Improvements in the Combination of Iron and Concrete or similar Materials for Building Purposes.
Year: 1891

page_text: Date of Application. 18th Feb., 1891
Complete Specification Left, 21st May, 1891-Accepted, 27th June, 1891
PROVIDIUNAD DILICATION.
Improvements in the Combination of Iron and Concrete or similar
Materials for Building Purposes.
I, FREDERICK GEORGE EDWARDS, of 120 Leighton Road, Kentish Town,
London, Builder's Assistant do hereby declare the nature of this invention to be as
follows:--
This invention consists of improvements in the methods of combining iron or steel
with concrete for the purpose of resisting the tensile stresses (and in some cases the.
compressional stresses also) in concrete floors, roofs, partitions, beams, girders, and
other structures. The iron with the aid of wirework may in some cases serve to
support the concrete while it is setting. Cement, artificial stone, and similar
materials, may be used in place of the concrete.
It has long been proposed to combine iron bars with the concrete by simply
embedding them but they have been found to slip when the stress has been brought
upon them.
I have discovered that by making the bars long in proportion to their
sectional area a point can be reached at which the bars will fail by tearing before
they can be drawn out of the concrete, and that this combination can be made to
serve some useful purposes.
Concrete studs for partitions may be formed in this way and used in a similar
manner to wooden studs. They would be moulded of a suitable section with, say,
four iron rods or wires embedded and a strip of soft concrete formed in the exposed
faces to receive nails. The moulds would be open at the top and the concrete
rolled in layers by specially shaped rolls so that the iron rods and soft concrete
can be conveniently inserted.
Concrete floor joists may be formed in a similar manner to the studs but with a
larger number of small rods embedded in the bottom flange. Rods may be
embedded in the upper flange to resist any accidental tensile stresses to which it
may be exposed.
This combination is also applicable for rafters and other beams.
My improvements also relate to solid concrete floors and roofs with bars crossing
each other at right-angles embedded in the under surface; and consists in the
employment of angle iron, one flange of which is used for the connections. and the
other distributes the stresses over the concrete. The concrete may be supported
while setting by means of wire netting supported by the iron framing.
Concrete girders may also be formed with iron compression and tension flanges
embedded and connected by inclined ties so that concrete replaces the ordinary
metal struts in braced girders; or if struts are used they may be of simpler section
as the concrete serves to stiffen them. This part of the invention is applicable to
different types of braced girders and these may be lightened by perforating the
concrete between the braces. Short angle irons may be rivetedacross the flanges
to distribute the stresses over the concrete.
Hoop iron, stranded wire, or iron bars
of section twisted spirally throughout
the length are very suitable for embedding in concrete.
Dated this Eighteenth day of February 1891.

page_text: COMPLETE SPECIFICATION.
Improvements in the Combination of Iron and Concrete or similar
Materials for Building Purposes.
I, FREDERICK GEORGE EDWARDS, of 120 Leighton Road, Kentish Town,
London, Builder's Assistant, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:--
This invention consists of improvements in the methods of combining iron or
steel with concrete for the purpose of resisting the tensile stresses (and in some
cases the compressive stresses also) in concrete floors, roofs, partitions, beams,
girders, and other structures.
It has long been proposed to combine iron bars with the concrete by simply
embedding them but they have been found to slip when the stress has been brought
upon them.
I have discovered that by making the bars long in proportion to their
sectional area a point can be reached at which the bars will fail by tearing before
they can be drawn out of the concrete, and that this combination can be made to
serve some useful purposes. This constitutes the first part of my invention.
I will now describe a series of beams constructed according to this part of the
invention, together with a fir beam and a concrete beam without iron, which were
tested by Messrs. Kirkaldy & Son, of Southwark, London, on the 28th April 1891
and reported in "The Builder" and "Engineering" the same week.
The bulk of the concrete was gauged with equal parts of Portland cement (Nine
Elms Brand) and coke breeze. The breeze for the twenty-one day specimens was
screened through a quarter-inch mesh and that for the seven day specimens through
a half-inch mesh. The strip of soft concrete inserted in one or both faces of the
specimens to receive nails was composed of one part of Portland cement to four
parts of fine coke breeze. The iron used was "Tudhoe Crown."
The different specimens are lettered in alphabetical order and corresponding
letters appear in the second column of an abridgement of Messrs. Kirkaldy & Son's
which follows.
A. A 7" x 3" concrete joist. (Fig. 1) with 1 flanges and 14" web having
six iron rods a in the bottom Hange and two in the top flange. A strip of soft
concrete x 1" was also inserted in the top face to receive nails for fixing floor
boards. Kept in air 21 days.
B. A 7" x 3" concrete joist (Fig. 2) with three " iron rods a in the underside
and a strip of soft concrete in the top side 3" x 1. Kept in air 7 days.
"
C and D. A 4" x 2" concrete partition stud (Fig. 3) with 1" flanges and two 16
iron rods a in each flange; also a strip of soft concrete in both faces " x 1".
Kept in air 21 days.
and F. A 5" x 3" concrete ground joist (Fig. 4) with 1" flanges and 1" web,
having four iron rods a in the bottom Hange and a strip of soft concrete b in the
top face "x1". Kept in air 21 days.
G and H. A 5" x 3" concrete ground joist (Fig. 5) with three 3" iron rods a in
the underside and a strip of soft concrete b in the top side 3" x 18". Kept in air
7 days.
J. A 5" x 3" concrete beam similar to G and H with the strip of soft concrete
in the top side " x 18", but without the iron rods. Kept in air 7 days.
3
16
K. A. 5" x 3" fir joist (dry) of 1st quality Gothenburg. Brand S crown F.
L. A 5" x 3" concrete lintel with six iron rods a (Fig. 6) embedded and
curved to meet the tensile stresses due to fixing the ends. No soft concrete
inserted. Kept in air 7 days.
Fig. 6 shows a section of this lintel at the centre and Fig. 7 is an elevation to a
smaller scale, the dotted lines indicating the position of the iron rods. Length of
lintel 6' 6".

page_text: The following is an abridgement of Messrs. Kirkaldy & Son's report :-
RESULTS OF
EXPERIMENTS. TO ASCERTALY THE REISTANCE TO BENDING
(Signed)
DAVID KIRKALDY & SON.
L.S.
The iron rods in each case were firmly held by the concrete, and the "rods in
the 21 day specimens must have been on the point of breaking. Sufficient holding
surface. can always be obtained for the required quantity of iron, for while the
sectional area of a rod varies as the square of the diameter, the surface exposed
for the adhesion of the concrete varies only as the diameter. For instance: two
"rods although only one half the sectional area of one " rod have exactly the
same amount of surface for the adhesion of the concrete.
The rectangular specimens with the coarser breeze (which gave the best results).
were only seven days old, but were nearly half the strength of the best fir timber."
As the concrete at this age has reached only a moderate proportion of its ultimate
strength, the strength of fir timber will be easily attained and the quan ity of iron
required for that purpose can be easily inserted..
The large deflection of the composite beams should also be noticed as this shows
they are capable of withstanding suddenly applied loads. Their flexibility also
adapts them for railway sleepers: they would not form a hard and unyield ng base
for traffic at high speeds like the stone blocks used at an early period in the history
of railways.
Steel may be economically used in place of the iron as its high tensile strength
is not weakened by forgings or holt holes. I prefer round rods or wires for
embedding in the concrete but stranded wire or bars of other section may be used.
Neat cement, artificial stone or any similar material, or concrete composed of
other ingredients may be used.
It should however be noticed that with concrete
composed as described the cement works itself around the iron rods and they become
embedded in neat cement whereby they are better protected from the atmosphere

page_text: and larger sized rods can be held by the concrete.
In other cases the rods may be
laid in neat cement or smaller rods used. The nailing fillet may also be composed
of the same materials as Wright's patent fixing blocks, Specification No. 2629,
A.D. 1881.
We have then a building material capable of large application, possessing the
strength of timber but incombustible and rot proof, suitable for building into brick-
work or masonry and for exposure to the weather.
The joists and partition studs previously described are intended to be used in a
somewhat similar manner to timber, being placed say, twelve inches apart and the
floor boards or lathing nailed to them. Small nailing fillets may be inserted in the
under-side of the joists. Rafters and other beams may be constructed in a similar
manner; and it is also evident that the beams may be moulded in a segmental or
cther curved form where required.
The lintels as described will render relieving arches unnecessary and will also
dispense with the use of chimney bars over fireplace openings.
The flanged joists (Figs. 1 and 4) may have coke-breeze concrete filled in
between them to form a solid floor. The nailing fillet is not then required.
Perhaps a more suitable section for this purpose would be as shown by Fig. 8.
Oval brads are very suitable for nailing to the concrete as they are not liable to
split the beams like ordinary floor brads.
One simple way of moulding is shown by Fig. 9. The joist is moulded on its
side with the iron rods a kept in position by bent wires c slipped over them and the
concrete worked in between them. A groove is formed for the soft concrete by a
former d extending the length of the mould which is pressed in and then removed.
The edge e is protected by a piece of hoop iron while the soft concrete is being
filled in.
The composite beams may be framed together by housing (Fig. 10) or by means
of a mortise and tenon (Fig. 11). In the latter case the iron rods are bent to pass
to the end of the tenon or the tenon may be strengthened by means of short iron
rods (Fig. 12) embedded. Fig. 13 shows a method of framing horizontal
members into the corner post of a structure. The horizontal members are housed
in and their rods a pass through holes in the post where the ends are secured by
screwed nuts resting on bearing plates g. The sinkings may be afterwards
filled up with cement. This joint is also applicable for other purposes.
Buildings or parts of buildings may be cheaply constructed of concrete and iron
beams framed together in this manier. The panels may be filled in with concrete,
or the framing may be lathed and plastered on both sides, or the outside may be
hung with tiles. This construction is also applicable for greenhouses.
Fig. 14 shows a section suitable for a window mullion to receive leaded lights.
Fig. 15 shows a section of a stair tread intended to be supported at both ends.
If the ends are to be fixed the bearing on each side should be at least or of the
span and the wires curved upwards at the ends as in the lintel (Fig. 7). Landings
which can be supported at both ends may be formed in a similar manner.
Fig. 16 shows a section suitable for a wall-plate or sleeper with a nailing fillet b
to which ordinary timber joists may be nailed.
Fig. 17 shows a section through a window sill which is strengthened by wires a
embedded both at the top and bottom. This is especially applicable for sills of long
lengths. Window heads may also be strengthened in this manner or after the
manner of the lintel (Fig. 7).
Figs. 18 and 19 show sections through rails suitable for fencing, the ends of which
would be housed into posts constructed as shown by the section Fig. 10. Nailing
fillets may be inserted in the rails so that cleft oak pales or other uprights may be
secured to them.
Figs. 20 and 21 show a plan and section of a railway sleeper with rods a at the
top and bottom. The chairs may be secured by spiking to the strip of soft
concrete which extends throughout the length of the beam and if required, cross-
wires may hold the rods together near these points to prevent the sleeper being

page_text: split by the spikes. Instead of the nailing strip holes may be formed in the
sleeper for the insertion of bolts or other fastenings. The drawing illustrates a
transverse sleeper but it is obviously applicable also as a longitudinal sleeper.
The second part of my invention relates to solid concrete floors or roofs.
Longitudinal angle-irons (Fig. 22) are bolted or riveted to transverse angle-irons
and the whole embedded in the under-side of the concrete forming the floor. One
flange of the angle-irons serves for the connections and the other distributes the
stresses over the concrete.
The third part of my invention consists of concrete girders with iron compression
and tension Hanges embedded and connected by inclined ties so that concrete
replaces the ordinary metal struts in braced girders; or if struts are used they may
be of simpler construction as the concrete serves to stiffen them.
Figs. 23 and 24 show one form of girder with compression and tension Hanges m
The whole is
and composed of angle-iron and connected by inclined ties o.
embedded in concrete as shown, and the girder is lightened by perforations p
through the concrete.
Struts, as indicated by dotted lines at 7 or 2, may also be used but as the concrete
serves to stiffen them they may be of rectangular or other simple section and are
not required so large as in ordinary braced girders.
Figs. 25 and 26 show other well-known forms of braced girders embodied in
concrete in a similar manner, having flanges m and n, and braces o, indicated by
dotted lines; and perforations p through the concrete.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. The method of combining iron and concrete (or similar materials) to form
beams for building purposes, the iron being in the form of a number of long rods
or wires whereby sufficient adhering surface is obtained to prevent them being
drawn out of the concrete.
2. The method of curving the rods to resist the tensile stresses in concrete beams
fixed at the ends as described with reference to Fig. 7.
3. The methods of framing the composite beams together as described with
reference to Figs. 10, 11, 12, and 13.
4. Joists, studs, rafters, lintels, mullions, stair-treads, landings, wall plates,
sleepers, window sills and heads, and similar beams, formed of concrete and iron
(or similar materials) as described with reference to Figs. 1, 2, 3, 4, 5, 6, 7, 8, 14,
15, 16, and 17.
5. Constructing fencing rails and posts of concrete and iron (or similar materials)
as described with reference to Figs. 18, 19, and 10, or any mere modification
thereof.
6. Constructing railway sleepers of concrete and iron (or similar materials) as
described with reference to Figs. 20 and 21.
7. Constructing solid concrete floors and roofs with angle-iron framing embedded
in the under-side as described with reference to Fig. 22.
8. Constructing combined concrete and iron girders with inclined ties as described
with reference to Figs. 23 and 24.
9. Constructing combined concrete and iron girders with inclined ties and' with
struts of simple section as described with reference to Figs. 23, 24, 25, and 26.
Dated this 20th day of May 1891.
FRED. G. EDWARDS.