Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a lightweight floor
panel made of a cementitious material.
Floor panels are commonly used in computer
rooms and o,her areas where it is convenient to raise the
floor on pedestals and to place wiring and other mecha-
nism beneath the floor for convenient access for ser-
vice~ Such floor panels have commonly in the past con~
sisted of materials such as pressed wood or chipboard
encased in metal sheets or two part welded steel panels~
The chipboard and metal panels, although relatively light
in weight, have proven expensive to manufacture and also
are not entirely fireproof~ The applicant therefore has
conceived a con~rete floor panel. ~o~ever, a major
difficulty with concrete floor panels has been that in
order to ahcieve sufficient strength (typically 1,500
pounds per square inch is required1, the panels have been
so heavy that they could not be handled/ installed, and
removed for access to the space below them without
special machinery~
Accordingly, it is an object of the invention
to provide a lightweight reinforced concrete floor panel
which has strength sufficient to serve as a raised floor
in many areas (e.g. computer rooms) and yet which is
sufficiently light in weight that individual panels can
be handled by one or two workmen. To this end the
invention provides in its broadest aspect a lightweight
floor panel comprising: a body of a cementitious mater-
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ial, the body being of generally thin and flat rectangu-
lar shape with a substantially planar upper surface and a
lower surface with ribs formed therein, said ribs provi-
ding strength and reducing the amount of material in the
panel. The body also defines corner regions at which the
panel can be supported in use. A set of reinforcing bars
is provided in the body and the bars are disposed sub-
stantially parallel to the upper surface of the body.
The set includes two bars arranged in a crossed configur-
ation generally centrally of and extending generallyparallel to sides of the panel, and four bars arranged
one along each side of thé panel within the body and
terminating at said corner regions. Each of the crossed
bars is arranged with respective end portions thereof
resting on the bars at respectively opposite sides of the
panel considering the panel oriented as in use so that
loads imposed on the panel tend to be transferred by said
bars to said corner regions. The panel also includes a
reinforcing mesh sheet member extending in said body
parallel to said upper surface and covering at least a
substantial portion of the panel area inwardly of said
side reinforcing bars.
Further objects and advantages of the invention
will appear from the following description, taken to-
gether with the accompanying drdawings which show a pre-
ferred embodiment of the invention, and in which:
Fig. 1 is a perspective view from above of a
panel according to the invention;
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Fig. 2 is a sectional view taken along lines
II-II of Fig. 1;
Fig. 3 is a perspective view from below of the
floor panel of Fig. 1; and~
~ig. 4 is a perspective view of a raised floor-
ing system utilizing the panels of ~ig. 1.
Reference is now made to the drawings, which
show a floor panel 10 according to the invention. The
panel 10 is essentially square and comprises a body of
fiber reinforced concre~e. Fiber reinforced concrete is
now well known and may consist of cement, sand, glass
fibers, water; it may also include a plasticizer and
polymers to strengthen the product. Pearlite or other
lightweight aggregates may also be included to reduce the
weight of the mix. The invention is not concerned with
the particular formulation but rather with the physical
design of the panel.
As shown, the panel 1 n has a substantially
planar upper surface 12 and a lower surface 14 having
ribs generally indicated at 16 formed therein. The panel
10 is very thin in relation to its length and width. The
length and width of the panel are typically 610 mm, while
the overall thickness of the panel (dimension t~ is ~ypi-
cally only about ~3 mm except at the corner regions (see
later). The ribs 16 are thus provided to increase the
strength of the panel while reducing the weight thereof.
The ribs 16 include four side ribs 18 one ex-
tending along each lower side of the panel 10, and two
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major ribs 20 arranged at right angles to each other and
dividing the lower surface of the panel into four quad-
rants 22. The height of each side rib and major rib 18,
20 (dimension dl) is about 20 mm; the width of each side
rib 18 (dimension d2) is about 38 mm at its base, and the
width of each major rib 20 (dimension d3) is about 30 mm
at its base.
Each quadrant 22 has formed therein a pair of
minor ribs 24 (Fig. 3) which extend parallel to one an-
other and parallel to the minor ribs in the other quad-
rants. The minor ribs 24 are much smaller than the major
ribs 20, being only about 3 mm in height and 12 mm in
width.
The panel is also shaped to define corner
regions which are generally denoted 26 in Fig. 3 and
which extend below the major ribs 80, 20 for example by
about 5 mm. These regions are designed to act as support
areas at which the panel can rest on pedestals or other
supports in an assembled floor system as will be des-
cribed in more detail later~ primarily with reference toFig. 4.
Panel 10 further includes a set of steel rein-
forcing rods 28 (Figs. 1 and 2) all extending generally
parallel to the upper surface 12 of the panel. There are
six reinforcing rods 28, one extending along each side of
the panel through each side rib 18 and two disposed in a
crossed configuration in the centre of ~he panel, and ex-
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tending through the respective major ribs 20. In Fig.1, the rods at the sides of the panel are individually
denoted 32 while the crossed rods are denoted 34. Typi-
cally, rods 32 will be say, 10 mm in diameter while rods
5 34 will be 7-8 mm in diameter~ The rods are spaced
slightly above the bottom of the panel, typi.cally about 5
mm above the bottoms of the side ribs 18 and the major
ribs 20. This spacing is achieved as follows. The mould
in which the panel is made (not shown) includes raised
supports, two for each reinforcing rod 28, one at each
end of each rod 28. The reinforcing rods 28 are placed
on the raised supports before the concrete i5 poured.
When the panel is removed from the mould, the raised sup-
ports leave small pockets 36 (Fig. 3) in the panel and
through which the rods 28 are exposed (although in prac-
tice, a thin "skin" of concrete tends to form over the
exposed surface sf the rod~. The pockets 36 are not
visible when the panel is installed and have a negligible
effPct on the strength of the panel. It will be noted
that pockets 36 are provided at the ends of the major
ribs 18 and 20. Thus, the pockets 36 in the side ribs 18
terminate adjacent and effectively define the corner
regions 26 while the pockets in the ribs 20 are located
where those ribs meet the side ribs 80.
As best seen in fig. 1, the reinforcing rods 32
at the sides of the panel terminate within the corner
regions 26 and the crossed rods 34 rest at their ends on
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the side rods 3~. Thus, loads imposed on the upper sur-
face of the panel in use will tend to be transferred ~y
way of the rods 34 to the rods 32 and, from those rods,
to corner regions 26 of the panel where the panel can be
supported. The two crossed rods 34 are arranged in con-
tact with one another approximately at their mid points
and may be wired together. The lower of ~he two rods 34
as seen in Fig. 1 is straight while the other rod 34 is
bent slightly at its mid point to define two rectilinear
sections and pass over the straight rod. The extent of
the bend is just sufficient that all four ends of both
rods 24 lie substantially in a common plane.
Panel 10 also includes a square expanded steel
mesh sheet 40 (Fig. 2), the overall dimensions of which
are approximately one or two centimeters smaller than the
length and width of the panel, placed just below the
upper surface 12. The expanded metal sheet 40 serves to
prevent cracking of the upper surface of the panel should
an impact occur such as when a heav~ piece of equipment
is dropped on the panel. Also, sheet 40 helps to resist
shrinkage stresses on curing of the concrete in manufac-
ture.
In fabrication of the panel, the rods 28 are
placed in the mould on the raised supports referred to
above and an appropriate fiber reinforced concrete mix-
ture is poured. When the level of the concrete almost
reaches the required finished surface, $he mesh sheet 40
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is placed on the concrete. Pouring is then completed and
the upper surface is finished.
The panel shown weighs only about 40 pounds and
yet could support a load of at least 1,500 pounds without
cracking.
For installation as part of an elevated floor-
ing system (see Fig. 4), each panel 10 includes a recess
42 in its upper surface at each corner region 26 (see
also Fig. l). Each recess includes a planar upper sur-
face 44 and an edge 46 perpendicular to the surface 44
and extending at 45 to each of the adjacent sides of the
panel. When four panels 10 are assembled together in a
square, the four adjacent recesses 42 define a square
composite recess 48 (Fig. 4) to accept a square hold down
plate 50 for coupling to a pedestal 51 below the panels.~hus hold down plate 50 is secured by a screw 52 to a
lower support plate 54 having a threaded hole 56 there-
in. Corners of plate 54 are turned up as indicated at
54a to engage behind the corner regions 26 of the panels
and assist in locating the same during installation.
Plate 54 is in turn welded to a tube 60. The tube 60
receives in its bottom a threaded post Ç2 welded to a
base plate 64. A levelling nut 66 or post 62 serves to
adjust the height of the support plate 54.
The lower surface of the panel also includes
recesses (denoted 70) below each of the recesses 42 in
the upper panel surface. These recesses 70 in effect
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define ledges at the corners of the panel which can be
engaged by mechanical lifting equipment for raising and
lowering the panels during installation. A notch 72 in
the extreme corner of the panel above recess 70 is also
provided to accommodate the lifting equipment.
It will of course be appreciated that the pre-
ceding description relates to a particular preferred
embodiment of the invention only and that many modifica-
tions are possible within the broad scope of the inven-
tion. For example, while a panel having a single set ofreinforcing bars has been shown, it would be possible to
provide a second similar set of bars above the bars
28. Also, mesh reinforcement can be provided along the
edges of the panel using narrow mesh sheets inserted per-
pendicular to the upper surface of the panel. The parti-
cular form of mesh used for sheet 40 is not believed to
be critical. ~or example, welded wire rod mesh or
plastic mesh could be used in place of expanded metal
sheets.
2~ ~inally, it should be noted that the particular
dimensions and materials referred to herein are given by
way of example only and may vary. For example, while a
square panel has been shown, panels of other rectangular
shapes are of course possible.
