Manufactured aggregate composite

Manufactured aggregates and/or composites having incorporated therein an asphaltic oxidation product.

BACKGROUND OF THE INVENTION 
This invention relates to a manufactured aggregate derived from the solid 
oxidation product of an asphaltic material and, more particularly, to a 
manufactured aggregate for use in the preparation of hot mix asphalt and 
related bituminous pavements. 
Coal fly ash is a waste material generated in large quantities at coal 
burning power plants. Considerable effort has been made to find an 
alternative to disposing this material. Various technologies have been 
developed as a result. For instance, coal fly ash can be treated to form a 
variety of structural products. Refer to U.S. Pat. No. 5,342,442 and the 
references cited therein which relate to the use of sewage sludge and coal 
fly ash in the formation of light weight aggregates. 
However, initial studies indicate that coal burning facilities can be 
converted to utilize naturally occurring asphalts as an alternative energy 
source. The solid oxidation products resulting therefrom are 
compositionally and chemically distinct from the various coal fly ash 
materials previously generated. As a result, such oxidation products have 
neither been used nor considered in the formulation of structurally useful 
materials. Coal fly ash typically contains SiO.sub.2, Al.sub.2 O.sub.3 and 
Fe.sub.2 O.sub.3. Coal fly ash is not typically water soluble. The 
oxidation products employed herein contain essentially no detectable 
levels of the above compounds normally found in coal fly ash. Furthermore 
the oxidation products used in this invention are composed 55% or more of 
magnesium sulfate, which is highly soluble in water. 
It is generally desirable to provide an inexpensive aggregate material, 
particularly one which is manufactured thereby providing the opportunity 
to tailor properties, for use in conjunction with a bituminous pavement 
surface, especially one having enhanced performance properties. 
Various features and advantages of the present invention will be apparent 
from this summary and included descriptions of preferred embodiments, and 
will be readily apparent to those skilled in the art having knowledge of 
manufactured aggregate materials, as can be used in the construction of 
bituminous pavements, roadways, and related surfaces. Such objects, 
features, benefits and advantages will be apparent from the above as taken 
in conjunction with the accompanying examples, tables, data and all 
reasonable inferences to be drawn therefrom. 
SUMMARY OF THE INVENTION 
The present invention is directed to the use of the oxidation product of a 
naturally occurring asphaltic fuel source in the preparation of an 
aggregate material. Such an aggregate can be used as part of a bituminous 
pavement. In particular, and without limiting this invention, the 
aggregates described herein can be incorporated with a hot mix asphalt for 
use as a roadway/driving surface. 
In part, the present invention is an aggregate composite which can be used 
with hot mix asphalt. The composite includes (a) a cementitious solid 
material including (1) a cement present in the range from about 40.0 to 
about 99.9 percent by weight of the cementitious solid, and (2) a solid 
oxidation product of naturally occurring asphalt from the Orinoco Belt of 
Venezuela present in a range from about 0.1 to about 60 percent by weight 
of the cementitious solid, with the cementitious material hydrated and 
formed into a nodule having pores resulting from curing of the 
cementitious material; and (b) an additive material. The additive material 
can be any one, or a mixture, of alkali silicates, alkali fluosilicates, 
vinyl acetates, latex emulsions or phenolic resins. The additive material 
is employed in an amount effective to permit retention of the cementitious 
solid in the formed nodule. We have found that relatively small quantities 
of the additive are effective, with amounts as low as 0.1 per cent by 
weight of the total composite being satisfactory. Due to the fact that the 
additive is a cost item in the production of the aggregate compositions of 
this invention, it is preferred to keep their use to a reasonable level, 
such as, not more than about 5 per cent by weight of the composite. While 
higher concentrations can be employed and are operative, there does not 
appear to be an advantage of going above about 5 per cent by weight. 
Usually we employ less than about 4, and even less than about 3, per cent 
by weight. At the lower end, we have generally used at least about 1 per 
cent by weight of the additives. 
In preferred embodiments, the oxidation product is obtained from oxidation 
of an aqueous emulsion of a naturally occurring asphalt from the Orinoco 
Belt of Venezuela. Such emulsion is commercially available under the 
trademark, Orimulsion.RTM.. Generally such oxidation product is present in 
the cementitious solid in an amount from about 35 to about 55 percent by 
weight. 
As described above, the inventive aggregate composites have incorporated 
therein an oxidation product of an aqueous emulsion of a naturally 
occurring asphalt from the Orinoco Belt of Venezuela. Generally and as 
will be well known to those skilled in the art made aware of the 
invention, such an oxidation product can be prepared by contacting the 
asphalt material with air and/or another oxygen-containing stream, through 
any one of several recognized processes or variations thereof, to provide 
the oxidation product in addition to combustion by-products such as heat, 
carbon dioxide and water. The oxidation product is the solid residual 
subsequently collected downstream from the point of combustion/oxidation. 
The oxidation product of the present invention can be generated in such a 
manner as to include the introduction of one of several auxiliary 
processes and/or additives upstream, downstream or at the point of 
combustion, to meet various process or combustion requirements, relating 
but not limited to emission control, reduced corrosion or enhanced 
operability. Depending upon the nature of these additives the combustion 
residue or by-products thereof can become intimately co-mingled with 
either the oxidation product described above and can be, where 
appropriate, considered part of, integral to, and used with the present 
invention. 
Illustrative of an auxiliary process and/or additive is the incorporation 
of a flue gas cleanup device-such as a wet lime-limestone 
scrubber----downstream from the combuster. Scrubber residues can be 
returned and/or reintroduced to the combustion/oxidation line at a point 
upstream of the final particulate separator, such that the residues are 
mixed with and incorporated into the oxidation product. Again, considering 
a scrubber process as illustrative of a number of available auxiliary 
processes, one skilled in the art will recognize that the 
identity/composition of the scrubber residues are a function of the 
identity of the particular scrubbing reagent, whether it be lime, 
limestone or a related scrubbing reagent, and the compositional components 
and their relative concentrations of the make-up water used in the 
scrubber. 
An asphaltic precursor to the oxidation product of this invention is 
commercially available from Bitor America Corporation, Boca Raton, Fla., 
under the Orimulsion.RTM. trademark. Without limitation, this commercial 
product is currently prepared by initial injection of steam into the 
asphalt formation until the viscosity is reduced to a point permitting it 
to flow into a well bore. A primary aqueous emulsion is prepared which 
further reduces asphalt viscosity and facilitates handling and 
transportation. The primary emulsion is then broken with the water 
substantially removed, leaving an asphalt material with less than 2 
percent water. Alternatively, the asphalt in the formation can be 
dissolved or suspended in a light hydrocarbon solvent, such as for 
example, kerosene, and the kerosene-containing bitumen removed to the 
surface where separation of the bitumen and kerosene can be effected. 
Fresh water is reintroduced and the asphalt is emulsified with a surfactant 
under strictly controlled protocols. For example, for a shear rate of 20 
s.sup.-1, a viscosity of about 450 mPa is achieved by handling the 
Orimulsion.RTM. at 30.degree. C. This and comparable production methods 
and techniques provide an aqueous emulsion with no more than 2 percent of 
the droplets having a diameter higher than 80 micrometers. The 
Orimulsion.RTM. material is further characterized by density (.about.1,010 
Kg/m.sup.3 at 15.degree. C.), flash point (.about.130.degree. 
C./266.degree. F.), and concentrations of vanadium (.about.0.300 ppm), 
nickel (.about.73 ppm), magnesium (.about.0.350 ppm), carbon (.about.60.0 
weight percent), hydrogen (.about.7.5 weight percent), sulfur (.about.2.7 
weight percent), nitrogen (.about.0.50 weight percent) and oxygen 
(.about.0.20 weight percent). 
It will be understood by those skilled in the art that the composites 
and/or aggregates of the present invention are not restricted by 
incorporation of an oxidation product of any one Orinoco-type asphalt 
material. Whereas a commercially-available Orinoco asphalt material might 
be described as a 30 percent aqueous emulsion prepared with a nonionic 
surfactant, the compositions of the present invention can suitably 
comprise, consist of, or consist essentially of the oxidation product of 
such material and/or oxidation products of other Orinoco-type asphalts, 
emulsified or otherwise processed. Each such oxidation product is 
compositionally distinguishable, characteristically contrasted, and can be 
practiced in conjunction with the present invention separate and apart 
from another. Accordingly, it should be understood that the inventive 
composites and/or aggregates, as illustratively disclosed herein, can be 
prepared and/or practiced in the absence of any one oxidation product or 
species which may or may not be specifically disclosed, referenced or 
inferred herein, the absence of which may or may not be specifically 
disclosed, referenced or inferred herein. 
While other compositions, mixtures or formulations involving a naturally 
occurring Orinoco-type asphalt can be used herewith, a useful source of 
the inventive oxidation product is available under the PCS trademark from 
the Pure Air division of Air Products and Chemicals, Inc. of Allentown, 
Pa. As described above, the compositional profile of an oxidation product 
will reflect any operation and/or additive auxiliary to the asphalt and/or 
oxidation process. However, any such oxidation product--while 
compositionally distinguishable, characteristically contrasted, and 
separately practiced--will to some extent reflect either the absolute or 
relative vanadium and nickel concentrations characteristic of a naturally 
occurring asphalt from the Orinoco Belt of Venezuela. 
The oxidation product, whether or not derived from an aqueous emulsion, can 
be used effectively over the weight percent range described above. At 
amounts under the lower end of the given range, cost effectiveness is 
compromised by increasing levels of a cementitious material. At 
concentrations of oxidation product beyond the referenced range, 
insufficient reaction and/or interaction with the cement component can 
present leachate concerns. However, improvements in existing technology 
and processing will serve to increase the effective and beneficial 
concentration range over which the inventive oxidation products may be 
employed. As is applicable to other aspects of this invention, various 
time, temperature and mix parameters, as recognized by those of skill in 
the art, can be used and/or modified with a given concentration of 
oxidation product to achieve a desired composite and/or aggregate. 
As described above, the aggregate composite also includes an additive 
material. Preferably, an aqueous silicate solution is used. The silicate 
composition can be, but is not limited to, an alkali silicate or an alkali 
fluosilicate. Sodium silicate, sodium metasilicate, and/or sodium 
fluosilicate can be used with beneficial effect. Alternatively, alone or 
in combination with a silicate additive, an organic binder material can 
also be used as an additive. Representative but not exclusive of such 
binders are vinyl acetate, phenolic resins, and latex emulsions. 
In certain embodiments, irrespective of the particular additive material 
utilized, a coal fly ash material can be included in the composite. 
Without limiting the invention and without adopting any one theory or mode 
of operation, it is thought that inclusion of such a coal fly ash can 
serve to minimize the potential for magnesium and/or sulfate leaching 
where such a phenomenon is a concern. As will be apparent to those skilled 
in the art, a variety of coal fly ash materials can be utilized. 
Illustrative of such materials are the Class F and Class C coal fly ashes, 
the physical and chemical parameters of which are described in American 
Society of Testing and Materials (ASTM) standard specification C 618 for 
their use as mineral admixtures with portland cements. (See Tables A-D, 
below.) Class F fly ash is normally produced from the burning of 
anthracite or bituminous coal. Class N is a raw or calcined natural 
pozzolan-siliceous or siliceous or aluminous material which chemically 
reacts with calcium hydroxide at ordinary temperatures to form compounds 
possessing cementitious properties. Such pozzolans can include 
diatomaceous earths, opaline cherts and shales, tuffs and volcanic ashes 
or pumicites, any of which may or may not be processed by calcination, and 
various other materials requiring calcination to induce satisfactory 
properties, such as various other clays or shales. Class F fly ash also 
has pozzolanic properties. 
TABLE A 
______________________________________ 
ASTM C 618 Chemical Requirements for Mineral Admixtures 
Mineral 
Admixture Class 
N F C 
______________________________________ 
Silicon dioxide (SiO.sub.2) plus aluminum 
70.0 70.0 50.0 
oxide (Al.sub.2 O.sub.3) plus iron oxide (Fe.sub.2 O.sub.3), 
min, % 
Sulfur trioxide (SO.sub.3), max, % 
4.0 5.0 5.0 
Moisture content, max, % 
3.0 3.0 3.0 
Loss on ignition, max, % 
10.0 6.0 6.0 
______________________________________ 
TABLE B 
______________________________________ 
ASTM C 618 Supplementary Optional Chemical Requirements 
for Mineral Admixtures 
Mineral 
Admixture Class 
N F C 
______________________________________ 
Available alkalies, as Na.sub.2 O, max, % 
1.5 1.5 1.5 
______________________________________ 
Applicable only when specifically required by the purchaser for mineral 
admixture to be used in concrete containing reactive aggregate and cement 
to meet a limitation on content of alkalies. 
TABLE C 
______________________________________ 
ASTM C 618 Physical Requirements for Mineral Admixtures 
Mineral 
Admixture Class 
N F C 
______________________________________ 
Fineness: 
Amount retained when wet-sieved 
34 34 34 
on 45 .mu.m (No. 325) sieve, max, % 
Strength activity index: 
With portland cement, at 7 days, 
75 75 75 
min, percent of control 
With portland cement, at 28 days, 
75 75 75 
min, percent of control 
Water requirement, max, percent of 
115 105 105 
control 
Soundness: 
Autoclave expansion or contraction, 
0.8 0.8 0.8 
max, % 
Uniformity requirements: 
The density and fineness of 
individual samples shall not vary 
from the average established by the 
ten preceding tests, or by all 
preceding tests if the number is less 
than ten, by more than: 
Density, max variation from average, % 
5 5 5 
Percent retained on 45-.mu.m (No. 325), 
5 5 5 
max variation, percentage points 
from average 
______________________________________ 
Care should be taken to avoid the retaining of agglomerations of extremely 
fine material. 
The strength-activity index with portland cement is not to be considered a 
measure of the compressive strength of concrete containing the mineral 
admixture. The strength activity index with portland cement is determined 
by an accelerated test, and is intended to evaluate the contribution to be 
expected from the mineral admixture to the longer strength development of 
concrete. The weight of mineral admixture specified for the test to 
determine the strength activity index with portland cement is not 
considered to be the proportion recommended for the concrete to be used in 
the work. The optimum amount of mineral admixture for any specific project 
is determined by the required properties of the concrete and other 
constituents of the concrete and should be established by testing. 
Strength activity index with portland cement is a measure of reactivity 
with a given cement and may vary as to the source of both the fly ash and 
the cement. 
If the mineral admixture will constitute more than 20% by weight of the 
cementitious material in the project mix design, the test specimens for 
autoclave expansion shall contain that anticipated percentage. Excessive 
autoclave expansion is highly significant in cases where water to mineral 
admixture and cement ratios are low, for example, in block or shotcrete 
mixes. 
Meeting the 7-day or 28-day strength activity index will indicate 
specification compliance. 
TABLE D 
______________________________________ 
ASTM C 618 Supplementary Optional Physical Requirements 
for Mineral Admixtures 
Mineral 
Admixture Class 
N F C 
______________________________________ 
Multiple factor, calculated as the 
-- 255 -- 
product of loss on ignition and 
fineness, amount retained when 
wet-sieved on No. 325 (45-.mu.m) 
sieve, max, %* 
Increase of drying shrinkage of mortar 
0.03 0.03 0.03 
bars at 28 days, max, difference, in 
%, over control 
Uniformity Requirements: 
In addition, when air-entraining 
20 20 20 
concrete is specified, the quantity 
of air-entraining agent required to 
produce an air content of 18.0 vol 
% of mortar shall not vary from the 
average established by the ten 
preceding tests or by all preceding 
tests if less than ten, by more than, % 
Reactivity with Cement Alkalies: 
Reduction of mortar expansion at 
75 -- -- 
14 days, min, % 
Mortar expansion at 14 days, max, 
0.020 0.020 0.020 
______________________________________ 
*Applicable only for Class F mineral admixtures since the loss on ignitio 
limitations predominate for Class C. 
Determination of compliance or noncompliance with the requirement relating 
to increase in drying shrinkage will be made only at the request of the 
purchaser. 
The indicated tests for reactivity with cement alkalies are optional and 
alternative requirements to be applied only at the purchaser's request. 
They need not be requested unless the fly ash or pozzolan is to be used 
with aggregate that is regarded as deleteriously reactive with alkalies in 
cement. The test for reduction of mortar expansion may be made using any 
high-alkali cement in accordance with Test Methods C 311, the section on 
Reduction of Mortar Expansion, if the portland cement to be used in the 
work is not known, or is not available at the time the mineral admixture 
is tested. The test for mortar expansion is preferred over the test for 
reduction of mortar expansion if the portland cement to be used in the 
work is known and available. The test for mortar expansion should be 
performed with each of the cements to be used in the work. 
Combinations of various coal fly ash materials can be used to provide an 
aggregate having a desired compositional make-up. Likewise, a 
concentration of any one or combination of fly ash materials can be gauged 
to provide a predetermined compositional make-up and/or to provide a 
certain degree of leachate control. For example a certain amount of Class 
C Fly ash can compensate for a corresponding decrease in the content of 
cement and Class F ash. 
While a number of hydraulic cementitious materials can be used to prepare 
the aggregates and/or composites of this invention, portland cements have 
been used with good effect. The chemical and physical parameters of 
various portland cements, which can be used in conjunction with the 
present invention, are as provided in ASTM standard specification C 150-as 
provided more fully in a co-pending application entitled "Modified Cement 
and Concrete Compositions," filed contemporaneously herewith. The tables 
corresponding to ASTM C 150 of the aforementioned co-pending application 
and the application, are incorporated herein by reference in their 
entirety. 
While any one of the available portland cements can be used with comparable 
effect, allowing for obvious modifications owing to differences in 
chemical composition, as well as chemical/physical properties, Type I 
portland cement is preferred as a matter of economy and general 
use/application. In preferred embodiments, where a coal fly ash material 
is utilized, a Type I portland cement is present in a range from about 40 
to about 50 percent by weight; the oxidation product of an Orimulsion.RTM. 
fuel is present in the range from about 40 to about 50 percent by weight, 
and the fly ash material--preferrably a Class F coal fly ash--is present 
in the range from about 0.1 to about 20 percent by weight. Such preferred 
embodiments can optionally include a sealant material comprising at least 
one of an alkali silicate solution and an aqueous latex emulsion. 
In part, the present invention is a manufactured aggregate which includes 
(1) a cementitious solid material including cement present in the range 
from about 40.0 to about 99.9 percent by weight of solids; (2) a solid 
oxidation product of a naturally occurring asphalt from the Orinoco Belt 
of Venezuela present in the range from about 0.1 to about 60 percent by 
weight of solids, the cementitious material hydrated and formed into a 
porous nodule; and (3) calcium and magnesium silicate hydrates. As 
described above, preferred embodiments of the manufactured aggregate 
include an oxidation product of an aqueous emulsion of a naturally 
occurring asphalt from the Orinoco Belt of Venezuela, in particular, an 
oxidation product of the commercially available Orimulsion.RTM. fuel, 
which can be present in a range from about 35 to 55 percent by weight. The 
concentration of oxidation product can be adjusted as described above and 
as needed to provide a stable aggregate. 
The calcium and magnesium silicate hydrates within the aggregate pores are 
at least in part the reaction products of calcium and magnesium cations, 
respectively, within the cementitious material and a silicate solution 
used as a binder. As described more fully above, such silicate binders can 
include sodium silicate, sodium metasilicate, and sodium fluosilicate. 
Without adopting any one theory or mode of operation, the precipitated 
silicate hydrates act to seal the aggregate pores and enhance the 
mechanical properties of the aggregate. Utilizing a fluosilicate sealant 
may result in deposition of bridged polysilicate anionic structures which 
also serve to seal the pores and enhance the mechanical properties of the 
aggregate. To this effect, a silicate binder having a relatively low 
sodium oxide to silica ratio is more beneficial. The more silica available 
for reaction with calcium (or magnesium), the greater percentage of the 
pores will be sealed and the mechanical properties of the aggregate will 
be enhanced. 
The manufactured aggregate of this invention can also include an organic 
binder material. Representative materials include, but are not limited to, 
vinyl acetates, latex emulsions, and phenolic resins. 
Likewise, as described in conjunction with the composite of this invention, 
the manufactured aggregate can include a coal fly ash material present in 
the range from about 0.1 to about 30 percent by weight. While Class F coal 
fly ash is preferred, Class C fly ash and a combination of Class F and 
Class C fly ashes can be utilized. Likewise, as described more fully 
above, whether or not the manufactured aggregate includes a fly ash 
material, the cement component of the cementitious solid material can be 
one of the various portland cements. Preferably, Type I portland cement is 
used because of its general applicability in a concentration which can 
vary with the concentration oxidation product, but is preferably about 40 
to about 50 percent by weight when a Class F coal fly ash material is 
utilized in the range from about 0.1 to about 20 percent by weight. 
In part, the present invention contemplates use of a manufactured 
aggregate, as described more fully above, in combination with a bituminous 
composition for construction of a pavement, roadway and/or driving 
surface. The bitumen component of such composition can be selected from 
the group of asphalts, coal tars, coal tar pitches, and asphaltenes, as 
described more fully in a co-pending application entitled "Bituminous 
Compositions Having Enhanced Performance Properties," in particular Tables 
A-D, E and H and the corresponding text--incorporated by reference herein 
in its entirety.

EXAMPLE OF THE INVENTION 
The following nonlimiting examples and data illustrate various aspects and 
features relating to the aggregates, composites, and combinations of the 
present invention, including the stability and utility of such aggregates 
and/or composites, for use in conjunction with or in the preparation of a 
variety of bituminous compositions. 
Example 1 
A sample of an oxidation product, in accordance with this invention was 
analyzed for chemical composition. Elemental metals were determined by 
flame absorption spectroscopy, compared to standard solutions, after 
dissolution of the sample in hydrochloric acid. Total sulfur content (as 
sulfate) was determined by a gravimetric method as more fully described in 
ASTM standard procedure C 114, after digestion of the sample in hydrogen 
peroxide and 1:4 (v/v) nitric acid/hydrochloric acid. The insoluble 
residue of the particular sample analyzed was not identified. 
______________________________________ 
Chemical Analysis (Wt. %) 
S(as SO.sub.4) 
Mg V Ni Ca Na Fe Mn Insol. Res. 
______________________________________ 
58.0 12.9 7.7 1.6 1.0 1.6 0.23 0.005 
0.11 
______________________________________ 
While the oxidation product of this example was derived from the 
combustion/oxidation of an aqueous emulsion of an Orinoco asphalt, the 
oxidation product/component of this invention can include, as more fully 
described above, various other constituents/residues manifesting one or 
more processes and/or additives auxiliary to the combustion/oxidation 
process-constituents/residues that would be reflected by their analytical 
profiles. By way of further example and without limiting this invention, 
depending upon the exact nature of a particular additive or auxiliary 
process, analysis of the oxidation product can reveal the presence of 
carbon, as well as altered levels of magnesium, calcium or sodium and/or 
the presence of one or more additional Group IA or IIA metals. 
Example 2 
The composites and/or aggregates of the present invention can be prepared 
in accordance with the following procedure or straightforward scale up 
modifications thereof: using a standard Hobart mixer, the cement material 
and an oxidation product were mixed for about 10 seconds to provide a 
somewhat homogenous mixture. The mixture was turned on slow speed and the 
dry ingredients were mixed for an additional 30 seconds, at which time an 
amount of water sufficient to provide the required and predetermined 
degree of hydration was added over a period of about one minute, with 
continued slow mixing. After additional of water, the mixture was 
immediately turned up to medium speed and a binder is added. Mixing is 
continued for about 1-2 minutes, at medium speed. The mixer is then turned 
off and the material is nodulized into a desired size and 
shape--preferably spherical particles averaging about 17 mm in diameter. 
The nodules are then cured for about 7-28 days, at room temperature and 
50% relative humidity. 
As described more fully above, a preferred binder material is a sodium 
silicate solution and/or a latex emulsion. Where a sodium silicate 
solution is utilized to bind the aggregate and seal any pores therein, it 
can be alternatively added toward the end of the mixing cycle or sprayed 
with suitable means onto the particle surface after nodulization. Useful 
sodium silicate solutions are commercially available from a number of 
sources, for example, the PQ Company. Sodium metasilicate and sodium 
fluosilicate sealant materials are likewise commercially available and 
known to those skilled in the art. Alternatively, a preferred binder 
material is a latex emulsion, commercially available from Air Products and 
Chemicals, Inc. under the trademark Airflex.RTM.. 
Example 3 
The aggregates of this example were prepared in accordance with the present 
invention and, generally, as described above. Mix 1 designates an 
aggregate comprising 15% hydrated lime, 25% Type I portland cement and 60% 
(by weight) of an oxidation product of this invention. Aggregate 3 is Mix 
1 treated with a commercial sodium silicate binder; generally known as 
water glass, and commercially available from P.Q. Industries of Valley 
Forge, Pennsylvania. It is sprayed on at a concentration of 0.2 to 3.5 per 
cent by weight. Aggregate 4 is Mix 1 treated with a commercial latex 
emulsion. The Airflex emulsion, which is a vinyl acetate based latex, is 
also sprayed on at a concentration of 0.3 to 4 per cent by weight. 
Aggregates 5-7 comprise latex-treated Mix 1 further treated with 1, 2 and 
3 coatings, respectively, of a commercially available hot mix asphaltic 
material to simulate incorporation of the subject aggregates into a 
pavement composition. (See Table 1, below.) 
TABLE 1 
__________________________________________________________________________ 
Water Extraction Results 
Aggregate (ml) 
O.P.(g) 
SO.sub.4 (g) 
SO.sub.4 (%) 
Mg(g) 
Mg(%) 
__________________________________________________________________________ 
Mix 1 279 30.20 
6.72 38.38 1.31 
33.65 
Mix 1 348 37.74 
7.45 34.92 1.39 
28.59 
Mix 1 and 
358 38.74 
7.45 33.14 1.38 
27.20 
Sodium Silicate 
Mix 1 338 36.40 
7.09 33.33 1.48 
31.48 
and Latex 
. . . 
4 and asphalt (1) 
75 18.8 3.53 32.84 
4 and asphalt (2) 
34 8.5 0.72 14.52 
4 and asphalt (3) 
37 9.3 0.87 16.07 
__________________________________________________________________________ 
Each of the above-described aggregates was tested for soluble sulfate and 
magnesium by Soxhlet extraction with a volume of water as indicated in 
Table 1, over a 24-hour period, to simulate accelerated weathering 
conditions. The oxidation product (O.P.) extracted from each aggregate is 
shown in Table 1. Given the constituent weight percents of Example 1, the 
amounts of sulfur (58%, as SO.sub.4) and magnesium (12.9%) were determined 
as described in Example 1 and calculated as a percentage of the total 
sulfur (as SO.sub.4) and magnesium levels. For instance, approximately 
one-third of the available SO.sub.4 and Mg were extracted for Aggregates 
1-4, irrespective of the presence and/or identity of a binder component. 
Treating Aggregate 4 with 1, 2 and 3 coatings of asphalt decreased 
leachability, as observed with Aggregates 5, 6 and 7, respectively. 
Example 4 
The aggregates of this example were prepared in accordance with the present 
invention, to minimize sulfate and magnesium leachability, and for the 
purpose of comparison with the aggregate of Example 3. Aggregate 1 was 
prepared using equal amounts of Type I portland cement and an oxidation 
product of this invention. Aggregate 2 is mixed to treat it with 3 per 
cent by weight of a commercial sodium silicate binder (37.5% by weight 
solids, Type N from P Q Company) SiO.sub.2 /NaO.sub.2 ratio=3.3. Aggregate 
3 mix includes 1.5 per cent of a commercial latex emulsion (Airflex RP245, 
available from Air Products and Chemicals, Inc.) and the same amount of 
silicate binder of Aggregate 2. Aggregate 4 comprises 40% (by weight) Type 
I portland cement, 40% (by weight) of an oxidation product of this 
invention, and 20% (by weight) of Class F fly ash, treated with the latex 
and silicate binders described above. All binders and latex were mixed in. 
Table 2a, below, compares the sulfate and magnesium extracted from the 
aggregates of Example 3 (Mix 1 ) with Aggregate 4 (Mix 2) of this example 
as determined after tumbling and by 24-hour Soxhlet extraction. (As 
mentioned above, the Soxhlet results are considered more representative of 
the weathering conditions under which the aggregate might be subjected, 
while the tumbling results would represent a worst-case scenario 
characterized by excessive abrasion and agitation. 
TABLE 2a 
______________________________________ 
Dependence on Cement Content of Asphalt Aggregate 
Percent Reduction in Leachability of Mg and SO.sub.4 
Mix 2 
Aggre- 
Mix 1 % Mg % Mg % SO.sub.4 
% SO.sub.4 
gate % Mg % SO.sub.4 
Soxhlet 
Tumbled 
Soxhlet 
Tumbled 
______________________________________ 
1 33.65 38.38 0.7 0.7 1.76 3.26 
2 28.59 34.02 0.47 2.4 2.24 2.93 
3 27.22 33.14 0.16 1.86 1.41 3.12 
4 31.48 33.58 &lt;0.08 &lt;0.08 1.81 1.71 
______________________________________ 
TABLE 2b 
______________________________________ 
% Reduction over Mix 1 using Mix 2 
% Mg % Mg % SO.sub.3 
% SO.sub.3 
Aggregate Soxhlet Tumbled Soxhlet 
Tumbled 
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1 97.92 97.92 95.41 91.51 
2 98.36 76.97 93.42 91.39 
3 99.41 76.52 95.75 90.59 
4 100 100 94.61 94.91 
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As can be observed from the results summarized in Tables 2a and 2b, 
increasing the cement concentration reduces both sulfate and magnesium 
leachability, irrespective of whether such aggregates are treated with 
binder. The incorporation of a Class F fly ash (Aggregate 4) further 
reduces sulfate and magnesium leachability, as compared to the Mix 1 
aggregates of Example 3. 
Consistent with the results of Example 3, Aggregate 4 of this example was 
treated with successive coatings of a commercially available hot mix 
asphalt material. A single coating of asphalt reduced the sulfate leached 
to 0.05 % of the sulfate present, and reduced the magnesium leached to 
0.01% of the magnesium present. 
Example 5 
Similar composite materials in accordance with this invention are prepared 
in the manner described in the preceding Examples but employing a Class C 
fly ash in some specimens and a Class N pozzolan in other specimens in the 
formation of the cementitious material. The additive material used is 
Na.sub.2 SiF.sub.6 along with a phenolic resin, such as phenol 
formaldehyde. The results obtained with these composites are similar to 
those shown in the previous Examples. 
Similar results are obtained when employing potassium silicate as the 
additive material in concentrations from about 1 to about 4 per cent of 
the aggregate composite. 
While the principles of this invention have been described in connection 
with specific embodiments, it should be understood clearly that these 
descriptions, along with the chosen tables and data therein, are made only 
by way of example and are not intended to limit the scope of this 
invention, in any manner. Other advantages and features of the invention 
will become apparent from the following claims, with the scope thereof 
determined by the reasonable equivalents, as understood by those skilled 
in the art.