Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
~ield of the Invention
The present invention relates to a cementitious composition -
for the molding of light-weight structural units and more particularly
to a cementitious sand/stack dust/fly ash aggregate conta:Lnlng
admixture which incorporates a significant proportion of a waste
polyethylene material ill strip form.: The invention further embraces
the method of preparing the cementitious composition for end use.
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Description of the Prior Art
As is well~known in the building industry, molded blocks
and other structural ~mits are used quite extensively in the fabrication
of masonry structures and the like. It is desirable that such bloc~s
~ be relatively inexpensive, of a density suitable to allow fastening
- devices to be inserted therein, insulative, relatively light-weight,
and yet sufficiently strong so as to be su:Ltable for the desired
utility. It i5 further desirable that such blocks present an appearance
which i5 aesthetically pleasing. Recent attempts at satisfying each
of these criteria with a single product have been adequate, but generally
leave much to be desired.
For example, it is well-known in the prior art to utilize
thermoplastic additives in the form of pellets to provide compositions
for the p~rpose of improving and varying their appearance. Of course,
it seems apparent -that the addition of such pellets ~ill adversely
affect, to a measurable degree, the load-bearing capabilities of the
final product prepared from such a composition. Accordingly, the cement
compositions are generally recommended for use only in relatively thin
layers on top of another material such as a conventional concrete product.
Furthermore9 In order to provide a pleasing appearance the
thermoplastic additives must be of relatively uni~orm sizes and
configurations. This necessarily increases the cost of such compositions
and products prepared therefrom.
In an attempt to reduce the cost of cement compositions and
end-use products manufactured from cement, the present state of the
art recognizes the utili~ation of fly ash, which is an industrial waste,
as an aggregate in the preparation of cement compositions. Of course,
fly ash has also been used as a replacement for at least a portion of
the portland cement element present in cement compositions.
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More ~ecently, as the availability oE aggregate has diminished
for commercial use there has been an attendant increase in the cost o~
cement mixtures and products made from cement. Whi~e the utilization
of ~ly ash in cement composition is clearly a step in the right direction,
both in conservation and in cost reduction, there is still a great
need in the art for other cement-type products to meet the ever-increasing
demand while at the same time maintaining a relatively stable cost
factor. Accordingly, t~lere is a need in the art for a novel compositlon
~or the molding of relatively light-weight struc~ural units wherein
heretofore useless waste materials may be utilized to produce a strong,
insulative composltiorl for the molding of structural units. Of course 9
such a cementitious composition should be able to withstand radical
changes in temperature without seriously affecting the structural
integrity of units manufactured therefrom, and it would further be
desirable if the elements of such a composition could be selectively
varied to render the composition suitable for the molding of structural
units primarily desired for their insulative properties as opposed,
for example, to structural units molded ~rom a composition primarily
intend~d to be utiliæed for their compressive strength. Finall~, it
is also desirable that such a composition provide an attractive appearance
in the ~inal end product.
SUM~9~Y OF THE INVENTION
The present invention relates to a cementitious composition
for the molding of structural units, to structural units manufactured
from the cementitious composition, and to the process utilized in
preparing the cementitious settable composition. Most simply stated,
the composition comprises an inorganic cementitious settable admi~ure
within which is incorporated a significant proportion of industrial
waste material consisting substantially of polyethylene strips and
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stack dust and/or fly asll.
Inasmuch as a sigaificant feature of the present invention
resides in the utilization of waste polye~hylene material, the manner
in which such material is derived as well as the general nature of
the material will now be described in greater detail. The polyethylene
is a heretofore substantially useless waste product derived from
the manufacturing of polyethylene-coated fiberboard cups and containers
or the like. In the container manufacturing industry a considerable
amount of polyethylene-coated fiberboard scrap material is generated
during cutting and trimming of sheets utilized to Eorm the containers.
Since these scraps represent an economic loss, particularly due to
- their predominant cellulosic fiber content, they are generallyreprocessed in order to extract the "contaminate" polyethylene coating
so as to facilitate recovering the cellulosic fiber. In one container
! manufacturing plant in excess of 30,000 tons of waste polyetbylene is
discarded yearly in public dumps. The waste polyethylene material
consists mainly of polyethylene, in the order of about 98 percent,
and about 2 percent of other materia~s which predominantly comprlse
celluloslc fibers.
2a Thus, it will be understood that the waste polyethylene
referred to herein is derived and has the approximate analysis as
set forth above. Accordingly, it will be appreciated that the nature
of the waste polyethylene utilized has been set forth in as definitive
a manner as is possible in view of the fact that the specific makeup
of the waste polyethylene unavoidably varies from time to time.
Additionally, the waste polyethylene utilized in the present
invention is preferably cut into elongated, ribbon-like strips.
For purposes of illustration, these strips are preferably on the
order of 8 inches long and 1/4 inch wide. In the final p~oduct, the
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polyethylene strips are not visible, but ~heir effect is quite apparent.
The polyethylene strips impart greater grip and permanence to fastening
devices such as screws, nails, etc. This improvement is attributable
to the flat ribbon-like shape of the strips and the fact that they
overlap and interlink in the present invention. Greater moisture
impermeability is also a result of the use of polyethylene strip~.
Not only does polyethylene offer great resistance to moisture penetration~
but also the ribbon-like shapes tend to randomly overlap forming a
further physical barrier to penetration by moisture~
As discussed above, the present invention ~urther contemplates
the use of stack dust or fly ash in combination with the sand, perlite,
vermiculite, etc., widely used as aggregate in cement and cementitious
mixtures. Stack dust is a by-product of commercial portland cement
manufacturing operations, and is presently considered to be without
r ~alue in concrete. Quite to the contrary, however, it has been
determined that stack dust is quite suitable for use in the cementitious
composition of the present invention. Fly ash, of coursei is a well-
known by-product of coal burning plants. Since both stack dust and
fly ash are considered to be undesirable by-products, and even
poIlutants, it is to be understood that their quality and precise
composition may vary widely depending upon, for example, their source,
the temperatures attained in the cement manu~acturing facilityj the
quality of the coal burned, and the equipment and operation of the
steam plantc Accordingly, it will be appreciated that the nature of
the stack dust and fly ash utilized has been set forth in as definitive
a manner as is possible.
The synthetic resin-inorganic cementitious settable
composition utili7ed to mold structural units in accordance with
the present invention comprises, on the basis oE volume, appro~imately
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one to four parts polyethylene strips, two to elght parts aggregate,
one to two parts of hydraul;c cement, such as portland or lime-
- containing cement, and one to four parts water. The aggregate is
selected from a group consisting of sand, stack dust~ fly ash, perlite
and vermiculite. However, as will be set forth in greater detail
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hereinafter, perlite and vermicul-lte are not used together in the
same mixture. Finally, as indicated above, the process for
prepar;ng the composition of the present invention is unlque when
compared with that cuxrently used in the preparation of cement
products. The present mixture of concrete calls for an adding of
all aggregates to the cement before any addition o~ water. This
mixing procedure has proved to be unsatisfactory for preparing
the composition of the present invention. Rather, the water and
polyethylene strips are first mixed, next the cement is added, and
r finally the selected aggregate is admixed.
The porportions of the components used in t~e present
composition determine the resilience of the structural unit molded
therefrom, and, accordin~ly, selectively varying the proportions
in a predetermined manner contributes to the versatility of the
resulting structural units. Units formed from the composition are
suit~ble for the reception of nails, screws, staples, glue, plaster~
paint, and may be drilled. Additionally, when compared with
presently available concrete products, the units exhibit markedly
increased waterproof qualities. Structural units molded of the
composition of the present invention will only absorb approximately
20 percent of their oun weight when submerged completely in water
for as long as 30 days with no additional precautions taken to
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enhance the waterproof qua:Lit:Les of the units prior to their being
submerged~ Compressive strength testing of a structural unit
produced u~ilizing the waste polyethylene-cementitious compositi~n
of the present inven~ion have sustained compression of as high as
354,240 pounds per square foot without fracturing. Other test
blocks which have been intentionally provided with fractures
running 50 percent to 60 percent of the distance through the
units have been subjected to a compresslve load of the order set
forth and still remain intact.
A plank 18 inches wide, 4 inches thick and 72 inches long
with two 5~8 inch reinforcing bars embedded therein and molded
from a composition as set forth herein, after being per~itted to
cure for eight days in the mold, was supported at either end by 4
inch bearings. A stress of 2,068 pounds was applied to the plank,
at its center point, and the plank did not fracture or collapse but
merely deflected about 3/4 inch. After removal of the stress
the plank made a full recovery within 20 minutes. This test
demonstrates the use of polyethylene strips in the present
in~ention imparts a greater tensile strength and resiliency to
this invention than is found in the prior art. This is primarily
due to the overlapping and interlinking of the polyethylene strips.
Furthermore, cured structural units produced in accord
with this invention are fire resistant in that in an exemplary test
an oxygen-acetylene torch producing a flame having a temperature
of about 7,000F. was applied to a 2 inch block without any
significant damage. For comparison purposes, a 2 inch block of
concrete, when subjected to the same flame for the same period of
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time (18 seconds) exploded and shattered. A 2 inch thick block of
asbestos had a hole burned completely through it.
Finally, standard frequency test conducted with concrete
and with the cementitious composition of the present invention
show that cured structural units produced in accordance with
this invention exceed concrete in sound reduction by about 43
percent. For example, an 8 inch thick concrete block transmitted
50 decibels of sound. A 4 inch block produced in accordance with
this invention transmitted only lS to 18 decibels oE sound.
10The invention accordingly comprises a composition
possessing the characteristics9 properties, and the relation o~
constituents which will be exemplified in the composition
hereinafter described, a process comprising the several
steps and the relation of one or more of such steps
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with respect to each of the others, which will be exemplified
in the process hereinafter disclosed, and a product possessing
the features,'properties and the relation of components which
will be exemplified in the product hereinafter described, and
the scope of the invention will be indicated in the claims.
In one particular aspect the present invention provides
a synthetic resin-inorganic cementitious setta'ble composition,
said composition consisting essentially of) by volume:
(a) about 1-4 parts elongated polyethylene StlipS;
(b) about 2-8 par~s aggregate, said aggregate being at
least one type selected from the group consisting of cement
stack dust, fly ash, perlite and vermiculite and mixtures
thereof with sand, subject to the proviso that perlite and
vermiculite not be selected concurrently;
(c) about 1-2 parts hydraulic cement; and
(d) about 1-4 parts water.
In another particular aspect the present invention provides
a process for preparing a synthetic resin-inorganic cementitious
settable composition, said process comprising the steps of:
(a) mixing about 1-4 parts, by volume, elongated poly-
ethylene strips and about 1~4 parts, by volume, water;
(b) admixing about 1-2 parts9 by volume, hydraulic
cement to the mixture of step (a);
(c) selecting a~ least one type of aggregate from the
group consisting of cement stack dust, fly ash, perlite and
vermiculite and combinations t'hereof with sand, su'bject to
the proviso that perlite and vermiculite not be selected
concurrently, and
(d) admixing about 2-8 parts, by volume, aggregate of
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step (c) to the mixture of step (b), in the followlng order:
stack dust, sand, perlite, vermiculite, fly ash.
- DETAIL~D DRSCRIPTION
The following examples are set forth in order to fully
describe the composition and process of the present invention.
In each of the following examples, each of the ingredients
of the composition are expressed in parts, by volume.
Furthermore, as will be set forth in gr~ater detail hereinafter,
each of the ingredients is listed in the preferred order of
their addition one to another in the process for preparlng the
lnventive composition.
EXAMPLE I
A waste polyethylene-cementitious composition was
formulated and intimately admixed utilizing:
Polyethylene Strips 1.0 part
Water 1.34 parts
Hydraulic Cement 1.0 part
Aggregate (sand, stac~
dust and perlite~ 3.5 parts
XAMPLE II
A waste polyethylene-cementitious composition was
formulated and intimately admixed utilizing:
Polyethylene Strips 2.0 parts
Water 2.67 parts
Hydraulic Cement 1.0 part
Aggregate (stack dust and
perlite) 8.0 parts
EXAMPL~ III
A waste polyethylene-cemen~itious composition was
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formula~ed and intimately admixed utili2ing:
Polyethyl~ne Strips 1.69 parts
~ater 1.69 parts
Hydraulic Cement 1.0 parts
Aggregate (sand and fly ash) 3.59 parts
EXAMPLE IV
A waste polyethylene-cementitious composition was
formulated and intimately admixed utilizing:
Polyethylene Strips 1.0 part
Water 1.0 part
Hydraulic Cement 2.0 parts
Aggregate ~perlite) 6.0 parts
EXAMPLE V
A waste polyethylene-cementitious compos-ition was
formulated and intimately admixed utilizing:
Polyethylene Strips 1.0 part
Water 1.0 part
Hydraulic Cement 1.0 part
Aggregate (vermiculite) 2.0 parts
EXAMRLE VI
A waste polyethylene-cementitious composition was
formulated and intimately admixed utilizing:
Polyethylene Strips 1.0 part
Water 3.0 parts
Hydraulic Cement 2.0 parts
Aggregate (vermiculi~e~ 6.0 parts
EXAMPLE VII
This example is generally presented for the purpose of
more specifically detailing the process utilized in preparing
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cementitious composition of the present application. Each
of ~he preceding Examples should be consulted in c~mbination
~ith the disclosure presented in this E~ample.
As indicated above~ the cementitious composition of the
present invention is prepared in a manner unlike that of
~ presently known and utilized cement and cementitious mixtures.
; The process utilized in the present invention may be
schematically presented in the following sequential steps:
l. First, the predetermined quali~ies o polyethylene
strips and water are intimately mixed.
2. Next, the corresponding amount of hydraulic cement
is added to the water-polyethylene mix~ure and ~horoughly
mixed.
3. Finally, the aggregate is admixed, and the resulting
cementitious composition is ready for production of the end-use
product. As shown in the preceding examples, a variety of
aggregate components may be utili2ed. Regardless of the
aggregate combination chosen the individual components are
preferably added in the following order:
a. Stack Dust
b. Sand
c. Perlite
d. Vermiculite
e. Fly Ash
Again, with specific regard to the preceding examples, it
should be noted that at no time are both perlite and vermiculite
utili~ed in the aggregate formulation for a single cementitious
composition prepared in accord with this invention.
It will thus be seen that the obiects set forth above,
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among those more apparent from the preceding description,
are efficiently attained, and, since certain changes may be
made in the above composition and process without departing
from the scope of the invention, it is intended th~t all matter
contained in the above description shall be interpreted as
illustrative and not in a limiting sense.
It is also to be understood that the following claims
are intended to cover all oE the generic and specifi-~ feat~lres
of the invention herein described, and all state~ents oE the
scope of the invention which, as a matter of language~ might
be said to fall therebetwe.en.
Particularly, it is to be understood that in said clalms,
ingredients or compounds recited ln the slngular are intended
to include compatible mixtures of such ingredients wherever
the sense permits.
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