Note: Descriptions are shown in the official language in which they were submitted.
~ BACKGROUND OF THE INVENTION
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This invention relates to new and useful improvements
in the process of forming a lightweight porous cementitious
material which can be poured into moulds and -the like and then
cured to form building materials such as blocks, slabs and -the
like which is lightweight with good structural properties,
good insulating properties, relatively fire-proof and easily
cut, drilled and handled.
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Attempts have been made in the past to produce such
~ 10 materials and cement slabs and the like incorporating a light-
; weight aggregate are well known. However, these are relative-
ly expensive and heavy and present many difficulties in working
or forming same.
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~UMMARY OF THE INVENTION
The present invention overcomes these disadvantages
by providing a cellular concrete building material which is
lightweight yet incorporates good structural properties.
In accordance with the invention there is provided
the process for manufacturing a lightweight building material
such as lightweight concrete and the like consisting of the
steps of combining Silica Sand in a proportion of between
58 1/2% and 52% by weight, Silica Flour in a propor-tion of be-
tween 23% and 26% by weight, Hydrated Lime in a proportion of
between 12% and 16% by weight, Quick Lime in a proportion of
between 3% and 4% by weight, Hydraulic Cement in a proportion
of between 2% and 4% by weight, a foaming agent, and a gelling
agent comprising a relatively small amount of sugar and Sodium
- Silicate, Mixing said raw material mixture with water to form
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a slurry, said slurry being poured into moulds, allowing foam-
ing to take place and then steam curing the resultant mass at
a pressure of between 140 and 200 pounds p.s.i. for a period
of between 10 hours and 4 hours depending upon the pressure
and then removing the resultant form from the mould.
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An advantage of the invention is to provide a process
which can produce this material by pouring same into moulds and
then steam curing same at least to the extent where it can be
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moved from the moulds, handled and stored under ambient condi-
tions for further curing.
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Yet another advantage of the invention is to provide
a process which is particularly suitable for use in the forma-
tion of building panels or blocks.
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Yet another advantage of the invention is to provide
a process in which reinforcing mesh is easily incorporated dur-
ing the pouring thereof. Furthermore, any necessary collar or
tray extensions are readily incorporated in the form prior to
filling same with the mix or slurry.
Still another advantage of the invention is to pro-
vide a process in which relatively inexpensive materials can beused yet at the same time providing a finished product which
can have an extremely fine finished surface if desired.
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A still further advantage of the invention is to pro-
vide a process which is simp]e in operation and o-therwise well
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suited to the purpose for which it is designed.
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With the foregoing in view, and other such advantages
. as will become apparent to those skilled in the art to which
this invention relates as this specification proceeds, my in-
vention consists essentially in the arrangement and construc-
tion of parts all as hereinafter more particularly described.
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DETAILED DESCRXPTION
Proceeding therefore to describe the process in
detail, it consists basically o~ a mixture of Silica Flour,
Silica Sand and Hydrated Lime which is formed into a slurry
with approximately an equal weight of water and allowed to
mix thoroughly. Calcium Oxide or "Quick Lime" is also added
and -the chemical action of the slurry is improved if the tem-
perature of same is raised.
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A relatively small proportion of Hydraulic Cement
such as Alumina Cement or Por-tland Cement is then added and
the resultant slurry foams to provide a cellular mass. This
cellular mass is then steam treated, as ~or example, by an
autoclave, in order to cure the material to the extent that
it can be removed from the moulds and stored ~or ~urther
curing to take place.
The addition o~ Plaster of Paris and Aluminum
Powder is advantageous under certain conditions and I have
also ound it advantageous to include a gelling agent to in-
crease the gelling of the cells when foaming takes place and
which assists in wa-terproofing the finished product.
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I have also ~ound it advantageous to add a deter-
gent which assists in the thorough mixing of the water with
the dry mix and in this respect, X have found a de-tergent
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~` sold by Harrison Cross~ield Company under the trade name
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"Harcoterge".
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It is advan-tageous that the Silica Flour be approx-
imately 200 mesh and that the Silica Sand be at least 90%
pure or ~ine.
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Given below are some examples o~ a mixture, all o~
: which have satis~actgrily ~ormed building bloeks or slabs;
90% fine SiO Elydrated Hot Plaster Aluminum
i SiO Sand Flour Lime CA0 Cement o~ Paris Powder
; 10 550 lbs. 25Q lbs. 135 lbs. 40 lbs 40 lbs 20 lbs 1 lb.
For this mix - 150 litres water.
600 lbs 300 lbs 180 lbs. 30 lbs 25 lbs. 10 lbs 1~ lbs
For this mix - 175 litres o~ water.
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500 lbs 200 lbs 120 lbs 40 lbs 16 lbs5 lbs 1 lb.
For this mix - 140 li-tres of water.
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Given below is a table illustrating the preerred
upper and lower ranges o~ the various ma-terials, but it will
be understood that some o~ the ranges will vary i~ some o~ the
ingredients sueh as Plaster o~ Paris or Aluminum Powder are
`~ 20 eliminated.
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Silica Sand 59 1/2% to 52% by weight
Silica Flour 23% to 26% by weight
Hydrated Lime Slaked 16% to 12% by weight
(Calcium Hydroxide)
CaO (Quick Lime) 3% to 4% by weight
Cement - Portland or 2% to ~% by weight
Alumina or mixture of both
Plaster of Paris or 0% to 2% by weight
Dolimitic Lime
Also, Aluminum Powder in the range of approximately
1 1/2% to 2 1/2% by weight may be added and a small proportion
of material such as sulphur, ground glass, sodium hydrochloride,
sodium bicarbonate and bleach such as Hydrogen Peroxide, may be
` added as these, in varying amounts, control the density and
- 15 the smooth surface at the mould interface.
I have found that an adequate gelling agent is form-
ed by a mixture of sugar and Sodium Silicate in relatively
small proportions.
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The sand used may be dune sand or tar sand tailings
: 20 which contain up to 2% bituminous or other foreign materials
and under these circumstances, I have found it advantageous
to mix the sand with some Quick Lime and a relatively small
amount of caustic soda to clean the sand grains and assist in
the action, before adding the designated amount of Calcium
Hydroxide.
When water is added to form the slurry, and while the
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hot lime ls slaking, the chemical action is assisted by rais~
; ing the temperature and at this time the detergent and gelling
agent can be added.
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The light Alumina Cement or Portland Cement together
with Dolimitic l,ime and some fine Silica Sand can be added at
this time in the proportion of four times by weight of the fine
Silica Sand to one part by weight of the cement and lime. This
permits ease of addition and assimilation of the aluminum de- -
pending upon the density and strength requirements. Also dif-
ferent grades or particle size of the aluminum and the amounts
of the chemicals mentioned will vary the texture of the finish-
ed product.
As the mix hegins to foam and become milky, it is
poured into trays, bins or moulds which preferably are prepared
` 15 as follows:
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; The moulds and the like are coated with a mould re-
lease such as that known as "Dow Corning 200"(Trade Mark) and
any necessary inserts are added for desired tongue and groove
or pat-
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,:,.',terned purposes. If desired, reinforcing mesh may be suspended
one inch ~rom the bottom of the tray or mould and any necessary
collars or tray extensions are added. It will also be appre-
ciated that for various sizes of blocks, moulds may be provided
with removable and expandable partiSions which are also coated
with the moulcl release preparation.
The trays and moulds, are ~illed with the milky
slurry and are left to foam up -to 50% depending on the amoun-t
o~ aeration desired.
The excess foam is -then trimmed of~ and the moulds
and trays are loaded into an autoclave. The steam is gradual-
ly released into the autoclave preferably taking approximately
one hour to attain 150 lbs. p.s.i. pressure and 360F tempera-
ture and this is maintained for eigh-t hours.
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It has been found that by increasing the pressure
to approxima-tely 180 pounds p.s.i., the autoclaving time has
been reduced to four hours wi-th better results in hardness.
I have therefore found -that the desired range o~
pressures o~ the autoclave is between 140 and 200 pounds
; 20 p.s.i. and a perio~ of time of between 10 hours ard 4 hours
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depending upon the pressure wi-thin the autoclave. The auto-
claving action on the Silica Flour and Lime develops a new
high crystallirle tobermorite substance which forms -the ~ono
Calcium Silicate ~Iydroate Matric bonding the other particles
of sand and or other aggregate such as expanded clay and
shale pozzolins, which can be incorporated if necessary.
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A~ter autoclaving, the boiler pressura is reduced
` and the autoclave released whereupon the slabs and/or blocks
are removed from their forms and palletized. They will con-
tinue venting and increasing strength as they dry for a day
or so under ambient conditions, but may be transported and
used immediately.
The material forms a cellular concrete building
material which is lightweight and is provided wi-th constructu-
ral properties. It is an excellent insulating material andis fire-proof. It is easily cut, drilled and handled and may
be reinforced when used as load bearing walls and for roo~
installations.
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~asier installation and cost savings are provided
through -time and wait reductions.
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Since various modiiications can be made in my in-
vention as hereinabove described, and many apparently widely
diiierent embodimen-ts oi same made within the spirit and scope
o~ -the claims without departing ~rom such spirit and scope, it
is intended tha-t all matter contained in the accompanying spe-
ci~ication shall be interpre-ted as illustra-tive only and not
in a limiting sense.
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