Hydraulic cement compositions

The processibility and initial mechanical strengths of hydraulic cement compositions, e.g., Portland cement, are improved by formulating therewith an adjuvant comprising (i) a water-soluble salt of the condensation product of an aromatic sulfonic acid with HCHO (formulated either alone or in admixture with a water-soluble salt of an aromatic sulfonic acid which has not been condensed with HCHO), (ii) lithium hydroxide, and (iii) a hydroxide of another alkali metal or of an alkaline earth metal.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for improving the processing 
parameters and the mechanical properties of mixtures based on hydraulic 
binders, especially Portland cements or similar cements. The invention 
also relates to novel compositions which can be used as adjuvants in 
mixtures based on hydraulic binders. 
2. Description of the Prior Art 
It is well known to this art that a mixture consisting of hydraulic cement, 
of water and of a filler such as sand or gravel [hereafter referred to as 
a hydraulic cement composition] gradually loses its fluidity once the 
mixture has been prepared, due to the progress of setting, and in the case 
of concrete this loss is referred to as the loss of ability to flow and 
spread. Thus, if a long time is provided between mixing the cement and 
casting same, it is necessary to prevent this loss in fluidity. 
In order to restore fluidity to the cement if the cement composition has 
become viscous, the addition of water has hitherto been employed. However, 
in such a process, the weight ratio of mixing water/cement [hereafter 
referred to as the W/C ratio] is altered (increased) by the addition of 
water, and this results in undesirable phenomena, such as a reduction in 
the mechanical strength of the finished product. 
In order to overcome the above-mentioned disadvantages, it has been 
proposed to add to the hydraulic cement compositions dispersing agents 
which function to bring the binder into a fluid and easy-to-work form, 
while tending to reduce the amount of water necessary for mixing; these 
agents are commonly referred to as water-reducing agents. 
The prior art, especially U.S. Pat. Nos. 2,141,569, 3,277,162 and 3,677,780 
and French Patent No. 2,165,681 teaches that from among the water-reducing 
agents, the best known and also the most commonly used are the 
water-soluble arylsulfonate or alkylarylsulfonate salts, the organic 
moiety of which either may or may not have been condensed with 
formaldehyde. However, these products are still not completely 
satisfactory because their use in cold weather, especially at temperatures 
of between 0.degree. and 15.degree. C., is accompanied by a slowing down 
of the hardening. If such dispersing agents are added to cements, good 
results are indeed observed in respect to fluidity, but, on the other 
hand, it is found that the initial mechanical strengths, for example, 
those measured after 24 hours, are substantially reduced. Accordingly, a 
serious need exists in this art for a process to improve the properties of 
hydraulic cement compositions which makes it possible to overcome the 
noted disadvantage of lowering of mechanical strengths as a result of cold 
weather, while at the same time preserving the above-mentioned advantages, 
in particular the fact that a fluid, easy-to-work binder is obtained. 
SUMMARY OF THE INVENTION 
There has now been found, and which is a major object of the present 
invention, a process which makes it possible to improve the processing 
parameters and the initial mechanical strengths of hydraulic cement 
compositions at temperatures as low as 0.degree. to 15.degree. C., which 
process comprises adding to the hydraulic cement composition a dispersing 
agent selected from the group comprising the water-soluble salts derived 
from the condensation products of aromatic sulfonic acids with 
formaldehyde, the said salts being employed separately or mixed with 
water-soluble salts derived from aromatic sulfonic acids, and said process 
being further characterized in that there is also added to the hydraulic 
cement composition a mixture of lithium hydroxide with a hydroxide of 
another alkali metal or of an alkaline earth metal. 
The mixture consisting of the various above-mentioned adjuvants, namely: 
(i) a water-soluble salt derived from an aromatic sulfonic acid condensed 
with HCHO (employed separately or as a mixture with a water-soluble salt 
derived from an aromatic sulfonic acid which has not been condensed with 
HCHO); 
(ii) lithium hydroxide; and 
(iii) a hydroxide of another alkali metal or of an alkaline earth metal, 
will hereafter be referred to as the adjuvant composition. 
DETAILED DESCRIPTION OF THE INVENTION 
More particularly, it has now surprisingly been found, that in comparison 
with those processes which employ water-soluble salts derived from 
aromatic sulfonic acids condensed with formaldehyde as adjuvants, only the 
use of the adjuvant composition according to the present invention 
manifests itself, in cold weather, not only by the maintenance of 
fluidity, but also by a substantial increase in initial mechanical 
strengths, for example, those measured after 24 hours, to the point that 
values very much greater than those obtained in the absence of adjuvant 
are achieved. In fact, the use of the binary mixtures of adjuvants, such 
as mixtures of: a salt of an aromatic sulfonic acid condensed with 
HCHO/lithium hydroxide, or a salt of a sulfonic acid condensed with HCHO/a 
different hydroxide, manifests itself in a slight loss in fluidity and 
does not produce an improvement in the initial mechanical strengths. 
It should furthermore be noted that the process according to the invention 
can be carried out without any disadvantage in respect of the medium term 
mechanical strengths, for example, those measured after 28 days. 
As dispersing agents to be incorporated in the cement, there are used, for 
the purposes of the invention, water-soluble salts of condensation 
products, of molecular weight between 1,500 and 10,000, obtained by 
condensing sulfonation products of aromatic monocyclic or fused polycyclic 
hydrocarbons, containing 1 to 12 benzene rings, with formaldehyde. 
By way of example, there are mentioned water-soluble salts obtained by 
condensing, with formaldehyde, sulfonation products of aromatic 
hydrocarbons such as benzene, naphthalene, fluorene, anthracene, 
phenanthrene, pyrene, naphthacene, pentacene, hexacene, heptacene, 
octacene, nonacene, decacene, undecacene, dodecacene and derivatives of 
these aromatic compounds having 1 to 3 linear or branched alkyl 
substituents containing from 1 to 3 carbon atoms. 
The condensation products which fall within the scope of the present 
invention are compounds of the formula: 
##STR1## 
in which: Ar represents monocyclic or fused polycyclic aryl groups 
containing from 1 to 12 benzene rings, such as the aryl groups derived 
from the aromatic hydrocarbons referred to immediately above, 
R.sub.1 represents a linear or branched alkyl radical having from 1 to 3 
carbon atoms, 
X is a cationic radical of inorganic or organic origin, selected such that 
the compound of the formula (I) shall be water-soluble, 
m is an integer ranging from 0 to 3 and 
n is a number which is adjusted so as to give a mean molecular weight of 
between 1,500 and 10,000. 
As dispersing agents of the formula (I) which are suitable for carrying out 
the process according to the invention, there are mentioned those in which 
the cationic radicals X associated with the sulfonate groups borne by the 
aromatic rings are inorganic cations derived from alkali metals or 
alkaline earth metals, such as sodium, potassium, calcium or barium, or 
are derived from metals selected from the group comprising lead, 
aluminium, zinc and copper; the cationic radicals X can also be ammonium 
ions NH.sub.4.sup..sym., or quaternary ammonium ions of the formula 
N(R.sub.2 R.sub.3 R.sub.4 R.sub.5).sup..sym., in which the radicals 
R.sub.2, R.sub.3, R.sub.4 and R.sub.5, which can be identical or 
different, each represent a linear or branched alkyl radical containing 
from 1 to 4 carbon atoms. 
Among the quaternary ammonium cations, there are mentioned, in particular, 
the tetramethylammonium, tetraethylammonium, methyltriethylammonium, 
tetrapropylammonium, triethylbutylammonium and tetrabutylammonium ions. 
As dispersing agents of the formula (I) which are preferably employed for 
carrying out the process according to the invention, there are mentioned 
those in which: 
Ar is a naphthyl group, 
R.sub.1 represents a methyl or ethyl radical, and 
the cationic radicals X represent inorganic cations derived from metals 
such as sodium, potassium, calcium and barium, ammonium ions 
NH.sub.4.sup..sym. and quaternary ammonium ions, such as the 
tetramethylammonium, tetrapropylammonium and tetrabutylammonium ions. 
Among these preferred dispersants, those which are most preferred are the 
sodium, potassium, calcium, barium, ammonium and tetramethylammonium salts 
of the condensation product, of molecular weight between 1,500 and 10,000, 
obtained by condensing .beta.-naphthalenesulfonic acid with formaldehyde. 
These salts of high molecular weight condensation products of 
.beta.-naphthalenesulfonic acid and formaldehyde are prepared by applying 
the method described in U.S. Pat. No. 2,141,569. 
As has been stated above, it is also possible to employ a mixture of 
dispersants comprising a salt of a high molecular weight condensation 
product selected from among those mentioned above, together with a 
water-soluble salt derived from the product of the sulfonation of fused 
polycyclic aromatic hydrocarbons, and corresponding to the general 
formula: 
##STR2## 
in which: Ar' represents fused polycyclic aryl groups containing from 2 to 
12 benzene rings, such as the aryl groups derived from the fused 
polycyclic aromatic hydrocarbons referred to above in the definition of 
the symbol Ar, 
R.sub.1, X and m have the meanings given above for formula (I) and 
p is an integer equal to 1 to 2. 
Preferred compounds of the formula (II) are those in which: 
Ar' is a naphthyl group, 
R.sub.1 represents a methyl or ethyl radical, 
X is a cationic radical representing the inorganic cations derived from 
sodium, potassium, calcium or barium, NH.sub.4.sup..sym. ions and 
quaternary ammonium ions, such as the tetramethylammonium, 
tetrapropylammonium and tetrabutylammonium ions, and 
p is an integer equal to 1. 
The aromatic sulfonic acid from which the dispersant of the formula (II) is 
derived can be the same as that which is used for the preparation of the 
dispersant of the formula (I) by subsequent condensation with 
formaldehyde. In such a case, the dispersant salt of the formula (II) can 
optionally be introduced, either in its entirety or in part, into the 
hydraulic cement composition at the same time as the dispersant salt of 
the formula (I), in the form of the by-product which is present when the 
condensation reaction between the aromatic sulfonic acid and HCHO is 
incomplete and unreacted aromatic sulfonic acid remains. 
Where a mixture of dispersants comprising a salt of a high molecular weight 
condensation product and a salt of a sulfonation product is employed, the 
proportion by weight of the latter in the mixture in general does not 
exceed 5%. 
The hydroxides of alkali metals, other than lithium, or of alkaline earth 
metals, to be employed in the process according to the present invention, 
comprise the hydroxides of sodium, potassium, magnesium, calcium, 
strontium and barium. 
As examples of mixtures of hydroxides which are very suitable, there are 
mentioned mixtures of lithium hydroxide with sodium hydroxide, potassium 
hydroxide and calcium hydroxide. 
The mixtures lithium hydroxide/sodium hydroxide and lithium 
hydroxide/potassium hydroxide are very particularly suitable. 
The adjuvants of the formulae (I) and (II) can be employed equally as well 
when they are in the form of an anhydrous or hydrated powder, or when same 
are in the form of a solution in water. The same is true of the hydroxides 
used. It should be noted that unless specifically stated otherwise, the 
various adjuvants according to the invention are to be understood as being 
in their anhydrous form. 
The amounts of the various adjuvants according to the invention which are 
introduced into the hydraulic cement compositions can vary over wide 
limits. 
More particularly, the various adjuvants are introduced in the following 
amounts: 
0.05 to 3%, by weight relative to the cement, of the salt of the high 
molecular weight condensation product of the formula (I), or of the 
mixture of such a salt with a salt of a sulfonation product of the formula 
(II), 
0.001 to 0.05%, by weight relative to the cement, of lithium hydroxide, and 
0.01 to 0.6%, by weight relative to the cement, of a hydroxide of another 
alkali metal, or of an alkaline earth metal. 
Preferably, the adjuvants according to the invention are employed in the 
following amounts: 
0.05 to 1%, by weight relative to the cement, of the salt of the high 
molecular weight condensation product (I), or of the mixture of such a 
salt with a salt of a sulfonation product (II), 
0.001 to 0.02%, by weight relative to the cement, of lithium hydroxide, and 
0.01 to 0.3%, by weight relative to the cement, of a hydroxide of another 
alkali metal or of an alkaline earth metal. 
The process according to the present invention is applicable to all types 
of hydraulic cements and, in particular, to cements of the Portland type 
in which the clinker with addition of gypsum represents at least 80% of 
the total weight; the possible additives, which amount to at most 20% by 
weight, can be fly ash from central heating plants, pozzolane, blast 
furnace slag or mixtures of such products. The process according to the 
invention is equally applicable to slag cements. 
When the cement is used for the production of concrete or mortar, the 
nature, proportion and particle size of the aggregate can also vary over 
wide limits. All mixtures of known types can be considered for the subject 
process. 
The adjuvant composition according to the invention can be introduced into 
the cement when the latter is ground together with the gypsum in the 
cement factory. It is also possible to disperse the adjuvant composition 
in the cement and the aggregate, or in the cement alone in the case of a 
thin mortar, before mixing with water, or to introduce it into the mixing 
water before the latter is used. The adjuvant composition can also be 
introduced into the fresh concrete immediately before the latter is poured 
into the shuttering. When the adjuvant composition is in the form of a 
powder, it can advantageously be mixed with a product which does not 
affect the behavior of the cement at the dose at which it is used, such 
as, for example, activated silica; this product is used to prevent any 
substantial uptake of moisture by the adjuvant composition during storage. 
The adjuvant composition employed in the present invention can be used 
successfully in conventional concretes, such as reinforced concrete, 
roadmaking concretes, concretes used for prefabrication, prestressed 
concretes and thin mortars used for injection. The adjuvant composition is 
of particular value in reinforced and prestressed concretes because it 
exhibits a very marked anti-corrosive character.

In order to further illustrate the present invention and the advantages 
thereof, the following specific examples are given, it being understood 
that same are intended only as illustrative and in nowise limitative. 
EXAMPLES 1 and 2 
These two examples were carried out by incorporating, into mortars based on 
artificial Portland cement containing blast furnace slag (type CPAl 325 
GUERVILLE cement), various proportions of the following three adjuvants: 
(1) the sodium salt of a condensation product of .beta.-naphthalenesulfonic 
acid and formaldehyde, having a mean molecular weight of 4,980, in the 
form of an aqueous solution containing 40% by weight of anhydrous salt, 
(2) crystalline lithium hydroxide, of the formula LiOH.H.sub.2 O, and 
(3) sodium hydroxide. 
By way of comparison, experiments were carried out on a mortar free from 
adjuvant (experiment A), on a mortar to which the solution of the sodium 
salt of the condensation product of .beta.-naphthalenesulfonic acid and 
HCHO was added (experiment B) and on mortars containing the following 
binary mixtures of adjuvants: 
(a) a solution of the sodium salt of the condensation product of 
.beta.-naphthalenesulfonic acid and HCHO, together with either 
LiOH.H.sub.2 O (experiment C) or with NaOH (experiment D), and 
(b) LiOH.H.sub.2 O together with NaOH (experiment E). 
Each mortar was made up at 5.degree. C. and had the following composition: 
NF.P. 15,403 sand 1,350 g 
C 325 L GUERVILLE 450 g 
Water 225 g (W/C=0.5). 
The mortar was made up in accordance with Standard Specification NF.P. 
15,403. The adjuvants were mixed beforehand with the mixing water. The 
proportions of the various adjuvants are given in percentages by weight, 
relative to the Portland cement, of the additive in anhydrous state. 
In the table which follows, the workability of the mortar was measured 10 
minutes after mixing, from the slump of the mortar which had before hand 
been molded in a truncated cone of base diameter 8 cm, upper diameter 7 cm 
and height 4 cm. The mortar was placed on a shock-imparting table and was 
then subjected to a series of 60 shocks at the rate of one shock per 
second. After release from the mold, the mortar was again subjected to a 
series of 15 shocks at the rate of one shock per second. The shock was 
caused by dropping the mortar through a height of 15 mm. The slump is 
expressed in centimeters and corresponds to the mean diameter of the cake 
obtained after the various shocks (flow test method). 
The measurements of the flexural strength and compressive strength were 
carried out in accordance with Standard Specification NF.P. 15,451. The 
strengths were determined on samples of size 4.times.4.times.16 cm which 
were kept in a chamber at 5.degree. C. and 95% relative humidity up to the 
time of the experiment. 
For the flexural experiment, the sample was placed on two supports 
consisting of 10 mm diameter rollers at a distance of 106.7 mm from one 
another; a third roller, of the same diameter, and equidistant from the 
two other rollers, transmitted a load which was increased by 5 da N/s. The 
flexural strength, corresponding to the breaking of the sample, is 
expressed in bars. 
For the compressive experiment, the measurement was carried out on the two 
pieces of sample resulting from the flexural break. The compression was 
transmitted by two hard metal plates of at least 10 mm thickness, 40 mm 
width and 40 mm length. The load was increased to the breaking point at a 
speed such that the increase in stress is 15 bars/s. The results are 
expressed in bars. 
The results given are the mean of the results on 3 samples broken under 
flexural stress, and hence of 6 compressive measurements. 
Such results are shown in the table which follows: 
TABLE I 
__________________________________________________________________________ 
EXPER- EXPER- 
EXPER- 
EXPER- 
EXPER- 
IMENT 
EXAMPLE 
IMENT 
IMENT 
IMENT 
IMENT 
EXAMPLE 
EXAMPLE/EXPERIMENT 
A 1 B C D E 2 
__________________________________________________________________________ 
Adjuvants: % by weight of 
adjuvant in the anhydrous 
state, relative to the cement: 
sodium polymethylene- 
0 0.12 0.12 
0.12 0.12 0 0.24 
naphthalenesulfonate 
lithium hydroxide 
0 0.0043 0 0.0043 
0 0.0043 
0.0086 
sodium hydroxide 
0 0.07 0 0 0.07 0.07 0.14 
Slump in cm 10 minutes 
after mixing 15 16.8 16.6 16.4 15.9 14.6 17.8 
Flexural strength in bars 
after 24 hours 4 6.5 4 4 3.5 4 6.5 
Compressive strength in 
bars after 24 hours 
10 15 8 7.5 6.5 7 15.6 
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PREATION OF THE SODIUM POLYMETHYLENE-NAPHTHALENE-SULFONATE: 
640 g (6.5 mols) of concentrated sulfuric acid (d=1.84) were introduced 
into a 3 liter flask, equipped with a mechanical stirrer and a heating 
system, and the temperature thereof was raised to a value of 160.degree. 
C. The stirring was commenced and 640 g (5 mols) of purified naphthalene 
were introduced slowly, the temperature being maintained at the 
above-mentioned value. 
Once the addition of the naphthalene had been completed, the reaction 
mixture was stirred at 160.degree. C. until all the naphthalene employed 
had reacted; the time required was about 4 hours. 
The sulfonation mixture was then cooled to 100.degree. C. and thereafter 
was diluted with 282 g of water. The temperature of the mixture was raised 
to 80.degree. C. and 76.8 g of an aqueous formaldehyde solution containing 
40% by weight of HCHO were then added. The reaction mixture was then 
stirred at 80.degree. C. for one hour. 
After this time, an additional 76.8 g of the aqueous formaldehyde solution 
were introduced into the reaction mixture and stirring was continued at 
80.degree. C. for one hour. This type of operation was repeated twice 
more. 
After the whole of the formaldehyde solution (307.2 g) had been added, the 
temperature of the reaction mixture was increased gradually to 
95-100.degree. C. over a period of about one hour. Once this temperature 
had been reached, the reaction mixture was stirred for an additional 18 
hours. 
After this time, it was cooled to ambient temperature (25.degree. C.) and 
potentiometric determinations were carried out on the sulfuric acid 
present (which corresponded to 1.5 mols of sulfuric acid) and on the 
sulfonic acid present (which corresponded to 5 mols of sulfonic acid). The 
reaction mixture was then neutralized accurately with an aqueous mixture 
containing 111.15 g of Ca(OH).sub.2 and 200 g of NaOH. The calcium 
hydroxide neutralized the sulfuric acid and gave a precipitate of hydrated 
calcium sulfate which was filtered off. The filtrate solution contained 
the desired sodium polymethylene-naphthalenesulfonate; the filtrate was 
concentrated so as to obtain an aqueous solution containing 40% by weight 
of pure sodium polymethylenenaphthalenesulfonate. 
EXAMPLES 3 and 4 
These two examples of a mortar were produced at 5.degree. C. by 
incorporating the adjuvant composition employed in Example 1 into mortars 
based on: 
Artificial Portland cement, type CPA 400 VICAT 
(Example 3), and 
Slag cement+clinker, type CLK 325 VICAT 
(Example 4). 
By way of comparison, mortar experiments were carried out with mortars free 
from adjuvant (mortar with CPA 400 VICAT cement--experiment F; mortar with 
CLK 325 VICAT cement--experiment G). 
The results were as follows: 
TABLE II 
______________________________________ 
Ex- Exper- Ex- Exper- 
ample iment ample iment 
EXAMPLE/EXPERIMENT 
3 F 4 G 
______________________________________ 
Slump in cm, 10 minutes after 
mixing 15.3 13.8 17 15.5 
Flexural strength in bars after: 
24 hours 11.3 8.3 5.5 0 
28 days 59 57 37.5 32 
Compressive strength in bars 
after: 
24 hours 28.1 21 7.4 6.1 
28 days 331 334 227 178 
______________________________________ 
Each mortar was made up as indicated in Examples 1 and 2. 
While the invention has been described in terms of various preferred 
embodiments, the skilled artisan will appreciate that various 
modifications, substitutions, omissions, and changes may be made without 
departing from the spirit thereof. Accordingly, it is intended that the 
scope of the present invention be limited solely by the scope of the 
following claims.