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Патент USA US3024135

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CROSS REFERENCE
,.
United States Patent 0 " ICC
1
3,024,125
CEMENT COMPOSITION
3,024,125
Patented Mar. 6, 1962
2
1
tural shapes or aggregate composed of silica. Apparently
at high temperatures, e.g., above 500° F., alkali metal
w
tends to flux the silica structure at the cement-silica inter-
William M. Lee, Ambler, Pa., assignor to Pennr'alt Chem
icals Corporation, Philadelphia, Pa., a corporation of 5 face, causing failure.
It has now been found, in accordance with the present
Pennsylvania
invention, that improved cements having the excellent
No Drawing. Filed Feb. 13, 1959, Ser. No. 792,979
mechanical strength characteristic of the cements of ap
19 Claims. (Cl. 106—287)
plication Serial No. 712,078 but free from the above
This invention relates to cement compositions utilizing
mentioned disadvantages, may be provided by employing
a silica sol as the cementing or bonding agent.
10 a silica sol as the bonding agent for the cement and
anica L
The use of asilicgggol. as the bonding agent in cement
_e ting a ent fo the $1 ica so comrisin an or
compositions has'b'een proposed in the past. In early
ase sili
hic
is e .
ly soluble m water,
attempts to use silica sol for this purpose the sol was al
preferred organic base silicates being the quaternar am
lowed to set or gel by dehydration, or the
’ was
monium silicates, amine silicates, quaternary pEosphomum 4
hastened by the addition of various e ectrolytes such as_ 15 silicates and ternary sulfonium vsilicates. s?'e‘rr'cemen ts
ma
rum su ate or magnesium s11co uor1 e. I
en
rthefsol 1S allowed to set by dehydration, tl?setting takes
have excellen
anical prope?i'é'swand acid resistance
and in addition have markedly increased water resistance,
place too slowly to be practical and furthermore, the
improved electrical properties and resistance to fluxing
mechanical strength of the cements is too low for most
at high temperatures.
applications. The addition of electrolytes such as mag 20
The silica sol employed in the cements of the present
nesium sulfate was found to hasten the setting, but the
invention should be an aqueous silica sol, which for the
mechanical strength of the cured cements is as low or
vast majority of applications should have a colloidal silica
even lower than strengths obtained when the sol is gelled
concentration of at least 10% by weight and preferably
by dehydration.
at least 20% by weight. There is apparently no upper
In copending application Serial No. 712,078, ?led 25 limits for the silica content, provided the sol is liquid
but sols of 45% silica by weight or more are difficult
January 30, 1958, and now US. Patent No. 2,914,413,
for Cement Composition and Method of Preparation by
Robert S. Mercer, cement compositions are described
to prepare and not generally available.
utilizing a silicaMsgL as a bonding agent and certain
known. One of the earliest processes 0 commercial im
.
Many methods for preparing aqueous silica sols are
alk ' M al‘ silicates [in solid form as the setting agent 30 portance is described in US. Patent No. 2,244,325 to Bird
the silica so.’ 15‘ sharp contrast to the silica sol
according to which a dilute sodium silicate solution is
cements previously suggested, the cements descri ed in
passed through a bed of an acidic ion exchange resin,
application Serial No. 712,078 have excellent mechanical
such as an acid treated carbonac
' , to reduce
strength. In conjunction with their high mechanical
the alkali metal ion content of the original silicate solu
strength, these cements display excellent resistance to 35 tion to low values, such that the ?nal SiOz:Na20 ratio is
acid corrosion and may be used in applications where
at least 10:1 and preferably higher, such as 50:1 or
they are exposed to boiling concentrated sulfuric, hydro
chloric acid and the like, being markedly superior both
then be concentrated by evaporation.
100:1. This yields a dilute aqueous silica sol which may
in mechanical strength and in acid resistance to the so
Another suitable method for the prepartion of a silica
called “water glass" cements based upon the use of a 40 aquasol is described in US. Patent 2,375,738 to White
sodium silicate solution as‘ the bonding or cementing
according to which a sodium silicate solution is neutralized
agent.
with acid to precipitate silica gel, after which the gel is
It has been found, however, that the cements of the
synerized, crushed, washed to remove soluble salts, cov
aforementioned application Serial No. 712,078 are not
ered with a dilute alkali (e.g., 0.1%NaOH) solution and
entirely suitable for some uses, apparently as a result of 45 then heated in an autoclave at temperatures between 80°
the alkali metal ions introduced into the cement by the
alkali metal silicate setting agent. For example, under
C. and 200° C. for several hours.
some circumstances, exposure to water may reverse the
as those described in US. Patents 2,574,902 and
setting process and weaken the ?nished cement. If, for
2,577,485. According to the process described in these
More recently, improved silica sols have appeared such
example, a cast article is soaked for a considerable time 50 patents, an aqueous silica sol, such as that produced by in a small amount of water, alkali metal silicate'will
the process of the Bird Patent 2,244,325 referred to above,
having colloidal silica particles of less than 10 millimi
leach out of the cement and the water will become
strongly alkaline. The alkali can then attack the cement
crons in size, is treated to increase the average size of
and weaken it. An application in which this type of
the silica particles. The sols produced by these processes
attack may occur is in the case of a grinding wheel in 55 are stable at concentrations of 20% to 35% by weight
which the abrasive grit is bonded with a silica sol set by
of colloidal silica, contain silica particles which are us
means of a sodium silicate setting agent. In wet grind
ually remarkable uniform in size, and are preferred in
ing operations, the grinding wheel is immersed in a water
the practice of the invention.
bath or sprayed with water, and under these circum
Other suitable processes for producing aqueous silica
stances leaching out of the sodium silicate will make 60 sols are described in US. Patents 2,680,721, 2,601,235,
the water alkaline, which will in turn attack the cement
2,668,149, and 2,650200. It is to be understood, of
and may cause rupture at high speeds.
course, that the invention is not limited to any particular
Another example where the relatively small alkali
method for preparing the silica sol, although as pointed
metal content of the cements of the aforesaid application
out above, the sols produced by certain methods are
may be disadvantageous is in the case of electrical appli 65 preferred.
cations (e.g., fabrication of resistors, potting of electrical
As is well known, silica sols, as distinguished from
components, etc.) where apparently the small amount
alkali metal silicate solutions, contain a low alkali con
of alkali metal silicate contained in the cement will cause
centration. As mentioned in the Bird Patent 2,244,325,
undesired variations in electrical properties. A further
in the case of silica sols containing sodium ions, a
example of undesirable side effects apparently arising out 70 SiO3:Na2O ratio of about 10:1 is the practical upper
of the small alkali metal content of such cements is in
limit of sodium concentration. As stated by Bird, higher
applications where the cement is used as a bond for struc
SiO3:Na3O ratios such as 50:1 or 100:1 are‘ preferred.
3,024,125
4
According to US. Patent 2,574,902 referred to above,
the desirable range of SiO2:Na20 ratios is given as
60:1 to 130:1, while in US. Patent 2,577,485 sols hav
ing SiO2:Na2O ratios ranging up to 500:1 are described.
In the preferred sols of the invention, considering cost 5
as well as desirability, the alkali content of the sol ex
pressed as the SiO2:Na2O weight ratio ranges from about
50:1 to 300:1. While lower ratios can be used (e.g.,
methyl piperazinium silicate.
Quaternary ammonium
silicates of this type are described in US. Patent 2,689,
245, and in Journal of Physical and Colloid Chemistry, -' n
v. 55, 1951, pages 187-195, R. C. Merrill and R. W.
Spencer. Particularly preferred are the tetraalkyl am
monium silicates in which the alkyl groups may have 1
to 4 carbon atoms and may be the same or different, such
I down to 10 SiOz:1Na2O in the case of sols containing
sodium ions), such sols are not as desirable because
as tetramethyl ammonium silicate, tetraethyl ammonium
silicate, ethyltrimethyl ammonium silicate, etc.
Another particularly suitable class of organic base
they introduce appreciable amounts of alkali, such as
sodium ions, into the cured cement which is undesirable
silicates are the amine silicates which may be prepared
by the reaction of strongly basic amines such as trimethyl
for the reasons pointed out above. Higher ratios can
amine or guanidine with a reactive form of silica. Still
also be employed, e.g., a SiO2:Na2O ratio of 500:1, but
another class of organic base silicates suitable for use
such extremely low alkali content sols are usually rather 15 in the invention are the quaternary phosphonium silicates
expensive. Some minimum content of alkali, in the
(i.e., those in which the quaternary phosphorus atom has
form of sodium, potassium, lithium, or ammonium ions
four carbon-to-nitrogen bonds) which may be prepared,
is desirable and indeed considered essential for impart
for example, by the reaction of a quaternary phos
ing good stability to the sol. The stabilizing eifect of
phonium hydroxide such as tetramethyl phosphonium hy
a small amount of sodium ions is discussed in US}. 20 droxide with a reactive form of silica. Still another
Patents 2,244,325 and 2,574,902, referred to above. The
suitable class of organic base silicates are the ternary
alkaline reacting sols described by these patents are thus
sulphonium silicates (i.e., those in which the sulfur atom
preferred for their stability. In the case of sols stabilized
has three carbon-to-nitrogen bonds) which may be pre
by sodium ions, maximum stability is usually obtained
pared by the reaction of a ternary sulphonium hydroxide
between a pH of about 8 to 10 although fairly stable 25 such as trimethyl sulphonium hydroxide with a reactive
sols are obtainable at lower and higher pH values.
form of silica.
Acid reacting silica aquasols are generally considerably
In all cases, the organic base silicate should be em
less stable and thus not as desirable or as convenient to
ployed in solid form, preferably as a ?nely-divided
use.
powder, e.g., a powder of 100 mesh ?neness or more.
A characteristic which distinguishes silica sols from 30 It has been found that in common with the alkali metal
materials which have sometimes been loosely referred to
silicates described in the aforementioned application, the
as silica sols, such as sodium silicate solutions, is the
organic base silicates apparently have a unique gelling
fact that the silica content of a silica sol of appreciable
action upon the silica sol through which cements of ex
silica concentration may normally be precipitated as a
cellent mechanical strength are obtained. Although the
silica gel by adding alkali such as NaOI-I, to the sol. An 35 mechanism of the setting of the silica sol is not fully
aqueous sodium silicate solution, on the other hand, is
understood, it is believed that the setting agents of the
merely made more alkaline by adding NaOH: a silica
invention produce a relatively slow, orderly precipitation
gel does not precipitate. Similarly, a sodium silicate
of the gel in a manner which leads to high bond strengths.
solution which has been partially neutralized by acid,
It is believed that the marked improvements in water
but not otherwise treated, may contain some material 40 resistance, electrical properties, and high temperature
which might be classi?ed as colloidal silica, but such a
performance obtained with the setting agents of the in
partially neutralized solution will not normally precipitate
vention is due to the fact that these setting agents in
silica gel when NaOH is added but will merely become
troduce no alkali metals into the cement.
more alkaline, the precipitated silica going back into
The composition of the ?ller is not critical. It may
solution as sodium silicate.
45 consist of any material which is essentially insoluble in
Broadly speaking, the setting agent for the silica sol
the water of the silica sol and which is substantially inert
may be anyorganic base silicate which is slowly soluble
with respect to the sol. It will be apparent that a great
in water. Preferably the organic base silicate should have
approximately the same rate of solubility and approxi
variety of substances fall within this classi?cation such
a variety of forms, both hydrated and anhydrous, crys
porosity.
as silica, various insoluble silicates including many
mately the same degree of solubility in water as sodium 50 minerals, such metallic oxides as the iron oxides, titania,
silicates which have an Na-,~O:Si02 ratio in the range of
zirconia and calcined alumina, such insoluble salts as .
1:1 to 1:42. By an organic base silicate is meant a
barium sulfate and calcium carbonate, silicon carbide and
silicate that may be prepared by the reaction of a strong
iron carbide, and such metals as iron and copper. Sulfur
organic base suchas a quaternary ammonium hydroxide
can be used and carbon such as powdered graphite. Or
or a tertiary amine with a reactive form of silica such 55 ganic ?llers such as ground walnut shell and wood
as a silica gel. Such silicates may be regarded as analog
?our may be employed. Even certain organic com
ous to the alkali metal silicates wherein the alkali metal
pounds as powdered naphthalene, which is water-in
ions have been replaced by a non-metallic function de
soluble, may be employed to obtain special effects; for
rived from a strong organic base. In common with the
example, naphthalene may be leached from the cement
metal silicates, the organic base silicates may exist in 60 after hardening to provide a structure of controlled
talline and vitreous, and in a variety of molecular con
?gurations depending upon the ratio of the organic func- i
.
/
tion to the silicate function.
Particularly preferred are the quaternary ammonium 6
silicates which may be considered as derived by the re
placement of the alkali metal ion of an alkali metal sili
‘cate with a quaternary ammonium group, i.e., an am
monium. group in which the quaternary nitrogen atom
has four carbon to nitrogen bonds. These may be pre
pared by reacting a quaternary ammonium hydroxide
with silica gel. Typical quaternary ammonium silicates
Typical speci?c ?ller materials that may be advan-~
tageously employed in the cements of the invention in
clude quartz (SiO2), beryl (3 Be0-Al,03-6Si0z), Oli
vine [(Mg, Fe)2SiO4], zircon (ZrSi04), wollastonite
' (CaSiO3),
asbestos, (H4Mg3SiaO9), nepheline sycnite
?uorspar
[(Na,
(CaFz), alumina (A1203),
amblygonite
and silicon carbide
(SiC).
Some materials, of course, are obviously unsuitable as
?llers, such for example as soluble materials, such as
suitable for use in the invention include tetramethyl am
sugar which would dissolve in the silica sol, or soluble
salts such as sodium chloride and magnesium sulfate
monium silicate, benzyltrimethyl ammonium silicate,
\_ phenyltrimethyl ammonium silicate, and N,N,N',N'-tetra- 75 which are unsuitable both because they would dissolve in
3,024,125
5
the sol and because they would interfere with the proper
action of the setting agent.
The wide variety of ?llers which can be employed sug
gests many of the uses to which the cements of the in
vention can be put. Depending on the ?ller employed,
for example, cements of the invention may be used for
the making of tiles, bricks, high temperature-resistant
6
very low density are employed, such as vermiculite, the
?ller may comprise somewhat less than 50% by weight
of the cured cement.
~
In most applications the weight ratio in the cured ce- ‘
ment of solids contributed by ?ller and those contributed
by the combination of the silica sol and the setting agent
will range from 97:3 to 80:20 and usually from 95:5 to
tubes and molded shapes, paint-like thin coatings, elec
85:15. In the great majority of cases, a high ?ller to
trical resistors (with organic or ceramic overglazes ap
silica sol ratio is desirable from the standpoint of mini
plied subsequent to forming), ?lters, partly metallic bear 10 mizing porosity in, the cured cement and shrinkage dur
ings, partly metallic structures of high electric resistance
ing curing. The silica sols commonly available, as previ
but good thermal conductivity, magnets, etc., and ce
ously pointed out, contain of the order of 30% of SiO,
ments suitable for use in chemically resistant construc-'
and the water content of mortar must, of course, be lost
tion, in particular cements which have high resistance to
by evaporation during curing.
aqueous acids. As pointed out previously, the cements 15
The proportion of organic base setting agent employed
of the invention, because of their markedly improved
may likewise vary. Generally speaking, it should be pres
water resistance, electrical properties and high tempera
ent in amounts of approximately 0.2% to 15% by weight
ture performance, will be suited for many applications
of the ?ller, and for most applications in amounts of
where these properties are important in which the ce
from 2% to 10% by weight of the ?ller.‘
ments of application Serial No. 712,078 would not be 20 The proportions of the dry ingredients to the liquid
entirely practical.
,
silica sol may vary within wide limits depending upon
As with other cements, the strength of the cured ce
the nature of the ?ller, its particle size and density, the
ments of the invention is dependent to some degree on
consistency of the mortar desired, and the silica content
the particle size and particle size distribution of the ?ller.
of the silica sol. Generally speaking, of course, the
' Even where it is desired to include in a cement mass a 25 amount of silica sol employed must be sut?cient to bond
‘ considerable portion of large aggregate (for example, ag
the ?ller into a coherent mass, the optimum ratio of
. gregate of 8 to 20 mesh), for reasons of economy or
solids to liquid sol being readily determined empirical
special purposes (e.g., grinding Wheels). some ?nely-di
ly in each particular case. As an illustration of the wide
_.~ vided ?ller (for example, from 100 to 200 mesh) should
variation possible in solid-liquid ratio, this ratio may
‘ generally be included in order to achieve the maximum 30 range from 0.5 :1 for a ?ller consisting of asbestos ?bers
strength. In those occasional instances where it is de
to 6:1 for a ?ller of a high density material such as zir
sir-able to create a cement mass of low strength, for ex—
con. When using primarily silica flour as the ?ller, and
ample, in making molds or cores for casting, ?ne ?ller
a 30% SiOg sol, optimum solids to liquid weight ratios
may be omitted.
are generally within the range of from about 3.0 to 4.0
It is frequently desirable to employ mixed ?llers. The 35 by weight.
mixture may be in terms of particle size, that is, a single
While in any case a single organic base silicate set
composition such as quartz might be used in three par
ting agent may be employed, it will often be desirable
ticle sizes, including gravel, ?ne sand and quartz ?our.
to employ a mixture of setting agents having different
solubility rates. In general, the more rapidly soluble the
their shape or porosity or density. Fibrous minerals such 40 setting agent, the more rapidly will it set the cement, but
:as asbestos may be included or laminar minerals such as
on the other hand, the shorter will be the working life
mica. Minute hollow bubbles which have recently he
of the mortar (that is, the period during which it may
come c mmercially available may be included. Such
be poured into containers, troweled, extruded or the like).
“microballoons” composed of phenolic resin or of alumi
With more slowly soluble setting agents the working life
Materials may be included in a mixture for the sake of
‘num oxide can both be used in the cements of this in 45 is improved but the setting time (that is, the elapsed
;vention to provide lighter structures which are good
period until unsupported shapes can be safely handled
vthermal insulator . Fibre glass and rock wool have been
without special precautions) is increased. To obtain an
,iused to make c? ntitious masses of particular prop‘fgerties. It is quite often desirable to add minor percent
time, that is, a working life long enough to be' practicable
optimum compromise between working life and setting
,1 ages of clay to a cement composition for the sake of the 50 and a setting time short enough to be practicable, a mix
plastic properties it gives to the initial mortar. Materials
such as kaolin allo hane
n
'
'_ , vermiculite,
ture of setting agents, one of which is relatively rapidly
water-soluble and the other which is relatively slowly
' attapulgite, bentonite etc, will often improve
e
W
water-soluble is advantageously employed.
ability of a mortar, and may be used if their presence in
If desired, the cements of the invention may be cured
the ?nal cement mass will not interfere with the use in~ 55 entirely at ambient temperatures. They require no ele
tended.
vated temperature curing to develop excellent mechanical
In preparing the cements of the invention, it is pre
properties. On the other hand, the cured cement may, if
ferred ?rst to mix the particulate ?ller with the setting
desired, be subjected to a post cure at slightly elevated
agent in the form of a ?nely-divided powder. Just before
temperatures, e.g., 60° C. to 100° C. for 1 to 24 hours,
use, the dry ?ller-setting-agent-blend is then mixed with 60 or may also be ?red at high temperatures, e.g., 600° C.
su?icient silica sol to prepare a cement mortar of proper
to 1000° C. for e.g., 1 to 4 hours. On ?ring, the cements
consistency. This method of preparing the cement is
preferred since the setting agent is homogeneously
blended with the tiller in advance, resulting in a more
of the invention will generally increase substantially in
strength. This may be due in part to the fact that the
organic moiety is thermally destroyed by such high tem- .
uniform distribution of the setting agent throughout the 65 perature treatment. In the case of the quaternary am
cement when the silica sol is added. 0n the other hand,
monium silicate and amine silicate setting agents, both
if desired, the silica sol and ?ller may be blended ?rst
the nitrogen and the organic portion is usually decom
and the solid ?nely-divided setting agent then added to
posed and driven o? from the ?red cement. In the case
the liquid slurry.
of quaternary sulphonium silicates, ordinarily both the
The proportions of the ingredients may vary rather 70 sulfur and the organic portion may be lost, the sulfur
widely depending upon the particular application involved
probably coming off as S0, or 80;, unless a material such
and the type of ?ller or mixture of ?llers employed. In
as calcium carbonate is present which may react with and
the great majority of cases, the ?ller will comprise the
tie up the sulfur in an insoluble form, e.g., as calcium
major proportion by weight of the cured cement com
sulfate. In the case of the quaternary phosphonium
position, although in a few special cases, where ?llers of 75 silicates, the organic portion is probably carbonized and
7
Q
3,024,125
liberated as CO2 in the presence of air while the phos
Example 3
phorus atom may become bonded in some way in the net
work of the cement, particularly if a small amount of a
material such as calcium carbonate is included in the ?ller
to form, e.g., a calcium phosphate.
The following examples are intended to illustrate the
invention:
A cement is prepared using the formulation of Ex
ample 1 except that instead of using 6 grams of tetra
methylammonium silicate there is used 3.0 grams of
benzyl trimethylammonium silicate in powdered fonn
(prepared as described in U.S. Patent 2,689,245 and in the
above-mentioned article by R.C. Merrill et al.). The
Example I
cement mortar is cast into 1" cylinders which are cured
at 60° C. for 24 hours and then heated to 700° C. for
A cement composition is prepared using the following
10 8 hours. The compressive strength of the cylinder thus
ingredients in the proportions stated:
cured is found to be 935 lbs./in.2.
Parts by weight
The cured cements prepared as in the foregoing ex
Tetramethylammonium silicate _____________ .._
3.0
Homer clay (essentially kaolinite) __________ __
Berkley Sand No. 1 ______________________ __
8.1
amples all display excellent resistance to deterioration
when immersed in small amounts of water. In contrast
24.15 15
to many of the cements made in accordance with afore
120 mesh quartz _________________________ .._ 114.25
mentioned application Serial No. 712,078, the water does
not become appreciably alkaline, and thus there is no
alkaline attack upon the cement.
186.50
I claim:
20
The tetramethylammonium silicate employed has the
1. A cured cement produced by blending a particulate
probable formula: (CH3)4NI-ISiO3-xI-I2O and is prepared
?ller in such proportion that the ?ller contributes the ma
by the reaction of tetramethylammonium hydroxide and
jor proportion of the solids content of the cured cement,
micronized silica gel by the method described in Journal
an aqueous silica sol containing at least 10% by weight
Silica sol
_
37.00
of Physical and Colloid Chemistry,‘vol. 55 (1951), pages
of silica as a binder for said ?ller in an amount su?icient
187-195, and in U.S. Patent 2,689,245. For use in the 25 to bond said ?ller into a coherent mass, and from 2% to
cement, the crystalline tetramethyl ammonium silicate is
15% by weight, based on the weight of said ?ller, of a
ground to a ?ne powder and mixed with the clay, sand
?nely-divided solid organic base silicate which is slowly
and quartz in the dry state before blending with the
soluble in water, said ?ller being essentially insoluble in
silica sol.
the water of said silica sol and being substantially inert
30
The Berkley Sand No. 1 is a quartz sand having the
with respect to said sol.
following Tyler screen analysis: 0.0% retained on 20
2. A cured cement produced by blending a particulate
mesh screen; 46.6% retained on 42 mesh screen; 40.4%
?ller in such proportion that the ?ller contributes the
retained on 60 mesh screen; 10.7% retained on 80 mesh
major proportion of the solid contents of the cured
screen; 1.3% retained on 100 mesh screen.
cement, an aqueous silica sol as a binder for said ?ller in
ing 30.4% by weight of SiO-z in the form of colloidal
silica particles, an NaZO content by weight of 0.14%, a
pH of 8.45, a viscosity of 16.1 centipoises at 22° C. and
mass, said sol containing at least 20% by weight of col
loidal silica, and from 0.2% to 15% by weight, based
The silica sol is an aqueous sol of colloidal silica hav 35 an amount su?icient to bond said ?ller into a coherent
a density of 1.206 grams per centimeter. This sol may
be prepared in accordance with the method described in
U.S. Patent 2,574,902.
To make the cement, the dry ingredients are thorough
ly blended. The silica sol is then added and mixed to
make a mortar. The mortar is cast into 1" cylinders for
testing. One set of cylinders is cured at room tempera
ture. Another set of cylinders is cured at room temper
ature for several days and then cured at 60° C. for 24
hours. A third set of cylinders is cured at 60° C. for 24
hours and then ignited to 700° C. for 8 hours. On heat
on the weight of said ?ller, of a solid ?nely-divided
quaternary ammonium silicate as a setting agent for said
silica sol, said ?ller being essentially insoluble in the water
of said silica sol and being substantially inert with re
spect to said sol.
3. A cured cement in accordance with claim 2 in which
said quarternary ammonium silicate is a tetraalkylam
45 monium silicate in which the alkyl groups contaian from
1 to 4 carbon atoms.
4. A cured cement composition in accordance with
claim 2 in which said quaternary ammonium silicate is
tetramethylammonium silicate.
ing to 700° C., the organic moiety burns out smoothly, 50
5. A cured cement in accordance with claim 2 in which
evolving fumes having an odor indicating decomposition
said quaternary ammonium silicate is benzyl trimethylam
of nitrogenous material. The three sets of cylinders cured
monium silicate.
under the above conditions are then tested for compres
sive strength with the following results.
Cure:
6. As a composition suitable for admixture with an
aqueous silica sol containing at least 10% by weight of
Compressive strength, lbs./in.2 55 silica to form a cement, the combination of an inert par
Cure at room temperature ______________ __ 2160
Post-cure at 60° C. ___________________ .. 1820
ticulate ?ller blended with from 0.2% to 15 % by weight,
based on the weight of said ?ller, of a ?nely-divided solid
organic base silicate which is slowly soluble in water, said
?ller being essentially insoluble in the water of said silica
Example 2
-60 sol and being substantially inert with respect to said sol.
7. A cured cement consisting essentially of silica pro
A second cement was prepared using the formulation
duced by blending a ?ller consisting essentially of silica,
of Example 1 except that the amount of tetramethylam
an aqueous silica sol containing at least 10% by weight
monium silicate is reduced from 6.0 parts to 3.0 parts.
of colloidal silica as a binder in an amount su?icient to
The mortar made from this formulation is cast into 1"
Ignited at 700° C ______________________ __ 3180
cylinders, one set being cured at room temperature for 65 bond said silica ?ller into a coherent mass, and setting
agent for said silica sol consisting essentially of a solid
several days and then at 60° C. for 24 hours and another
quaternary ammonium silicate in an amount of from .2%
set cured at 60° C. for 24 hours and then heated to 700°
C. for 8 hours. Compressive strength tests on the cylin
ders' thus cured show the following results.
Cure’:
Compressive strength, lbs/in.2
Post-cure at 60° C. ___________________ .._ 1150
Ignited at 700° C. _____________________ __. 1270
to 15 % by weight based on the weight of said silica ?ller,
said cement having been ?red at a temperature sufficient
70 to decompose the organic portion of said quaternary am
monium silicate.
8. As a cement composition, the combination of a par
ticulate ?ller contributing the major portion of the solids
content of the cement, an aqueous silica sol containing at
As may be seen, the smaller amount of setting agent
75 least 10% by Weight of silica as a binder in an amount
produced a cement of somewhat lower strength.
3,024,125
10
sut?cient to bond said ?ller into a coherent mass, and
in which said setting agent is tetramethylammonium sili
from .2% to 15% by weight based on the weight of said
?ller of a solid organic base silicate which is slowly solu
ble in water as a setting agent for said silica sol, said
?ller being essentially insoluble in the water of said silica
sol and being substantially inert with respect to said sol.
cate in solid form.
9. As a cement composition, the combination of a par
-
13. A cement composition in accordance with claim
10 in which said setting agent is benzyl trimethylam
monium silicate in solid form.
14. A cement composition in accordance with claim 9'
in which said setting agent is a solid amine silicate.
ticulate ?ller contributing the major portion of the solids
15. A cement composition in accordance with claim 9
content of the cement, an aqueous silica sol containing at
in which said setting agent is a solid quaternary phos~
least 10% by weight of silica as a binder for said ?ller 10 phonium silicate.
in an amount sufficient to bond said ?ller into a coherent
16. A composition in accordance with claim 6 in which
mass, and as a setting agent for said silica so], from .2%
said setting agent is a solid ?nely-divided quaternary am
to 15% by weight based on the weight of said ?ller of
monium silicate.
a solid organic base silicate selected from the class con
17. A composition in accordance with claim 6 in which
sisting of quaternary ammonium silicates, amine silicates,
quaternary phosphonium silicates, and ternary sulphonium
silicates, said ?ller being essentially insoluble in the water
of said silica sol and being substantially inert with respect
said setting agent is a solid ?nely-divided amine silicate.
18. A composition in accordance with claim 6 in which
said setting agent is a solid ?nely-divided quaternary phos
phonium silicate.
to said sol.
19. A composition in accordance with claim 6 in which
10. As a cement composition, the combination of a 20 said setting agent is a solid ?nely-divided ternary sul
particulate ?ller contributing the major portion of the
phonium silicate.
solids content of the cement, an aqueous silica sol con
taining at least 10% by weight of silica as a binder in an
amount su?icient to bond said ?ller into a coherent
mass, and from .2% to 15% by weight based on the 25
weight of said ?ller of a solid quaternary ammonium
silicate as a setting agent for said silica sol, said ?ller
being essentially insoluble in the water of said silica sol
and being substantially inert with respect to said sol.
11. A cement composition in accordance with claim 10
in which said setting agent is solid tetraalkylammonium
silicate in which the alkyl groups have from 1 to 4 carbon
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,380,945
2,509,026
2,689,245
2,803,566
2,856,302
2,914,413
1945
1950
1954
1957
1958
1959
FOREIGN PATENTS
atoms.
12. A cement composition in accordance with claim 10
Collins _______________ __ Aug. 7,
White _______________ .._ May 23,
Merrill ______________ __ Sept. 14,
Johannsen ____________ __ Aug. 20,
Reuter _______________ __ Oct. 14,
Mercer _____________ __ Nov. 24,
576,808
Canada _______________ .._ June 2, 1959
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