Method for inhibiting corrosion of internal structural members of reinforced concrete

An improved method for inhibiting corrosion of internal structural members of reinforced concrete, such as the corrosion of reinforcing steel members in a concrete bridge deck or a concrete paved driving surface, due to salt migration into the reinforced concrete. In general, the method comprises applying an effective amount of a hydrolyzable organo silicon compound to the surface of the reinforced concrete to substantially cover the surface of the structure with the organo silicon, and contacting the resulting organo silicon coated surface, after a period of time effective to allow the organo silicon compound to migrate into the structure, with an effective amount of water to substantially wet the surface of the organo silicon impregnated structure.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a method for inhibiting corrosion of internal 
structural members of reinforced concrete structures, and more 
particularly, but not by way of limitation, to a method for inhibiting 
corrosion of the structural reinforcing member of reinforced concrete due 
to salt migration into the concrete. 
2. Description of the Prior Art 
It is well known that water repellancy has been provided buildings 
constructed of masonry cement by treating the surfaces of such buildings 
to render them repellant to liquid water. Many different compositions and 
methods have been proposed, including impregnating the surface of 
materials containing free hydroxyl groups, i.e., cement and lime, with 
organo silicon compounds having a hydrophobic effect in order to make the 
surface of the material water repellant and thus more resistant to the 
action of the weather. Further, it has heretofore been known that the 
application of such organo silicon compounds to a structure formed of a 
material containing free hydroxyl groups reduces the adherence of frozen 
water, ice, to the surface of the structure and thus the ice can be more 
readily removed. 
Even with the advance of technology relating to the water repellancy of 
masonry cement buildings, problems have nevertheless remained relating to 
the deterioration of reinforced concrete structures, such as bridge decks 
and concrete paved roadways, due to deterioration of such reinforced 
concrete structures because of corrosion of the reinforcing steel members 
of the structure as a result of salt migration into the structure, or 
de-icer scaling of the surface of the structure subjected to wear. 
The reinforcing steel corrosion problem is of greatest magnitude on bridge 
decks which are subject to frequent applications of deicing salt. The 
spalling resulting from the corrosion of the reinforcing members in the 
concrete structure affects the riding surface, thus forcing continual 
maintenance and eventually destroying the structural integrity of the 
deck. A similar problem exists in coastal areas when the bottom of bridge 
decks, beams, piling, and piers are exposed to saltwater or salt spray. 
In an effort to retard or eliminate the corrosion of reinforcing steel in 
structural concrete, the most prevalent cause of deterioration of 
structural concrete, several different procedures have been proposed, 
namely, (a) methods to keep chlorides out of the concrete or at least to 
keep the chlorides from reaching the reinforcing steel, (b) coating the 
reinforcing steel itself so as to protect the steel from the influence of 
the chlorides, (c) methods to apply cathodic protection, (d) development 
of a noncorrosive deicer, and (e) other methods to neutralize the effect 
of chlorides. 
Although the corrosion of the reinforcing steel in concrete has been 
recognized as the most prevalent cause of deterioration of structural 
concrete, and several possible methods have been proposed as a means to 
prevent or substantially reduce the corrosion of the reinforcing steel, 
problems have still remained, especially when attempting to solve the 
problems with water-repellant sealer compositions. The problem of using 
water-repellant sealer composition is that "Although some sealers have 
been found to reduce freeze-thaw scaling of non-air entrained concrete, 
none has been found which will eliminate significant chloride penetration 
into bridge deck riding surfaces subject to abrasive traffic wear for long 
periods of time." (FCP Annual Progress Report, Year Ending Sept. 30, 1978 
under the project entitled "Eliminate Premature Deterioration of Portland 
Cement Concrete"). 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an improved method for 
preventing premature deterioration of reinforced concrete structures. 
Another object of the present invention is to provide an improved method 
for inhibiting corrosion of steel reinforcing members of reinforced 
concrete structures. 
Another object of the present invention is to prevent the deterioration of 
concrete paved roadways and bridge decks by inhibiting corrosion of 
internal steel reinforcing members in the concrete paved roadways and 
bridge decks. 
These and other objects, advantages and features of the present invention 
will become apparent to those skilled in the art from the reading of the 
detailed description of the present invention in conjunction with the 
appended claims. 
According to the present invention we have discovered an improved method 
for inhibiting corrosion of reinforcing members of reinforced concrete 
structures by retarding salt migration throught the concrete structures. 
Broadly, the method of the present invention comprises applying an 
effective amount of an organo silicon compound to at least one surface of 
the structure to substantially cover the surface of the structure, and 
applying to the organo silicon treated surface, after a period of time 
effective to allow the organo silicon compound to migrate into the 
concrete structure, an effective amount of water to substantially wet the 
surface of the structure. More specifically, the organo silicon compound 
is applied to a substantially dry surface of the concrete structure and 
the organo silicon is allowed to migrate into the concrete structure for 
at least about 30 minutes before wetting the surface of the structure with 
water. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The present invention provides a new and novel method of inhibiting 
corrosion of structural reinforcing steel in reinforced concrete 
structures, such as the reinforcing in paved concrete roadways and bridge 
decks. Broadly, the invention resides in the discovery that one can 
substantially eliminate salt migration into a steel reinforced concrete 
structure, and thereby inhibit corrosion of the steel, by applying an 
organo silicon compound to a dry surface of the reinforced concrete 
structure, allowing the organo silicon compound to migrate into the 
concrete for an effective period of time, and thereafter applying water to 
the surface of the structure previously covered with the organo-silicon 
compound to substantially wet such surface. 
The organo silicon compounds which can be employed in the method of the 
present invention can be any organo silicon compound capable of migrating 
into the concrete and which can be hydrolyzed within the concrete to form 
cross-linked polymers containing--Si--O--Si--moieties which can react with 
the free hydroxyl groups present in the concrete. While any suitable 
organo silicon satisfying the beforementioned requirements can be used in 
the practice of the present invention, we believe that because of their 
commercial availability, silanes and siloxanes are most desirable. 
The silanes, employed as the organo silicon compound in the method for 
inhibiting corrosion of the steel reinforcing members of structural 
concrete in accordance with the present invention can be represented by 
the general formula 
##STR1## 
wherein: R is a moiety selected from the group consisting of an alkyl 
containing from 1 to about 30 carbon atoms, an alkenyl, an aryl, a 
cycloalkyl, a cycloalkenyl, an aralkyl, or an aralkenyl; and 
R.sub.1 is a moiety selected from the group consisting of an alkyl 
containing from 1 to about 30 carbon atoms, a hydroxyalkyl, or an 
alkoxyalkyl. 
The siloxanes employed as the organo silicon compound in the method for 
inhibiting corrosion of the steel reinforcing members of structural 
concrete in accordance with the present invention can be represented by 
the general formula 
##STR2## 
wherein: each R.sub.2 is the same or different, and R.sub.2 is a moiety 
selected from the group consisting of an alkyl containing from 1 to about 
30 carbon atoms, an alkenyl, an aryl, a cycloalkyl, a cycloalkenyl, an 
aralkyl, or an aralkenyl; and 
y is an integer of at least 2. 
The alkyl moieties of the above-identified silanes and siloxanes can have a 
straight chain or branched chain configuration and, as previously 
indicated, can contain from 1 to about 30 carbon atoms. Exemplary of such 
alkyl moieties are methyl, ethyl, propyl, butyl, isopropyl, 2-ethylhexyl, 
n-octyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, 
n-tricosyl, decacosyl, 4-ethyl-3, 3-dimethylheptyl, 
7-(1,2-dimethylpentyl)-5-ethyltridecyl, 
6-(1-methylbutyl)-8-(2-methylbutyl) tridecyl, 
2,3,5-trimethyl-4-propylheptyl, 6-(1-ethylpropyl)-7-(1-pentylhexyl) 
tetradecyl, and the like. However, because of their commercial 
availability the silanes and siloxanes containing alkyl moieties of from 1 
to about 8 carbon atoms are preferred. 
The alkenyl moieties of the silanes and siloxanes defined hereinbefore can 
also have a straight chain or branched chain configuration. The length of 
the alkenyl moieties can vary widely but will generally be from 1 to about 
30 carbon atoms. Exemplary of such alkenyl moieties are vinyl, crotyl, 
propenyl, isopropenyl, 2-ethylhexenyl, butadienyl, n-nonenyl, 
n-tetradecenyl, n-eicosenyl, n-tetracosenyl, n-octacosenyl, triacontenyl, 
4-ethyl-3,3-dimethyl-1-noneyl, 5-ethyl-7-n-propyl-14-methyl-1-eicosenyl, 
and the like. 
The cycloalkyl moieties (i.e., R and R.sub.2) of the silanes and siloxanes 
defined by the before-mentioned general structures contain from 4 to 8 
carbon atoms in the ring portion of the moiety, and the alkyl portion of 
the moiety is as defined above. However, it is preferred that the alkyl 
portion be a lower alkyl containing up to about 8 carbon atoms such as 
methyl, ethyl, propyl, n-hexyl, n-octyl, and the like. Exemplary of the 
ring portion of the moiety are cyclobutyl, cyclohexyl, and cyclooctyl. It 
should be noted that the ring portion of the cycloalkyl moieties defined 
above can have one or more alkyl substitutes, the only limit being the 
number of replaceable hydrogen atoms on the carbon atoms forming the ring 
portion of the particular cycloalkyl moiety. 
The cycloalkenyl moieties which are represented by R, and R.sub.2 in the 
before-described general formulas for the silanes and siloxanes which can 
be employed in the method of the present invention are similar in all 
respects to the above-described cycloalkyl moieties with the exception 
that the alkenyl substituent of the moiety contains at least one site of 
ethylenic unsaturation. 
The aryl moieties (i.e., R and R.sub.2) of the above-defined silanes and 
siloxanes which can be employed as the organo silicon compound in the 
practice of the present invention can be mono-, di-, or tricylic, and the 
rings may be fused or unfused. Further, the aryl moieties may contain one 
or more inert substituents thereon, such as the before defined alkyl 
moieties. Exemplary of the aryl moieties which can be employed as R and 
R.sub.2 in the general structures representing the silanes and siloxanes 
useful in the practice of the present invention are phenyl, naphthyl, 
diphenyl, phenyl methyl phenyl, and the like. 
The aralkyl moieties represented by R and R.sub.2 in the general formulas 
for the silanes and siloxanes which can be employed as the organo silicon 
compound in the practice of the present invention include an aryl 
substituent and at least one alkyl substituent. The aryl substituent can 
be a mono-, di-, or tricyclic constituent as hereinbefore defined; and the 
alkyl constituent can any suitable alkyl moiety containing from 1 to 30 
carbon atoms as also defined hereinbefore. 
Similarly, the aralkenyl moieties represented by R and R.sub.2 in the 
general formulas for the silanes and siloxanes which can be employed as 
the organo silicon compound in the practice of the present invention 
include an aryl substituent and at least one alkenyl substituent. The aryl 
substituent can be, as defined above, a mono-, di-, or tricyclic moiety, 
and the alkenyl constituent can be any suitable alkenyl moiety containing 
from 1 to about 30 carbon atoms as also defined hereinbefore. 
As previously set forth the silanes which can be employed as the organo 
silicon compound in the practice of the present invention are represented 
by the general formula R--Si--(OR.sub.1).sub.3 wherein R is as heretofore 
defined and R.sub.1 is a hydrolyzable moiety selected from the group 
consisting of an alkyl containing from 1 to about 30 carbon atoms, a 
hydroxyalkyl, or an alkoxyalkyl. The alkyl substituent of the hydroxyalkyl 
and the alkoxyalky moieties can also contain from 1 to about 30 carbon 
atoms. Further, the before mentioned alkyl moiety or the alkyl substituent 
of the hydroxyalkyl and alkoxyalkyl moieties can have a straight chain or 
branched chain configuration. Exemplary of such alkyl moieties and alkyl 
substituents are methyl, ethyl, propyl, butyl, isopropyl, 2-ethylhexyl, 
n-octyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, 
n-tricosyl, decacosyl, 4-ethyl-3,3-dimethylheptyl, 
7-(1,2-dimethylpentyl)-5-ethyltridecyl, 
6-(1-methylbutyl)-8-(2-methylbutyl)tridecyl, 
2,3,5-trimethyl-4-propylheptyl, 6-(1-ethylpropyl)-7-(1-pentylhexyl) 
tetradecyl, and the like. Any silanes as defined by the Generic Structure 
I and having hydrolyzable moieties can be employed in the practice of the 
present invention. Preferrably the silane can also be solubilized in a 
suitable inert, volatile solvent so that the silane can be applied to the 
concrete in a liquid vehicle so as to assist the migration of the silane 
from the concrete surface to which it is applied into the concrete 
structure. However, silanes represented by the general structure 
EQU R--Si--(OR.sub.1).sub.3 
wherein R is an alkyl moiety containing from 1 to about 8 carbon atoms, and 
R.sub.1 is an alkyl moiety having from 1 to about 8 carbon atoms, a 
hydroxyalkyl moiety having from 1 to about 4 carbon atoms in the alkyl 
substituent, or an alkoxyalkyl moiety having from 1 to about 4 carbon 
atoms in the alkyl substituent are believed to be particularly effective 
in practicing the present invention. Examples of such silanes are 
ethyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, 
methyl-tris-(2-methoxy-ethoxy)-silane, 
ethyl-tris-(2-methoxy-ethoxy)-silane, 
propyl-tris-(2-methoxy-ethoxy)-silane, 
butyl-tris-(2-methoxy-ethoxy)-silane, tris-(2-ethoxy-ethoxy)-silane, 
phenyltriethoxysilane, cresyltriethoxysilane, and the like. It should be 
noted that while the above silanes are believed particularly effective in 
the practice of the present invention other silanes can be employed which 
meet the generic definition of the silanes such as n-dodecysilane, 
n-tetradecylsilane, n-hexadecylsilane, n-octadecylsilane, 
n-tricosylsilane, decacosylsilane, branched chain higher molecular weight 
silanes and the like. 
Similarly, any siloxane as defined above by generic structure II and having 
a hydrolyzable moiety can be employed in the practice of the present 
invention. Preferably the siloxane can be solubilized in a suitable inert, 
volatile solvent so that the siloxane can be applied to the concrete in a 
liquid vehicle so as to assist the migration of the siloxane from the 
concrete surface to which it is applied into the concrete structure. 
However, siloxanes represented by the general structure 
##STR3## 
wherein each R.sub.2 is the same or different moiety selected from the 
group consisting of an alkyl containing from 1 to about 8 carbon atoms, an 
alkenyl containing up to about 8 carbon atoms, an aryl as heretofore 
defined, or a cycloalkyl, cycloalkenyl, aralkyl or aralkenyl wherein the 
cyclo substituent contains from about 4 to 8 carbon atoms, the alkyl 
substituent contains from 1 to about 8 carbon atoms, the alkenyl 
substituent contains up to about 8 carbon atoms, and y is an integer of 
from 2 to about 100 are believed to be particularly effective as the 
organo silicon compound in the practice of the present invention. 
Exemplary of suitable siloxanes meeting the above definition are 
hexamethyl disiloxane, hexaphenyl disiloxane, dimethyltetraphenyl 
disiloxane, tetramethyldiphenyl disiloxane, 
.alpha.,.omega.-bis-trimethylsiloxypolydimethyl siloxane, 
.alpha.,.omega.-bis-trimethylsiloxypolydiphenyl siloxane, 
.alpha.,.omega.-bis-dimethylvinylsiloxypolydimethyl siloxane, 
.alpha.,.omega.-bis-triethylsiloxypolydiphenyl siloxane, mixtures of such 
siloxanes and the like. It should be noted that while the above siloxanes 
are believed particularly effective in the practice of the present 
invention, other siloxanes meeting the definition of the siloxanes as 
represented by Generic Structure II can be employed. 
The preparation of silanes and siloxanes useful in the practice of the 
present invention are accomplished by generally known methods and many of 
such compounds are commercially available. Thus, no discussion of the 
preparation of such organo silicon compounds is believed necessary to 
describe the subject invention. 
The organo silicon compounds employed in the practice of the present 
invention, and which are in a liquid state, can be applied directly to the 
surface of the reinforced concrete structure; or the organo silicon can be 
dissolved in a suitable liquid vehicle so that upon application of the 
organo silicon to the surface of a reinforced concrete structure the 
organo silicon compound is substantially uniformly dispersed over the 
surface of the structure. Further, the liquid vehicle may assist in the 
migration of the organo silicon compound into the interior portion of the 
structure. The liquid vehicle employed with the organo silicon compound 
can be any suitable volatile organic solvent. Further, the liquid vehicle 
should be anhydrous and inert to both the reinforced concrete structure 
and the organo silicon compound (i.e., the liquid vehicle should have no 
adverse effects on either the reinforced concrete structure or the organo 
silicon compound). 
A variety of different classes of organic solvents can be employed as the 
liquid vehicle for the organo silicon compounds, such as the silanes and 
siloxanes heretofore described. Preferably the solvent employed as the 
liquid vehicle for the organo silicon compounds will have an evaporation 
rate sufficiently low to permit the organo silicon compound to be spread 
uniformly over the area being treated, such as a bridge deck or the paved 
traveling surface of a concrete roadway, while functioning as a vehicle to 
assist the migration of the organo silicon compound into the interior 
portion of the structure. 
Exemplary of suitable organic solvents which can be employed as the liquid 
vehicle for the organo silicon compounds in the practice of the present 
invention are the aromatic or aliphatic organic solvents, including 
cycloaliphatic hydrocarbon solvents and alcohols, such as toluene, xylene, 
high boiling naphthas, cyclohexane, tetra-, hydro-, and 
decahydronaphthalenes, ethanol, propanol, isopropanol, butanol, and the 
like. 
The amount of organic solvent and organo silicon employed to form the 
solution for treating the reinforced concrete structure can vary widely 
provided sufficient organo silicon compound is present in the treating 
solution to substantially cover the surface of the structure being 
treated, such as the traveling surface of a concrete paved roadway or the 
concrete deck of a bridge. Generally, an effective amount of the organo 
silicon compound is present in a treating solution if the treating 
solution contains from about 0.5 to about 99 weight percent of the organo 
silicon compound. 
The organo silicon compounds as heretofore defined are applied, together 
with the organic solvent, to a surface of a reinforced concrete structure 
in accordance with the method of the present invention to inhibit 
corrosion of the reinforcing steel members of a reinforced concrete 
structure wherein corrosion of the reinforcing steel member is due 
primarily to salt migration into the structure. Broadly, the method of the 
present invention comprises covering a concrete surface of a concrete 
reinforced structure with an effective amount of the treating solution to 
substantially coat the concrete surface with the organo silicon compound, 
allowing the organo silicon compound to penetrate into the reinforced 
concrete structure for an effective period of time, while also allowing 
the organic solvent in the treating solution to evaporate, and thereafter 
applying an effective amount of water to the treated surface of the 
concrete structure to substantially wet the surface of the structure. The 
organo silicon containing solution can be applied to the surface of the 
concrete reinforced structure by any suitable means such as spraying, 
brushing and the like. 
The surface of the concrete reinforced structure to which the organo 
silicon compound is applied is preferably a clean, dry surface. The term 
"dry" as used herein is understood to mean a substantially moisture-free 
surface. The term "clean" as used herein is understood to mean 
substantially free of excess dirt, hydrocarbon deposits, grease and the 
like. When the organo silicon compound is to be applied to a structure, 
such as a concrete paved roadway or concrete bridge deck, which has had 
considerable use and contains large amounts of dirt, grease and 
hydrocarbon deposits thereon, the surface is desirably mechanically 
cleaned by any suitable means, such as sand blasting and the like. If 
water is used in the cleaning operation of the surface of the structure it 
is desirable that the surface of the structure be allowed to dry to the 
substantially dry condition before applying the organo silicon compound to 
the cleaned surface. 
The organo silicon dissolved in a suitable liquid carrier as heretofore 
defined is, as previously stated, applied to the clean, dry surface of the 
concrete reinforced structure in an amount effective to substantially 
cover the surface being treated with the organo silicon. Thereafter, the 
organo silicon compound is allowed to migrate into the reinforced concrete 
structure for an effective period of time to insure that the portion of 
the concrete structure adjacent the surface being coated with the organo 
silicon becomes impregnated with same. The period of time required to 
allow the organo silicon to migrate into the reinforced concrete structure 
can vary widely and will be dependent, to a large degree, upon the 
viscosity of the solution formed of the organic solvent and the organo 
silicon, and the porosity of the reinforced concrete structure. However, 
it is desired that organo silicon be allowed to migrate into the 
reinforced concrete structure for at least about 30 minutes, more 
desirably for a period of time from about 1 hour to about 24 hours, before 
contacting the surface of the organo silicon treated structure with water. 
Once the organo silicon has been allowed to migrate into the reinforced 
concrete structure for a period of time effective to provide the organo 
silicon impregnated structure, an effective amount of water is applied to 
the surface of the concrete structure previously treated with the organo 
silicon to wet such surface. Any suitable means can be employed to apply 
the water to the treated surface, such as spraying and the like. While the 
exact mechanism resulting from the application of the water to the surface 
of the organo silicon impregnated concrete structure is not known, it is 
believed that the addition of the water enables the hydrolysis of the 
organo silicon to go to completion and form within the structure a 
polymeric configuration which retards the migration of salt into the 
structure, and thus substantially eliminates corrosion of the internal 
reinforcing steel members of the concrete structure. 
In order to more fully describe the present invention the following example 
is set forth. However, it is to be understood that the example is for 
illustrative purposes and is not to be construed as limiting the scope of 
the present invention as defined in the appended claims.

EXAMPLE 
A series of tests were conducted where a commercially available organo 
silicon.sup.(a) was applied to a plurality of concrete slabs having no 
surface abrasion. Each slab had dimensions of 4 feet.times.4 feet.times.4 
inches. The tests were to determine the effect of the organo silicon in 
preventing salt migration (chloride) into the organo silicon treated 
slabs. A plurality of concrete slabs were used as control, non-treated 
slabs, and slabs identical in composition to the control slabs were 
treated with the organo silicon by brushing the organo silicon over the 
entire surface of the slabs at a rate of 1 gallon of organo silicon per 32 
square feet of concrete. One slab was treated with the organo silicon 
while the slab was wet with moisture, one slap was air dried prior to 
application of the organo silicon, and one slab was oven dried prior to 
the application of the organo silicon. The concrete slabs were allowed to 
absorb the organo silicon in substantial absence of moisture; and 
thereafter the slabs were wetted with water. The slabs were then exposed 
to outdoor, unprotected environmental conditions for several months. The 
slabs were then salted daily for 150 days with an aqueous salt solution 
containing 3 percent sodium chloride. The salt treated slabs were cored 
after the salt treatment to determine the salt migration into the slabs at 
various depths. Two core samples were pulled from each slab at the depths 
being investigated to determine the amount of salt (chloride) in the slabs 
at such depths. The results of the tests are tabulated in Table I. 
TABLE I 
______________________________________ 
Total Chloride - lbs/yd3 for Indicated Depth 
Slab Core 1/16-1/2 In. 
1/2-1 In. 
1-11/2 In. 
______________________________________ 
Control 10.8 7.8 4.4 
(Average) (Average) 
(Average) 
Treated 
Sample (b) 
1 0.32 0.15 0.25 
2 0.13 0.04 0.14 
Treated 
Sample (c) 
1 0.26 0.18 0.34 
2 0.83 0.22 0.32 
Treated 
Sample (d) 
1 1.36 0.10 0.14 
2 0.44 0.0 0.19 
______________________________________ 
(a) Chemtrete.RTM. Silane--an organo silicon marketed by Dynamit Nobel of 
America, Inc. containing 40 weight percent of an alkylalkoxysilane 
dissolved in ethyl alcohol. 
(b) Slabs were fogroom cured for 35 days and Chemtrete.RTM. Silane was 
applied to the wet slab. 
(c) Slabs were fogroom cured for 28 days, then dried in laboratory air fo 
7 days and Chemtrete.RTM. Silane was then applied. 
(d) Slabs were fogroom cured for 28 days, then ovendried for 8-10 hours a 
300.degree. F. Chemtrete.RTM. Silane was applied after cooling. 
The above data initially indicated that the moisture content of the 
concrete at the time of treatment with the organo silicon had no apparent 
effect on performance. However, for a product to be acceptable the product 
must be capable of withstanding a large number of salt applications while 
still inhibiting salt migration into the concrete. In order to determine 
the long range effectiveness of an organo silicon in preventing salt 
migration into concrete, the tests were continued and daily salt 
applications as set forth above applied to the slabs for 386 days. The 
results of the extended testing are tabulated in Table II. 
TABLE II 
______________________________________ 
Total Chloride - lbs/yd3 for Indicated Depth 
Slab Core 1/16-1/2 In. 
1/2-1 In. 
1-11/2 In. 
11/2-2 In. 
______________________________________ 
Control 13.55 10.91 9.34 6.03 
Treated 
Sample (b) 
1 4.03 1.42 0.61 0.52 
2 5.88 3.32 0.95 0.76 
Treated 
Sample (c) 
1 5.11 2.96 0.78 0.59 
2 1.28 0.66 0.62 0.52 
Treated 
Sample (d) 
1 0.66 0.47 0.40 0.34 
2 0.80 0.49 0.37 0.29 
______________________________________ 
(a) Chemtrete.RTM. Silane--an organo silicon marketed by Dynamit Nobel of 
America, Inc. containing 40 weight percent of an alkylalkoxysilane 
dissolved in ethyl alcohol. 
(b) Slabs were fogroom cured for 35 days and Chemtrete.RTM. Silane was 
applied to the wet slab. 
(c) Slabs were fogroom cured for 28 days, then dried in laboratory air fo 
7 days and Chemtrete.RTM. Silane was then applied. 
(d) Slabs were fogroom cured for 28 days, then oven dried for 8-10 hours 
at 300.degree. F. Chemtrete.RTM. Silane was applied after cooling. 
The data set forth in Table II clearly indicates the improved protection 
afforded a concrete slab against salt intrusion when dry concrete is 
treated with an organo silicon, and after migration of the organo silicon 
into the concrete, the organo silicon impregnated concrete is subsequently 
wetted with water. 
While the subject invention has been described in terms of certain 
preferred embodiments, such are intended for illustrative purposes only 
and alternatives or equivalents may readily occur to those skilled in the 
art without departing from the spirit or scope of the invention as set 
forth in the appended claims.