Specification
Aqueous suspensions comprising aluminous cement and binding compositions
Field of the invention
The present invention relates to aqueous suspensions comprising aluminous
cement and/or calcium sulfoalumtnous cement and to binding compositions
comprising said aqueous suspension in combination with organic binders, which are
stable at room temperature and at hrgh temperature, as well as the methods for
preparing the same.
Description of the background art
Aqueous suspensions comprising hydraulic binders that are commonly called
''slurry" come in the form of more or less fluid suspensions. The advantage of such
suspensions is that they form ready to use solutions to be directly employed in any
application for construction chemistry such as adhesive formulation, soil preparation,
floor covering, tile flooring, wall preparation, exterior rendering, concrete repairs,
ready-mixed concretes, shotcretes, sewerage systems, waterproofing, road repair
works, binding, anchorage devices, paints and coatings and prefab rication and
refractory and peri-refractory applications.
Stabilization consists in stopping hydration of the hydraulic binder by adding a
blocking agent (or inhibitor). Amongst known blocking agents, boric acid and salts
thereof reveal particularly efficient for stabilizing hydraulic binder-based aqueous
suspensions comprising aluminous cement
The patents EP 0241 230, EP 0 113 593, the patent application EP 0081365
and the French certificate of utility FR 2763937 disclose, for example, compositions
comprising an aluminous cement in aqueous phase which has been retarded for
several months through addition of boric acid, or a salt thereof, being suspended in
water.
However, using such a blocking agent has some drawbacks. The aluminous
cement aqueous suspensions are not stable for sufficient periods of time at high
temperature. This phenomenon is even more marked when these aqueous
suspensions are associated with resins or organic binders. This phenomenon gets
worse when the aqueous suspension is used in high proportions as compared to the
aqueous suspension -organic binder mixture.
Another drawback of boric acid is that it is quite toxic and ecotoxic as well.
US 2004/211562 and US 2004/211564 discfose cement composition
comprising by weight/weighty hydrate «mem- 20 to 80% of calcium aluminate; 20 to
80% of a silica source (fly ash); 1 to 10% of a soluble phosphate like sodium
polyphosphate, sodium hexamethaphosphate, sodium phosphate or a mixture
thereof; 0,1 to 5% of a set retarder (carboxyltc acid like citric acid; tartaric acid); and
30 to 50% of water to obtain pumpable slurry. The function of the soluble phosphate
is to improve the corrosion resistance of the cement composition. The examples in
US 2004/211562 show that the set retarders tested retard the hydration of the
cement compositions up to a maximum of 16 hours.
Thus, the use of a carboxylic acid as blocking agent does not provide aqueous
suspensions of aluminous cement which are stable for a sufficient period of time,
such as for example, one month,
JP 2007/254196 discloses a hydraulic composition comprising: aluminous
cement, Portland cement, gypsum (the total of the three components is 100 parts by
weight), water and optionally, a set modifier. The set modifier is sodium
pyrophosphate (Na^O?) and/or sodium tartrate.
KR 100 913 496 discloses a dry concrete composition for paving to improve
drainage and water retention. The composition comprises a binder and aggregates
having a mean diameter between 2.5 and 5 mm. In particular, the binder is a dry
composition based on a calcium sulfoalum in ate clinker, gypsum, an intensity
accelerator selected for example from alkaline metal carbonates or bicarbonates and
a retarder.
US 2008/302276 discloses a cement composition \n the form of a rapid set
aqueous composition comprising: active hydraulic cement (Portland cement, calcium
aluminate, calcium sulfate and fly ashes), set accelerators, water and optionally, set
retarders selected from citric acid, sodium citrate, sodium tartrate or potassium
tartrate. The set accelerators are selected from a mixture of an alkanolamine and a
phosphate or polyphosphate (sodium trimetaphosphate, sodium or potassium
tripolyphosphate, tetra potassium or tatrasodium pyrophosphate) that act in synergy.
The rapid set of the aqueous composition occurs by mixing the different components
at a temperature above 32.2X.
Therefore, it is necessary to find new blocking agents for aqueous
suspensions comprising aluminous cement and/or calcium sulfoaluminous cement
which would not suffer from the hereinabove mentioned drawbacks.
Summary of the invention
It is therefore an object of the present invention to provide aluminous cement
and/or calcium suffoaluminous cement based aqueous suspensions with the
following properties:
- they have a high lifetime, that is to say the aqueous suspensions should not set
when they are stored at a temperature ranging from about 15°C (room
temperature) to 55°C (high temperatures), for a period ranging from a couple of
weeks to several months, preferably for at least one month, more preferably two
months or more and most preferably for at least 6 months, so as to be protected
against any storage or delivery delay, and
- they remain fluid and do not segregate, especially during transport, so that the
implementation on site can be guarantied,
- they may be associated in high amounts with organic resins without setting,
- they are poorly toxic and ecotoxic.
As used herein, «lifetime » is intended to mean the time during which a
component remains in the form of an aqueous suspension of stable solid products,
but is able to come back to an aqueous suspension state through a simple
mechanical stirring, without setting.
As used herein, « stable » is intended to mean that the aqueous suspension
viscosity does not change much during storage and that the system does not set
One amongst the indicators used to monitor the stability of the mixture is the pH
value of the suspension. This one should remain relatively constant during the
storage period. Any increase in the pH value may be interpreted as a beginning of
« destabilization » of the suspension.
Thus, the. object of the invention consists in a stabilized aqueous suspension
comprising:
- at least one hydraulic binder comprising an aluminous cement and/or calcium
sulfoaluminous cement and
- at least one blocking agent comprising a phosphorus-containing compound
selected from metaphosphoric acid, phosphorous acid, phosphoric acid,
phosphonic acid and any compound which may form any of these compounds by
reacting with water,
said suspension comprising from 0.1% to 20%, preferably from 0.1 to 15%,
preferably from 0.1 to 10% and more preferably from 0.3 to 10% by weight of
phosphorus-containing compound relative to the total weight of aluminous cement
and/or calcium sulfoaluminous cement.
The applicant discovered surprisingly that the above mentioned phosphoruscontaining
compounds could very efficiently replace boric acid for stabilizing aqueous
suspensions comprising aluminous cements and/or calcium sulfoaluminous cements.
These compounds enable especially:
- to obtain a good level of stabilization at room temperature,
- to significantly improve stabilization of aqueous suspensions at high temperature,
- to associate in any proportions such stabilized aqueous suspensions with organic
binders, for example of the latex type.
The abject of the invention also consists in a method for making an aqueous
suspension such as described above, comprising successively the following steps:
- introducing water into a mixing tank,
- stirring,
- adding the phosphorus-containing compound,
- optionally adding the one or more dispersing agent(s),
- adding the one or more hydraulic binder(s),
- maintaining the stirring and,
- optionally adding the other components,
- stirring for at least 5 minutes.
The invention also relates to a method for retarding the setting of an aqueous
suspension comprising a hydraulic binder, said hydraulic binder comprising at least
one aluminous cement, characterized in that it consists in adding to said aqueous
suspension at least one blocking agent comprising a phosphorus-containing
compound selected from metaphosphoric acid, phosphorous acid, phosphoric acid,
phosphonic acids and any compound which may form any of these compounds by
reacting with water, said phosphorus-containing compound representing from 0.1 to
20% by weight relative to the total weight of the aluminous cement.
The present invention further relates to a binding composition comprising:
(i) an aqueous suspension such as described above and
(ii) at least one organic binder.
Detailed description of the invention
According to the invention, aluminous cements are combinations of aluminum
oxide AlzGs, noted A in the cement nomenclature, with catcium oxide CaO, noted C
in the cement nomenclature, which are combined with one or more crystalline and/or
amorphous phases, in such amounts that the weight addition of phases C+A is at
least 20% to 100% of aluminous cement total weight.
According to the invention, it is considered that aluminous cement has a high
alumina content when its alumina content is higher than 60% by weight relative to the
aluminous cement total weight.
According to the invention, it rs considered that aluminous cement has an
intermediate alumina content when its alumina content ranges from 45% to 60% by
weight relative to the aluminous cement total weight.
According to the invention, it is considered that aluminous cement has a low
alumina content when its alumina content is lower than 45% by weight relative to the
aluminous cement total weight.
According to the invention, calcium sulfoaluminous compounds or cements
correspond to compounds comprising calcium oxide (CaO, noted C in the cement
nomenclature), aluminum oxide (Al203, noted A in the cement nomenclature) and
sulfur oxide {noted S in the cement nomenclature) combined with one or more
5 crystalline and/or amorphous phases, in such amounts that the weight addition of
phases C+A+S is at least 10% to 100% of the calcium sulfoalurninous compound
total weight.
The invention therefore relates to a stabilized aqueous suspension comprising:
- at least one hydraulic binder comprising aluminous cement and/or calcium
10 sulfoa luminous cement and
- at least one blocking agent based on a phosphorus-containing compound selected
from metaphosphoric acid, phosphorous acid, phosphoric acid, phosphonic acid
and any compound which may form any of these compounds by reacting with
water,
15 said suspension comprising from 0.1% to 20 %, preferably from 0.1 to 15 %,
preferably from 0.1 to 10 %, and more preferably from 0.3 to 10% by weight of the
phosphorus-containing compound relative to the aluminous cement and/or calcium
sulfoaluminous cement total weight.
Preferably, the amounts of aluminous cement andfar of sulfoaluminous
20 cement by weight relative to the hydraufic binder total weight are higher than any of
the following values: 50%. 60%, 70%, 80%, 90%, 95%, 99% or are 100%.
According to alternative embodiments of the invention, the aqueous
suspension may comprise:
- at feast one phosphonic acid and at least one compound selected from
25 metaphosphoric acid, phosphorous acid, phosphoric acid and any compound
which may form any of these compounds by reacting with water,
- in addition, a further blocking agent, where said further blocking agent may be
selected from mineral acids such as boric acid and salts thereof and from
carboxylic acids, the carboxylic acids being preferably selected from citric acid,
30 tartaric acid, aminoacids (such as aspartic acid and glutamic acid), mandelic acid,
humic acid, fulvjc acid, quinic acid,
- a combination:
- of at least one phosphonic acid,
- of at least one compound selected from metaphosphoric acid, phosphorous
35 acid, phosphoric acid and any compound which may form any of these
compounds by reacting with water and
- of at least one carboxyEic acid.
When the aqueous suspension further comprises a blocking agent different
from a phosphorus-containing compound such as carboxylic acid, this or these
blocking agent(s) represent(s):
- from 0.3 to 5%, preferably from 0.3 to 2.5% by weight of the aqueous suspension
5 total weight or
- from 0.3 fo 9%, preferably from 0.5 to 5% by weight of the hydraulic binder total
weight.
It wifl be easily understood that when the suspension further comprises a
blocking agent different from a phosphorus-containing compound, the amounts of the
10 phosphorus-containing compounds maybe minimum because of the presence of this
additional blocking agent.
Therefore, in an advantageous embodiment of the invention, the stabilized
aqueous suspension may comprise:
- from 0.1 to 20%, preferably from 0.1 to 15%, preferably from 0.1 to 10%, and more
15 preferably from 0.3 to 10% by weight of phosphorus-containing compound relative
to the aluminous cement and/or calcium sulfoatum incus cement total weight,
- from 0.3 to 9%, preferably from 0.5 to 5% by weight of a blocking agent different
from a phosphorus-containing compound relative to hydraulic binder total weight.
II is particularly interesting to note that the phosphorus-containing compounds
20 used as blocking agents according to the invention enable to stabilize all types of
aluminous cements but that they are particularly efficient when the aluminous cement
used is an alumina high-content cement. Indeed, the applicant discovered that the
minimum optimal amounts of phosphorus-containing compounds to obtain a good
stabilization are inversely proportional to the alumina content in the hydraulic binder
25 or in aluminous and/or calcium sulfoaluminous cement. Moreover, with alumina highcontent
aluminous cements, a stabilization can be obtained that may last for over
6 months even if the aqueous suspensions are stored at 50°C.
Depending on the aluminous cement type in the hydraulic binder, the aqueous
suspension of the invention is preferably defined as follows;
30 - when the aluminous cement is an alumina high-content aluminous cement with an
alumina content of more than 60% by weight relative to the aluminous cement total
weight, the suspension comprises from 0.5 to 20%, preferably from 0.5 to 15%,
preferably from 0.5 to 10%, preferably from 0.5 to 5% and more preferably from 0.5
to 2% by weight of phosphorus-containing compound relative to the total weight of
35 alumina high-content aluminous cement,
- when the aluminous cement is an alumina intermediate-content aluminous cement
with an alumina content ranging from 45 to 60% by weight relative to the aluminous
cement total weight, the suspension comprises from 2 to 20%, preferably from 2 to
15%, preferably from 2 to 10%, preferably from 3 to 7% and more preferably from 3
to 5% of phosphorus-containing compound relative to the total weight of alumina
intermediate-content aluminous cement,
- when the aluminous cement is an afumina low-content aluminous cement with an
5 alumina content of less than 45% by weight relative to the aluminous cement total
weight, the suspension comprises from 5 to 20 %, preferably from 5 to 15%,
preferably from 5 to 10%, preferably from 6 to 9% and more preferably from 8 to 9 %
by weight of phosphorus-containing compound relative to the total weight of alumina
low-content aluminous cement,
10 Preferably, the suspension comprises, by weight relative to the total weight of
said aqueous suspension:
- from 20 to 80%, preferably from 50 to 70% and more preferably from 55 to 65% of
aluminous cement, and/or
- from 20 to 60%, preferably from 30 to 50% and more preferably from 35 to 45% of
15 water, and/or
- from 0 to 5% of additional additives.
According to the invention, the phosphorus-containing compound acting as a
blocking agent may be selected from:
- metaphosphoric acid of raw formula HP03 (CAS registry number: 37267-86-0),
20 - phosphorous acid, also called orthophosphoric add, chemical compound of
formula HjP03 (CAS registry number: 10294-56-1),
- phosphoric acid of formula H3PO4 (CAS registry number; 7664-38-2),
- phosphonic acids of formula HP(-0)(OH)z and P-hydrocarbyl derivatives thereof
(definition from «Compendium de terminologie chimique, Recommandations
25 IUPAC&, Jean-Claude Richer),
- any compound which may form any of these compounds by reacting with water.
"Compounds which may form any of these compounds by reacting with water"
can especially correspond to compounds able to directly form in contact with water
metaphosphoric acid, phosphorous acid, phosphoric acid, phosphonic acid and
30 hydronium ions (H30+), the phosphorous acid being capable of converting into
metaphosphoric acid in contact with water.
To be mentioned are the following compounds that may hydrolyze to
phosphoric acid:
- phosphorus pentoxide or phosphoric anhydride of raw formula P4O10 (CAS registry
35 number: 1314-56-3),
- pyrophosphoric acid, also called diphosphoric add, a chemical compound of
formula H4P207l (CAS registry number: 2466-09-3),
- tripolyphosphoric acid of raw formula HU^O^o, which may hydrolyze to phosphoric
acid (CAS registry number: 10380-08-2).
To be mentioned are especially the following compounds amongst the
hydrocarbyf derivatives to be suitably used in the invention: amino trimethylene
5 phosphonic acid (ATMP, NXAS 6419-19-8), AEPN: 2-aminoethyl phosphonic acid,
HEDP: 1-hydroxy ethylidene-1,1-diphosphonic acid, EDTMP: ethylene diamine
tetramethylene phosphonic acid, TDTMP: tetramethylene diamine tetramethylene
phosphonic acid, HDTMP: hexamethylene diamine tetramethylene phosphonic acid,
DTPMP: diethylenetriamine penta methylene phosphonic acid, PSTG;
10 phosphonobutane-tricarboxylic acid, PMIDA: N-(phosphonomethy I) iminodiacetic
acid, CEPA; 2-carboxyethyle phosphonic acid, HPAA: 2-
hydroxyphosphonocarboxylic acid.
As it wilE be demonstrated in the example part below, the phosphoruscontaining
compound, acting as a blocking agent, thus enables at relatively low
15 doses, to block the dissolution of the aluminous cement-based aqueous suspension.
The aqueous suspension is thus stabilized over extended periods of time (of more
than 1 month) and including at relatively high temperatures (for example 50°C).
The phosphorus-containing compound also enables to significantly lower the
pH value of the aqueous suspension. Advantageously, the pH value of said stabilized
20 aqueous suspension is less than 9, more advantageously less than 8 and in
particular less than 7, especially less than 6.5.
According to certain embodiments, the phosphorus-containing compound has
a pka of less than 9, especially less than 8, in particular, such compounds suitable for
the implementation of the invention may have a pka of less than 7, or less than 6.8.
25 However, as described hereinabove, blocking agents described in the
background art, such as carboxylic acids or phosphate salts, do not enable to block
the dissolution of the hydraulic binder over periods of time as long as those of the
phosphorus-containing compound according to the invention.
For example, the Applicant calculated that an aqueous suspension comprising
30 by weight/weight of the total suspension:
- 58.5% of calcium aluminates, 36.5% of water, 3.7% of sodium tripolyhposphate
and 1.3% of other additives, or
- 57% of calcium aluminates, 35.7% of water, 6.1% of sodium
h exam eta phosphate (HMPNa) and 1.2% of other additives, or
35 - 58.4% of calcium aluminates, 36.5% of water, 3,9% of trisodium phosphate and
1.2% of other additives, or
- 58.5% of calcium aluminates, 36.6% of water, 3.6% of hydrogenophosphate
and 1.3% of other additives,
enabled to block the hydraulic setting over, respectively, only less than 18 hours at
50flC and 2 days at room temperature (25DC); less than 17 hours at 50DC or at room
temperature; less than 18 hours at SOX and less than 48 hours at room temperature;
less than 24 hours at 50X and less than 4 days at room temperature.
5 Additives in the suspensions comprise for example dispersants or thickenings
known to those skilled in the art.
Also, the Applicant calculated that tartaric acid or citric acid enables to
stabilize a hydraulic cement-based aqueous suspension (calcium aluminate or
suifoalaminate) only during 18 hours at 50*0 and 6 days at room temperature (25°C).
10 The blocking agent comprising the phosphorus-containing compound
according to the invention has therefore an unexpected and surprising effect
compared to the blocking agents described in the background art.
When the aluminous cement is alumina high-content cement, it is considered
that to obtain a lifetime of at least six months, preferably about 1 to 10% by weight of
15 phosphorus-containing compound relative to the aluminous cement total weight is
required.
Preferably, the alumina high-content aluminous cement used according to the
invention has an alumina content ranging from 65% to 75% and more preferably
ranging from 68% to 72% by weight relative to the aluminous cement total weight.
20 Preferably, the chemical composition of the alumina high-content aluminous
cement, defined by weight relative to the aluminous cement total weight is the
following one:
- Al203: > 60%, preferably 60 - 75%,
- CaO: > 25%, preferably 25 - 50%,
25 - Si02: < 5%, preferably < 4% and more preferably < 2%,
- Pe^O^: < 10%, preferably < 5% and more preferably <1%.
Aluminous cements typicaify comprise a crystallized mineralogical phase
selected from CA, C12A7, C3A, CA2, C2AS, ferhtes; an amorphous phase or a
mixture of one or more of said crystallized mineralogical phases and/or an
30 amorphous phase.
According to the invention, the hydraulic binder may further comprise calcium
sulphates. Calcium sulphates may be derived from a compound selected from
anhydrites, semi-hydrates of the plaster type, gypsum, or mixtures thereof.
The aqueous suspension may comprise, by weight relative to the aqueous
35 suspension total weight, from 0 to 50%, preferably from 5 to 30% of calcium
sulphate.
The combined use of aluminous cement and calcium sulphates may form an
ettringite binder. As used herein, an ettringite binder is intended to mean a binder
which components, upon hydrating under the normal conditions of use, give ettringite
as the main hydrate, which is calcium trisuffoaluminate of formula
3CaO.A!303.3CaS04.32H?0.
In an embodiment of the present invention, the aqueous suspension
5 comprises a hydraulic binder comprising by weight relative to the total weight of the
hydraulic binder-forming components:
- from 0 to 50%, preferably from 1 to 35 and more preferably from 5 to 30% of
calcium sulphates,
- from 50 to 100%, preferably from 50 to 99% and more preferably 70 to 95% of
10 aluminous cement.
Aluminous or calcium sulfoaluminous cements used according to the invention
preferably have a Blaine surface area higher than or equal to 1500 cm2/g, preferably
ranging from 2000 to 6000 cm2/g and more preferably ranging from 3000 to 4500
cm2/g,
15 The aqueous suspension may also comprise additional additives. These
additives are preferably selected from dispersants, rheological agents and biocidal
agents but may ateo include superplasticizers, anti-foaming agents and thickeners.
To be mentioned as a suitable dispersant for use in the present invention are
Sokaian® CP10, marketed by the BASF company, Optima®206 or Premia®196
20 marketed by the Chryso company. The dispersant typically represents:
- from 0.1 to 3%, preferably from 0.5 to 1% by weight of the aqueous suspension
total weight or
- from 0.1 to 5%, preferably from 0,6 to 1.8% by weight of the hydraulic binder total
weight.
25 The rheological agent(s) are preferably selected from organic products such
as xanthan gum, welan gum, DIUTAN® gum, starch-derived ethers, guar-derived
ethers, polyacryiamide, carrageenan, agar agar, or mineral products such as clays
(bentonite for example) and their mixtures.
The rheological agent(s) typically represent(s):
30 - from 0.1 to 1%, preferably from 0.25 to 0.5% by weight of the aqueous suspension
total weight or
- from 0.2 to 2%, preferably from 0,25 to 3.4% by weight of the hydraulic binder total
weight.
The composition of the invention may also comprise an antibacterial agent.
35 Suitable antibacterial or biocidal agents for use in the present invention include
compounds of the isothiazolinone family, such as methyl is othtazolinone (MIT) and
benzisothlazolinone (BIT) as well as combinations thereof. To be mentioned are
esperiatly ECOCIDE® K35R, marketed by the PROGfVEN company and Nuosepl®
OB03 marketed by the ISP company. The antibacterial agent then preferably
represents;
- from 0.005 to 0,1%, preferably from 0.01 to 0r02% by weight of the aqueous
suspension total weight or
5 - from 0.01 to 0.2%, preferably from 0.02 to 0,04% by weight of the hydraulic binder
total weight.
Superplasticizers are preferably selected in the family constituted of
polyp hosphonate-polyox, polycarbo*y late-poly ox PCP and poly aery lates or
copolymers of acrylic acids and afkoxy-acrylic acids, and their mixtures.
10 Polycarboxyiate-polyox type superplasticizers are known compounds which are
especially described in the patents US 2003/0127026 and US 2004/049174.
Polyphosphonate-polyox compounds are especially described in the patents FR-A-
2810314 and FR-A-2698736, as well as FR-A-26S9895. These superplasticizers are
products which are commercially available. To be mentioned as an example are
15 OPTIMA 100® and PREMIA 150® marketed by the CHRYSO company, or
MELMENT F10® MELFLUX® marketed by the SKW company or Sokalan® CP 10
marketed by the BASF company.
Other additional additives such as antifoaming agents like Defoam® 50PE
marketed by the Peramin company, may be introduced into the aqueous suspension
20 formulation.
The solid content of the aqueous suspension is thus preferably higher than
50% and more preferably ranging from 55 to 80%.
The aqueous suspension of the invention may be associated with organic
binders so as to form binding compositions.
25 The invention therefore also relates to a binding composition comprising:
(i) an aqueous suspension such as defined hereinabove and
(fi) at least one organic binder.
Preferably, this binding composition may comprise, by weight relative to the (i)
and (ii) component total weight;
30 - from 10 to 90% of an aqueous suspension,
- from 10 to 90% of an organic binder.
Organic binders used according to the invention are preferably polymer resins
comprising poEymers and copolymers of the latex type.
Lastly, the aqueous suspension of the invention may be associated with fillers
35 to form other compositions. These compositions thus comprise:
(i) an aqueous suspension such as defined hereinabove and
(ii) at least one filler.
Fillers may be mineral or organic in nature and selected from siliceous
compounds (sand, quartz, fumed silica), carbonate compounds (calcium carbonate,
dolomite), pigments, titanium oxides, light fillers like perlite or vermiculite.
Preferably, the fillers represent from 1 to 50%, preferably from 10 to 30% by
5 weight of the composition total weight. The remainder is made of the aqueous
suspension.
To initiate the aqueous suspension or binding composition setting, a pH
modifier simply has to be added so as to increase the pH value in the medium at a
value higher than 9r preferably higher than 7 (beyond this value, the higher the pH
10 value, the more rapid is the kinetic of the unbloking reaction) and thus makes
inoperative the blocking agent of the aluminous or calcium sulfo-aluminous cement
with optionally an additional lithium source.
The possible combinations are exemplified in the patent FR 2 918 055 which
describes an initiating system based on lithium, lithium hydroxide and lithium sulfate
15 or carbonate or in the patent FR 2 763 937, which describes an initiating system
associating hydrated lime with a sodium and fluoride, sulfate or carbonate salt. Other
combinations may be envisaged. Sodium or potassium hydroxide or sodium
aluminate may be especially used as a pH modifier, in combination with an
accelerator such as a lithium salt or a sodium or potassium salt, of the sulfate,
20 carbonate, chloride or fluoride type.
The present invention further relates to a method for making an aqueous
suspension such as previously mentioned.
According to the invention, this method comprises successively the following
steps of:
25 - introducing water into a mixing tank,
- stirring preferably at a rate higher than 600 rpm, preferably higher than 800 rpm
and more preferably of 1000 rpm, preferably with a rayneri stirring comprising a
deflocculating blade,
- adding the phosphorus-containing compound and preferably mixing until
30 dissolution is complete,
- optionally adding the one or more dispersant(s),
- adding the one or more hydraulic binder(s), preferably gradually,
- maintaining stirring and preferably increasing the stirring speed over 1000 rpm,
preferably 3000 rpm,
35 - optionally adding the other components, that is to say optionally the one or more
i heological agent(s) and biocidal agent(s),
- stirring for at least 5 minules, preferably for 10 to 15 minutes.
When the aqueous suspension is associated with an organic binder to form a
binding composition, the organic binders are preferably added under stirring, either
directly at the end of the preparation of the aqueous suspension, or by simply mixing
a posteriori, preferably at a rate of 600 rpm. The method for preparing the binding
5 composition comprises, as compared to the method for preparing the aqueous
suspension, an additional step of adding organic binders under stirring, either directly
once the aqueous suspension preparation has been completed, for example when
introducing the other components, or by simply mixing a posteriori.
The invention can be used for example as a surface coating obtained from the
10 aqueous suspension defined hereinabove.
Lastly, the present invention relates to a method for retarding the setting of an
aqueous suspension comprising a hydraulic binder, the hydraulic binder comprising
at least one aluminous cement, characterized in that it consists in adding to said
aqueous suspension, at least one blocking agent comprising a phosphorus-
15 containing compound selected from meta phosphoric acid, phosphorous acid,
phosphoric acid, phosphonic acids and any compound which may form any of these
compounds by reacting with water, said phosphorus-containing compound
representing from 0.1 to 20%, preferably from 0.1 to 15%, preferably from 0.1 to
10%, and more preferably from 0,3 to 10% by weight relative to the aluminous
20 cement total weight.
According to this method, the aqueous suspension may have all the
characteristics as defined hereabove.
The method for retarding the aqueous suspension setting also enables to
retard the setting of a binding composition.
25 The invention therefore further relates to a method for retarding the setting of a
binding composition comprising:
i) an aqueous suspension comprising a hydraulic binder, the hydraulic binder
comprising at least one aluminous or calcium sulfoaluminous cement, and
it) at least one organic binder.
30 In this instance, the method consists in adding to said aqueous suspension, at
least one phosphorus-containing compound selected from metaphosphoric acid,
phosphorous acid, phosphoric acid, phosphonic acids and any compound which may
form any of these compounds by reacting with water, said phosphorus-containing
compound representing from 0.1 to 20%, preferably from 0.1 to 15%, preferably from
35 0.1 to 10%, and more preferably from 0.3 to 10% by weight relative to the aluminous
and/or calcium sulfoaluminous cement total weight.
The following examples, without being limitative, illustrate the present
invention.
Example
A. Preparation of the compositions
I. Products used
1. Introduction
Function
Solvent
Blocking agent
Dispersant
Aluminous cement
Calcium sulphate
Rheological agent
Biocidal agent
Organic binder
Nature
Water
Acid
Sodium polyacryLale
Calcium agminate
-Anhydrite
- Somihydrale
Xanthan gum
isothiazo[inones
acrylic styrene
Produci
water
Boric acid
Phosphoric acid
Sokalan® CP10
TemaS© White
Temal© RG
Tern a|® EV
Secar®51
Fondu® Fos
Rhodopofr® G
Ecocide® K35R
Nuosept® OB03
Acrona^ S 790 BASF
2, Chemical and mineralogical composition of the cements
Nlineraioqical phases"
C12A7/CA
Composition Chimlquo
Alumina (Ai203) %
Lime (CaO) %
Silica tSiQ2) %
Iron £Fe203J %
Blaine-SSB(cm2/o)
Ternaf® White
<003
HTA
68.7 - 70.5
20.5 - 30.5
0.2 - 0.6
0 . 1 - 0 .3
3800 - 4400
TernaKD RG
n
the aqueous suspension (i.e. 3.5% or 7% by calculating the percentage as a function
of the hydraulic binder weight) has an influence on the slurry stability. With a 7%
dosage by calculating the percentage as a function of the hydraufic binder weight, a
good stability of the slurry could be observed for 1.5 month (45 days). In conclusion,
it could be seen that when using phosphoric acid as a blocking agent, these slurries
may be stabilized for periods ranging from 20 days to 2 months depending on the
phosphoric acid dosage and the aluminous cement type associated therewith.
V. Us# of a phosphonic acid / phosphoric acid / citric acid combined system
In these assays, a combination of phosphonic acid, phosphoric acid and
carbolic acid, i. e. citric acid, was used. This product Deques!® 2000 corresponds
\o ATfrftP \armno \rimetVryierie pYiospYioriic acid),
1. Composition tested
Slurries Dosage (%)'
Solvent
Phosphoric acid (diluted to 65%)
Deques!® 2000
Citac £tcid
Dispsrsant
Cemeflt. SECAR®51
Biocidaf agenl
Total
2. Stability monitoring
Figures 10 to 12 illustrate for Slurries 10 to 12 respectively, kept at 5
0 015
100%
Claims
1. A stabilized aqueous suspension comprising;
- at least one hydraulic binder comprising aluminous cement and/or calcium
sulfoa luminous cement and
- at least one blocking agent comprising a phosphorus-containing compound
selected from metaphosphoric acid, phosphorous acid, phosphoric acid,
phosphonic acids and any compound which may fonn any of these compounds by
reacting with water,
said suspension comprising from 0,1% to 20% by weight of phosphorus-containing
compound relative to the aluminous cement and/or calcium sulfoa luminous cement
total weight.
2. A stabilized aqueous suspension according to claim 1, wherein compounds
which may form metaphosphoric acid, phosphorous acid, phosphoric acid or
phosphonic acids are selected from: phosphorus pentoxyde, pyrophosphoric acid,
tripoly phosphoric acid, amino trimethylene phosphonic acid, 2-aminoethyl
phosphonic acid, 1-hydroxy ethylidene-1,1-diphosphonic acid, ethylene diamine
tetra methylene phosphonic acid, tetra methylene diamine tetra methylene phosphonic
acid, hexamethylene diamine tetra methylene phosphonic acid, diethylene triamine
pentamethylene phosphonic acid, phosphonobutane tricarboxylic acid, N-
{phosphonomethyl)iminodiacetic acid, 2-carboxyethyl phosphonic acid, 2-hydroxy
phosphonocarboxylic acid.
3. A stabilized aqueous suspension according to any one of the preceding
claims, characterized in that it has a pH value iower than 9.
4. A stabilized aqueous suspension according to any one of the preceding
claims, characterized in that the aluminous cement is an alumina high-content
aluminous cement with an alumina content of more than 60% by weight relative to
the aluminous cement total weight and in that the suspension comprises from 0.5 to
20% by weight of a phosphorus-containing compound relative to the alumina highcontent
aluminous cement total weight
5. A stabilized aqueous suspension according to any one of claims 1 to 3,
characterized in that the aluminous cement is an alumina intermediate-content
aluminous cement with an alumina content ranging from 45 to 60% by weight relative
to the aluminous cement total weight and in that the suspension comprises from 2 to
20% by weight of a phosphorus-containing compound relative to the alumina
intermediate-content aluminous cement total weight.
6. A stabilized aqueous suspension according to any one of claims 1 to 3,
characterized in that the aluminous cement is an alumina low-content aluminous
cement with an alumina content of less than 45% by weight relative to the aluminous
cement total weight and in that the suspension comprises from 5 to 20% by weight of
a phosphorus-containing compound relative to the alumina low-content aluminous
cement total weight.
7. A stabilized aqueous suspension according to any one of the preceding
claims, characterized in that it further comprises another blocking agent selected
from carboxylic acids.
8. A stabilized aqueous suspension according to any one of the preceding
claims, characterized in that it comprises by weight relative to the total weight of said
aqueous suspension:
- from 20 to 80% of aluminous cement,
- from 20 to 60% of water,
- from 0 to 5% of additional additives.
9. A stabilized aqueous suspension according to claim 4, characterized in that
the aluminous cement has the following chemical composition, by weight relative to
the aluminous cement total weight;
- Al203; > 60%, preferably 60 - 75%,
- CaO; > 25%, preferably 25 - 50%,
- Si02: < 5%, preferably < 4% and more preferably < 2%,
- Fez03: < 10%, preferably of < 5% and more preferably <1%.
10. A stabilized aqueous suspension according to any preceding claims,
characterized in that the hydraulic binder further comprises calcium sulphates.
11. A stabilized aqueous suspension according to any preceding claims,
characterized in that the aqueous suspension solid content is higher than 50%,
12. A method for preparing a stabilized aqueous suspension according to any
one of claims 1 to 11 comprising the foilowing steps of;
- introducing water into a mixing tank,
- stirring,
- adding the phosphorus-containing compound,
- optionally adding the one or more dispersant(s),
- adding the one or more hydraulic binder(s),
- maintaining the stirring and,
- optionally adding the other components,
- stirring for at least 5 minutes.
13. A method for retarding the setting of a stabilized aqueous suspension
comprising a hydraulic binder, the hydrauiic binder comprising at least one aluminous
cement, characterized in that it consists in adding to said aqueous suspension, at
least one phosphorus-containing compound selected from metaphosphoi ic acid,
phosphorous acid, phosphoric acid, phosphonic acids and any compound which may
form any of these compounds by reacting with water, said phosphorus-containing
compound representing from 0.1 to 20% by weight relative to the aluminous cement
total weight.
14. A binding composition comprising:
(E) a stabilized aqueous suspension according to any one of claims 1 to 11 and
(ii) at least one organic binder.