U.S. patent number 3,842,562 [Application Number 05/299,683] was granted by the patent office on 1974-10-22 for interlocking precast concrete slabs.
This patent grant is currently assigned to The Veggo F. Larsen Co.. Invention is credited to John P. Daigle.
United States Patent |
3,842,562 |
Daigle |
October 22, 1974 |
INTERLOCKING PRECAST CONCRETE SLABS
Abstract
Precast concrete slabs are joined together to form a walk or
patio-like matrix by embedding a plurality of rods in each slab and
providing cavities in the bottom faces of each slab. Each rod has a
hooked end portion which projects beyond opposing end walls of the
slab, the hooked end portions and the cavities being positioned
such that the hooked end portions of one slab are receivable in the
cavities of another slab, whereby the slabs may be interlocked end
to end to form a strip of slabs. Similar cavities and rods having
hooked ends may be positioned in each slab at right angles to the
aforementioned rods and cavities to permit sidewise connection of
the slabs along with the end-to-end connection.
Inventors: |
Daigle; John P. (Trumbull,
CT) |
Assignee: |
The Veggo F. Larsen Co.
(Hamden, CT)
|
Family
ID: |
23155805 |
Appl.
No.: |
05/299,683 |
Filed: |
October 24, 1972 |
Current U.S.
Class: |
52/583.1; 52/604;
404/50 |
Current CPC
Class: |
E01C
5/08 (20130101); E04C 2/06 (20130101); E04F
15/08 (20130101); E01C 2201/12 (20130101) |
Current International
Class: |
E04F
15/08 (20060101); E01C 5/06 (20060101); E01C
5/08 (20060101); E04C 2/06 (20060101); E04c
002/06 () |
Field of
Search: |
;52/583,587,582,436,431,432,593,595,604,422,588,589
;404/40,41,28,29,34,50 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Friedman; Carl D.
Attorney, Agent or Firm: DeLio and Montgomery
Claims
What is claimed is:
1. In a precast concrete slab for connection with other said slabs
to form a generally horizontal, stable, load bearing surface, the
improvement which comprises a plurality of rods firmly embedded in
said slab and a plurality of cavities in the lower face of said
slab and spaced from the adjacent edges thereof, said rods
providing a plurality of first hooked end portions projecting
beyond a first end wall of said slab adjacent the plane of said
lower face and a plurality of second hooked end portions projecting
beyond an opposing end wall of said slab also adjacent the plane of
said lower face, said end walls corresponding to said adjacent
edges, said hooked end portions being adapted to lie beneath a
peripheral edge portion and to be received in said cavities of an
adjacent slab having similar hooked end portions and cavities, said
cavities and said hooked end portions of each slab corresponding in
number, whereby a plurality of said slabs are interlockable end to
end by a scissor action to form a strip of slabs.
2. A concrete slab as in claim 1 wherein said plurality of rods
comprises first and second pairs of rods, the hooked end portions
of said first pair projecting beyond an end wall of said slab
opposite the end wall beyond which project the hooked end portions
of said second pair.
3. A concrete slab as in claim 2 wherein the hooked end portions of
said first pair of rods are spaced farther apart than the hooked
end portions of said second pair of rods.
4. A concrete slab as in claim 2 wherein the hooked end portions of
said first pair of rods are spaced apart substantially the same
distance as the hooked end portions of said second pair of
rods.
5. A concrete slab as in claim 1 wherein said plurality of rods
comprises a pair of rods, each end of each rod defining a said
hooked end portion and the end portions of each rod projecting
beyond opposite end walls of said slab.
6. A concrete slab as in claim 5 wherein said rods are embedded
generally parallel in said slab such that each rod passes between a
pair of said cavities.
7. A concrete slab as in claim 6 wherein the hooked end portion of
each rod is equidistant from the hooked end portion of the other
rod which projects beyond the same end wall, whereby said slab is
interlockable from either end with either end of another said
slab.
8. A concrete slab as in claim 1 further including a slot
corresponding to each cavity extending from each cavity to the
adjacent end wall of said slab, and wherein said hooked end
portions include projecting intermediate rod portions, said slots
being positioned to receive said intermediate rod portions of
others of said slabs whereby said intermediate rod portions, when
said slabs are interlocked end to end, lie in a plane no lower than
the lower faces of said slabs.
9. A concrete slab as in claim 1 further including an additional
rod embedded in said slab, said slab having an additional cavity in
the lower face thereof, said additional rod having a hooked end
portion and an intermediate portion each projecting beyond a side
wall at a generally right angle to said other hooked end portions,
said cavity being positioned to receive said additional hooked end
portion of an adjacent slab, whereby said slabs are interlockable
side by side to form a matrix with others of said slabs which are
interlocked end to end.
10. A concrete slab as in claim 9 further including a slot
corresponding to each said additional cavity extending from each
said additional cavity to an adjacent end wall of said slab, said
slot being positioned to receive said projecting intermediate rod
portion of another of said slabs whereby said intermediate rod
portion, when said slabs are interlocked side by side to form said
matrix, lies in a plane no lower than the lower faces of said
slabs.
11. A precast slab for constructional use which comprises a slab
body having substantially parallel first and second surfaces and
end walls lying substantially normal to said surfaces, and at least
one metal rod, said rod having an extended portion firmly embedded
in said slab, an end portion bent to exit from the slab through
said second surface, bent again to lie adjacent the plane of said
second surface and to project beyond the adjacent end wall, the
projecting end being further bent to lie substantially parallel to
said end wall and having a length less than the thickness of the
slab between the first and second surfaces, said second surface
being provided with a recess spaced from said end wall and having a
depth at least equal to the length of said last named rod bent
end.
12. A precast slab according to claim 11 wherein the recess is
spaced from the end wall by a distance equal to the length of the
projecting rod from said end wall to said last named bent end.
13. A precast slab according to claim 11 which includes two rods as
claimed lying substantially parallel and projecting beyond the same
end of the slab and two recesses as claimed.
14. A precast slab according to claim 13 which includes another two
rods as claimed lying substantially parallel and projecting beyond
an opposite end wall and another two recesses spaced from said
opposite end wall as claimed.
Description
BACKGROUND OF THE INVENTION
This invention relates to precast concrete slabs, and more
particularly to precast concrete slabs of the reinforced type for
use in the construction of generally horizontal load-bearing
surfaces, such as walks, roads, patios and the like.
It has long been recognized that precast concrete slabs must not
only have inherent strength for good load bearing qualities and
resistance to weathering and cracking, but also provision must be
made for relative movement of the slabs and the expansion and
contraction of individual slabs, due to various external or
internal forces such as temperature differentials, weather
conditions, natural expansion or contraction of the slab material,
settling of the base or foundation material under the slabs,
contours of the base or foundation, and characteristics of loads on
the slabs, especially whether dead or alive.
For these and other reasons it has been the common practice to
reinforce concrete slabs by embedding steel rods or the like in the
slabs. Movement due to the foregoing forces often is accommodated
simply by laying the slabs loosely adjacent one another to provide
sufficient clearance to permit the movement, or by grouting the
clearance between the slabs with a material which will readily
expand or contract. Various attempts have also been made to reduce
movement by connecting the slabs with mechanical devices, as by
steel hooks and eyes, or the like, as in U.S. Pat. No. 2,780,150 --
Yeoman.
Despite the foregoing improvements, substantial problems still
exist with respect to the stability of the slabs (when laid end to
end or even when connected so as to prevent undue movement or
shifting) relative to one another in one or more of the three
principal planes and intermediate planes. The problem of movement
or shifting becomes especially acute when settling of base or
foundation material occurs under some of the slabs but not under
adjacent slabs, or when it is not practical to prepare a perfectly
level or solid base or foundation. Moreover, while it may be
possible to mechanically connect slabs so rigidly as to avoid such
undue relative movement, these efforts tend to be too complicated
for efficient connection and laying of the slabs in many
situations, such as the formation of walks and roads. Ease of
placement and connection of concrete slabs is an extremely
important consideration in the mass laying of roads, walks and the
like.
OBJECTS AND SUMMARY
Accordingly, an object of the invention is to provide new and
improved precast concrete slabs which can be connected to form a
relatively stable, load bearing surface which at the same time
permits the natural relative movement of such slabs due to various
internal and external conditions.
Still another object is to provide new and improved precast
concrete slabs reinforced in a manner which also provides for ease
of connection and placement of the slabs in strips or in
matrices.
These and other objects, features and advantages of the invention
will be apparent from the specification which follows.
In summary outline, the precast concrete slabs of the invention
satisfy the foregoing and other objects by the improvement of
embedding in each slab a plurality of rods having hooked end
portions projecting beyond opposing end walls of the slab, and by
providing in each slab a plurality of cavities in the lower face of
the slab corresponding in number to the hooked end portions, such
that the hooked end portions of one slab are receivable in the
cavities in another slab whereby the slabs are interlockable end to
end to form a strip of slabs. Side-by-side connection of the strips
of slabs to form a patio-like matrix is accomplished by providing
similar hooked end portions and cavities at right angles to the
first-mentioned hooked end portions and cavities.
The invention accordingly comprises an article of manufacture
possessing the features, properties, and the relation of elements
which will be exemplified in the article hereinafter described, and
the scope of the invention will be indicated in the claims.
DETAILED DESCRIPTION
For a fuller understanding of the nature and objects of the
invention, reference is had to the following description taken in
conjunction with the accompanying drawings, in which:
FIG. 1 is a partially diagrammatic perspective view of several
slabs of the invention connected end-to-end to form a strip of
slabs;
FIG. 2 is a partially diagrammatic plan view of the bottom faces of
the strip of slabs of FIG. 1;
FIG. 3 is a vertical section along the line 3--3 of FIG. 2;
FIG. 4 is the same view as FIG. 3 except for slight relative
displacement of the slab sections shown;
FIG. 5 is a partially diagrammatic elevational view illustrating a
method of laying a strip of slabs of the invention;
FIG. 6 is a bottom plan view of another embodiment of slab of the
invention;
FIGS. 7 and 8 are fragmentary bottom plan views of still other
embodiments of concrete slabs of the invention;
FIG. 9 is a vertical section along the line 9--9 of FIG. 8;
FIG. 10 is a vertical section similar to FIG. 9 showing a method of
connection of two concrete slabs of the invention;
FIG. 11 is a partially diagrammatic bottom plan view of still
another embodiment of concrete slabs of the invention joined
together to form a strip of slabs;
FIG. 12 is a partially diagrammatic bottom plan view of a
modification of the concrete slabs of FIG. 11 to illustrate how the
slabs of FIG. 11 can be connected side by side as well as end to
end;
FIG. 13 is a partially schematic top plan view of a plurality of
the concrete slabs illustrated in FIG. 12 connected laterally and
longitudinally to form a portion of a patio;
FIG. 14 is a partially diagrammatic vertical section along the line
14--14 of FIG. 13; and
FIG. 15 is a partially diagrammatic vertical section along the line
15--15 of FIG. 13.
With reference to FIGS. 1-4, one embodiment of precast concrete
slab 20 of the invention, having a top face 21, a bottom face 22,
end walls 23 and 24, and side walls 25 and 26, has embedded therein
a plurality of reinforcing rods such as the four rods 27. As shown,
the rods 27 have hooked end portions 28 projecting from the end
walls of the concrete slab 20 so as to provide at least two such
hooked end portions 28 projecting from end wall 23 and two such
hooked end portions 28 projecting from end wall 24, in opposite
directions. The pair of hooked end portions 28 projecting from end
wall 23 is axially offset from the pair of hooked end portions 28
projecting from opposing end wall 24 so as to avoid interference
with identical hooked portions extending from slabs placed adjacent
one another to form a strip of slabs. Thus, in the arrangement of
FIGS. 1-4, the rods 27 projecting from end wall 23 are positioned
axially inside the rods 27 projecting from end wall 24, but other
arrangements are useful as explained below.
Intermediate portions 29 of each of rods 27 are of a length
sufficient to bridge a slight gap between adjacent slabs 20 and to
support part of the weight of the adjacent slab, as explained
below. Conventional reinforcing rods 31 may be embedded in the
concrete slabs angularly to rods 27, if desired.
Corresponding in number to the rods 27 in each slab are cavities or
recesses 32. The cavities or recesses 32 are dimensioned to receive
in locking engagement the hooked end portions 28 of next-adjacent
concrete slabs. With reference particularly to FIGS. 3 and 4, it
will be noted that in this embodiment the intermediate rod portion
29 extends below each slab 20 and supports a portion of the bottom
face 22 of the next adjacent slab. By reason of this support it
will be evident that the next adjacent slab is stabilized with
respect to relative vertical movement, while at the same time the
engagement of the hooked end portion 28 in cavity 32 prevents undue
movement in a horizontal (lateral and longitudinal) direction.
Accordingly, upon connection of adjacent slabs in the manner
illustrated, the slabs are held together so as to minimize relative
movement, thereby stabilizing the connected slabs against undue
movement. Since in this embodiment of the invention the
intermediate rod portions 29 extend below the bottom faces 22 of
the slabs, such slabs are more usually employed on a relatively
soft foundation so that the intermediate rod portions 29 may sink
into the foundation.
FIGS. 4 and 5 illustrate a method of connection and placement of
slabs of the invention on a surface 33. One end wall of a slab 20
of the invention is inclined slightly upwardly from the surface 33,
either by lifting or by placement thereunder of a block 34. While
so oriented, the hooked end portions 28 of another slab are
inserted under the raised end wall of the first slab, and the
second slab is then lowered slowly into generally co-planar
relative position such that the hooked end portions 28 slide into
the cavities 32 of the other slab, the interengagement being
effected by a scissor-like action of the slabs, with the edge of
wall 23 (FIG. 4) resting on the rod 29 of the adjacent slab, as a
pivot point. The opposing end wall of the second slab similarly
then may be held in a slightly inclined position, again as by
insertion of a block 34 thereunder, and the operation repeated. By
this method, the rods 27 facilitate quick joinder of the slabs to
form a stable strip, as in a roadway or walk.
FIGS. 6 and 7 show other arrangements of rods and cavities of
concrete slabs of the invention. With reference to FIG. 6, there is
embedded in a concrete slab 35 a pair of rods 36 wherein the ends
of each rod form hooked end portions 37 and 38. Each rod 36 also
includes intermediate portions 39 and 41 which project together
with the hooked end portions from opposing end walls of the slab
35, providing the same functions as the rods 27 of FIGS. 1-5. As in
the embodiment of FIGS. 1-5, the hooked end portions 37 are
slightly offset with respect to the opposing hooked end portions 38
so that when the slabs are joined end to end, there will be no
interference as between the rods 36. In the embodiment of FIG. 6,
the hooked end portions are arranged such that hooked end portions
37 are axially outside of hooked end portions 38. The cavities 42
of this embodiment also are correspondingly offset slightly so as
to mate with the corresponding hooked end portions of rods of
another slab of this embodiment, in formation of a strip of such
slabs, essentially as described with reference to FIGS. 1-5. One
differencee, of course, from the embodiment of FIGS. 1-5 is that
the concrete slab of FIG. 6 requires only two such rods 36, thus
simplifying manufacture.
The offset feature of the rods 36 may be provided in many ways, one
of which may be the angular or bent design of the rod 43
illustrated in FIG. 7.
For placement of slabs of the invention on a solid surface where it
is desired to avoid clearance between the surface and the bottom
face of the slabs, a slot 44 extending from each of the cavities 42
to an adjacent end wall of the slabs is provided, as illustrated in
FIGS. 8-10. It will be noted that the slot 44 is positioned such
that the intermediate portion 39 of the rod 36 of the next adjacent
slab is received in the slot and such that the bottom surface of
the portion 39 is co-planar with the bottom face of the slab. At
the same time, the intermediate portion 39 retains its function of
supporting the weight of the next adjacent slab so as to stabilize
the next adjacent slab against undue vertical movement. Of course,
in this embodiment, the rod 36 is embedded in the slab to a
slightly greater depth than it is in the slabs 20 of FIGS. 1-5 in
order to avoid projection of the intermediate portion 39 below the
bottom face of the slab.
The inconvenience of carefully orienting each slab so that the
appropriate end walls are made adjacent for engagement, as required
in the embodiments of FIGS. 1-8, is avoided by a preferred
arrangement of the rods 36 as illustrated in FIG. 11. In the
embodiment of FIG. 11, it will be noted that the distance between
the hooked end portions 37 is equal to the distance between the
hooked end portions 38, although the pair of hooked end portions 37
is offset slightly from the pair of hooked end portions 38 so as to
avoid interference between the hooked portions when the slabs are
adjacent. By the equidistant positioning of the hooked end
portions, each slab is interlockable from either end with either
end of another slab, as illustrated in FIG. 11 with respect to the
adjacent end walls A-B and adjacent end walls B--B.
The slabs can also be modified in another embodiment of the
invention to permit side-by-side engagement as well as the
end-to-end engagement depicted in FIGS. 1-5 and 11. With reference
to FIGS. 12-15, it will be noted that at least one additional rod
47 is embedded in each concrete slab at generally right angles to
the above-described rods 36, and also that each slab is provided
with the same number of additional cavities 45 as additional rods
47, for mating with hooked end portions 48 of rods 47 of next
adjacent slabs. The intermediate rod portions 49 may extend below
each of the slabs, as illustrated in FIGS. 1-5, but preferably a
slot 46 is provided from the cavity 45 to the next adjacent side
wall of the slab so that the intermediate rod portion 49 of the
next adjacent slab will be carried in the slot and spacing between
the bottom face of the slabs and a foundation surface is avoided,
analogous to the embodiments described with reference to FIGS.
8-10. The additional rods 47, of course, are positioned offset from
cavities 42 and rods 36 so that interference between the rods and
cavities is avoided upon joinder of slabs. Such orientations are
shown in FIGS. 14 and 15.
FIG. 13 illustrates a method of laying the slabs of FIG. 12 to form
a patio-like matrix. In constructing the matrix, it is convenient
first to form a strip of the slabs I, II and III, as described
above with reference to FIGS. 4 and 5. In the next step, since the
additional rod 47 extends downwardly from slab I in the view of
FIG. 13, and slab IV has a slot 46 running from the adjacent side
wall to the cavity 45, the slab IV is simply placed adjacent slab I
so that the rod 47 fits into the slot 46 and hooked end portion 48
fits into cavity 45. Each additional slab, such as slabs IV, V, VI
and VII, may then be placed side-by-side with other slabs in the
same manner. However, the end-to-end connection, as between slabs
IV, V and VI is achieved as described with reference to the first
strip of slabs I, II and III. If desired, upon completion of the
matrix, the projecting hooked end portions 37 and 38 may be
severed, especially in layouts where a border or curb co-planar
with the upper face of the slabs is not used.
Many variations of the foregoing embodiments will be evident. For
example, the dimensions of the cavities and hooked end portions may
be such as to provide a tight engagement. Preferably, however, some
clearance is desirable to accommodate slight relative movements as
between adjacent slabs and to facilitate layout of the slabs. Also,
while the number and arrangements of rods as shown in the drawings
ordinarily will be sufficient, a greater number of rods and
cavities other than those illustrated may be employed, especially
when the dimensions of the slabs require greater reinforcement and
stronger locking engagement. Still further, many variations are
possible upon the slabs and rods themselves, such as different
curvatures to accommodate placement of the slabs on inclined or
curved foundations. Also, while the connecting rods in some
instances need be the only reinforcing members embedded in the
concrete, in some applications it may be desirable to enhance the
reinforcement by embedding additional reinforcing rods in the
slabs.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in the above
article without departing from the spirit and scope of the
invention, it is intended that all matter contained in the above
description and shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
* * * * *