Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
The present invention relates to a compound binder, to a
process for obtaining it and to its application in highway
surfacings.
In the present invention a compound binder means a homo-
geneous product consisting of at least one mineral substance whose
hardening is a result of a hydration reaction in the presence of
at least one specific adjuvant and of an aqueous emulsion of at
least one hydrocarbon substance.
For some applications the compound binder of the invention
is filled with mineral, metallic or organic matters.
PRIOR ART
It has been known for a very long time that hydraulic
setting binders: cement, mixed lime which are used in combination
with soil earthworks make it possible to improve their boyancy and
to increase the strength of the fills. For several decades now,
the systematic study of the properties of these binders has made
it possible to specify the conditions which are required to permit
their use in the production of modern highway structures.
The courses which are thus bonded form a material endowed
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with Zl high rigidity, independent of temperature and ensuring a
good load distribution: the rigidity modulus is at least
15,000 MPa. On the other hand, they exhibit appreciable dis-
advantages. The material is brittle, because of its high rigidity,
S resulting in cracks during small movements of the soil, for
example; a low relative deformation is observed: from 20 to
60 x 10-6. The upper part of the course has a lower strength, and
this requires a thick surfacing course if the traffic is average
or heavy. Setting or thermal shrinkage fissures are always observed
in these courses. Finally, progressive development of structures
with these materials i8 impossible, which prevents the subsequent
adaptation of the course to the traffic.
Concurrently with hydraulic sand-gravel mixes, there have
been developed over a number of decades techniques based on bitumen
emulsions whosé most highly developed forms are referred to by the
name "emulsion-sand-gravel mix". Materials treated with hydrocarbon
binders have advantages under a number of headings. They are
capable of deforming under slow stress: relative deformation: 90
to 150 x 10-6 at 10C. In addition, these materials have a good
surface strength, which permits thin surface courses. Lastly, they
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offer the possibility of progressive development of structures in
which they are involved. On the other hand, they have the dis-
advantage of exhibiting a low rigidity: the rigidity modulus at
15C lies between 1000 and 5000 MPa and more commonly between 2000
and 3500 MPa.
A person skilled in the art has therefore been obliged to
make a choice between two cold techniques, both offering advan-
tages, but also presenting specific disadvantages. In the past it
has indeed been envisaged to resort to binders of two kinds, on the
one hand hydraulic and on the other hand hydrocarbon, but each of
these binders was introduced separately into the mineral framework.
Such an application technology was not without risk~ insofar as the
mutual compatibility of these binders was concerned, it being even
possible for their action to be perturbed in some cases.
As far as is known hitherto there i5 no known liquid
compound binder containing phases which are completely homogeneous
between the aqueous emulsion of hydrocarbon binder and the
hydraulic binder.
FR-A-75 45,074 describes a self-curable mass for immediate
application, consisting of an emulsion of bitumen in water and of
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a mixture of cement and of a fluid mineral oil.
FR-A-86 16,023 describes a compound binder consisting of a
hydrocarbon product as a dispersed phase and of cement dispersed
in water. This product is not wholly satisfactory because it is not
homogeneous enough.
There is therefore a need for a homogeneous compound binder
capable of being stored and employed subsequently.
The compound binder according to the present invention
permits uniform proportioning. It is easy to apply because of its
high homogeneity. Its liquid form ensures very easy utilization.
A person ~killed in the art knows that it is difficult to
mix well products which are quite different in their nature.
SUMMARY OF T~E INVENTION
The present invent1on meets the needs referred to above by
permitting the manufacture of a homogeneous compound binder with
which treated materials which offer many advantages are obtained.
The rigidity contributed by the hydraulic binder ensures good
distribution of the fillers: the rigidity modulus varies with
temperature. The ability to deform under repeated loading is
greater than that of a material treated with hydraulic binders.
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There is no, or very little, cracking due to setting or to thermal
shrinkage. Insofar as the proportioning of the binder in the
materials to be treated is concerned, the advantages are of two
orders: qualitatively a better distribution of the hydraulic
fraction of the binder is obtained, the latter being in the form
of an aqueous dispersion, than in the case of introduction in the
form of dry powder; quantitatively, measuring a liquid is easier
and more reliable than continuous proportioning of a powder by
weight.
10The emulsion of the invention must be suitably formulated
to be compatible with the hydraulic binder. In particular, the
hydraulic binder must not flocculate and must not set quickly.
It is also appropriate to choose a suitable surfactant and
a suitable ratio of the constituents.
DESCRIPTION OF PREFERRED EMBODIMENT
The subject of the present invention is a compound binder
comprising an aqueous emulsion of at least
; one hydrocarbon binder and, at least one
hydraulic binder. Said compound binder also contains at least one
adjuvant intended to control the rate of setting of the hydraulic
binder in order to obtain a liquid product with a viscosity of less
than 1 Pa s.
Another object of the present invention is a process for
obtaining the compound binder, which consists in:
a) introducing at least one surfactant into water
at a temperature of between approximately 10C and approximately
80C;
b) heating at least one hydrocarbon binder to a temperature
of between approximately 100 and 200C in a separate container;
c) mixing the surfactant into the hydrocarbon
binder so as to obtain an aqueous emulsion;
d) conveying the aqueous emulsion to a homogenizer while
introducing a hydraulic binder separately into this homogenizer;
e) introducing an ad~uvant at any stage to control the rate
of setting of the hydraulic binder;.
f) optionally adding one or more fillers before or after
the mixing in the homogenizer;
g) storing the final product for its subsequent
utilization.
A further object of the present invention is the
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application of the compound binder in highway surfacings.
Another object of the present invention is the following
features :
- the adjuvant is chosen from setting-retarders, cure
accelerators, thinners, plasticizers, inhibitors, thixotropic
agents and organic polymers;
- the adjuvant is gluconate;
- the compound binder additionally comprises at least one
mineral filler;
- the compound binder additionally comprises at least one
organic filler;
- the compound binder additionally comprises at least one
metal filler;
- the mineral filler consists of siliceous flours, limestone
flours, natural fibers, manufactured fibers or any one mixture
thereof;
- the organic filler consists of vegetable fibers, synthetic
fibers, polyamide, polyvinyl chloride, polyesters, polyethylene,
polypropylene or any one mixture thereof,
- the metal filler consists of aluminum powder, iron
filing , copper alloys or any one mixture thereof.
- the compound binder comprises, per 100 parts of hydraulic
binder, from approximately 30 to 300 parts of aqueous emulsion of
hydrocarbon binder, from approximately 0.2 to 1 part of adjuvant,
from 0 to 1 part of mineral filler and from 0 to 15 parts of metal
filler;
- the adjuvant is added directly to the aqueous emulsion
of hydrocarbon binder;
- the adjuvant is added after the mixing of the aqueous
emul~ion of hydrocarbon binder and of hydraulic binder in the
homogenizer;
- the hydrocarbon binder is chosen from pure bitumens,
; regenerated bitumens, paraffinic, naphthenic or aromatic petroleum
solvents, petroleum compounds resulting from steam-cracking
distillates, pure tars, coal fluxing oils, heavy oils and soft and
special pitches;
- the hydraulic binder consists of cement or of slag cement
containing lime, to which water is added if necessary.
In the hydraulic binder of the invention the ratio added
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water:cement is within the range of 0 to 50 parts of water per 100
parts of cement.
It is quite obvious that a sufficient quantity of water is
added if necessary to have a liquid product.
It is appropriate to make it clear that when the aqueous
emulsion is being obtained in the homogenizer the ratio hydrocarbon
binder:aqueous phase is from 30:70 to 75:25.
The ratio of hydrocarbon binder to the aqueous phase is
generally 60:40.
The temperature of the emulsion may vary in the range from
5 to 70C and that of the cement in the range from 5 to 50C.
Obviously everything depends on the climatic conditions of
application.
The compound binder of the invention does not cure before
an extended period of time, and this permits its storage and its
subsequent utilization.
The compound binder of the invention comprises, as a mixture
before it is employed:
[1] One or more hydrocarbon substances in the form of
aqueous emulsion. These hydrocarbons may originate from the
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distillation of crude oil and/or may be produced from derivatives
of the coal industry.
If hydrocarbons from a petroleum source are involved, the
following will be employed:
- pure bitumens such as those specified in French Standard
T 65-001;
- bitumens which are not specified in French Standards and
are produced by oil refineries to meet particular criteria and
uses: this is the case, for example, of some so-called
''regeneratedll bitumens obtained by mixing a base from deasphalting
using propane, which is softened with a solvent-extracted distil-
lation cut. The main features of these mixtures are that they are
poor in asphaltenes and rich in aromatic compounds;
- paraffinic, naphthenic or aromatic petroleum solvents;
- petroleum compounds resulting from steam-cracking
distillates, from the bottom of a column for distilling condensates
recovered from natural gas or from other petrochemical treatment
processes.
In the case of hydrocarbons of coal origin there may be
mentioned :
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- pure tars such as thos~ specified in French Standard
T 65-021;
- coal fluxing oils produced from mixtures of primary
distillation oils and of fractions corresponding to cuts of
specific characteristics; heavy oils called 'creosotes" can be
included in this series of products;
- soft and special pitches resulting from mixing pure tars
and coal plasticizing oils ;
[2] One or more categories of hydraulic binders; these may
be cements such as those defined by French Standard NF P 15-301,
and/or other hydraulic binders, for example slag cements containing
lime (French Standard NF P 15-305) and natural cements (French
Standard NF P 15-308);
~3] At least one adjuvant intended to contribute specific
characteristics or properties.
When it is appropriate to modify the hydrocarbon sub-
stance(s), it is possible to employ organic polymers which are
introduced either in the base hydrocarbon before it is emulsified,
or in the aqueous phase of the said emulsion, or, again, in the
finished emulsion before it is mixed with the hydraulic binder(s).
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When modification of the behavior of the hydraulic setting
fraction is involved, use will be made of setting-retarders, cure
accelerators, thinners, plasticizers, inhibitors and other similar
agents.
When it is appropriate to modify the characteristics of the
compound binder, one or more agents will be employed which are
intended to affect the rheological behavior of the combined
components. For example, thixotropic agents will be involved in
this specific example.
[4] Mineral fillers (siliceous and/or limestone flours,
natural or manufactured fibers such as rock fibers or glass fibers)
or organic fibers of the vegetable fiber kind, synthetic fibers
such as polyamides, polyvinyl chloride, polyesters, polyethylene
or polypropylene and the like.
[5] Metal fillers, examples of which are aluminum powder,
iron filing or copper alloys and the like.
In the compound binder of the invention the hydrocarbon
emulsion is a direct emulsion (of the lipophilic/hydrophilic type)
or optionally a multiple emulsion of the hydrophilic/lipophilic/-
hydrophilic type. The use of microemulsions can also be envisaged.
Bearing in mind the nature of the surfactants employed
for conferring the stability which is required of hydrocarbon
substances dispersed in the aqueous phase, the emulsion may be
anionic or cationic. However, the choice of the surface agents
resorted to is not limited solely to these two categories alone;
in fact, it is also possible to employ ampholytic or nonionic
surfactants. Among the large number of surface-active substances
capable of beinq employed there will be mentioned, by way of
example, quaternary ammonium salts in the case of cationic surface-
active agents, potassium salts of proteins of animal or vegetableorigin in the case of the ampholytic surfactant~ and, lastly,
polyethoxylated alkylphenols in the case of the nonionic
surfactants.
It is quite obvious that the various above products are
given by way of examples, no limitation being implied.
The invention is illustrated by the non limiting examples
below, where the quantities which are given in parts are to be
understood per 1000 parts of total compound binder.
EXAMPLE 1
219.2 parts of naphthenic bitumen with a penetrability of
.
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between 60 and 100 tenths of a mm (measured according to French
Standard NF T 66-004) are heated to approximately 140C. 165.4
parts of a surfactant solution are prepared separately, made up
of 4.6 parts of casein which is reacted with 0.8 parts of potas-
sium hydroxide in 159.4 parts of water heated to 40C. 0.6 partsof 30% formaldehyde are added to this aqueous pnase.
The two phases are then dispersed in
a homogenizer of the colloid mill type. 384.6 parts of an emulsion
containing 57% of bitumen are obtained.
When this emulsion is cooled 175.9 parts of cold water and
438.5 parts of cement are added to it with fast stirring. The
liquid compound binder is ready for use.
EXAMPLE 2
To 135.8 parts of a hard base from deasphalting using
lS propane, with a penetrability not exceeding 30 tenths of a mm
(measured according to French Standard NF T 66-004), heated to
approximately 180C, are added 81.6 parts of a solvent-extracted
aromatic oil with a kinematic viscosity at 50C of between 300 and
500 mm2/s (measured according to French Standard NF T 60-100),
heated to approximately 80C. These two starting materials are then
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mixed and the homogeneous mixture is maintained at approximately
130C. 144.9 parts of a solution of a surface-active agent are
prepared separately, made up of 5.6 parts of polyethoxylated
nonylphenol, of 1.4 parts of plasticizer for concrete and of 137.9
parts of water heated to 40C.
The two phases are then dispersed in
a homogenizer of the colloid mill type. 362.3 parts of an emulsion
containing 60~ of dispersed hydrocarbon phase are obtained.
When this emulsion is cooled 202.9 parts of cold water and
434.8 parts of cement are added to it with fast stirring. The
liquid compound binder i8 ready for use.
EXAMPLE 3
241.3 parts of paraffinic bitumen with a penetrability of
between 50 and 70 tenths of a millimetre (measured according to
French Standard NF T 66-004) are heated to approximately 150C.
333.4 parts of a solution of surface-active agent are prepared
separately, made up of 9.4 parts of stearylpentamethyldiammonium
chloride in solution at a concentration of 50~ in a hydro-
isopropanolic medium, of 0.6 parts of calcium chloride hexahydrate
and of 323.4 parts of water heated to 40C.
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The aqueous phase and the bitumen, to which 10.1 parts of
lamp oil of characteristics defined in French Standard NF M 15-003
are added extemporaneously before it is introduced into the colloid
mill, are then dispersed by being passed through a homogenizer of
the colloid mill type. The homogenous extemporaneous mixture of the
bitumen and of the lamp oil is obtained by passing through a static
dispersing device. 584.8 parts of an emulsion are thus obtained,
containing 43~ of dispersed phase consisting of a thinned bitumen
containing 4~ of lamp oil.
When this emulsion is cooled, 415.2 parts of cement are
added to it with rapid stirring. The liquid compound binder is
ready for use.
At present, the most sati~factory adjuvant in making use
of the present invention has been a yellowish liquid with a
relative density of 1.17 at 25C and of neutral pH, known under
the trade name of Plastiretard, supplied by the company Sika S.A.
This product, which is in accordance with French Standards NF P
18-337 and NF P 18-336, is a gluconate.
It is important to note that while the adjuvant can be mixed
directly with the emulsion of hydrocarbon binder before it is mixed
,
.
.
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with the hydraulic binder or consequently after the mixing between
the emulsion of hydrocarbon binder and the hydraulic binder, on the
other hand the various possible fillers must be introduced after
the mixing of the emulsion of the hydrocarbon binder and of the
hydraulic binder which has received at least the adjuvant intended
to control the rate of setting of the hydraulic binder.
The invention is not limited to the embodiments shown and
described in detail, and various modifications can be introduced
therein without departing from its scope.
