FR2646845A1 - Process for the preparation of blast furnace slag having improved mechanical performance, slag thus obtained and its applications - Google Patents

Abstract

The process is characterised by the incorporation, into the slag to be used as one of the constituents of a hydraulic binder, of the following ternary composition: lignosulphonate in an amount of 2800 to 15,000 g/tonne, preferably 3200 to 3600 g/tonne; a hydroxycarboxylic acid or its salts in an amount of 200 to 1500 g/tonne, preferably 300 to 900 g/tonne and triethanolamine in an amount of 0.200 to 0.800 litre/tonne, and preferably 0.300 to 0.500 litre/tonne.

Description

The present invention relates to a process for preparing a blast furnace slag with increased mechanical performance.

It also relates to a slag prepared according to the process.

It also relates to a hydraulic binder consisting of slag prepared according to the invention and clinker cement (Portland).

Finally, it relates to a concrete whose hydraulic binder is part of the invention.

For several decades, the blast furnace slag has been used with clinker to produce cement with a lower mechanical strength than the clinker made only from clinker.

Improving the mechanical resistance of slag cement has been the subject of research in various countries for several years.

This is to value the blast furnace slag; byproduct of the reduction of iron ore in blast furnaces ranging in size from 300 to 800 kg / tonne of pig iron extracted.

It is known from Japanese Patent No. 55,075,747 (1978) that a binary composition consisting of triethanolamine and hydroxycarboxylic acid or its alkali metal salts is used as a grinding agent for pulverizing blast furnace slag.

This slag is for use with clinker to make cement.

 It is taught in this patent that the mechanical characteristics of the cement produced are improved.

Triethanolamine is used at a level of 0.001 to 0.5% of the slag and preferably from 0.001 to 0.1% and the hydroxycarboxylic acid or its salts (gluconic acid, citric acid, tartaric acid, etc.) are used. at a level of 0.01 to 0.5% and preferably 0.01 to 0.1%.

Tests, measuring the breaking stress on a concrete whose hydraulic binder consists of clinker cement and slag prepared according to this Japanese patent, were developed, as is demonstrated later, by us.

The result of these tests showed that the breaking stress of such concrete is still low.

One of the aims of this invention is therefore to propose a process for preparing blast furnace slag with increased mechanical performance.

This slag is to be used as one of the components of hydraulic binder composed of said slag at a rate of 15 to 50% by weight and clinker cement at a rate of 50 to 85%.

Another object of this invention is to provide a high performance hydraulic binder consisting of blast furnace slag and clinker cement.

Another object of this invention is to provide a concrete with interesting mechanical characteristics of which the hydraulic binder is made according to the invention.

For this purpose and according to an arrangement of the present invention, the process for preparing the blast furnace slag with increased mechanical performance is characterized by the incorporation into the said slag of a ternary composition consisting of
a) sodium or potassium lignosulfonate,
melamine, sulfonated naphthalene or a mixture of them
at a rate of ........... 2800 to 15000 g / tonne of slag,
and preferably from 3200 to 3600 g / ton,
(b) hydroxycarboxylic acid (s), one or more
its alkali metal salts or a mixture of them,
at a rate of 200 to 1500 g / ton,
and preferably 300 to 900 g / ton.

(c) triethanolamine,
at a rate of ............... 0,200 to 0,800 1 / tonne,
and preferably from 0.300 to 0.400 I / ton,
these dosages being given for one ton of slag.

According to a second provision, the blast furnace slag for use as a constituent of hydraulic binder is characterized in that it comprises the ternary composition described in the process.

According to a third provision, the hydraulic binder forming part of the present invention is characterized in that it consists of
- clinker cement of .................... 50 to 85% and,
- slag prepared according to the invention of .... 15 to 50%
weight.

According to a fourth provision of the present invention, the concrete part of it, is characterized by the use of a hydraulic binder prepared according to the same invention.

The present invention will be better understood on reading the detailed description given below.

Table (I) shows the results of compression tests on concrete specimens whose hydraulic binder consists of blast furnace slag and CPA 55 cement (French standards) made from clinker.

In the mixture of this concrete, a sodium gluconate-triethanolamine binary composition was incorporated according to the concentrations taught by the Japanese patent referenced above.

TABLE (1)
COMPOSITION: Gravel 10/20 - ............... 690 kg / m3,
Gravel 6/10 mm. ............... 540 kg / m3,
Sand 0/6 mm. ............... 810 kg / m3,
cpa 55 ............... 200 kg / m3,
Dairy ..................... 60 kg / m3,
additives
1 / Sodium gluconate ..... 24 g,
2 / Triethanolamine .......... 35 g,
Water, 180 liters.

CHARACTERISTIOUES OF THE TEST: Diameter 16 ci, height 32 cm.

<Tb>

AGE <SEP> IN <SEP> CONSTRAINT <SEP> FROM <SEP> BREAK
<tb> DAYS <SEP> AVERAGE <SEP> IN <SEP> M.Pa
<tb> 7 <SEP> 13.9
<tb>: <SEP> 28 <SEP>: <SEP> 20.55
<Tb>
Table (2) shows the result of compression tests on concrete specimens in which the hydraulic binder consists of CPA 55 cement and slag prepared according to the invention.

TABLE (2)
COMPOSITION: Gravel 10/20 mm. ............... 690 kg / m3,
Gravel 6/10 mm. ............... 540 kg / m3,
Sand 0/6 mm. ............... 810 kg / m3,
CPA 55 cement ............... 200 kg / m3,
Dairy ........................ 60 kg / m3,
additives
1 / Sodium gluconate 24 g,
2 / Triethanolamine 35 g,
3 / sodium lignosulfonate 280 g,
Water ............................. 180 liters.

CHARACTERISTICS OF THE TEST: Diameter 16 ci, height 32 cm.

<Tb>

: <SEP> AGE <SEP> IN <SEP>: <SEP> CONSTRAINT <SEP> FROM <SEP> BREAK
<tb> DAYS <SEP> AVERAGE <SEP> IN <SEP> M.Pa
<tb> 7 <SEP> 20.9
<tb>: <SEP> 28 <SEP>: <SEP> 31.35
<Tb>
The comparison between the results presented in Tables 1 and 2 shows the surprising increase in the breaking stress in the case where the slag used contains the ternary composition sodium gluconate - triethanolamine - sodium lignosulfonate.

The same tests were repeated by changing only the additives contained in the slag.

Table (3) presents the results of these tests.

TABLE (3)
COMPOSITION: Gravel 10/20 mm. ............... 690 kg / m3,
Gravel 6/10 mm. ............... 540 kg / m3,
Sand 0/6 - 810 kg / a3,
CPA 55 cement ............... 200 kg / m3,
Dairy ........................ 60 kg / m3,
additives
1 / Sodium gluconate 24 g,
2 / Triethanolamine ......... 35 g,
3 / sodium lignosulfonate 200 g,
sulphonated naphthalene ..... 200 g,
Water ............................. 180 liters.

CHARACTERISTICS OF THE TEST: Diameter 16 ci, height 32 ci.

<Tb>

: <SEP> AGE <SEP> EN <SEP>: <SEP><SEP> CONSTRAINT <SEP> FROM <SEP> BREAK
<tb> DAYS <SEP> AVERAGE <SEP> IN <SEP> M.Pa
<tb> 7 <SEP> 19.8
<tb>: <SEP> 28 <SEP>: <SEP> 29.7
<Tb>
The breaking constraints of Tables (2) and (3) are comparable.

This shows the effect equivalence of sodium lignosulfonate and sulfonated naphthalene.

Other tests have also shown the equivalence between sodium lignosulfonate, sulfonated naphthalene and melamine.

To verify whether this ternary composition acts on the clinker cement (CPA 55) or on the slag, other tests were carried out using only CPA 55 cement as hydraulic binder.

The composition of the concrete tested was similar to that of Tables 1, 2 and 3 except that 260 kg / m3 of cement was used instead of 200 kg / m3 of cement and 60 kg / m3 of slag.

First additives identical to those contained in the slag of Table (2), then those of Table (3) were tested respectively.

The breaking stresses in both cases were comparable to those in Tables (2) and (3).

This shows the equivalence between the CPA 55 cement plus the additives in Tables 2 or 3 and the cement plus the slag plus the additives in Tables 2 or 3.

We can therefore think that these additives (the ternary composition) acts mainly on the slag (low-performance hydraulic binder) and makes it comparable to clinker cement.

To verify this hypothesis, two series of compression tests were carried out on test specimens of poor hydraulic binder concrete (220 kg / m3).

In one of the two series, the binder used was CPA 55 cement and in the other series the binder used was a mixture of cement and slag prepared according to the invention.

Measurements were made for concrete aged 2, 7, 28 and 90 days.

Tables (4) and (5) summarize the results.

TABLE (4)
COMPOSITION: Gravel 10/20 mm. ............... 710 kg / m3, Gravel 6/10 fl. 540 kg / a3,
Sand 0/6 1. ............... 830 kg / m3,
CPA 55 cement ............... 220 kg / m3,
Water ............................. 160 liters.

CHARACTERISTICS OF THE TEST: Diameter 16 ci, height 32 ci.

<Tb>

: <SEP> AGE <SEP> IN <SEP>: <SEP> CONSTRAINT <SEP> FROM <SEP> BREAK
<tb> DAYS <SEP> AVERAGE <SEP> IN <SEP> M.Pa
<tb> 2 <SEP> 3.0
<tb> 7 <SEP> 6.0
<Tb>
: 28 12.0
: 90: 13.6
TABLE (5)
COMPOSITION: Gravel 10/20. ............... 710 kg / m3,
Gravel 6/10 to ............... 540 kg / m3, Sand 0/6 a. 830 kg / m3,
CPA 55 cement 155 kg / m3,
Dairy ............................. 65 kg / m3,
additives
1 / sodium lignosulfonate 280 g,
2 / Sodium gluconate .... 24 g,
3 / Triethanolamine ......... 35 g.

CHARACTERISTICS OF THE TEST: Diameter 16 ci, height 32 cm.

<Tb>

: <SEP> AGE <SEP> IN <SEP>: <SEP> CONSTRAINT <SEP> FROM <SEP> BREAK
<tb> DAYS <SEP> AVERAGE <SEP> IN <SEP> M.Pa
<tb> 2 <SEP> 5
<tb> 7 <SEP> 10.9
<tb>: <SEP> 28 <SEP>: <SEP> 22.9
<tb>: <SEP> 90 <SEP>: <SEP> 28.03
<Tb>
The comparison of these two tables shows that said ternary composition acts essentially on the slag.

It demonstrates, in addition, that in the case of concrete poor in hydraulic binder, the partial replacement of CPA 55 cement by the slag prepared according lrinvention promotes the mechanical strength of concrete.

The slag that was used in these tests is a slag from the blast furnace for extracting iron from iron-rich ore.

The additives used to improve the mechanical characteristics of this slag can be added as a powder (sodium gluconate) and as a liquid (triethanolamine) during the milling of the slag.

Gluconate and lignosulfonate may be added during milling as an aqueous solution.

In this case of addition during milling, gluconate and triethanolamine act, as it is known, as a grinding agent.

The slag used in our tests was ground at 3200 cm2 / g surface area.

The dosages given in additives take into account the granulometry of the slag and also its rate in the hydraulic binder "clinker cement-slag".

It is known that lignosulfonate and hydroxycarboxylic acids and their alkali metal salts have a retarding effect on clinker cement.

In the case where the slag content increases (more than 50%) in the hydraulic binder mixture, ie in the case where the clinker cement content decreases, the dosages given above may have a retarding effect. take on the cement.

To overcome this disadvantage, the following solutions are possible - reduce the dosage of lignosulfonate and sodium gluconate.

The lack of lignosulphonate can be compensated by an increase in the dosage of melamine or naphthalene sulphonated, - use within the limits of the dosages given above, a mixture of sodium lignosulfonate and sodium hydroxide whose proportions are in order 75% and 25 t.

The use of sodium hydroxide promotes the setting of cement and therefore compensates for the delay in setting the cement under the effect of sodium lignosulphonate. - Use a slag with a greater specific surface area than the one used in our tests (3200 cm2 / g).

These additives can be added, of course, after grinding.

They can be added even during concrete preparation.

A slag prepared according to the invention can be mixed with a clinker cement thus constituting a binder ready for use.

This binder consisting of clinker cement and slag prepared according to the invention has characteristics superior to another binder consisting of clinker cement and slag without additives.

The mixture cement clinker (Portland) and slag prepared according to the invention may have, depending on the application envisaged very variable proportions.

The slag content in the clinker-slag cement mixture can vary from 50% to 50% by weight.

The low cost of the slag prepared according to the invention shows the economic interest of the present invention.

Claims (8)

 1. Process for the preparation of blast furnace slag increasing its mechanical performance as a constituent of hydraulic binder composed of 15 to 50% of said slag and other ingredients including clinker cement at a rate of 50 to 85%, the process being characterized by the incorporation into the said slag of a ternary composition constituted by  a) sodium or calcium lignosulfonate,  melamine, sulfonated naphthalene or a mixture of them  at a rate of 2800 to 15000 g / ton,  and preferably. .. 3200 to 3600 g / ton,  (b) hydroxycarboxylic acid (s), one or more  its alkali metal salts or a mixture of them,  at a rate of 200 to 1500 g / ton,  and preferably from 300 to 900 g / ton.  the dosages being given for a ton of slag.  and preferably from 0.300 to 0.500 l / ton,  at a rate of .......... 0.200 to 0.800 1 / tonne,  (c) triethanolamine,  2. Method according to claim 1 characterized in that said ternary composition is  a) Sodium lignosulfonate  at a rate of .......... 3200 to 3600 g / tonne,  b) sodium gluconate  at a rate of .......... 300 to 900 g / tonne,  c) triethanolamine  * a rate of 0.300 to 0.500 l / ton.  3. Method according to claim 1 characterized in that said ternary composition is  a) sodium lignosulfonate of 2000 to 2500 g / tonne,  + sulfonated naphthalene of ... 2000 to 7500 g / tonne.  c) triethanolamine of ......... 0.300 to 0.500 l / ton.  b) sodium gluconate of 300 to 900 g / ton,  4. Method according to claim 1 characterized in that said ternary composition is  a) sodium lignosulfonate from 2000 to 2500 g / ton  + melamine from 2000 to 7500 g / ton,  b) Sodium gluconate 300 to 900 g / ton  c) triethanolamine of ......... 0.300 to 0.500 l / ton.  5. Method according to claim 1 characterized in that said ternary composition is  a) sulfonated naphthalene from 2000 to 7500 g / tonne,  + melamine from 2000 to 7500 g / ton,  b) sodium gluconate 300 to 900 g / ton,  c) triethanolamine of 0.300 to 0.500 I / ton.  6. Blast furnace slag for use as a constituent of hydraulic binder characterized in that it comprises the ternary composition according to one of claims R1-R4.  7. Hydraulic binder characterized in that it is constituted by  - clinker cement of ............. 50 to 85%,  slag according to claim 6 of 50% by weight.  8. Concrete characterized by the use of a hydraulic binder according to claim 7.