GYPSUM FIRE BREAK COMPOSITION

COMPOSITION AU GYPSE POUR COUPE-FEU

English Abstract

GYPSUM FIRE BREAK COMPOSITION
ABSTRACT OF THE DISCLOSURE
A gypsum plaster composition which, on
admixture of water, has improved plasticity and slip,
together with other characteristics essential in a
plaster for fire breaks and fire stops, such as used
with electrical cables, consisting essentially of
calcined gypsum, expanded vermiculite, bentonite clay,
a dispersant and a set control additive for the gypsum.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A gypsum fire barrier composition
consisting essentially of about 50 to 80 parts by
weight calcined gypsum, about 15 to 30 parts by
weight expanded vermiculite and about 5 to 20 parts
bentonite clay, said composition being free of
diatomaceous earth.
2. A gypsum fire barrier composition as
defined in claim 1 wherein said composition additionally
includes about 1% or less of a dispersant, and set
retarder as needed for said calcined gypsum.
3. A gypsum fire barrier composition as
defined in claim 1 consisting essentially of about
65% calcined gypsum, 25% expanded vermiculite and 10%
bentonite clay.
4. A gypsum fire barrier composition as
defined in claim 3, wherein said composition additionally
includes about 1% or less of a dispersant, and set
retarder as needed for said calcined gypsum.
5. A gypsum fire barrier composition as
defined in claim 1 wherein said calcined gypsum has a
fineness such that 95% passes through a 100 mesh
screen, said expanded vermiculite is No. 4 Grade, and
said bentonite clay has a fineness such that 80% passes
through a 200 mesh screen.
6. An aqueous settable gypsum slurry
comprising about 100 parts by weight of the composition
of claim 1 and about 120 to 160 parts by weight of
water.
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7. An aqueous settable gypsum slurry
comprising about 100 parts by weight of the composition
of claim 2 and about 120 to 160 parts by weight of water.
8. An aqueous settable gypsum slurry
comprising about 100 parts by weight of the composition
of claim 3 and about 120 to 160 parts by weight of water.
9. An aqueous settable gypsum slurry
comprising about 100 parts by weight of the composition
of claim 4 and about 120 to 160 parts by weight of water.
10. An aqueous settable gypsum slurry
comprising about 100 parts by weight of the composition
of claim 5 and about 120 to 160 parts by weight of water.
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Description

4~43
This invention relates to a specialized
plaster composition for uses such as fire breaks and
fire stops surrounding electrical cables. In particular
it relates to compositions containing essentially
calcined gypsum, expanded vermiculite and bentonite
clay.
Compositions containing calcined gypsum as
the potential binder formulated for use as fire breaks
and fire stops around electrical cables are known,
examples being the formulations disclosed in U. S. Patent
4~278,468, all of which contain diatomaceous earth,
glycerine and boric acid. In addition to these essential
ingredients of this prior patent disclosure, it is
taught that other aggregates may be expanded vermiculite9
expand~d perlite, glass microspheres, wollastonite or
the like. This prior patent also recognizes the
importance of flow properties of a slurry of this gypsum
composition and water.
The present invention is directed to pro~iding
a gypsum composition with characteristics more like the
characteristics being sought in this prior patent than
the compositions disclosed therein. The characteristic
which is particularly improved upon is the flow
; characteristic; however, other advantages are also
noticeable~ The invention resides essentially in the
combination of calcined gypsum, expanded vermiculite
and bentonite clay, and also the absence of diatomaceous
earth.
. ..~ -_ ` r,
~'`

It is an object of the present invention to
provide a novel improved gypsum composition for fire
stops and fire breaks.
It is a further object to provide such a
composition having particularly improved flow or slip
properties.
In accordance with the invention, gypsum
compositions are provided consisting essentiaLly of
; calcined gypsum, expanded vermiculite and bentonite
clay, which have characteristics, when mixed with water9
particularly suited for use as a fire break or fire stop
around a group of electrical cables, or other slightly
high temperature utility lines capable of, otherwise,
conducting fires therealong.
A group of electrical cables with flammable
insulation create a potential problem of spreading
fires within a room, or from room to room through
openings provided for passage of the cables. Aqueous
settable gypsum slurries have been provided for encasing
2~ the group of cables. The formulation of the present
invention permits such a slurry to more thoroughly and
easily encase a group of cables.
EXAMPLE I
The preferred formulation of the invention is
; as follows:
Parts by Wei~ht
Calcined Gypsum (CaS04-1/2H20) fiS
Expanded Vermiculite (#4 Grade) 25
Bentonite Clay 10
Lignin SulEonic Acid (Dispersant) 0.4
Hydrolyzed Proteinaceous Set Retarder (As required)
Water - 2 - 120-160

The amount of water to be used in the preerred
formulation may be varied in accordance with the degree
of fluidity desired. The calcined gypsum has a fineness
of 95% through a 100 mesh screen. The expanded
vermiculite, of No. 4 grade, is available from the W. R.
Grace Company. No. 4 grade has a 6 to 10 #/cu ft density,
with 0-5% retained on 16 mesh, 15-65 on 30 mesh, 60-98%
on 50 mesh and 90-100% on 100 mesh. A suitable bentonite
clay is grade SPV-200 from American Colloids Company,
with 80% below 200 mesh, a ph of 9 and a moisture content
of between 5 to 9 percent. The lignin sulfonic acid
dispersant may be .~merican Can Company's Marasperce C-21.
The hydrolyzed proteinaceous set retarder can
be prepared in accordance with U.SO Patent 2,865,905.
The amount desired will vary with individual job require-
ments.
-EXAMPIES II and III
The amount of calcined gypsum can be varied
from about 50% to about 80% of the total weight of the
dry ingredients as follows:
II III
Parts b~ Wei~h~ _arts by Wei~ht
Calcined Gypsum 50 80
Expanded VeL~iculite 30 15
Bentonite Clay 20 5
Lignin Sulfonic Acid 0.6 0.2
Set Retarder (As required)
The wet mix density of the ~rmulations of the
invention, with 120 to 160 parts water added, is about
66 to 68 lbs/cu ft, while the dry set densities are about

~$~ 3
28 to 33 lbs/cu ft. Compressive strengths of the set
products vary from 70-180 psi. The percent of setting
expansion is about .19% to .25%.
The thermal conductivity K value at 3Q lbs/cu
ft dry density is about .97 BTU/hr/ft2 - 0F/in.. The
drying time, under ambient conditions, of a two~inch
thick section is about 4 to 5 days.
It will be particularly noted that the
formulations of the invention are free of any
diatomaceous earth. The bentonite clay functions to
thicken an aqueous slurry of the formulations of the
invention, holding water and providing excellent slip.
Having completed a detailed disclosure of the
preferred embodiments of my invention so that those
skilled in the art may practice the same, I contemplate
that variations may be made without departing rom the
essence of the invention or the scope of the appended
claims.
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