adjacent lateral faces with the lateral faces of each pair forming an integral angle of approximately 90° with the other, the lateral faces having equal lengths of from approximately 3? inches to approximately 5 inches;
said two longitudinal faces each forming at opposite ends thereof an angle of approximately 135°
with one of the lateral faces of each pair, to thereby define a hexagon, the longitudinal and lateral faces having lengths such that the length of the hexagon section from one 90° angle to the other is from approximately 9 inches to approximately 11 inches;

said square section having a periphery of four vertical faces each having a length equal to the length of the lateral faces of said hexagonal section, said square section having one of its vertical faces lying in the plane of one of the lateral faces of the hexagonal section such that the vertical faces of said square section adjacent the plane form external angles of 135° and 180°, respectively, with the respective longitudinal and lateral faces of the hexagonal section adjacent the plane.

2. The slab element of claim 1, wherein each lateral face and each longitudinal face has an upper edge portion which is chamfered.

3. A ground or similar surface cover comprising a plurality of interlocking ceramic slab elements, each slab element including:
a hexagonal section and a square section integrally formed of a single piece of ceramic mate-rial having a thickness less than half of the greatest dimension of the stone;
said hexagonal section having a periphery formed of six vertical faces, said six faces including four identical lateral faces and two identical longi-tudinal faces;
said four lateral faces disposed as two opposing pair of adjacent lateral faces with the lateral faces of each pair forming an integral angle of approximately 90° with the other, the lateral faces having equal lengths of from approximately 3? inches to approximately 5 inches;
said two longitudinal faces each forming at opposite ends thereof an angle of approximately 135°
with one of the lateral faces of each pair, to thereby define a hexagon, the longitudinal and lateral faces having lengths such that the length of the hexagon section from one 90° angle to the other is from approximately 9 inches to approximately 11 inches;
said square section having a periphery of four vertical faces each having a length equal to the length of the lateral faces of said hexagonal section, said square section having one of its vertical faces lying in the plane of one of the lateral faces of the hexagonal section such that the vertical faces of said square section adjacent the plane form external angles of 135° and 180°, respectively, with the respective longitudinal and lateral faces of the hexagonal section adjacent the plane.

4. The ground or similar surface cover of claim 3 including a first plurality of said elements arranged in a first repeatable configuration, said first repeatable configuration comprising a first and a second of said interlocking slab elements each shaped substantially identically, and wherein the longitudinal faces of the hexagonal sections of each of said elements include a first longitudinal face adjacent said square section and second longitudinal face, said first longitudinal face of said first slab element being located proximate to said first longi-tudinal face of said second slab element.

5. The ground or similar surface cover of claim 4 wherein a substantial number of said first plural-ities of said first repeatable configuration are arranged such that any face of a slab element located proximate to a longitudinal face of another slab element is a longitudinal face.

6. The ground or similar surface cover of claim 3 including a second plurality of elements arranged in a second repeatable configuration, said second repeat-able configuration comprising a first and a second of said interlocking slab elements each shaped substan-tially identically, and wherein one of said faces of said square section of said first slab element being located proximate to said lateral face of said hex-agonal section of said second slab element next to the lateral faces to which said square section of the second element is joined.

7. The ground or similar surface cover of claim 6 wherein in said second repeatable configuration said first longitudinal face of said first slab element is located proximate to said second longitudinal face of said second slab element.

8. The ground or similar surface cover of claim 7 wherein a substantial number of said second plural-ities of said second repeatable configuration are arranged such that any face of a slab element located proximate to a face of a square section of another slab element is a hexagonal section lateral face.

9. The ground or similar surface cover of claim 7 wherein a substantial number of said second plural-ities of said second repeatable configuration are arranged such that at least one square section face of one of said slab elements is located proximate to one square section lateral face of another of said slab elements.

10. The ground or similar surface cover of claim 3 including a third plurality of a third repeatable configuration, said third repeatable configuration comprising a first and a second of said interlocking slab elements each shaped substantially identically, and wherein one of said faces of said square section of said first slab element is located proximate to said third lateral face of said hexagonal section of said second slab element.

11. The ground or similar surface cover of claim 10 wherein in said third repeatable configuration said first longitudinal face of said first slab element is located proximate to said second longitudinal face of the second slab element.

12. The ground or similar surface cover of claim 3 including a fourth plurality of a fourth repeatable configuration, said fourth repeatable configuration comprising a first and a second of said interlocking slab elements shaped substantially identically, and wherein one of said lateral faces of said square section of said first slab element is located proxi-mate to one of said faces of said square section of said second slab element.

13. The ground cover of claim 3 including a fifth plurality of a fifth repeatable configuration, said fifth repeatable configuration comprising a first and second of said interlocking slab elements each shaped substantially identically, and wherein the lateral faces of the hexagonal sections of said first and second slab elements opposite from the lateral faces to which the square sections of the elements are joined are adjacent.

14. The ground cover of claim 3 including a sixth plurality of a sixth repeatable configuration, said sixth repeatable configuration comprising a first and second of said interlocking slab elements each shaped substantially identically, and wherein the lateral face of the hexagonal section which is oppo-site to the lateral face to which the square section is joined to the first element is adjacent to the face of the square section of the second element which is opposite the face of that square section which is joined to the hexagonal section of that element.

15. The ground cover of claim 3 including a first plurality of said element arranged in a seventh repeatable configuration, said seventh repeatable configuration comprising a first and a second of said interlocking slab elements each shaped substantially identically, and wherein the longitudinal faces of the hexagonal sections of each of said elements include a first longitudinal face adjacent a face of said square section and a second longitudinal face, said first longitudinal face of said first slab element being located proximate to said first longitudinal face of said second slab element;
whereby, pairs of identical first and second slab elements form cooperating load bearing interlocking pair of paving stones having overall dimensions of from approximately 10 inches to approximately 14 inches by from approximately 11 1/2 to approximately 14 1/2 inches.

16. The ground cover of claim 15 including a plurality of said seventh repeatable configurations arranged with respect to each other such that a second longitudinal face of a first slab element is located proximate to a second longitudinal face of a second slab element of another one of said seventh repeatable configurations.

17. The ground cover of claim 16 wherein any adjacent faces of a square section of a slab element of any of said plurality of said seventh repeatable configurations are located proximate lateral faces of slab elements of different ones of said seventh repeatable configurations.

18. An integrally formed tile-like slab element of cast ceramic material comprising:
a seven sided top face;
a seven sided bottom face identical to but a mirror image of said top face and parallel thereto;
and seven side faces each perpendicular to said top and bottom faces and each being rectangular, said seven side faces including first through seventh faces, wherein:
the second, third, fifth and sixth faces have equal lengths, and the first and fourth faces have equal lengths, that are perceptibly more than half, and perceptibly less than twice, the length of the second, third, fifth and sixth faces, and the length of the seventh face is twice the length of the second face; and said first face adjoining and forming an internal angle of approximately 135° with said second face, said second face adjoining and forming an internal angle of approximately 90° with said third face, said third face adjoining and forming an internal angle of approximately 135° with said fourth face aid fourth face adjoining and forming an external angle of approximately 135° with said fifth face, said fifth face adjoining and forming an internal angle of approximately 90° with said sixth face, said sixth face adjoining and forming an internal angle of approximately 90° with said seventh face, and said seventh face adjoining and forming an internal angle of approximately 135° with said first face.

19. The slab element of claim 18 wherein:
the length of the second, third, fifth and sixth faces is from approximately 3 1/2 inches to approximately 5 inches; and the length of the first and fourth faces is such that, when added to the length of the second face multiplied by the square root of 2, is from approximately 9 inches to approximately 11 inches.

20. The slab element of claim 18 wherein:
the second, third, fifth and sixth faces having lengths of from approximately 2 1/2 inches to approximately 3 1/2 inches.

21. The paving stone of claim 20 wherein the overall length of the stone is slightly less than or approximately equal to, but not greater than, 240 mm., and the overall width of the stone is slightly less than or approximately equal to, but not greater than 160 mm.