CA1144773A

CA1144773A - Flooring system

Info

Publication number: CA1144773A
Application number: CA000372266A
Authority: CA
Inventors: John Ball; Leslie Hughes; James Work
Original assignee: GLASS REINFORCED CONCRETE (GRC) Ltd; Tinsley Building Products Ltd
Current assignee: GLASS REINFORCED CONCRETE (GRC) Ltd; Tinsley Building Products Ltd
Priority date: 1980-03-22
Filing date: 1981-03-04
Publication date: 1983-04-19
Also published as: GB2077792A; DE3109703A1; GB2077792B; BE888045A; NL8101210A; FR2478704A1

Abstract

ABSTRACT OF THE DISCLOSURE
CASTING REINFORCED CONCRETE FLOORS
A method of casting reinforced concrete floors of the ribbed or troughed type using permanent formwork. The invention is also related to the parts and form-work used in casting the floor. Conventional trough shaped form-work(F) is used in conjunction with a composite plank (P). The composite plank (P) consists of a skin (1) of fibre reinforced cement forming an open trough with flat bottom (4) and vertical or substantially vertical sides (2, 3).
Metal reinforcement (5) is placed in this trough and held in place by concrete (10) cast around the part of the reinforcement lying in the trough.
The plank (P) is preferably shaped with side channels (11, 12) to receive the permanent form-work (F) and positively position such form-work.

Description

~ ~44~3 This invention relates to a method of casting reinforced concrete floors of the ribbed or troughed type using per~nanent form-work and the par*s and form-work used in the casting of such floors.
Floors of the ribbed or troughed type are formed by laying out the area to be floored with form-work arranged to receive the concrete .
when poùred. Such form-work normally rests upon a supporting structure such a~ walls,~beams or a combination of both to support the span of the floor. The base of each of the troughs which when filled with concrete form the ribs of the floors in some forms of construction consists of a concrete plank, the trough being formed by each of the longitudinal edges of the form-work used to position the shallower part of the floor resting on an edge of the ~ank. Such conerete planks must be stiffened by the pro~ision of reinforcing rods and carry some or ~11 of the steel reinforcement req~ired in the trough~
In forming auch concrete plank~ and setting the associated reinforcing metal in the plank, the metal reinforce~ent must be held accurately in position by some form of support system. It " .
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, is not possible to locate the edges of the form-work used to form the shallow part of the floor accurately on the appropriate edge of the plank so as to give a flush fit. Furthermore each plank must be prepared with the correct dimensions and steelwork for a particular floor loadi~g. It is thus impossible to carry an inventory of standard planks, and it is normal ~, to cast planks against orders for a particular ~
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floor in a particular building. It i9 therefore s impossible to accommodate any changes in design at the last moment or any changes in site dimen-sions. The concrete planks being made of pre-cast concrete are subject to damage on site ;
or during transport to the site as the material is not resistant to impact. Concrete also tend~
to spall in a fire~
We have n~w devised a composite plank which can be used in a troughed or ribbed flooring system to directly support the form-work which can be made in standard lengths no matter what loading ~ ~ and which, in addition9 increases the fire - ~ resistance of the flooring and reduces the risk of damage due to impact before and after installation, This composite plank is also~shaped 4~773 _ 3 _ to receive the edge of the form-work so as to provide a flush fitting and position the form- .
work edge positively on the edge of the plank~ , Our invention also provides a new method of forming a troughed or ribbed floor utilising the composite plank of the pre~ent invention .
in which all or a substantial part of the reinforcing steel other than that required to proYide the necessary stiffening of the composite plank to remain rigid between temporary supp~s, is placed in position after the form-: work and planks are assembled together on site.
The composite plank of our invention therefore consists of a skin o~ fibre reinforced .
: 15 osment forming an open trough with a flat bottom and vertical or substantially vertical sides :into which at least the metal rein~orcement .
necessary to maintain the plank rigid acros~
temporary supports is placed and held in place by concrete cast around that portion of the : :
. metal reinforcement that lies within the con~
: -fine3 of the trough~ We prefer to use a skin :
of 5 to 10 mm thickness of cement which has ~ :
been reinforced with alkali resistant glass :
fibre such as that sold under the trade name ~ ` ` :

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"Cem-~IL" by Fibreglass Limited. In casting the concrete within the skin of fibre reinforced cement we prefer to arrange the casting such that a longitudinal channel is formed at the upper part of each wall ofthe skin, between the wall and the concrete. The concreta between the channels is preferably cast so as to be ~
raised above the top of the walls of the fibre d reinforced skin. The channel thus formed provides an opening into which a suitably shaped longitudinal edge of the form-work which is to rest on the composite plank can be slotted.
This enables such form-work to be positively positioned in place. The longitudinal edges ~;
of the for~-work are preferably the lower edges ~
o~ the walls of inverted troughs, the hollow i space formed between the walls of the trough facing the area beneath the floor being cast.
The fibre rein~orced skin, because of its increased impact resistance, provides a protection against the kind of damage l1kely ~rS
to be experienced by an unprotected concrete planX resulting in either the need for remedial work or an unsatisfactory finish to the u~der-side of the floor. In our preferred embodiment . .

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s alkali resistant glas4 fibre is used as the s, reinforcing material as this material can be readily incorporated into the cement ma-trix when spraying a mixture of glass fibre in chopped form and cement onto a m~uld shaped to that desired ~or the skins for the composite , plank. .The skins may also be made by forming a flat sheet and shapin~ it on a former while l ~
still in the green or uncured state. It is js 10 ' possible by the use o~ these techniques to produce articles with a skin thickness in the range 5 to 10 mm which, when cured, can be readily handled and delivered to where concrete - - is to be ca-~t. Below.a skin thicknes~ ~f 5 mm ; 15 problems may be experienced in forming a atisfactory edge to the cha~nel which ~ to .
receive the sultably shaped edge of the ~orm-- work and, at thicknesses above 10 mm, the quantity of glass fibre needed even at levels o~ the order of 5~ renders the final product unattractive .
because of cost. At thicknesses in the range .5 to lO mm adequate impact strength and an :
adequate increase in fire re~istance i~ obtained ~ ~
. of the order of several hours over that which ~ .
would be obtained with a concrete plan~ not ~

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1~773 provided with an outer skin Or glass fibre reln~orced cement. Organic ~ibres such as polypropylene fibres can also be used but such material does not have the same degree of fire resistance. Asbestos fibre, while usable, is tending to become unacceptable in exposed situations within buildings because of health hazards. It is not so con~enient to use in .
forming relati~ely thin skinned articles with a high impact strength. We prefer to use as the metal reinforcement to be held in place in the composite plank, an assembly of steel wire or rod in which two rods are plàced along the trough spaced apart from one another and a . ~ . .
further rod spaced abo~e and betwe~n them and held in place relative to the rirst tw~ rods by a serie~ of inverted V-shaped trus~es arranged along the length of the trough. An arrangement such as this enables any load on the plank to be tran~ferred along the plank and give the necessary rigidity or stiffness to enable the planks to be used with the minimu~ of temporary ; supports. In the absence of this metal re-inforcement the pla~k~ would require temporary support6 at perhaps a maxi~um Or 1 metre inter~al-.

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. 7 ! . y ,j The oomposite plank Or our inventio~ can ~pan ¦:, at least 2 metres betw~*n temporary s~pports and accept the load of site installed metal j~
reinforcement and concrete ~hile the concrete is curing. -Our in~ention also includes a method :
` of ~orming a ribbed or trough~d $kor in which a .
: plurality of composite planks as described above are laid on temporary supports with a space ~
between them, and the space between them is , then filled with form-work arranged so that their longitudinal edges re~t in channels along the : edges o~ the composite planks, metal reinforcement ~: : . is mounted on the planks and form-work and finally concrete iB poured into place to cast the floor~
One form of our inventlon will now .
be described with reference to the aocompanying drawings in which:-~igure 1 is a part-ser~onalside ~iew o~ a composite plank according to the invention; ~ .
~: Figure ~ ls a cross-sectional viewsubstantially taken ~rom the line 2-2 in Figure 1;:
Figure 3 is a cross-sectional view :`

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j , of a portion of a floor before the concrete is cast and the remaining metal reinforcement provided;
Figure 4 is a fragmentary perspective ! ~' - . 5 view corresponding to part of Figure 3 showing an inverted trough engaged in the channel formed ~
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in the plank; and ~igure 5 is a fragmentary perspective view showing another type of form-work mounted across a pair of planks. . ~'s The composite plank P in the preferred form shown in ~igures 1 and 2 ~omprises a fibre ~
: reinrorced cement outer skin 1 which is in the i;
~orm of an elongated trough, with side walls 2 .
: 15 and 3, and base 4 forming a container in which .
a matal reinforcement assembly 5 is placed~
This assembly comprises two steel rods 6 and 7 placed along the base 4 and which are inter- .
connected with a ~rther rod 8 by a series o~
inverted V-shaped trusses 9 which are welded - ~ at contact points to the rods 6~ 7 and 8. ~
This interconnected structure thus formed .
maintains the rigidity of the plank. The rods 6 and 7 and the portions of the trusses adjacent these rods are covered wlth concrete.

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The concrete covering 10 is cast so as to leaYe two longitudinal channels or slots 11 and 12 at each side of the plank into which the longitudinal edges of form-work can be slotted.
,5 The overall arrangement of a floor is shown in Figure 3 and the method of casting ; a floor will now be described with reference to that drawing~ Three planks P as in ~igures 1 and 2 are shown. These planks would be placed where the span is acceptable from wall to wall in the area to be ~loored. If necessary temporary supports can be provided to reduce the span. The spacing between the planks is adJusted to allow the related edges 13 of permanent form-work F to be ~itted ~nto the - longitudinal channels provided along the sldes of the planks so as to give ~irtually a flush fit at the contact point between the outer ed~e of the wall of the channel and the bottom surface of the form ~rork. The form-work F
forms voids V, and is preferably made o~ glass fibre reinforced cement. The use of this material for the form-work and the outer ~kin of the composite planXs means that ths inter-connectlng parts of the planks and form-work ', 7~3 ' can be accurately formed e~-~though they are relatively thin. 5uch part~ either could not be formed easily in concrete or, if formed, would be very vulnerable to damage both before , 5 and during installation. Once the form-work and planks have bsen assembled as shown in Figure 3, the remaining metal reinforcement required for the particular floor loading is placed-and concrete cast to form the floor in a manner well known to those practised in the art of forming floors.
Figure 4 indicates a continuous - uniform section or trough unit Fr for th0 form-work, while Figure 5 indicates that by pro~iding form-work with spaced ralsed portions R it is possible to form a solid transverse stiffening rib in the space ~ without any specially shaped additlon}l form-work being required.

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Claims

WHAT WE CLAIM IS:-

1. A composite plank for use in casting reinforced concrete floors, the plank consisting of a skin of fibre reinforced cement forming an open trough with a flat bottom and vertical or substantially vertical sides into which at least the metal reinforcement necessary to maintain the plank rigid across temporary supports is placed and held in place by concrete cast around that portion of the metal reinforcement that lies within the confines of the trough.

2. A composite plank as in Claim 1, wherein the skin is of 5 to 10 mm thickness of cement which has been reinforced with alkali resistant glass fibre.

3. A composite plank as in Claim 1, wherein the metal reinforcement consists of an assembly of steel wire or rod in which two rods are placed along the trough spaced apart from one another and a further rod spaced above and between them and held in place relative to the first two rods by a series of inverted V-shaped trusses arranged along the length of the trough.

4. Permanent shuttering for use in casting concrete floors and consisting of a plurality of composite planks spaced apart and form-work supported by the planks, each plank consisting of a skin of fibre reinforced cement forming an open trough with a flat bottom and vertical or substantially vertical sides into which at least the metal reinforcement necessary to maintain the plank rigid across temporary supports is placed and held in place by concrete cast around that portion of the metal reinforcement that lies within the confines of the trough.

5. Permanent shuttering as in Claim 4, wherein each plank has a longitudinal channel formed at the upper part of each wall of the skin, between the wall and the concrete, and the form-work has suitably shaped longitudinal edges slotted into the channels in the planks.

6. Permanent shuttering as in Claim 5, wherein the concrete between the channels is cast so as to be raised above the top of the walls of the fibre reinforced skin.

7. Permanent shuttering as in Claim 5 or Claim 6, wherein the longitudinal edges of the form-work are the lower edges of the walls of inverted troughs, the hollow space formed between the walls of the trough facing the area beneath the floor being cast.

8. Permanent shuttering as in Claim 4, wherein the form-work is made of glass fibre reinforced cement.

9. A method of forming a concrete floor with a ribbed or troughed underside comprising forming permanent shuttering consisting of a plurality of composite planks spaced apart, supporting form-work on the planks, and casting concrete in situ over the composite planks and form-work, each plank consisting of a skin of fibre reinforced cement forming an open trough with a flat bottom and vertical or substantially vertical sides into which at least the metal reinforcement necessary to maintain the plank rigid across temporary supports is placed and held in place by concrete cast around that portion of the metal reinforcement that lies within the confines of the trough, with a longitudinal channel formed at the upper part of each wall of the skins between the wall and the concrete, and the form-work consisting of inverted troughs with suitably shaped longitudinal edges slotted into the channels in the planks.

10, A concrete floor with a ribbed or troughed underside comprised by permanent shuttering consisting of a plurality of composite planks spaced apart, form-work supported on the planks, and concrete cast in situ over the composite planks and form-work, each plank consisting of a skin of fibre reinforced cement forming an open trough with a flat bottom and vertical or substantially vertical sides into which at least the metal reinforcement necessary to maintain the plank rigid across temporary supports is placed and held in place by concrete cast around that portion of the metal reinforcement that lies within the confines of the trough, with a longitudinal channel formed at the upper part of each wall of the skin, between the wall and the concrete, and the form-work consisting of inverted troughs with suitably shaped longitudinal edges slotted into the channels in the planks.