Conductive cathodic protection compositions and methods

Disclosed are improved compositions useful in providing a conductive layer or coating on or within a substrate. The compositions contain elemental carbon and a polymeric matrix or binder. The improvement comprises employing a unique ground calcined, coal-based coke which approaches graphite in terms of its performance as a conductive additive or pigment but does not possess the disadvantages associated with the use of graphite. The unique coke employed in the compositions and methods of the present invention has a significant level of graphitic structure. This level of graphitization can be most easily recognized by utilizing x-ray powder diffraction. More specifically, when the value of E.sub.c, or the inverse peak width (of the 002 peak), is measured for this material using Mo K.alpha. radiation (.lambda.=0.71 .ANG.), the value is in the range of about 27 to about 80, and preferably about 28 to about 75. The final compositions employ a polymer resin or matrix system as a binder which, when allowed to dry or cure, in situ, is water-permeable. They are useful as cathodic protection coatings for concrete and other building materials which are reinforced with low carbon steels and the like. The invention also relates to the method of applying the compositions to the reinforced substrate, and the resulting coated articles.

The present invention relates to improved compositions which are useful in 
providing a conductive coating or layer upon or within a substrate. The 
compositions, which contain elemental carbon and a polymer binder or 
matrix, are improved by the addition of a unique 
high-conductivity/low-resistivity calcined coal-based coke. 
More specifically, present invention relates to a composition useful in the 
protection of concretes or other building materials or components which 
are reinforced with many ferrous-based low carbon steel structures or 
elements. The composition is applied to the exterior surfaces of the 
concrete or building material. The invention also relates to the method of 
improving corrosion resistance and protecting concrete or other building 
materials by applying these compositions. The invention further relates to 
the resultant coated structure or material itself. 
The present invention is based upon the well-known principle of cathodic 
protection. 
BACKGROUND OF THE INVENTION 
It is well known that when many ferrous-based low carbon steels and other 
metals are exposed to moisture and air they rust, corrode or otherwise 
degrade. When these low carbon steels are used to reinforce concrete or 
other building materials, they frequently become exposed to harsh weather 
and brine from road salts or the sea which greatly accelerate this 
corrosion and accordingly greatly reduce the life span of the reinforced 
elements or roadway. The Department of Transportation of the State of 
Florida estimates that this damage to bridge decks and associated support 
structures alone imposes a repair cost of from 160 to 500 million dollars 
anually in the U.S. alone. 
The process underlying this deterioration of the roadway is the 
deterioration and volume expansion of the reinforcing steel element. This 
in turn is caused by the conversion of the iron (Fe) within the low carbon 
steel to iron oxide--rusting. 
The underlying corrosion is caused by the formation of electrolytic cells 
in which different parts of the steel reinforcement can be both the anode 
and the cathode of an electrolytic cell when in the presence of moisture. 
Differences in ionic concentrations at different sites determine whether a 
particular site is cathodic or anodic. Anodic reaction products (i.e. iron 
oxide) have a greater volume than the original steel, so great internal 
pressure is applied within the concrete, causing it to crack and spall. 
Cathodic protection is one method recognized as being useful in preventing 
or retarding the process. It involves introducing a separate additional 
electrode (anode) and applying an impressed current such that all of the 
steel reinforcement becomes cathodic, thus preventing the formation of 
iron oxide. 
Many cathodic protection systems are known. For example, U.S. Pat. No. 
3,868,313, issued to P. J. Gay, Feb. 25, 1975, discloses a cathodic 
protection system comprising applying an electrically insulating coating 
on the substrate followed by the application of an electrically conductive 
coating over the insulating coating. A D.C. voltage is then applied 
between the metal substrate and the conductive coating. 
U.S. Pat. No. 3,151,050, issued Sept. 19, 1964, discloses methods for 
cathodic protection for vehicles and components in storage. The method 
comprises the application of an electrically conductive paint to the metal 
to be protected. The paint is a suspension of carbon, manganese dioxide, 
ammonium chloride and an organic filler and a solvent such as 
methyl-ethyl-ketone. A second coating of resin containing metallic copper 
is then applied, followed by a final coat of paint or enamel. Lastly, a 
D.C. voltage is applied between the conducting paint and the metal base. 
Other polymer compositions containing various carbon based materials are 
also known. U.S. Pat. No. 4,035,265, issued July 12, 1977, to J. A. 
Saunders discloses electrically conductive paint compositions employing 
graphite and colloidal carbon. The graphite is subjected to wet grinding 
so as to reduce the graphite to thin platelets. The colloidal carbon 
employed consists of particles having a size from 20 to 50 millimicrons. 
The final composition (including the article it is applied to) is used as 
a heat source when electrical current is passed through the coating. 
Other efforts at carbon-containing coatings are found in 
(1) U.S. Pat. No. 3,505,263, which discloses finely divided calcined 
petroleum coke in a polymer latex binder; 
(2) U.S. Pat. No. 3,404,019, which discloses the use of fluid petroleum 
coke as a filler or pigment in polymeric compositions; 
(3) U.S. Pat. No. 2,730,597, which discloses resistance elements which 
optionally employ various materials in a resin base; 
(4) U.S. Pat. No. 4,476,265, which discloses poly (arylene sulfide) 
compositions which contain a "black carbonaceous pigment"; 
(5) U.S. Pat. No. 4,444,837, which discloses coating or sealing-type 
plastisols which contain carbon dust as a filler; 
(6) U.S. Pat. No. 3,391,103, which discloses phenolic resin compositions 
which employ "oxidized carbon particles"; 
(7) U.S. Pat. No. 3,615,754, which discloses an ink which employs 2 to 10 
percent of ground coke; and 
(8) U.S. Pat. No. 3,444,183, which discloses a film forming composition 
made from a heat-resistant polymer and a dispersion of carbon particles. 
SUMMARY OF THE INVENTION 
The present invention relates to improved compositions useful in providing 
a conductive layer or coating on or within a substrate. The compositions 
contain elemental carbon and a polymeric matrix or binder. The improvement 
comprises a unique ground calcined, coal-based coke which approaches 
graphite in terms of its performance as a conductive additive or pigment 
but does not possess the disadvantages associated with the use of 
graphite. 
The unique coke employed in the compositions and methods of the present 
invention has a significant level of graphitic structure. This level of 
graphitization can be most easily recognized by utilizing x-ray powder 
diffraction. More specifically, when the value of E.sub.c, or the inverse 
peak width (of the 002 peak), is measured for this material using Mo 
K.alpha. radiation (.lambda.=0.71.ANG.), the value is in the range of 
about 27 to about 80, and preferably about 28 to about 75. In a highly 
preferred embodiment, the cokes employed in the compositions and methods 
of the present invention contain SiO.sub.2, Fe.sub.2 O.sub.3, Al.sub.2 
O.sub.3, Ca.sub.2 O, K.sub.2 O and Na.sub.2 O. They have a carbon content 
of at least about 90 percent, and more preferably about 94.5 percent, by 
weight of the coke, and an ash content of about 0.1 percent to about 1.5 
percent, by weight of the coke. The weight:weight ratio of SiO.sub.2 
:Fe.sub.2 O.sub.3 in the ash is in the range of about 3:1 to about 7:1, 
and the weight:weight ratio of Fe.sub.2 O.sub.3 :Al.sub.2 O.sub.3 in the 
ash is in the range of about 1:1 to about 6:1. 
The final compositions employ a polymer resin or matrix system as a binder 
which, when allowed to dry or cure in situ, is water-permeable. They are 
useful as cathodic protection coatings for concrete and other building 
materials which are reinforced with low carbon steels and the like. 
The invention also relates to the method of applying the compositions to 
the reinforced substrate, and the resulting coated articles.

DETAILED DESCRIPTION OF THE INVENTION 
It will be appreciated that a wide variety of carbon-based materials 
possessing a wide variety of particle shapes and sizes have been employed 
in polymer-based coatings. These materials have been generally employed as 
pigments to add conductivity to the final composition. However, it has now 
been discovered that a certain heretofore unrecognized ground coal-based 
calcined coke can be employed in combination with a polymer resin to 
provide an improved resin-coke system for conductive coatings of wide 
utility. These systems have particular utility as a cathodic protection 
coating for arresting or preventing corrosion of and preserving concrete 
roads, structures and the like reinforced with ferrous-based low-carbon 
steel elements or structures. 
It will also be appreciated from the above background section that while 
many elemental carbons and carbon-based materials have been used as 
conductive additives or pigments, when good conductivity is necessary 
graphite has been the additive or pigment of choice. 
Graphite, due to its allotropic form and crystalline structure, can be 
incorporated into a solvent or solvent/resin matrix and provide a final 
composition which has high conductivity and low resistivity. However, 
graphite suffers from some disadvantages which make it difficult to employ 
in coatings; two of these disadvantages appear to be associated with the 
very crystalline structure which make it so valuable as a conductive 
material. 
Graphite is an allotropic form of elemental carbon consisting of layers of 
hexagonally arranged carbon atoms in a planar, condensed ring system. The 
layers are stacked parallel to each other in two possible configurations, 
hexagonal or rhombohedral. This structure, along with the covalent 
(sp.sup.2 hybridization) bonding within the layers and Van der Waals 
forces holding the layer-layer arrangement together, make graphite 
extremely efficient as a conductive material and as a lubricant. 
However, when incorporated into a polymer resin system which is applied to 
a surface and allowed to dry or cure, the incorporated graphite within the 
system will easily "transfer" to or rub off onto a second surface if the 
two surfaces are brought into frictional contact. 
For example, if graphite is placed in an acrylic latex coating at a level 
that will provide conductivity, the resulting coating must be protected 
from contacting any other surface. Frictional contacting, such as simply 
rubbing your finger across the coated surface, would result in the 
transfer of a noticeable amount of graphite to your finger, i.e., the 
graphite will "rub-off" onto your finger. 
As a result of this transfer property, the graphite-containing composition 
cannot be durably overcoated, i.e., it will not accept a decorative or 
protective overcoat. For the reason discussed above, the second coating 
will not adhere to the graphite-containing material. 
Another disadvantage associated with the use of graphite as an additive in 
polymer compositions is that graphite interferes with some curing 
catalysts, e.g., peroxide-types. 
A fourth (and frequently prohibitive) disadvantage associated with graphite 
is that graphite, when compared to other carbon-based conductive 
additives, is extremely expensive. 
As a result of these disadvantages, primarily the "transfer" property, the 
art has frequently turned to other types of elemental carbons such as 
carbon black, petroleum-based coke, and the like. It will be appreciated 
that the carbon blacks which are adequately conductive are extremely 
expensive; normal petroleum-based cokes are not adequately conductive. 
Coke is generally considered to be the highly carbonaceous product 
resulting from the pyrolysis of organic material at least parts of which 
have passed through a liquid or liquid-crystalline state during the 
carbonization process and which consists of non-graphitic carbon. See 
Carbon, 20:5, pp 445-449 (1982), incorporated here by reference. Some 
cokes are capable of acting as conductive additives and pigments; some 
cokes provide no conductivity. 
In addition to being less expensive than most highly conductive graphites, 
conductive cokes possess the added advantage of not exhibiting transfer. 
However, because conventional cokes do not conduct as efficiently as 
graphite, the cokes which are conductive must be added at extremely high 
pigment:binder ratios. Due to its reduced cost when compared to graphite, 
even at these high levels coke can be economically employed. 
Regardless of the level employed, however, conventional conductive cokes 
simply have not been capable of achieving the level of conductivity that 
graphite can provide. There are therefore many uses where graphites had to 
be employed in spite of its transfer, overcoatability and other 
disadvantages. 
It has now been surprisingly discovered that a certain unique coke material 
is capable of demonstrating a conductivity/resistivity closely approaching 
that of graphite, but which does not possess the curing, rub off, 
overcoatabilty and cost disadvantages usually associated with graphites. 
This unique coke material provides improved conductivity at reduced cost in 
a wide range of resin and resin solvent systems. The resulting 
compositions provide a wide variety of utilities. Further, this unique 
coke has the added unexpected advantage of being able to accept other 
non-carbonaceous pigments in the resin system while maintaining 
significant conductivity. Thus, the final composition can be pigmented 
other than black. 
When employed at the levels and ratios described herein, the final 
compositions of the present invention possess a conductivity/reduced 
resistance nearly equivalent to systems employing more expensive graphite, 
but without many of the disadvantages associated with graphite. 
As mentioned above, the term "coke", as generally used in the art, refers 
broadly to the many high carbonaceous products of the pryolysis of organic 
material at least parts of which have passed through a liquid or 
liquid-crystalline state during the carbonization process and which 
consist of non-graphitic carbon. However, the term "coke" as applied to 
the compositions and methods of the instant invention refers to a small 
select subclass of cokes. From a structural viewpoint, the term "coke", as 
used herein, characterizes the state of a graphitizable carbon before the 
actual beginning of graphitization, i.e., before the solid state 
transformation of the thermodynamically unstable non-graphitic carbon into 
graphite by thermal activation. 
The cokes useful in the practice of the present invention are cokes which 
have high conductivity/low resistivity and include only a select fraction 
of the materials generally referred to in the art as "coke". They are 
coal-based, calcined ground materials. 
The cokes useful in the practice of the present invention are primarily 
classified by the possession of a level of graphitic order which is high 
enough to provide high conductivity/low resistivity when placed into a 
polymer matrix, but below that which results in a tendency to rub off 
and/or the inability to accept an overcoat. These cokes may be used in 
place of graphite in certain compositions and methods; they may also be 
used in combination with graphite. They are particularly useful in these 
circumstances (where graphite is to be employed) because they will allow 
the graphite to be used at a significantly reduced level while allowing 
overcoatability and enhancing conductivity. 
The most effective way of characterizing the cokes of the present invention 
is by x-ray powder diffraction. The material may be examined employing a 
conventional powder diffractometer fitted with a pyrolytic graphite 
monochromatic source. A power source such as a 12 kw rotating anode 
generator may be employed operating at about 55 kV and 160mA; a molybdenum 
anode (K.alpha.radiation), providing an average x-ray wavelength .lambda. 
of about 0.71.ANG., is also employed. The sample should be placed in a 
Lindeman glass tube having a diameter of about 0.8 mm. The c-axis 
carbon-carbon d-spacings and range of ordering along the c-axis are 
determined from the width of the carbon (002) peak produding an E.sub.c 
value. In general the larger the E.sub.c value, the better the ordering, 
i.e., graphites have E.sub.c 's in the range of greater than 200. Cokes of 
the present invention possess an E.sub.c value of about 27 to about 80, 
more preferably about 28 to about 75, and still more preferably about 2 to 
about 65. 
Useful cokes of this class may contain greater than about 80 elemental 
carbon by weight. The cokes preferred for use in the present invention 
possess a carbon content of greater than about 90 percent, more preferably 
about 94.5 percent, and still more preferably about 95.0 percent, by 
weight. In a highly preferred embodiment, the cokes of the instant 
invention have a carbon content of about 95.0 to about 97.75, and even 
more preferably about 95.30 to about 95.40, by weight. 
The preferred cokes for use in the present invention have an ash content of 
about 0.1 to about 1.5 percent, by weight of the coke. Even more 
preferably, the ash content is in the range of about 0.80 to about 1.25, 
and still more preferably about 1.0 to about 1.15, by weight. 
In a highly preferred embodiment, the weight:weight ratio of SiO.sub.2 
:Fe.sub.2 O.sub.3 in the ash is in the range of about 3:1 to about 7:1, 
and still more preferably about 4:1 to about 6:1; in a highly preferred 
embodiment the ration is about 5:1. In these embodiments, the 
weight:weight ratio of Fe.sub.2 O.sub.3 :Al.sub.2 O.sub.3 in the ash is in 
the range of about 6:1 to about 1:1, and still more preferably about 2:1. 
The cokes preferred for use in the present invention contain a level of CaO 
in the ash of less than about 2.5 percent, more preferably less than about 
1.0 percent, and still more preferably less than about 0.5 percent, by 
weight of the ash. In a highly preferred embodiment, the coke contains a 
level of CaO of about 0.5 percent, by weight of the ash, or about 0.00005 
percent, by weight of the coke. 
The cokes preferred for use in the present invention contain a level of 
K.sub.2 O of less than about 0.75 percent, and more preferably about 0.5, 
and even more preferably about 0.25, percent by weight of the ash. In a 
highly preferred embodiment, the coke contains a level of K.sub.2 O of 
less than about 0.20 percent by weight of the ash, or about 0.00002 
percent by weight of the coke. 
The coke may be employed with polymer-based binders or matrices alone, or 
in combination with other conductive and non-conductive pigments, 
including other carbon-based materials. However, in a preferred 
embodiment, the final composition is substantially free of graphite, due 
to graphite's interference with the stability of overcoatability of the 
final coating composition. 
Other suitable material useful in combination with the cokes described 
above include other elemental carbon fillers and pigments selected from 
the group consisting of carbon black, petroleum coke, calcined petroleum 
coke, fluid petroleum coke, metallurgical coke; other non-carbon pigments 
and additives which are useful include, without limitation, metals and 
metallic conductive and non-conductive materials such as zinc, aluminum, 
copper, nickel, ferrophosphorous, and the like. 
The coke is blended or otherwise combined with a resin or matrix system as 
a binder. It will be appreciated that the selection of the binder is 
primarily dependant upon the end use of the conductive coating. For 
example, when selecting a binder for use in a composition to be employed 
as a cathodic protection material, it has been observed that it is 
important to select a binder which will adhere well to concrete, will be 
easy to apply, and which can be easily overcoated; it is also important 
that the binder-coke combination, when allowed to dry set up or cure, be 
water permeable. The final coating must breathe, i.e., it must permit 
moisture to pass through as temperature and relative humidity change. This 
prevents water from being trapped within the concrete and negating the 
effects of the cathodic protection and interfering with adhesion of the 
coating to the concrete. 
Preferred resins for the binders or binder systems of the present invention 
include acrylics, acrylic emulsions, mixtures, and acrylic latexes 
including methacrylates, polyvinylacetate and polyvinylacetate acrylic 
polymers. 
Particularly preferred are materials selected from the group consisting of 
methyl arylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, 
allyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and 
mixtures thereof. A typical material would include an acrylic emulsion, 
such as AC-64 manufactured by Rohm & Haas. Optionally, RM5, also 
manufactured by Rohm and Haas, may be employed as an acrylic thickener to 
modify viscosity. 
Suitable conventional binder-compatible solvents and components may be 
employed in the coke-binder systems. For example, a suitable solvent, 
solvent blend or carrier solvent may be employed. The solvent may be, for 
example, an organic sovlent such as a conventional acrylic or methacrylic 
solvent system, including aromatic and aliphatic hydrocarbons, halogenated 
aromatic and aliphatic hydrocarbons, esters, ketones, and alcohols. Water 
may also be employed as a solvent, co-solvent, or as a solvent for one or 
more phases of an emulsion system. 
Other common resin compatible components may also be employed at their 
art-established levels, including, without limitation, surfactants, 
emollients, wetting agents or other surface active agents, thickeners, 
buffers, neutralizing agents, chelating agents, anti-oxidants, curing 
agents, anti-microbials, anti-fungals, and the like. 
In the wet (uncured) compositions of the present invention which are 
intended to be used as cathodic protectants, the resin polymer such as 
methyl acrylate, ethyl acrylate, methyl methacrylate or ethyl methacrylate 
is preferably employed at a level of from about 5 to about 50 percent, by 
weight of the wet composition. More preferably, the resin is employed at a 
level of about 10 to about 20 percent, and still more preferably at a 
level of about 10 to about 15 percent, by weight. 
The coke (as expressly defined herein) is employed in the preferred 
cathodic protection compositions of the present invention at a level of 
about 0.5 percent to about 30 percent, by weight of the wet, uncured 
composition. More preferably, the coke is employed at a level of about 2 
to about 25 percent, and still more preferably, at a level of about 5 to 
about 15 percent, by weight of the wet composition. In a highly preferred 
embodiment, the cathodic protection compositions of the instant invention 
employ a level of coke of about 5 percent to about 10 percent, by weight 
of the wet composition. 
As noted above, the coke may be employed alone, or with other carbonaceous 
materials. When other elemental carbons are employed, such as carbon 
black, petroleum coke, calcined petroleum coke, fluid petroleum coke, 
metallurgical coke, and the like, the total elemental carbon in preferred 
compositions comprises about 5 percent to about 75 percent, by weight of 
the final wet composition. Of this total elemental carbon, about 5 percent 
to about 75 percent (of the total elemental carbon) is the unique ground 
coal-based calcined coke described herein. More preferaby, the total 
elemental carbon is present at a level of about 25 percent to about 60 
percent, of which about 10 percent to about 25 percent is the coal-based 
calcined coke. 
The highly preferred cathodic protection compositions of the present 
invention are substantially free of graphite, i.e., they employ less than 
about 10 percent, more preferably less than about 5 percent, and still 
more preferably less than about 1 percent graphite, by weight of the wet 
composition. 
In a highly preferred embodiment, the cathodic protection compositions of 
the instant invention employ about 10 to about 25 percent deionized water, 
by weight; about 0.1 to about 10 percent of a thickener, such as 
hydroxyethyl cellulose and/or an acrylic thickener; about 0 percent to 
about 50 percent of a second carbon-based pigment or filler; about 0.01 
percent to about 2.5 percent of a C.sub.3 -C.sub.12 alcohol; and about 
0.01 percent to about 2.5 percent of an antimicrobial-antifungal agent 
such as 2, 2-methylene-BIS-(4 -chlorophenol). 
In such preferred embodiments, a surfactant or emollient is also employed. 
Such surfactants are employed at a level of about 0.025 to about 5 
percent, by weight of the wet composition, and more preferably at a level 
of about 0.05 to about 4 percent. In a highly preferred embodiment, the 
surfactant is employed at a level of about 1 percent to about 2 percent, 
by weight of the wet composition. 
Any conventional compatible surfactant may be employed in the cathodic 
protection composition of the present invention. Preferred surfactants 
include TAMOL SN, a neutral sodium salt of a condensed aryl sulfonic acid 
sold by the Rohm & Haas Company. 
The preferred compositions are preferably about 50 to about 80 percent 
total solids, and still more preferably about 70 to about 75 percent total 
solids, and preferaby possess a viscosity of about 3000 to about 4500 cps. 
Such a combination gives a final product which is easy to apply and which 
demonstrates excellent adhesion to concrete and the like. 
The preferred compositions, when applied to a non-conductive surface at a 
rate which results in a coating thickness of ten mils after drying or 
curing, demonstrate a resistance of less than about 20 ohms per square 
unit, and even more preferably demonstrates a resistance in the range of 
about 10 to about 15 ohms per square unit, when a direct current is 
applied across a one inch distance and measured point to point. 
By the term ohms/square or ohms per square, as used herein, is meant ohms 
per any practical square unit. That is, when a coating of a uniform 
thickness is examined, the resistance to a direct current from point A to 
point B, (t), is a function of the width, (w), of the square, the distance 
between the points, (d), the thickness of the coating, (t), and the nature 
of the conductive coating or material. The resistance varies directly with 
d and inversely with t and w. This can be expressed as R=(K)(d)(t.sup.-1) 
(W.sup.-1). In all squares w=d; therefore, the above equation simplifies 
to become R=k/t. (Again, this is because w=d regardless of whether the 
square unit is an inch or a foot.) 
The compositions of the present invention are preferably applied to 
concrete or other reinforced building materials in a fluid or gelatinous 
form and allowed to cure or dry in situ. The compositions can be applied 
in any conventional manner such as brushing, spraying, dipping, 
roller-coating, troweling and the like. 
The compositions are applied at a rate such that the coating thickness, 
after drying/curing, is in the range of about 0.5 to about 50 mils; 
preferaby about 1 to about 30 mils; and more preferably about 2 to about 
20 mils. 
In a highly preferred embodiment, the cured protective coating and the 
ferrous-based low carbon steel reinforcement are contacted with a direct 
current power source such that the carbon-containing coating is anodic 
with respect to the reinforcement metal which is cathodic. 
The resulting coated structure, which can be a roadway, bridge span, 
parking garage, dock or wharf, or any other sturcture which is exposed to 
brine, sea water or road salts and which is reinforced with a 
ferrous-based low carbon metallic element, will resist deterioration which 
results from the rusting or corrosion of the reinforcing element. 
The compositions of the present invention may also be added to concrete, or 
other building materials, to provide static discharge protection and/or 
conductivity to the structural element fashioned from the concrete. This 
provides a structural element which can be heated and which can accept a 
durable overcoat for purposes of protection or decoration. 
Such an addition also provides static discharge protection for areas which 
have concrete floors, walls, and the like. Such protection can be 
extremely important in work areas where static discharge can be extremely 
hazardous or harmful. Such environments would include, for example, 
surgical areas or other areas where explosive gases are employed. Other 
examples would include areas where computer chips are manufactured or the 
processing of information on magnetic storage devices occurs. 
Such conductive concretes are prepared by first blending an aqueous 
pre-blend comprising elemental carbon, water, and other conventional 
additives described herein, such as a thickener, an anti-microbial 
antifungal, biocides, an alcohol, a surfactant, and the like. The 
pre-blend is then added to a conventional concrete pre-mix along with more 
elemental carbon and water. 
It will be appreciated that preferably about 50 to about 95 percent of the 
elemental carbon, by weight, should be the ground calcined, coal-based 
cokes described herein. 
In order to further illustrate the benefits and advantages of the present 
invention, the following examples are provided. It will be understood that 
the examples are provided for illustrative purposes and are not intended 
to be limiting of the scope of the invention as herein disclosed and as 
set forth in the claims. 
All ingredients are added and admixed in a conventional manner unless 
otherwise indicated. 
See also commonly assigned U.S. patent application Ser. No. 757,085, 
"Conductive Coatings for Elongated Conductors", Robert E. Wiley, and U.S. 
patent application Ser. No. 757,029, "Conductive Coatings and Foams for 
Anti-Static Protection, Energy Absorption, and Electromagnetic 
Compatability", Robert E. Wiley, both filed herewith; both expressly 
incorporated herein by reference. 
EXAMPLE I 
__________________________________________________________________________ 
CATHODIC PROTECTION COATINGS 
A B C D 
__________________________________________________________________________ 
Component 
Source Identity 
Coke* Carbon 9.32 8.93 7.68 7.42 
Carbon Black Carbon 1.37 1.32 1.13 1.09 
Cellosize 
Union Hydroxyethyl 
0.31 0.30 0.26 0.25 
QP4H Carbide Cellulose 
Sindar G-4 
Givardon 
2,2 Methylene 
0.10 0.10 0.09 0.08 
BIS (4- 
Chlorophenol) 
Octyl Alcohol 
Matheson 
1-Octanol 
0.07 0.07 0.06 0.06 
Tamol SN Rohm and Haas 
Neutral Sodium 
0.17 0.16 0.14 0.14 
Salt of 
Condensed Aryl 
Sulfonic Acid 
Deionized Water Deionized Water 
20.38 19.55 16.81 16.25 
31.72 30.43 26.17 25.29 
The above items are charged into a pebble mill and run for about 24 hours 
to about an 8 Hegmann. 
The following are then added: 
AC-64 (60% 
Rohm and 
Acrylic 15.86 15.22 13.08 12.64 
NVM) Emulsion 
Coke #1 (conventional) 
Carbon 23.80 27.17 23.36 22.57 
Coke #2 (conventional) 
Carbon 23.80 27.18 23.36 22.47 
Ground Coke (conventional) 
Carbon 4.82 -- -- -- 
999 Troy Chem 
Non-silicone 
-- -- -- 0.10 
Defoaming 
Surfactants 
5% Ammonia 
ACUS Ammonia -- -- 4.68 4.51 
(23%) in 
DI Water 
5% Natrosol 
Hercules 
Hydroxyethyl 
-- -- 9.35 6.78 
MR in DI Cellulose 
Water 
5% RM5 in DI 
Rohm and Haas 
Acrylic Thickener 
-- -- -- 5.64 
100.00 
100.00 
100.00 
100.00 
% Solids 73-74 73-74 76-77 73-74 
Viscosity (Cps) 3200 cps 
3100 cps 
3700 cps 
4200 cps 
Resistance at 10 mils (.OMEGA.) 
16-18 14-16 10-14 10-15 
(1 inch Point to Point) 
Adhesion (On Concrete Block) 
Excellent 
Excellent 
Excellent 
Excellent 
Pigment/Binder 6.70/1 
7.14/1 
8.86/1 
8.84/1 
__________________________________________________________________________ 
The above coatings A through D when applied to a concrete surface and air 
dryed, demonstate good adhesion to concrete, excellent water resistance, 
and good overcoatability. They have low resistance and are suitable for 
use in cathodic protection; they are substantially graphite free. 
Substantially similar results are obtained when the conductive carbon 
black, and/or conventional cokes #1, #2, or the conventional ground coke 
is replaced, in whole or in part, with the coke* of the present invention. 
FNT *indicates that this material has an E.sub.c of about 29. 
EXAMPLE II 
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CONCRETE ADDITIVE 
Ingredient Source Identity 
______________________________________ 
Base No. 1 
29.34 Coke* 
4.32 Carbon Black Pellets Carbon 
0.99 Cellosize QP40H 
Union Hydroxyethyl 
Carbide Cellulose 
0.33 Sindar G-4 Givardon 2,2 Methylene BIS 
(4-Chlorophenol) 
0.22 Octyl Alcohol Matheson 1-Octanol 
0.54 Tamol SN Rohm and Neutral Sodium Salt 
Haas of Condensed Aryl 
Sulfonic Acid 
64.26 Deionized Water 
ACUS 
100.00 
The above ingredients are ground for about 24 hours in a 
Pebble mill. 
% Solids 35.5 
Hegmann 8+ 
pH 8+ 
Viscosity 600-700 cps (Brookfield) 
Base No. 2 
23.25 Coke* Carbon 
4.65 Carbon Black Pellets Carbon 
0.93 Cellosize QP40H 
Union Hydroxyethyl 
Carbide Cellulose 
0.32 Sindar G-4 Givardon 2,2 Methylene BIS 
(4-Chlorophenol) 
0.22 Octyl Alcohol Matheson 1-Octanol 
0.84 Tamol SN Rohm and Neutral Sodium Salt 
Haas of Condensed Aryl 
Sulfonic Acid 
69.79 Deionized Water 
ACUS 
100.00 
The above ingredients are ground in a Pebble mill for 40 hours 
to an 8 Hegmann. 
% Solids 30-32% 
Weight/Gallon 
9.83 lbs. 
pH 8+ 
Viscosity 100-200 cps (Brookfield) 
Hegmann 8 
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Suitable compositions within the scope of the present invention would be as 
follows: 
______________________________________ 
Range Ingredients 
______________________________________ 
10-50 parts Base 1 or Base 2 
20-10 parts Elemental Carbon 
20-10 parts Coke 
50-30 parts Preblended concrete mix and water as needed 
100 100 
______________________________________ 
When the use of either of the above dispersions using coke* conjointly 
employ conventional coarse coke or carbon, they will react synergistically 
to produce lower resistances than normally attainable with just the coarse 
carbon. This will allow for denser, stronger concrete structures. 
However, substantially similar results are obtained if all of the remaining 
carbonaceous material were replaced, in whole or in part, with coke*. 
FNT *indicates that this material has an E.sub.c value of about 29.