U.S. patent application number 11/658042 was filed with the patent office on 2007-11-22 for high belite-containing sulfoaluminous clinker, method for the production and the use thereof for preparing hydraulic binders.
Invention is credited to Ellis Gartner, Guanshu Li.
Application Number | 20070266903 11/658042 |
Document ID | / |
Family ID | 34946787 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070266903 |
Kind Code |
A1 |
Gartner; Ellis ; et
al. |
November 22, 2007 |
High Belite-Containing Sulfoaluminous Clinker, Method for the
Production and the Use Thereof for Preparing Hydraulic Binders
Abstract
The present invention concerns a belite-rich sulphoaluminous
clinker, a method for producing such a clinker and its use for
preparing hydraulic binders, and comprising as a mineralogical
formulation: 5 to 25%, preferably 10 to 20%, of a calcium
aluminoferrite phase with a formulation corresponding to the
general formula C2AXF(1-X), with X comprised between 0.2 and 0.8.
15 to 35%, preferably 20 to 30%, of a calcium sulphoaluminate phase
"yee' limit" (C4A3$), 40 to 75%, preferably 45 to 65% belite (C2S),
from 0.01 to 10% of one or several minor phases selected from
calcium sulphates, alkaline sulphates, perovskite, calcium
aluminates, gehlenite, free limestone and periclase, and/or a
vitreous phase, and at least one or several secondary elements
selected from sulphur, magnesium, sodium, potassium, boron,
phosphorus, zinc, manganese, titanium, fluorine, chlorine, the
total content of these secondary elements being less than or equal
to 15%.
Inventors: |
Gartner; Ellis; (Lyon,
GB) ; Li; Guanshu; (Beijing, FR) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET
2ND FLOOR
ARLINGTON
VA
22202
US
|
Family ID: |
34946787 |
Appl. No.: |
11/658042 |
Filed: |
July 19, 2005 |
PCT Filed: |
July 19, 2005 |
PCT NO: |
PCT/FR05/50595 |
371 Date: |
January 22, 2007 |
Current U.S.
Class: |
106/693 ;
106/692 |
Current CPC
Class: |
Y02W 30/91 20150501;
C04B 7/323 20130101; C04B 2111/00215 20130101; Y02P 40/10 20151101;
Y02P 40/148 20151101; Y02P 40/145 20151101; Y02W 30/92 20150501;
Y02W 30/94 20150501; C04B 28/065 20130101; C04B 7/323 20130101;
C04B 7/24 20130101; C04B 7/3453 20130101; C04B 7/52 20130101; C04B
28/065 20130101; C04B 14/28 20130101; C04B 18/08 20130101; C04B
18/141 20130101; C04B 22/064 20130101; C04B 2103/12 20130101; C04B
2103/408 20130101; C04B 28/065 20130101; C04B 14/28 20130101; C04B
18/08 20130101; C04B 18/141 20130101; C04B 22/143 20130101; C04B
2103/12 20130101; C04B 2103/408 20130101 |
Class at
Publication: |
106/693 ;
106/692 |
International
Class: |
C04B 7/32 20060101
C04B007/32; C04B 28/06 20060101 C04B028/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2004 |
FR |
0451586 |
Claims
1. A sulphoaluminous clinker, characterised in that it contains as
phase formulation, compared with the total weight of clinker: 5 to
25%, preferably 10 to 20%, of a calcium aluminoferrite phase with a
formulation corresponding to the general formula C2AXF(1-X), with X
comprised between 0.2 and 0.8. 15 to 35%, preferably 20 to 30%, of
a calcium sulphoaluminate phase "yee' limit" (C4A3$), 40 to 75%,
preferably 45 to 65% belite (C2S), from 0.01 to 10% of one or
several minor phases selected from calcium sulphates, alkaline
sulphates, perovskite, calcium aluminates, gehlenite, free
limestone and periclase, and/or a vitreous phase, and in that it
contains one or several secondary elements selected from sulphur,
magnesium, sodium, potassium, boron, phosphorus, zinc, manganese,
titanium, fluorine, chlorine, present in the following quantities:
from 3 to 10% of sulphur expressed in sulphuric anhydride, up to 5%
of magnesium expressed in magnesium oxide, up to 5% of sodium
expressed in sodium oxide, up to 5% of potassium expressed in
potassium oxide, up to 3% of boron, expressed in boron oxide, up to
7% of phosphorus expressed in phosphoric anhydride, up to 5% of
zinc, manganese, titanium or mixtures of these, expressed in oxides
of these elements, up to 3% of fluoride, chloride, or mixtures of
these, expressed in calcium fluoride and calcium chloride, the
total content of said additives being less than or equal to
15%.
2. A sulphoaluminous clinker according to claim 1, characterised in
that it comprises one or several secondary elements in the
following quantities, by weight compared to the total weight of the
clinker: from 4 to 8% of sulphur expressed in sulphuric anhydride,
from 1 to 4% of magnesium, expressed in magnesium oxide, from 0.1
to 2% of sodium, expressed in sodium oxide, from 0.1 to 2% of
potassium, expressed in potassium oxide, up to 2% of boron,
expressed in boron oxide, up to 4% of phosphorus expressed in
phosphoric anhydride, up to 3% of zinc, manganese, titanium or
mixtures of these, expressed in oxides of these elements, up to 1%
of fluoride, chloride, or mixtures of these, expressed in calcium
fluoride and calcium chloride.
3. A sulphoaluminous clinker according to claim 1, characterised in
that it comprises the following secondary elements, in the
following quantities, by weight compared to the total weight of the
clinker: from 0.2 to 1% of sodium, expressed in sodium oxide, from
0.2 to 1% of potassium, expressed in potassium oxide, from 0.2 to
2% of boron, expressed in boron oxide a fluorine plus chlorine
content less than or equal to 1%, expressed in calcium fluoride and
chloride.
4. A sulphoaluminous clinker according to claim 1, characterised in
that it comprises at least the following main oxides present in the
relative proportions expressed in % of the total weight of the
clinker: CaO: 50 to 61% Al.sub.2O.sub.3: 9 to 22% SiO.sub.2: 15 to
25% Fe.sub.2O.sub.3: 3 to 11%
5. A sulphoaluminous clinker according to claim 1, characterised in
that the belite phase of the clinker is partially or totally
crystallised in the .alpha.' form.
6. A sulphoaluminous clinker according to claim 1, characterised in
that the belite phase of the clinker in the .alpha.' form accounts
for at least 50% by weight of the clinker.
7. A sulphoaluminous clinker according to claim 1, characterized in
that it comprises an accelerator or retarder of setting and/or
hardening.
8. A production method of a clinker according to claim 1,
characterised in that it comprises: a) the preparation of a raw mix
comprising at least one raw material or a mixture of raw materials
able by clinkerisation to provide the phases C2AXF(1-X), with X
comprised between 0.2 and 0.8, C4A3$ and C2S in the required
proportions; b) adding to and mixing into the raw mix at least one
additive supplying a secondary element selected from sulphur,
magnesium, sodium, potassium, boron, phosphorus, zinc, manganese,
titanium, fluorine, chlorine, or mixtures of these, in quantities
calculated to provide a clinker according to any one of claims 1 to
4; c) calcinating the mixture at a temperature of 1150.degree. C.
to 1350.degree. C., preferably from 1220.degree. C. to 1320.degree.
C., for at least 15 minutes in an atmosphere that is sufficiently
oxidising to avoid the calcium sulphate being reduced to sulphur
dioxide.
9. A production method for a sulphoaluminous clinker according to
claim 8, characterised in that the raw materials used in the
production are selected from among phosphate limestone, magnesium
limestone, clays, fly ash, hearth ash, fluidised bed ash, laterite,
bauxite, red mud, slag, clinker, gypsum, desulphogypsum,
phosphogypsum, desulphurisation mud, industrial slag, and mixtures
of these.
10. A production method of a clinker according to claim 8,
characterised in that the clinker obtained is then ground with or
without calcium sulphate, in the form of gypsum, or hemihydrate, or
anhydrite, until a Blaine specific surface of over 3000 cm.sup.2/g
is obtained, advantageously over 3500 cm.sup.2/g.
11. A hydraulic binder comprising a mixture of clinker according to
claim 1 and source materials of calcium sulphate and/or calcium
oxide.
12. A binder according to claim 11 characterised in that it
contains as much as 30% by weight of the total weight of the
binder, of at least one material selected from limestone,
pozzolana, fly ash and blast furnace slag.
13. A binder according to claims 11, characterised in that it
contains as much as 15% by weight of the total weight of the
binder, of a material selected from gypsum, anhydrites and
hemihydrates.
14. A binder according to claim 11, characterised in that it
contains at least one setting retarder selected from among
gluconates, saccharides, retarders of the phosphoric acid or
carboxylic acid type or mixtures of these.
15. A binder according to claim 11, characterised in that it
contains at least one dispersing agent selected from
polynaphthalene sulphonates, polymelamine sulphonates,
hydroxycarboxylic acids, (poly)acrylic acids, their derivatives and
their corresponding salts, derivatives of phosphonic acid, and
mixtures of these.
16. A binder according to claim 11, characterised in that it is
used to produce a slurry, mortar or cement.
Description
[0001] The present invention concerns a belite-rich sulphoaluminous
clinker, a method for producing such a clinker and its use for
preparing hydraulic binders.
[0002] Most modern concretes are made with hydraulic cements
generally obtained from Portland cement clinkers.
[0003] Portland cement is produced by heating a fine, intimate
mixture of limestone, clay, silica and iron ore, to a temperature
of over 1400.degree. C. in a rotary oven. The calcined mixture, the
clinker, takes the form of hard nodules which, after cooling, are
ground with calcium sulphates and other added minerals to form the
Portland cement.
[0004] The mixture of raw materials put into the oven needs to be
very rich in limestone in order to obtain a clinker for which the
main mineral phase is alite.
[0005] Alite is an impure form of calcium trisilicate,
Ca.sub.3SiO.sub.5, for which the conventional notation is C3S.
[0006] A high percentage of alite, generally over 50%, is
indispensable in the mineralogical composition of modern cements,
because this is what allows the strength properties to develop
rapidly just after setting, and allows the strength properties at
28 days and over to develop sufficiently, in order to meet the
specifications, in this area, of most cement standards.
[0007] For the remaining of the description of the invention, the
following abbreviated notations will be used, unless explicitly
stated otherwise, to designate the mineral components of the
cement.
[0008] C represents CaO,
[0009] A represents Al.sub.2O.sub.3,
[0010] F represents Fe.sub.2O.sub.3,
[0011] S represents SiO.sub.2,
[0012] $ represents SO.sub.3.
[0013] Over the last decades, the level of carbon dioxide,
CO.sub.2, in the atmosphere has increased considerably and
continues to grow increasingly rapidly. This is linked to human
activity, and scientists are unanimous in recognizing that this
increase will have important effects on climatic conditions in the
future.
[0014] Many governments today are taking steps to reverse the trend
and are studying how to reduce CO.sub.2 emissions, particularly
industrial emissions. The cement industry contributes greatly to
these emissions, being responsible for 5% of all industrial
emissions of CO.sub.2.
[0015] CO.sub.2 emissions in Portland cement clinker production can
be reduced by about 10% if the alite is almost totally eliminated.
This can be done if the quantity of limestone introduced into the
oven is reduced by 10%; the quantity of CO.sub.2 linked to the
decarbonatation of limestone during calcination is reduced, as is
the amount of fuel necessary for supplying the energy to
decarbonate the limestone.
[0016] This is accompanied by a reduced oven temperature, which has
advantages, as described by E. Gartner, Cement and Concrete
Research, "Industrially interesting approaches to low CO.sub.2
cements", 2004, article in press CEMCON-02838.
[0017] Portland cement clinkers with a low alite content are always
rich in belite, an impure form of calcium disilicate,
Ca.sub.2SiO.sub.4, for which the conventional notation is C2S. But
the belite-rich Portland cements obtained do not make it possible
to obtain sufficient mechanical strength properties in the short
term to meet standard requirements, nor to obtain the performance
required at present from modern concrete applications.
[0018] For these reasons the production of belite-rich Portland
cement clinkers are not a satisfactory solution for reducing
industrial CO.sub.2 emissions by 10% or less.
[0019] In order to develop commercially useable cements, the
production of which is associated with low industrial emissions of
CO.sub.2, it is necessary to examine other types of hydraulic
cement clinkers among these, systems based on calcium aluminates
and/or calcium sulphates.
[0020] Alumina-rich cements, such as "Fondu Cement" by LAFARGE, are
known for their property of acquiring high resistance in the short
term; but they sometimes present the well-known problem of
"conversion", which is accompanied by a drop in the mechanical
strength properties, and moreover highly specialised equipment is
needed for their production, and a high fuel consumption, in spite
of the low limestone content in the raw materials, and relatively
expensive raw materials such as bauxite.
[0021] Besides, sulphate-based cements, such as gypsum and
anhydrites, are inexpensive and generate little CO.sub.2 during
their production, but cannot be used in most concrete applications,
due to their low mechanical strength properties and their poor
resistance to water.
[0022] However, certain types of cements based on calcium
sulphoaluminates, written as CSA, are very important because they
have simultaneously the positive effects of calcium aluminates and
of calcium sulphates in terms of low industrial CO.sub.2 emission
without having to use expensive raw materials, to the extent that
the use of high quality bauxites could be minimised or be
substituted by other materials.
[0023] Over the last 30 years, the Chinese cement industry has
developed technology and set up a series of national standards
concerning sulphoaluminous cements known as the "TCS series",
described by Zang L., Su M. Z., and WONG Y. M., in the journal
"Advances in Cement Research", Volume 11, n.sup.o1, 1999.
[0024] However, these cements have not been developed with the
intention of reducing industrial emissions of CO.sub.2; they have
mainly been developed for application in which high strength had to
be obtained in the short term, as for prefabrication.
[0025] These "TCS series" sulphoaluminate cements are very rich in
the calcium sulphoaluminate C4A3$ phase, known as "Klein salt" or
"yee' limit", which makes it possible to obtain high resistance in
the short term, but in order to be formed during production, they
necessitate introducing into the oven large quantities of high
quality bauxite as a raw material. The cost of these cements is
prohibitive for them to be used in many applications. Nevertheless,
they can be produced with conventional rotary ovens.
[0026] The typical formulations of CSA aluminate cements are given
in Table 1 below. TABLE-US-00001 TABLE 1 Phases C4A3$ (%) C2S (%)
C4AF (%) CSA (low ferrite 55 to 75 15 to 30 3 to 6 content) CSA
(high ferrite 35 to 55 15 to 35 15 to 30 content) CSA:
Sulphoaluminous cement
[0027] At the same time, P. K. Mehta in the USA developed other
clinkers, the composition of which is based on the calcium
sulphoaluminate phase C4A3$ "yee' limit", and described in the
journal "World Cement Technology" of May 1980, pp 166-177, and the
journal "World Cement Technology" of July/August 1978, pp
144-160.
[0028] The clinkers described by Mehta differ from the "TCS series"
mainly by their very high free calcium sulphate content in the form
of anhydrite.
[0029] Although the clinkers described by Mehta have never been
marketed, the clinker # 5 reference quoted seems to correspond to
the requirements of low industrial emission of CO.sub.2 and have
performances that are roughly those of modern Portland cements.
[0030] This clinker contains 20% of C4A3$ "yee' limit", 20%
anhydrite C$, 45% belite C2S and 15% tetracalcium aluminoferrite
C4AF.
[0031] However, in spite of the good performances obtained in the
laboratory, this clinker and the others quoted by Mehta in his
publications, have the disadvantage linked to their high calcium
sulphate content; indeed, it is well known that calcium sulphate is
unstable at high temperatures at which it dissociates, generating a
gas, sulphur dioxide SO.sub.2, particularly in a reducing
atmosphere or when the oxygen pressure is low, as is the case in
rotary ovens. Therefore the clinkers proposed by Mehta would be
difficult to produce in conventional rotary ovens without creating
serious environmental problems related to the emission of sulphur
dioxide SO.sub.2.
[0032] The clinker # 5 quoted by Mehta in the journal "World Cement
Technology" of May 1980, pp 166-177 has the following mineralogical
composition, by weight compared with the total weight of
clinker:
[0033] C2S: 45% C4A3$: 20% C4AF: 15% C$: 20%
[0034] with C$: calcium sulphate (anhydrite).
[0035] It would nonetheless be desirable to have clinkers leading
to reduced industrial CO.sub.2 emissions during their productions,
also requiring reduced energy consumption that would make it
possible to give added value to industrial by-products which are
not usually used as raw materials that enter into their
formulation, and which at the same time would make it possible to
obtain hydraulic binders with rheological and mechanical strength
properties at least equal to those of conventional Portland
cements, particularly as to the mechanical performance when young
and the development of resistances in the medium and long term.
[0036] The aforementioned aims are met according to the invention,
by a belite-sulphoaluminous clinker which has, compared with the
total weight of the clinker, the following mineralogical
composition:
[0037] 5 to 25%, preferably 10 to 20%, of a calcium aluminoferrite
phase with a formulation corresponding to the general formula
C2AXF(1-X), with X comprised between 0.2 and 0.8.
[0038] 15 to 35%, preferably 20 to 30%, of a calcium
sulphoaluminate phase "yee' limit" (C4A3$),
[0039] 40 to 75%, preferably 45 to 65% belite (C2S),
[0040] from 0.01 to 10% of one or several minor phases selected
from calcium sulphates, alkaline sulphates, perovskite, calcium
aluminates, gehlenite, free limestone and periclase, and/or a
vitreous phase such as a blast furnace slag or a hydraulic
glass.
[0041] According to the invention, the clinker contains one or
several secondary elements selected from among sulphur, magnesium,
sodium, potassium, boron, phosphorus, zinc, manganese, titanium,
fluorine, chlorine, present in the following quantities:
[0042] from 3 to 10% of sulphur expressed in sulphuric
anhydride,
[0043] up to 5% of magnesium expressed in magnesium oxide,
[0044] up to 5% of sodium expressed in sodium oxide,
[0045] up to 5% of potassium expressed in potassium oxide,
[0046] up to 3% of boron expressed in boron oxide,
[0047] up to 7% of phosphorus expressed in phosphoric
anhydride,
[0048] up to 5% of zinc, manganese, titanium or mixtures of these,
expressed in oxides of these elements,
[0049] up to 3% of fluoride, chloride, or mixtures of these,
expressed in calcium fluoride and calcium chloride,
[0050] the total content of said additives being less than or equal
to 15%.
[0051] Preferably, the clinker according to the invention comprises
as secondary elements in the chemical formulation:
[0052] from 4 to 8% of sulphur expressed in sulphuric
anhydride,
[0053] from 1 to 4% of magnesium, expressed in magnesium oxide,
[0054] from 0.1 to 2% of sodium, expressed in sodium oxide,
[0055] from 0.1 to 2% of potassium, expressed in potassium
oxide,
[0056] up to 2% of boron, expressed in boron oxide,
[0057] up to 4% of phosphorus expressed in phosphoric
anhydride,
[0058] up to 3% of zinc, manganese, titanium or mixtures of these,
expressed in oxides of these elements,
[0059] up to 1% of fluoride, chloride, or mixtures of these,
expressed in calcium fluoride and calcium chloride,
[0060] More preferably, the clinker according to the invention
comprises as secondary elements in the chemical formulation:
[0061] from 0.2 to 1% of sodium, expressed in sodium oxide,
[0062] from 0,2 to 1% of potassium, expressed in potassium
oxide,
[0063] from 0,2 to 2% of boron, expressed in boron oxide,
[0064] a fluorine plus chlorine content less than or equal to 1%,
expressed in calcium fluoride and chloride.
[0065] Preferably in the preferred clinker above the sodium and the
potassium are both present.
[0066] The preferred element according to the invention is boron
which, introduced into the raw mix in the form of borax, encourages
the formation of the belite .alpha.' phase during
clinkerisation.
[0067] Thus, advantageously the belite phase of the clinker is
partially or totally crystallised in the .alpha.' form.
[0068] Preferably, at least 50% by weight of the belite phase of
the clinker, is in the .alpha.' form.
[0069] The clinker comprises at least the following main oxides
present in the relative proportions expressed in % of the total
weight of the clinker:
[0070] CaO: 50 to 61%
[0071] Al.sub.2O.sub.3: 9 to 22%
[0072] SiO.sub.2: 15 to 25%
[0073] Fe.sub.2O.sub.3: 3 to 11%
[0074] By comparing with the alite phase (C3S), the main component
of Portland cements, a larger amount of belite phase (C2S) in the
clinker is totally beneficial. It leads to the reduction of
industrial emissions of CO.sub.2 and of the energy consumption.
Moreover, the belite contributes to the development of the long
term strength of belite-sulphoaluminous cement.
[0075] The cement can be obtained by co-grinding the clinker with
an adequate quantity of gypsum or other forms of calcium sulphate
determined by trials or theoretical calculations. In the case where
an excess of calcium sulphate is introduced into the raw mix in
order to obtain anhydrite in the clinker, the cement can be
prepared directly by grinding the clinker without additional gypsum
added to the clinker.
[0076] These belite-sulphoaluminous cements can be used with one or
several dispersing agents selected from polynaphthalene
sulphonates, polymelamine sulphonates, hydroxycarboxylic acids,
(poly)acrylic acids, their derivatives and corresponding salts,
derivatives of phosphonic acid, and mixtures of these.
[0077] These admixtures are commercially available products. As an
example, mention can be made of the products OPTIMA 100.RTM. and
OPTIMA 175.RTM., marketed by CHRYSO.RTM..
[0078] The sulphoaluminous clinker according to the invention can
advantageously comprise an accelerator or retarder for setting
and/or hardening.
[0079] Another object of the invention is to provide a production
method of a sulphoaluminous clinker comprising:
[0080] a) the preparation of a raw mix comprising a raw material or
a mixture of raw materials able by clinkerisation to provide the
phases C2AXF(1-X), with X comprised between 0.2 and 0.8, C4A3$ and
C2S in the required proportions;
[0081] b) adding to and mixing into the raw mix at least one
additive supplying a secondary element selected from sulphur,
magnesium, sodium, potassium, boron, phosphorus, zinc, manganese,
titanium, fluorine, chlorine, or mixtures of these, in quantities
calculated so that, after clinkerisation, the quantity
corresponding to secondary elements, expressed as indicated above,
is less than or equal to 15% by weight compared with the total
weight of clinker; and
[0082] c) calcinating the mixture at a temperature of 1150.degree.
C. to 1350.degree. C., preferably from 1220.degree. C. to
1320.degree. C., for at least 15 minutes in an atmosphere that is
sufficiently oxidising to avoid the calcium sulphate being reduced
to sulphur dioxide.
[0083] Thus, the emission of CO.sub.2 is decreased by more than 25%
with respect to that resulting from the clinkerisation of a typical
Portland cement.
[0084] The raw materials used in the production of the clinker
according to the invention are selected among phosphate limestone,
magnesium limestone, clays, fly ash, hearth ash, fluidised bed ash,
laterite, bauxite, red mud, slag, clinker, gypsum, desulphogypsum,
phosphogypsum, desulphurisation mud, industrial slag, and mixtures
of these.
[0085] The additives supplying secondary elements can be raw
materials themselves to the extent that they contain the required
secondary elements in appropriate proportions or particular
compounds of these secondary elements, for example oxides such as
the oxides of sodium, potassium, magnesium, boron (particularly
borax), zinc, magnesium, titanium, halides such as calcium fluoride
and chloride and sulphates particularly calcium sulphate.
[0086] The term "additive supplying secondary elements" as used for
the present invention is understood to mean compounds that improve
the clinkerisation capacity of the mixture of raw materials, and
that stabilise a required crystalline form of the phase in order to
improve its reactivity.
[0087] The production of the binder, in particular of the clinker
according to the invention, consists in grinding the clinker with
gypsum until it is fine enough to activate its hydraulic
properties. The greater the specific surface of the clinker, the
better its reactivity from a hydraulic point of view.
[0088] Preferably, the clinker is ground until a Blaine specific
surface of over 3000 cm.sup.2/g is obtained, advantageously over
3500 cm.sup.2/g.
[0089] The binder can comprise source materials of calcium sulphate
and/or calcium oxide.
[0090] Advantageously, the binder according to the invention
comprises as much as 15% by weight of the total weight of the
binder, of a material selected from gypsum, anhydrites and
hemihydrates.
[0091] According to another advantageous embodiment, the binder
according to the invention can also comprise as much as 30% by
weight of binder based on the total weight, of at least one
material selected from limestone, pozzolana, fly ash and blast
furnace slag.
[0092] The binder according to the invention can also comprise at
least one setting retarder.
[0093] Such setting retarders can be selected from gluconates,
saccharides, retarders of the phosphoric acid or carboxylic acid
type or mixtures of these.
[0094] Preferably, the binder according to the invention comprises
at least one dispersing agent selected from polynaphthalene
sulphonates, polymelamine sulphonates, hydroxycarboxylic acids,
(poly)acrylic acids and their corresponding salts, derivatives of
phosphonic acid, and mixtures of these.
[0095] The invention also includes the production of a slurry, a
concrete or a mortar using the binder according to the
invention.
[0096] The invention is illustrated by the following examples.
[0097] In these examples, and unless otherwise indicated, all
quantities and percentages are expressed by weight.
[0098] FIG. 1 presents the evolution over time of mechanical
strength properties of different mortars prepared according to the
invention compared to that of a reference mortar.
EXAMPLE 1
Preparation of a Raw Mix of Sulphoaluminous Clinker
[0099] For the production of a sulphoaluminous clinker according to
the invention, raw materials are used that are selected from among
Orgon limestone marketed by MEAC, BS4.RTM. brand alumina-rich clay
and/or BS5.RTM. brand clay that is less rich in alumina marketed by
AGS-BMP, and crushed natural gypsum from Villiers. Small quantities
of iron oxide or iron ore, indicated in Table 3, are also used to
adjust the ferrite phase content of the clinker.
[0100] The chemical formulations of the raw materials used are
given in Table 2. TABLE-US-00002 TABLE 2 % Loss on CaO SiO.sub.2
Al.sub.2O.sub.3 Fe.sub.2O.sub.3 SO.sub.3 MgO TiO.sub.2 K.sub.2O
Na.sub.2O ignition Orgon fines 55.71 0.01 0.08 0.03 0.05 0.19 0.01
0.01 0.01 43.67 BS4 clay 0.14 41.88 40.26 0.66 0.34 0.08 0.87 0.16
0.12 16.03 BS5 clay 0.38 51.04 32.78 1.30 0.20 0.18 1.33 1.02 0.08
11.92 Gypsum 32.68 1.05 0.15 0.08 44.64 0.11 0.02 0.02 0.02
21.43
[0101] The raw materials are dried at 100.degree. C. for 4 hours
(except gypsum), then ground so that they can be passed through a
sieve with a 80 .mu.m mesh.
[0102] The crushed and ground gypsum and the BS4 clay have been
previously sieved with a 100 .mu.m sieve before incorporating them
into the mixture of raw materials.
[0103] However, all the particles with a size of over 80 .mu.m
account for less than 5% of the mixture of raw materials.
[0104] Thus the basic raw mixes are obtained by mixing together
limestone, clay, gypsum and iron oxide, for example with BS4 clay
following the proportions given in Table 3. TABLE-US-00003 TABLE 3
% by weight Orgon "BS4" Villiers limestone clay gypsum
Fe.sub.2O.sub.3 Clinker without 60.1 28.34 6.58 5.07 anhydrite
[0105] From these basic raw mixtures, different raw mixtures are
produced by adding an additive or a mixture of additives selected
from borax, zinc oxide, magnesium oxide and gypsum (SO.sub.3). The
proportions of additives are indicated in Table 4. TABLE-US-00004
TABLE 4 Additive Basic raw mix Raw mix obtained Type % by weight (%
by weight) Basic raw mix -- -- 100 Raw mix + borax Borax 4.03 95.97
Raw mix + ZnO ZnO 2.17 97.83 Raw mix + MgO MgO 2.40 97.60 Raw mix +
SO.sub.4 Gypsum 6.98 93.02
[0106] The raw mixes obtained are mixed and homogenised by
successive dilutions.
[0107] The raw mixes obtained are then conditioned in the form of
nodules using a rotary granulator until nodules are obtained with a
diameter of 5 to 10 mm.
[0108] The nodules obtained in this way are placed in a oven at
100.degree. C. for 12 hours.
EXAMPLE 2
Preparation of a Sulphoaluminous Clinker
[0109] 250 g of raw mix from Table 4 are placed in crucibles with a
diameter of 7 cm and a height of 10 cm.
[0110] The crucibles are first brought up to a precalcination
temperature comprised between 950 and 975.degree. C., with a rate
of heat increase of about 15.degree. C./min. The raw mix is
precalcined for 30 minutes.
[0111] Then the crucibles are rapidly transferred to a high
temperature oven which has previously been heated to a temperature
comprised between 950 and 975.degree. C.
[0112] The crucibles transferred in this way are brought to thermal
equilibrium to be at between 950 and 975.degree. C., then the
temperature is increased by 5.degree. C./min, until it reaches a
temperature comprised between 1150 and 1350.degree. C. during a
period of time comprised between 30 and 60 minutes.
[0113] After the baking time, the clinkers obtained in this way are
cooled in the open air until they reach ambient temperature.
[0114] The reduction of CO.sub.2 emission during clinker production
is more than 25% compared with ordinary Portland cements, as is
shown in Table 5. TABLE-US-00005 TABLE 5 Quantity of Emission of
limestone CO.sub.2 from raw % needed materials reduction (Kg/t
clinker) (Kg/t clinker) of CO.sub.2 Sulphoaluminous clinker 880 387
26% according to the invention Clinker from typical 1200 528 --
Portland cement
[0115] Moreover, the low clinkerisation temperature and the use of
large proportions of gypsum in these sulphoaluminous clinkers, also
contribute to the reduction of the emission of CO.sub.2 and the
reduction of the amount of energy needed for the clinkerisation of
over 20%.
EXAMPLE 3
Preparation of Sulphoaluminous Cement
[0116] The cements corresponding to the different clinkers are
obtained by co-grinding, using a laboratory grinder with a capacity
of 1 kg, with 8% of gypsum as a setting regulator, except for the
clinker corresponding to the raw mix +SO.sub.4 in Table 4 which
already contains the required amount of gypsum.
EXAMPLE 4
Evaluation of the Consistency, Setting Time and Mechanical Strength
Properties on Mortar
[0117] Using the different cements obtained from the clinkers in
example 2, mortars are produced having the following
composition:
[0118] 500 g of cement
[0119] 500 g of sand-lime with a granulometric size of 0/0.315
mm
[0120] 250 g of water
[0121] After successively introducing the three components into a
Kenwood mixer, the mixture is mixed for 30 seconds at low speed,
then for 30 seconds at high speed.
[0122] These two speeds correspond to those of a standardised mixer
used for trials on mortar according to standard EN 196-1.
[0123] The mortars obtained are evaluated for their consistency and
for their setting time at 20.degree. C.
[0124] The setting tests are carried out with a Vicat device,
according to standard EN 196-3.
[0125] The consistency is evaluated according to the mini-slump
method described in the publication Aitcin P. C, Jolicoeur C, and
MacGregor J. G., "Superplasticizers: How they work and why they
occasionally don't", Concrete International, vol. 16, n.sup.o15,
1994, pp 32-45.
[0126] Their mechanical strength properties are measured on
2.times.2.times.10 cm.sup.3 test specimens of prismatic mortar
prepared at 20.degree. C. using metal moulds and unmoulded after 6
hours or 24 hours depending on the case. The test specimens are
then kept in water at 20.degree. C. until the end of the
measurement.
[0127] The resistance of the samples obtained is tested according
to standard EN 196-1.
EXAMPLE 5
Comparative Tests on Samples of Mortars According to the
Invention
[0128] A mortar comprising a Portland cement "Saint Pierre la Cour"
(SPLC), CPA CEM I, 52 ,5 according to standard EN 197-1, is
produced according to the method in example 4, to be used as a
comparative sample for the different tests.
[0129] The results of these tests are given in Table 6 below:
TABLE-US-00006 TABLE 6 Compression Compression Compression Setting
resistance at 6 h resistance at resistance at 28 Cement Consistency
time (h) (Mpa) 24 h (MPa) days (MPa) CPA SPLC Firm .about.5.0 0
20.2 62.7 Basic CSA Plastic Not 14.5 15.0 27.0 measured CSA Borax
Fluid .about.4.0 3.2 20.0 53.5 CSA SO.sub.3 Plastic .about.3.5 3.8
18.0 34.0 CSA ZnO Firm .about.2.0 9.6 18.2 28.0 CPA SPLC: Saint
Pierre La Cour Portland Cement CSA: Sulphoaluminous cement Basic
CSA: Sulphoaluminous cement without additives
[0130] The results obtained show that the preferred formulation CSA
Borax, according to our invention, has performances comparable to
those of SPLC Portland cement.
[0131] They also show the influence of the additive on the setting
time and the acquisition of mechanical strength properties,
particularly for the CSA Borax compound.
EXAMPLE 6
Comparative Tests
[0132] A new raw mix of basic sulphoaluminous clinker was prepared
in the same way as in example 1, using the same raw materials.
Starting from this basic raw mix, five modified raw mixes are
produced, in the same way as in example 1, by adding a finely
ground additive or mixture of additives. These additives are
chemically pure compounds.
[0133] Six sulphoaluminous clinkers were prepared from the basic
raw mix and from the five modified raw mixes following the
operating parameters described in example 2, and using a maximum
clinkerisation temperature of 1300.degree. C. for 30 minutes.
[0134] The chemical formulations of the six CSA clinkers were
determined by combining the direct ultimate analyses with
calculation methods. The results are given in Table 7:
TABLE-US-00007 TABLE 7 Estimated formulations of clinkers expressed
in % by weight of oxides Cement used CaO Al.sub.2O.sub.3 SiO.sub.2
Fe.sub.2O.sub.3 SO.sub.3 MgO TiO.sub.2 K.sub.2O Na.sub.2O
P.sub.2O.sub.5 B.sub.2O.sub.3 1 Basic CSA 52.5 16.9 17.6 7.8 4.5
0.2 0.4 0.1 0.1 0.0 0.0 2 2% Borax 51.5 16.6 17.2 7.6 4.4 0.2 0.4
0.1 0.7 0.0 1.4 3 1% P.sub.2O.sub.5 + 2% Borax 51.3 16.5 17.2 7.2
4.3 0.2 0.3 0.1 0.6 1.0 1.4 4 2% K.sub.2SO.sub.4 + 2% Borax 50.8
16.3 16.8 7.4 5.1 0.2 0.3 1.1 0.6 0.0 1.4 5 2% K.sub.2SO.sub.4 + 2%
Borax + 50.9 16.0 16.5 7.3 5.8 0.2 0.3 1.1 0.6 0.0 1.4 2%
CaSO.sub.4 6 1% P.sub.2O.sub.5 + 2% Borax + 50.1 15.8 16.5 6.9 6.1
0.2 0.3 1.1 0.6 1.0 1.3 2% K.sub.2SO.sub.4 + 2% CaSO.sub.4 Entries
2 to 6 Basic CSA + additives
[0135] The clinkers obtained are then ground so as to obtain
cements with a Blaine specific surface of 3800.+-.100 cm.sup.2/g,
according to the method described in example 3, except that the
weight of gypsum is 12% compared to the clinker in each case.
[0136] Six mortars were prepared from these six cements, and their
properties were tested (consistency, setting time, mechanical
strength properties) in the same way as in example 4.
[0137] As a comparison, a new batch of the same Portland cement as
that used in example 5 (St. Pierre La Cour CEM I 52.5) was used for
the entry 7 mortar.
[0138] The results of these mortar tests are given in Table 8 and
in FIG. 1. TABLE-US-00008 TABLE 8 Mechanical properties of prepared
mortars Mechanical strength properties (MPa) Fluidity at Time in
days Cement used 15 minutes 0.25 1 7 14 28 1 Basic CSA normal 6 19
20 24 32 2 2% Borax normal 2 24 26 50 64 3 1% P.sub.2O.sub.5 + 2%
Borax high 3 23 29 28 53 4 2% K.sub.2SO.sub.4 + 2% Borax fairly
high 10 23 31 29 47 5 2% K.sub.2SO.sub.4 + 2% Borax + 2% CaSO.sub.4
fairly high 10 24 34 36 36 6 1% P.sub.2O.sub.5 + 2% Borax + 2%
K.sub.2SO.sub.4 + 2% CaSO.sub.4 normal 15 29 37 39 40 7 CPA SPLC
(CEM I 52.5) normal 0 15 48 56 67 Entries 2 to 6 Basic CSA +
additives
[0139] Table 8 and FIG. 1 show clearly that all the CSA-based
cements lead to better mechanical strength properties at short
times than the control Portland cement (N.sup.o 7). However at 28
days, the control Portland cement leads to a slightly better
mechanical strength (67 Mpa) than that of the best modified CSA
cement (64 Mpa). Nevertheless, all the CSA cements modified by
additives lead to mechanical strengths in an acceptable range for
Portland cements according to European cement standards (>35
MPa).
[0140] All the mixtures produced, except for the one prepared from
a mixtures of alkalis, possess an acceptable initial fluidity and
setting time.
* * * * *