Cement coloring composition and method of producing same

Thixotropic compositions for coloring cement or concrete or similar products comprise particulate pigment particles (about 20-80% by weight), at least one stabilizer (about 0.4-15%), a dispersent (about 0.1-3.0%) and water (about 12-77%). Methods of making these compositions are also explained.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
This invention relates to formulations and methods for preparing such 
formulations for coloring materials for cement and concrete products. In 
particular, it relates to such formulations and methods for forming 
thixotropic stabilized suspensions of such pigment particles which resist 
settling out. 
2. PRIOR ART 
Conventional cement or concrete coloring compositions comprise powders 
which are added by hand or by a screw conveyor in their dry state to a wet 
concrete or cement mix in a mixing apparatus. It is difficult to 
accurately add desired amounts of such powders to the wet concrete mix and 
there is often waste of such coloring material. Furthermore, with powders 
it is difficult to obtain a sufficiently thorough mixing of the powders 
into the wet cement mix so as to achieve a homogeneous color throughout 
the mixture. Conventional methods also require the concrete or cement 
contractor to maintain large inventories of the coloring composition and 
involve certain health hazards as well. 
It is highly desirable to have a system for coloring wet cement and 
concrete mixes by the addition of the coloring material in a liquid form 
to the mix. 
It is also desirable to have a system in which the coloring material may be 
added by liquid pumps to the wet concrete mix. 
It would also be highly advantageous to have a suspension of color pigment 
material which will not settle out within a relatively short time. 
It is another object of the present invention to provide a liquid slurry or 
mixture of particulate color pigments for each of several colors which can 
easily be mixed with one another or with a wet cement mix by the user to 
obtain a full range of composite colors. 
Still another object of the invention is to provide a system for adding 
pigment material to cement and concrete mixtures which can be automated to 
a greater extent than has heretofore been the case. 
These and other objects of the present invention, which will appear to one 
skilled in the art upon perusal of the present specification, the 
drawings, and the claims herein, are attained by the use of the formulas 
and processes as explained hereinbelow. 
SUMMARY OF THE INVENTION 
A thixotropic composition principally comprising a particulate pigment, a 
stabilizer, a dispersant and a liquid carrier which is predominantly water 
.

DESCRIPTION OF THE PREFERRED EMBODIMENTS--FIG. 1 
Example 1 
A mixing tank having a slow speed or low energy agitator revolving between 
at 80-200 rpm is partially filled with 47.17% of water (by weight). A 
natural gum such as gum arabic in the amount of 5% by weight is then added 
as well as 0.66% of a dispersant such as sodium laurate, which is a sodium 
salt of lauric acid sulphonate. At ambient temperatures, the water, 
dispersant and stabilizer are premixed until all are dissolved. Then, 
while the mixer is still running, 47.17% by weight of a pigment such as 
black iron oxide is added and the entire mixture is then mixed for up to 
about one hour, for example, until it is uniform and homogeneous whereupon 
it will have a predetermined specific gravity. 
Next, the material is pumped into a high speed or high energy mill such as 
a stone mill, for example, to reduce the particle size of the pigment 
component of the slurry down into the micron range. This can be checked by 
the use of a grinding "wedge" or other gauge. Preferably, the particle 
size distribution should include largest particles with a maximum 
dimension of about 40 microns, large particles whose average size is about 
25 microns, smaller particles whose average size is in the 1-2 micron 
range, and smallest particles down to a minimum size of about 0.5 microns. 
If the particle distribution is generally higher than these ranges, the 
coloring strength of the slurry is adversely affected. If the sizes of the 
particles are generally below these ranges they may be washed out of dried 
concrete by normal weathering. 
The procedure described above may also be applied to many other 
formulations such as are set forth in the following examples: 
Example 2 
Black Iron Oxide:47.17% 
Water:47.73% 
Gum Arabic:5.00% 
Sodium Laurate:0.10% 
Example 3 
Carbon Black:20.00% 
Water:76.60% 
Gum Arabic:0.4% 
Ethylene Oxide Condensate:3.0% 
Example 4 
Carbon Black:25.0% 
Water:59.0% 
Alginate L. V.:15.0% 
Sodium Laurate:1.0% 
Example 5 
Spanish Red Oxide:80.0% 
Water:12.69% 
Gum Arabic:7.0% 
Ethylene Oxide Condensate:0.4% 
Example 6 
Red Oxide (Natural):60.00% 
Water:30.00% 
Gum Arabic:9.20% 
Sodium Laurate:0.80% 
Example 7 
Red Oxide (Synthetic):50.00% 
Water:47.00% 
Gum Arabic:2.80% 
Sodium Laurate:0.20% 
Example 8 
Yellow Oxide (Synthetic): 47.00% 
Water:49.5% 
Gum Arabic:3.2% 
Sodium Laurate:0.3% 
Example 9 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Sodium Alginate (Manute RS):3.2% 
Sodium Laurate:0.3% 
Example 10 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Carboxymethyl Cellulose (CMC) High Viscosity grade:3.2% 
Sodium Laurate:0.3% 
Example 11 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Gum Arabic: 3.4% 
Triethanolamine: 0.l% 
Example 12 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Gum Guar:3.2% 
Sodium Laurate:0.3% 
Example 13 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Gum Tragacanth:3.2% 
Sodium Laurate:0.3% 
Example 14 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Locust Bean Gum:3.2% 
Sodium Laurate: 0.3% 
Example 15 
Yellow Oxide (Synthetic): 47.00% 
Water:49.5% 
Dextrine:3.2% 
Sodium Laurate:0.3% 
Example 16 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Potato Starch: 3.2% 
Sodium Laurate:0.3% 
Example 17 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Polyvinyl Alcohol:3.2% 
Sodium Laurate:0.3% 
Example 18 
Yellow Oxide (Synthetic):47.00% 
Water:49.5% 
Polyvinyl Pyrolidone:3.2% 
Sodium Laurate:0.3% 
While it might be possible to make a cement coloring composition without 
using a dispersant such as those mentioned above, preferred embodiments of 
the present invention do employ them as they help the slurry to keep its 
suspended state for long periods of time, and they allow more of the 
pigment to be incorporated into the slurry. They also tend to prevent 
flocculation of the pigment when the slurry is added to the cement mix 
since the latter contains free calcium ions. Less flocculation makes for 
more intense coloring of the cement mix. It should be noted that, while 
the foregoing examples and description only have mentioned water as the 
liquid carrier for the slurry, aqueous solutions may alternatively be 
used. Thus, aqueous solutions of various monohydric or polyhydric alcohols 
or ketones could be used instead of water alone for anti-freeze or other 
purposes. For example, methyl alcohol up to 15% by weight could be added 
to the water. Similarly aqueous solutions of acetone, glycols or glycerols 
could be substituted for water alone. 
It is important that the viscosity of the formulation be controlled so as 
to insure that the formulation can be fluidized when being dispensed 
thereby to optimize the mixing of the formulation with the cement or 
concrete components. The product is therefore checked as to its viscosity 
which should fall substantially within the limits (measured in poise) as 
shown in FIG. 2. While the data shown in the graph of FIG. 2 just deals 
with iron oxides, the desirable viscosity ranges for other pigments will 
also fall within the maximum and minimum ranges shown in that drawing. The 
data plotted on time ordinate in FIG. 2 was determined by the use of the 
"Rotothinner" brand viscometer manufactured by ICI. This viscometer works 
by detecting mechanical shear, not by the detection of heat generation. 
The color quality of the slurry may be tested by adding to it a 
predetermined quantity of titanium dioxide (white) in the 3:1-5:1 ratio 
range. This measures the relative value of the color since a given sample 
may require a different amount of the coloring pigment to produce the same 
tint as another batch of the slurry. 
Other usable stabilizers include active clays such as Bentonite, Kieselgur 
or Benagel, uncooked corn or wheat starch, water-soluble celluloses such 
as hydroxy ethyl cellulose or methyl cellulose, and polyvinyl pyrolidone. 
Other usable dispersants include other fatty amines and alkylamines. 
Optionally, other substances may also be added to impart desired 
characteristics to the composition. For example, a small percentage on the 
order of say, 4-7% of an anti-efflorescent agent such as barium carbonate 
can be added. Or small percentages (say about 2%) of water-repellent 
chemicals such as calcium stearate, aluminum stearate or silicones can be 
added to the pre-mix of the dispersant and the stabilizer in water or in 
the aqueous carrier. 
Alternative Procedures and Equipment 
The premixing step may be alternatively accomplished by using a hydraulic, 
variable speed cavitation mixer such as those marketed by Torrance & Sons 
of Bristol, England or by Cowles in the United States. Present cavitation 
mixers are, however, somewhat limited in processing capacity. 
The reduction of the particle size of the original slurry may be done by 
mills other than the stone mill. Alternatively, a Premier brand colloid 
mill manufactured by Premier Colloid Mills or other types of comminuting 
apparatus may be employed. Stone mills may be those manufactured by 
Moorhouse in the United States or by Fryma in Switzerland. Ball mills or 
rod mills have also been satisfactorily used, but they have the 
disadvantage of requiring more processing time. Attrition mills such as 
sand mills or pearl mills also are effective, but also usually take longer 
than high speed mills or colloid mills. 
Slurry Dispensing System 
As stated before, one of the main advantages of the present system and 
formulation is that thixotropic slurries of various main colors produced 
according to the present invention may be packaged in drums or other 
containers and the suspensions will not settle out for relatively long 
periods of time, i.e., on the order of 6-12 months. Thus, if the concrete 
or cement contractor wishes, he can keep perhaps 3-5 pigment slurries in 
individual drums, each slurry being operatively connected to a batching 
system which controls the amounts of said slurries to be added to the 
concrete mix. A charging pump may be inserted into each drum of slurry 
connected through a delivery tube to a metering container or tube. The 
tube may for example, contain a first (higher) measuring probe connected 
to a batching control unit whose height is adjustable (or predetermined) 
depending upon the amount of slurry to be measured out. Operation of the 
charging pump delivers the slurry to the metering tube until it touches 
the lower end of said first measuring probe whereupon a circuit is 
actuated which cuts off the pump. The charging pump for applying the 
slurry to the metering tube may be an air-operated positive displacement 
piston pump such as those marketed by Graco, Inc. of Minneapolis, Minn. 
Then the contents of the metering tube start to be withdrawn from the 
metering tube by the action of a dispensing pump (controlled by the 
batching unit) and to be applied (with water) to a concrete mixer of any 
conventional type. When the level of the metered slurry falls below the 
lower end of a second probe coupled to the batching unit, a signal is 
generated which stops the dispensing pump. 
If the contents of the slurry drum have not been used for excessive lengths 
of time, it may be advisable to insert a recycling valve branching off 
from the output of the charging pump and being connected to a recycling 
tube which returns to the drum. The return of the slurry back to the drum 
will produce a certain amount of agitation of the contents of the drum. 
Instead of the batching system described above, it is also possible to use 
a positive displacement pump of the said Graco type or of the "Mono" brand 
type marketed by Mono Pumps Ltd. of Great Britain. The latter pump is also 
marketed in the United States under the "Moyno" brand by Robbins and 
Meyers. The pump is set to run for a timed period so that, since the rate 
of flow is known, the amount of pumping time required to produce a given 
volume can easily be calculated. The timers may be wired to the electric 
motor starters of the pumps. 
Still another method is to pump the slurry around a continuous circuit via 
a three-way valve which is air or electrically operated. The valve is 
connected to a timer that can switch it from continuous circuit to 
injection by-pass, either straight into the mixing apparatus or 
indirectly, via a weighing scale, into the mixer so as to provide a double 
check on the quantity required for addition.