Method for sealing and priming prepared substrates for roadways

The present invention provides a method of sealing and priming a prepared substrate, such as a base or sub-base for a roadway, comprising the application of an amount of an emulsion consisting essentially of a first phase of a combination of resinous petroleum oil and an asphalt, a second phase of water, and suitable emulsifiers and stabilizers. The first phase comprises from about 0.25% to 21% asphalt and from about 3.33% to 33.95% resinous oil based on the total weight of the emulsion. The second phase of water provides from about 62.5% to 91.5% of the total weight of the emulsion. The emulsifiers and stabilizers are from about less than 0.16% to about 2.5% of the total weight of the emulsion. The contemplated ratios of the first asphalt and resinous oil phase to the second water phase in the total emulsion applied to the base course are from about a 1:1.8 to 1:11 ratio in the total emulsion.

FIELD OF INVENTION 
This invention relates to the surface treatment of prepared substrates, 
such as roadway base or sub-base courses, including the sealing and 
priming of the exposed surfaces of the substrates. 
BACKGROUND OF THE INVENTION 
The construction of a roadway typically requires the preparation of a base 
or sub-base course which receives and supports the one or more layers of 
pavement materials. A base course may be composed of a variety of 
materials, such as soil, clay, sand, pulverized shell or the combination 
of such materials. The base course may also be stabilized with cements, 
limefly ash or other such products, or by mechanical means. The pavement 
materials applied to the base course to complete the roadway may include 
one or more layers of hot-mix asphalt, asphalt cement and aggregate, and 
concrete, among others. 
In many instances, before the pavement may be applied to the base course, 
the surface of the course must be sealed and also frequently primed to 
receive the pavement materials. A coating of a suitable sealant is 
employed to ensure that the moisture content of the base course is 
sufficient to maintain the course in a compacted and stable condition. If 
this moisture content is not maintained within acceptable limits, the base 
course may deteriorate over time requiring repair and additional grading 
prior to placement of the finished pavement. 
Similarly, in many applications involving asphaltic pavements, the unpaved 
earthen surface of the base course must be primed with a suitable material 
to encourage the fusion or fluxing of the pavement material with the 
surface of the base course. Insufficient adhesion between the base course 
and roadway pavement material frequently is the cause of pavement 
separation and cracking during installation, and subsequent failures and 
premature deterioration of the pavement surface. Such failures may cause 
dangerous traffic conditions that require costly repairs. 
Cutback asphalts and emulsions of asphalts and water have been used in the 
past to seal and prime roadway base courses. The asphalt emulsions include 
products with asphalt residues in a range of from about 30% to 60% or 
greater by weight of the total product. The cutback asphalts typically 
include asphalt residues in excess of 60% by weight of the total product 
combined with solvents such as napthas, kerosenes, oils or other such 
products to maintain the asphalt in a liquid, flowable condition. 
A number of difficulties, however, limit the utility of the prior art 
sealing and priming methods. A relatively thick coat of both the cut-back 
asphalts and the asphalt emulsions is normally required to provide an 
effective sealer coat on a base course, and such products require 
relatively long cure times (as long as 2 to 7 days or more) before traffic 
may be permitted to pass over the treated area. In many states, the prior 
art sealers must further be covered with sand, fines, a protective layer 
of sand bituminous mixture or with pavement materials during the curing 
process to prevent damage to the sealer and pick up of the sealer by 
vehicular traffic passing over the sealed surface. Both the extended cure 
time and the necessary application of a cover layer significantly increase 
the cost and the difficulty of using such products. 
Moreover, the tendency of asphalt sealers to adhere to the tires and wheels 
of vehicles passing over the sealed surfaces frequently results in the 
loss of the prior art sealer coatings on entire sections of the base 
course. This loss of portions of the sealed surface substantially 
interferes with the ability of the prior art coatings to seal and prime 
the surface of the base course. As a result, multiple applications of such 
the asphalt sealers are often required to repair the sealed surface. 
The use cutback asphalts and asphalt emulsions, in addition, may require 
equipment adapted to maintain those products at an elevated temperature 
throughout the application procedure. Such equipment is often expensive to 
operate and difficult to maintain. Furthermore, as the cutback asphalts 
and some asphalt emulsions cure, solvents that have been proven to damage 
the environment are released into the atmosphere. As a result, such 
products are, or will be, prohibited from general usage in many states. 
The prior art asphaltic products are also frequently sensitive to alkali 
and other soil conditions which prevent the product from properly adhering 
to the base course. 
Petroleum products containing asphalt or asphalt derivatives have also been 
used as dust palliatives, i.e. a treatment to reduce airborne soil 
particles and soil erosion. These include resinous petroleum oil fractions 
that are applied to deeply penetrate unpaved roadway surfaces and other 
exposed soil surfaces. These dust palliatives are formulated to coat 
individual dust particles, to the extent possible, and to bind the soil 
particles together without the formation of a substantial surface coating 
or crust. Such crusts or coatings typically crack, separate or 
disintegrate with exposure to the elements to release fugitive dust and 
permit undesirable erosion. As a result, dust palliatives are normally 
applied at a rate and concentration adjusted to achieve the maximum long 
term penetration and to minimize the formation of crusts or coatings by 
the palliative. 
Examples of dust palliatives of resinous petroleum oils include those 
discussed in U.S. Pat. No. 2,646,361, and those sold under the "Coherex" 
tradename. Other such products are sold by Blacklidge Emulsions, Inc., 
Gulfport, Miss., and Dust Allayers, Incorporated, Mansfield, Ohio, under 
the tradename "Dust Bond" and by Shell Oil Company under the tradename 
"Shellflex Oils." 
Another dust palliative comprises a combination of resinous petroleum oil 
fractions and an asphalt in a highly diluted emulsion, i.e. one part oil 
and asphalt in about 6 to 15 parts water. Such products include "Dust Bond 
Dark" supplied by Dust Allayers, Incorporated. These products are applied 
at dilutions and rates to encourage their penetration into an exposed soil 
surface to prevent soil erosion and the creation of fugitive dust. 
SUMMARY OF THE INVENTION 
The present invention provides a method of sealing and priming a prepared 
substrate, such as a base or sub-base for a roadway, comprising the 
application of an amount of an emulsion consisting essentially of a first 
phase of a combination of resinous petroleum oil and an asphalt, a second 
phase of water, and suitable emulsifiers and stabilizers, effective to 
seal and prime the substrate. The first phase comprises from about 0.3% to 
21% asphalt and from about 3.3% to about 34% resinous oil based on the 
total weight of the emulsion. The second phase is of water which provides 
from about 62.5% to about 91.5% of the total weight of the emulsion. The 
emulsifiers and stabilizers are from about less than 0.16% to about 2.5% 
of the total weight of the emulsion. The contemplated ratios of the first 
asphalt and resinous oil phase to the second water phase in the total 
emulsion applied to the base course are from about a 1:1.8 to 1:11 ratio 
in the total emulsion. 
The asphalts used in the method include those with a viscosity at 60 
degrees centigrade preferably of about 400 poise to about 4800 poise, and 
may include asphalts with a greater or lesser viscosity having an actual 
or adjusted viscosity suitable for use in the method of the invention. The 
resinous oils include paraffinic and napthenic petroleum oil fractions, as 
well as rubber extender oils. The emulsion is applied at a rate of from 
about approximately 0.1 to 0.5 gal/sq. yd., and preferably from about 
approximately 0.2 to 0.3 gal/sq. yd. 
This method produces sealing and primer coating that may be applied 
relatively easily, that is both very effective and cost efficient, and 
that uses readily available materials that may be used cost effectively in 
large quantities. The sealer coating and primer applied with this method 
significantly reduces the escape of moisture from the base course and 
prevents the penetration of undesirable moisture into the treated surface. 
Unlike other methods, the invention produces a tough and durable surface 
coating that cures very rapidly, in as little as 1-8 hours, and resists 
cracking and separation from the base course. In addition, the properly 
cured surface of the sealer and primer coat is resistant to damage by 
vehicle tires and does not require expensive post-application covers of 
sand, fines or pavement coatings to protect the treated surface from 
traffic. The invention also does not require the use of heated application 
appliances or the use of large quantities of energy to maintain the sealer 
at elevated temperatures during treatment of the base course. Similarly, 
the method substantially eliminates the need for large volumes of solvents 
or thinners that endanger the environment when they are released during 
the curing process.

DETAILED DESCRIPTION OF THE INVENTION 
The method of the invention comprises the application of an emulsion of 
asphalt and resinous petroleum oil to a base or sub-base course for a 
roadway. Prior to application of the emulsion, the base course is graded 
and compacted to the proper specifications and the moisture content of the 
base course is adjusted to a level necessary to obtain optimum compaction 
of the course. Similarly, unnecessary dust or fine soil apparent on the 
surface of the prepared course is preferably removed. 
The emulsion is preferably prepared prior to application by the dilution 
with water of a concentrate containing the asphalt and oil components, 
such as supplied under the tradename "EPR-1 Prime" by Blacklidge 
Emulsions, Inc. and Dust Allayers, Incorporated. This concentrate may 
comprise primarily the first asphalt and oil phase of the final emulsion, 
as well as an amount of water, emulsifiers and stabilizers. The final 
emulsion may also be prepared by other means, such as the direct mixing of 
its individual components in a central tank prior to or simultaneously 
with the treatment of the base course, with the application of heat where 
necessary to aid in the emulsifying process. 
The contemplated concentrate used in the preferred embodiment has the 
following characteristics: 
______________________________________ 
Concentrate Composition 
Asphalt And Oil 
Component Emulsifiers And 
(First Phase) 
Stabilizers Water 
______________________________________ 
Approx. Max. 
70% 5% 49% 
Approx. Min. 
50% less than 25% 
1% 
Preferred 58%-67% 1-2% 31%-41% 
Approx. 
Amounts 
Second Pre- 
60%-65% 1-2% 33%-39% 
ferred Approx. 
Amounts 
______________________________________ 
When the final emulsion is prepared with the preferred concentrate, the 
contemplated ratio of concentrate to added water in the final emulsion is 
from about 1:1 to 1:5. Based on present state regulations, the preferred 
ratio of concentrate to water is from about 1:3 to 1:5, and depending on 
soil conditions, the preferred ratio is 1:3. If the first asphalt and oil 
phase exceed the maximums or fall below the minimum amounts as set forth 
above, the stability of the concentrate, and of the final diluted emulsion 
as applied to the base course, may be threatened. The components of the 
concentrate or the final emulsion may clump and separate during storage, 
and thus become unusable or require expensive and time consuming remixing. 
In the above concentrate, the contemplated weight percentage of the asphalt 
component of the asphalt and oil phase in the concentrates is from about 
3% to about 60% of the total weight of the concentrate. The contemplated 
weight percentage of the resinous petroleum oil component of that phase of 
the concentrate is from about 40% to about 97% of the total weight of the 
concentrate. 
From the above, it can be seen that the contemplated weight percentage in 
each component of the final emulsion, prepared with the preferred 
concentrate diluted at concentrate to water ratios of about 1:1, about 1:5 
and about 1:3, are as follows: 
______________________________________ 
Weight Percentages Of Components 
For Concentrate And Final Emulsions 
Concen- Wt. Perct. In Final 
trate Emulsion At Concen. 
Max. and Min. Amounts 
Wt. To Water Ratios of 
Of Components Perct. 1:1 1:3 1:5 
______________________________________ 
First Asphalt And Oil 
Phase 
Approx. Max 70% 35% 17.5% 11.7% 
Approx. Min. 50% 25% 12.5% 8.3% 
Asphalt 
Approx. Max. 60% 21.0% 10.5% 7.0% 
Approx. Min. 3% 0.8% 0.4% 0.3% 
Resin. Pet. Oil 
Approx. Max. 97% 34.0% 17.0% 11.3% 
Approx. Min. 40% 10.0% 5.0% 3.3% 
Second Water Phase 
Approx. Max. 49% 74.5% 87.3% 91.5% 
Approx. Min. 25% 62.5% 81.9% 87.5% 
Emulsifiers and Stabilizers 
Approx. Max. 5% 2.5% 0.63% 0.8% 
Approx. Min. &lt;1% &lt;0.5% &lt;0.25% &lt;0.16 
______________________________________ 
As shown below, the ratios of first asphalt and oil phase to second water 
phase for final emulsions with the above compositions which contain an 
approximate maximum and minimum percentage of the asphalt and oil phase 
are as follows: 
______________________________________ 
Ratios of First Asphalt and Oil Phase To Second Water 
Phase In Final Emulsion 
Concentrate Ratio 
To First To 
Water Percentage First 
Second 
Mixture Ratio To Second Phase 
Phase 
______________________________________ 
Approx. Max. 
1:1 35%:62.5% 1:1.8 
Of First (approx. 2.5% surfact. 
Asphalt And and emulsif.) 
Oil Phase 
Approx. Min. 
1:5 8.3%:91.5% 1:11 
Of First (approx. .2% surfact. 
Asphalt And and emulsif.) 
Oil Phase 
Preferred 1:3 17.25:81.9 1:4.75 
Amount Of (approx. .85% surfact. 
Conc., Approx. and emulsif.) 
Max. Of First 
Asphalt And 
Oil Phase 
______________________________________ 
The above final ratios reflect the components of the first asphalt and oil 
phase, whether from the preferred concentrate or from any other single or 
combination of sources. The total water includes that added to prepare the 
final emulsion, as well as the water present in the preferred concentrate 
(or any other source) if such a concentrate is used. 
The specific ratio of first asphalt and oil phase to second water phase 
chosen for a particular application will depend on factors such as the 
composition of the base course, the number of planned applications, the 
desired cure time and state regulations. For example, where the base 
course is of an open grade and granular composition, the preferred 
concentrate is mixed at a ratio of about 1:3 to 1:5 of concentrate and 
water to obtain sufficient penetration of the course by the sealer and 
primer to more effectively bind the loose upper soil surface of the course 
together. 
When the base course is non-porous, such those made of clay soils, the 
ratio of concentrate to water is preferably from about 1:1 to 1:3. Such 
soils are unlikely to permit the penetration of the surface of the course 
and increasing the amount of water diluent will typically encourage 
undesirable pooling of the emulsion on the treated surface. In the 
preferred method of the invention, deep penetration of the base course is 
avoided to provide a more effective sealer and primer on the exposed 
surface of the course. Similarly, in applications where quick curing is 
desirable, dilution ratios of first phase to second phase of about 1:5 are 
preferred. These greater dilution ratios produce an emulsion that is 
relatively thin and cures relatively quickly. 
The emulsion may be applied by hand spreading and through conventional 
spraying equipment, as well as comparable techniques. An effective amount 
of the emulsion is normally obtained at a rate of about 0.1 to 0.5 
gal./sq. yd. The rate of application of the emulsion, in addition, may 
vary with the conditions of the base course and other factors. The 
application rate for very compacted, water-laden soils is typically about 
0.1 gal./sq. yd. Based on state regulations, the preferred application 
rate for typical soil conditions is about 0.1 to 0.3 gal./sq. yd. 
The sealer and primer typically cures in about 15 minutes to 8 hours after 
the emulsion is applied to the exposed surface of the base course, 
depending on the rate of application, the dilution ratios used, the base 
course conditions and the weather, among other considerations. If the base 
course contains excess moisture, the curing time of the emulsion will be 
increased and penetration of the emulsion into the surface of the course 
will be delayed. If insufficient moisture is present in the base course, 
the emulsion may not properly adhere to the treated surface. 
It is not necessary in most instances to add sand, fines or other such 
products to cover and protect the treated surface from traffic damage when 
properly cured. After the sealer and primer is cured, traffic may be 
permitted to pass over the roadway, and a paving surface may later be 
applied to the course. The treated surface, in addition, may be covered 
with a protective layer of sand, fines or pavement layer if the surface 
must be exposed to traffic before the sealer coating and primer has fully 
cured. 
The asphalt component of the emulsion preferably includes asphalts of the 
grades AC-5 to AC-40, and may include asphalt grades in excess of AC-40 or 
less than AC-5, if those asphalts have an actual or adjusted viscosity 
suitable for use in the method of the invention. The AC-5 to AC-40 grade 
asphalts typically have viscosities at 60 degrees centigrade (140 degrees 
Fahrenheit) from about 400 poise to about 4800 poise, as determined 
pursuant to AASHTO Procedure 201-90 and 202-90, which correspond to ASTM 
D2170-81 and ASTM D2171-81, respectively. 
The resinous petroleum oil component of the emulsion may comprise petroleum 
oil extracts, including paraffinic or napthenic oils. Typically, such 
petroleum oils are used as rubber extenders oils and have low asphaltene 
contents. Examples of such products are discussed in U.S. Pat. No. 
2,646,361 and include "Shellflex" oils supplied by the Shell Oil Company, 
"Textract" by supplied by Texaco Oil Company, "DAI 89 Base Resin" supplied 
by Dust Allayers, Incorporated and similar products. 
A wide variety of emulsifiers and stabilizers may be used to suspend the 
two phases of the emulsion. These emulsifiers, in addition, may be 
nonionic, anionic, cationic or a combination of such products. Examples of 
such products may be found in U.S. Pat. No. 2,646,361. The preferred 
emulsifiers and stabilizers are those found in the concentrate sold under 
the tradename "EPR-1 Prime" by Blacklidge Emulsions, Inc. and Dust 
Allayers, Incorporated. 
An emulsion formed by the mixture of the above components of the first and 
second phases, emulsifiers and stabilizers in other orders or in different 
combinations may also be used for the purposes of the invention. For 
example, each component of asphalt, resinous oil, emulsifier, stabilizer 
and water may be added separately, or in any desirable combination, to a 
central mixing tank. The charged tank may then be agitated and, if 
necessary, the asphalts, oils and the tank may be heated to ensure proper 
mixture of the components and the emulsification of the asphalt and oil 
phase. 
EXAMPLES 1-4 
Sections of a prepared roadway base course were sprayed using conventional 
equipment with an emulsion of EPR-1 Prime concentrate and water in the 
ratios and at the application rates set forth below: 
______________________________________ 
Example 
1 2 3 4 5 
______________________________________ 
Ratio Of 1:3 1:2 1:6 1:5 1:3 
Concentrate to 
Water Diluent 
Application 0.3 0.2 0.25 0.2 0.1 
Rate (gal./sq. (applied 
yd.) twice) 
______________________________________ 
For examples 1-3, the base course was composed of an open grade lime and 
fly ash aggregate mixture and the emulsions were applied in mid-afternoon. 
In each experimental application, the sealer and primer was sufficiently 
cured in about 2 hours to allow the passage of automobile traffic over the 
treated surface without loss of surface integrity. The emulsion penetrated 
the surface of the base course approximately 0.5 to 0.75 inches and left a 
waxy coat that repelled water. 
The sections of base course treated with the base coat and primer of the 
invention were inspected one day, five days and nineteen days later. At 
each inspection, the surface of the sealer and primer was lifted and it 
was observed that the moisture content of the underlying base course had 
been maintained by the sealer and primer. Damage from construction traffic 
was negligible, and there was essentially no evidence of adhesion of the 
sealer and primer to the tires of vehicles. 
A control of emulsified asphalt primer (EA-1) was also applied to surfaces 
adjacent the test area. The inspection of the control areas revealed 
numerous damaged sections where the emulsified asphalt had been penetrated 
or removed by the vehicular traffic. The surface of the base course in and 
around the damaged portions had noticeably dried, including areas under 
the emulsified asphalt primer. 
For Example 4, the base course was composed of a medium to close grade 
cement stabilized soil that had previously been cement treated and 
re-pulverized. During the observation period, the base coat and primer did 
not evidence signs of disruption by local traffic passing over the treated 
sections. A second treatment of the experimental sections was then applied 
at the same dilution and application rate prior to the installation of the 
first of the pavement layers to the base course. 
A control of emulsified asphalt primer (SS-1 Asphalt Emulsion) was also 
applied to surfaces adjacent the test area. The inspection of those 
control areas revealed numerous instances of scabs of bare soil at random 
locations throughout the control area. Several reapplication of the SS-1 
emulsified asphalt primer were required to repair the damaged areas and 
restore the integrity of the coating. 
For example 5, the base course was composed of a close grade limestone soil 
and the emulsion achieved no observable penetration of the surface of the 
base course. The sealer and primer was exposed for approximately a week 
under very light traffic conditions. During the observation period, there 
were no observable defects or problems with the coating. 
Thus, the method of the invention produces a durable and dependable sealer 
coating and primer for substrates such as roadway base courses that is 
unexpectedly superior to the prior art sealers. The materials used and the 
elimination of expensive heating equipment and procedures makes this 
method cost efficient and practical for use in many applications, 
including extensive road construction projects. The invention may also be 
used where similar concerns relating to the sealing of substrates of soils 
or other such materials are present, or for applications in road building 
where fluxing of a pavement material to other substrates, such as old 
pavement surfaces, is required. 
While the invention has been described by reference to certain specific 
descriptions and examples which illustrate preferred materials and 
conditions it is understood that the invention is not limited thereto. 
Rather, all alternatives, modifications and equivalents within the scope 
and spirit of the invention so described are considered to be within the 
scope of the appended claims.