WO1991017127A1

WO1991017127A1 - Admixture of cement-based grout, mortar or concrete

Info

Publication number: WO1991017127A1
Application number: PCT/FR1991/000365
Authority: WO
Inventors: François LOUVET; Camille Defosse; Alain Fevrier; Marcel Verhille
Original assignee: Ciments Français
Priority date: 1990-05-04
Filing date: 1991-05-03
Publication date: 1991-11-14
Also published as: FR2661670A1; FR2661670B1

Abstract

Admixture for cement-based products characterized in that it is obtained by the combination of at least three products belonging respectively to the following families: an anionic water reducing agent (agent A); a nonionic water-insoluble surface agent (agent B), having a low molecular weight or non polymerized; a water-soluble or dispersible surface agent (agent C). This admixture is particularly interesting for its numerous properties, particularly its excellent workability during a long period of time without deterioration of the mechanical strength characteristics, and the water-repellent character of the set products.

Description

Admixture for mortar grout or cement concrete

The present invention relates to an adjuvant for the implementation of cements. Generally, this implementation presents three kinds of difficulties:

1- in terms of ludification of concrete, it is well known to those skilled in the art that the use of a water reducer often leads to premature stiffening of the concrete after having given it high initial maneuverability. As a result, the workability often becomes unsatisfactory after 30 minutes of mixing, which leads to adding water just before processing. The consequences of such additions of water boil down to the reduction in resistance by increasing the porosity, to the internal decohesion of the material and therefore to the increase in the risks of segregation. This always results in a loss of durability of the cured material.

2- moreover, in terms of water repellency, it is well known that adjuvants claimed as such, have the side effect of more or less significant drops in resistance at all ages.

3- similarly, for air entraining admixtures, experience has shown that they improve the handling of fresh concrete, that they can guarantee better resistance to the aggressiveness of freeze-thaw cycles depending on the size of the bubbles and their spatial distribution. However, it is also known to those skilled in the art that the size of these bubbles and their possible coalescence can reduce the mechanical performance on hardened material.

The invention aims to respond to these triple difficulties by formulating an adjuvant which, simultaneously, does not cause cases of mechanical strength, gives better cohesion during implementation, ensures good handling of the concrete spread in the time and gives it a water repellency, these characters are not usually grouped simultaneously.

The originality of the invention lies in the mixture and the choice of the three compounds or families of compounds which are incorporated into the formulation of the admixture on the one hand and, on the other hand, into the applications and improvements made to the handling of fresh concrete and to the water repellency of hardened concrete.

The subject of the present invention is an adjuvant for cement-based products, characterized in that it is obtained by the combination of at least three products belonging respectively to the following families:

- an anionic water reducing agent (agent A), - a non-ionic and water-insoluble surfactant (agent B) of low molecular weight or not polymerized,

- a dispersible or water-soluble surfactant (agent C).

The function of the water reducing agent (agent A) is to decrease the porosity of the material by reducing the amount of mixing water, therefore to increase the mechanical strengths of the grouts, mortars or concretes and to improve the fluidity of the paste-aggregate mixture.

The non-ionic surfactant, of low molecular weight, and insoluble in water (agent B), by its own hydrophobic character, completes the water-repellent effect provided by the water reducer. It also has the property of being anti-foaming; therefore it increases the compactness of the grout, mortar or concrete, and therefore improves their mechanical strengths. The choice of a low molecular weight for agent B is brought about by the need to combine the conditions of association of B with C. In the case of high molecular weight, for example with polymers such as polyethylene glycol, the agent It could not act, and play its role.

The dispersible or water-soluble surfactant (agent C) has the function of emulsifying the nonionic and water-insoluble surfactant. Without this third component, the adjuvant which is the subject of the invention would be unstable before being used. On the other hand, by its known function as a foaming agent, it provides an air entrainment which also improves the fluidity of the grouts, mortars and concretes. The invention is also remarkable for the following characteristics:

- the water reducing agent belongs to one of the following families:

. polynapthalenes sulfonates (condensate of naphthalenesulfonate and formalin in the form of Na, K, NH ₄ +, Ca, Mg ... salts) abbreviated PNS.

. lignosulfonates, purified or not

. melamine sulfonates (condensate of melamine sulfonate and formalin in the form of Na salt,

K, NH ₄ +, Ca, Mg ...)

. salt of a polyhydroxy acid such as gluconic acid, glucoheptonic acid.

- The surface agent B is a surfactant having an HLB (hydrophilic lipophilic balance) of less than 10. This molecule can belong to one of the following families:

. polyoxyethylenated fatty alcohol having 2 or 3 ethylene oxide (NP2 or NP3),

. polyoxyethylenated nonylphenol having 2 or 3 ethylene oxide,

to which antifoams should be added such as:

. tributyl phosphate,

. polypropylene glycol,

. acetylenic diols such as "Surfinol 104" sold by the Company Air Products,

. hydrophobic silicas such as "L300" from the company BEROL-NOBEL,

. hydrocarbons such as linseed oil,

. fatty alcohols such as octyl alcohol,. salts of fatty acids such as calcium stearate, zinc, ...

. silicones such as "RHODORSIL silicone

414 "from RHONE-POULENC.

- The dispersive or soluble surfactant can belong to one of the following families:

. lauryl ether sulfate having 4 to 20 ethylene oxides

. polyoxyethylenated nonylphenol having from 4 to 20 ethylene oxides (NP4 to NP20), . pol yoxethylenated fatty alcohol having from 4 to 20 ethylene oxides,

to which foaming agents such as:

. ethylene oxide-propylene oxide copolymers, such as "SYNTHIONIC 80-20" from the company WITCO,

. acid esters and half esters

fosuccinique,

. organof1 uorës, such as the products of

ATOCHEM company sold under the name "FORAFAC",. alkyl sulfonates and alkylbenzene sul fonates.

- The proportions (by weight of active compound relative to the weight of cement) will be:

. for the anionic water reducer 0.1% to 51,. for the nonionic surfactant and insoluble in water 0.01% to 0.5%,

. for the dispersible or water-soluble surfactant 0.001 to 0.5%.

In the illustrated tests, it is preferred to choose:

1- for the water reducer a condensate of naphththalene sulfonate and formalin in the form of the salt of Na, K, NH ₄ +, Ca, Mg (polynapththalene sulfonate) (PNS)

2- for the nonionic surfactant and insoluble in water, a polyoxyethylenated nonylphenol having 2 ethylene oxides (NP2)

3- for the dispersible or water-soluble surfactant, a polyoxyethylenated nonylphenol having 6 ethylene oxides (NP6), but these choices are not limiting within the meaning of the invention. In addition, these three compounds will preferably be in the following proportions:

. 55 parts of pol ynaphthalene sulfonate PNS,. 11 parts of polyoxyethylenated nonylphenol having

2 ethylene oxides (NP2),

. 4 parts of polyoxyethylenated nonylphenol having

6 ethylene oxides (NP6),

which leads to the formula: 55 PNS + 11 NP2 + 4 NP6 The proportion (by weight of active compounds relative to the cement used in the grout, mortar or concrete) used will be between approximately 0.1 and 2.5% depending on the cement used, and preferably between approximately 0, 2 and 1.5%.

Finally, the adjuvant can be combined with any other known adjuvants. In addition, it can be produced in solid form, for example by mixing powdery constituents or else in liquid form, the constituents being dissolved and / or dispersed in water. One or the other of the forms will be preferred depending on the conditions of transport or storage or production of concrete.

Furthermore, the invention also relates to concrete or mortar produced with the adjuvant thus defined.

The association NP2 and NP6 was chosen because, in addition to the proper action of each of the components, NP6 facilitates the emulsion of NP2 in the PNS solution and the dispersion during the preparation if the formulation in liquid form, or at the time of mixing if the formulation is used in solid form. Furthermore, if one wants to guarantee the stability of the mixture of the 3 components (of the formulation) in solution before use, it is necessary that the concentration of active products is less than or equal to 35%. This is especially important in the case of exposure to low temperatures (storage at around 0ºC).

The combination of these three agents brings multiple advantages:

1- the stiffening generally observed for grouts, mortars and concretes with reduced water content, disappears and the maintenance over time of the workability of said grouts mortars and concretes is greatly prolonged. We manage to exceed two hours of maintenance of high workability in continuous mixing in a concrete mixer.

2- the quantity of mixing water necessary for the implementation of grouts, mortars and fluid concretes, is reduced, which is a guarantee of good resistance, of better cohesion both in the fresh state and in the 'state hardened, of an absence of segregation in spite of the fluidity of the grouts, mortars and concretes thus prepared.

3- air entrainment improves the rheological behavior of the fresh material as well as the resistance to freeze-thaw cycles.

4- water uptake by capillary rise, grout, mortar and hardened concrete, are reduced; water repellency is therefore improved.

The originality of the air entrained by the adjuvant, object of the invention, is to be gradually incorporated during continuous mixing and, then, to be stabilized around an average value fixed by the mixture of 3 constituents taken into account in the formulation of the adjuvant.

The results of the tests carried out to demonstrate the characteristics which the formulations object of the invention give to mortars and concretes are shown in the attached tables and graphs:

- table nº 1 "Tests on standardized mortar of

CPA.55 ";

- graph 1 "Highlighting the stiffening caused by the use of PNS alone in concrete dosed at 350 kg of CPA 55 per m ³ (variation of W / C for a constant PNS content);

- Graph 2: "Demonstration of the stiffening caused by the use of PNS alone in concrete dosed at 350 kg of CPA 55 per m ³ (variation in PNS content at constant W / C);

- table nº 2 "Comparison of subsidence and resistance and air trapped on concrete without and with additives";

graph 3 "Improvements in rheology brought by the NP2 / NP6 association added to the PNS;

- Tables 3 to 5 "Activity of the admixture on a cement from different factories".

- Graph 4: curves comparing the results of Tables 2 to 5. The tests presented are carried out in accordance with AFNOR standards of the NF P 15 series for tests on mortars and NF P 18 for tests on concretes and additives. The spreading test on mortar, not standardized in France, is carried out with the equipment described in the American standard ASTM C 230-83, the spreading being measured after 10 shocks. We use an inverted cone placed on a flat support. This support rests on a device causing vertical shocks. The prepared mortar is introduced from the top of the open cone until filling. The cone is removed, then the shock producing device is started.

The width occupied by the mortar after the impact is produced is measured.

Table 1 highlights on standard mortar, compared to 3 controls:

- a witness made without adjuvant

- a witness comprising a commercial waterproofing adjuvant,

- a witness comprising PNS alone,

the effects of different formulations according to the invention.

We aknowledge :

the fluidifying effect: reduction in the water / cement weight ratio for identical rheological characteristics (constant spreading),

- an improvement in the initial resistance (at 2 days) and a maintenance of the resistance at 28 days,

- the water-repellent effect (measured according to standard NF 18334 (December 1986),

- there is no abnormal lengthening of the setting time.

We notice that :

- the commercial water repellent if it is well water repellent, reduces the compressive strengths,

- PNS, used alone, does not give the mortar a water repellency

The following tables and graphs show the results obtained on concrete.

Graphs 1 and 2 show the stiffening over time (decrease in the weakening at the Abrams cone) when an admixture comprising PNS alone is introduced into concrete,

- with constant PNS content (0.6%) and variable water / cement ratio (0.42 to 0.44);

- with variable PNS content (0.4% to 0.6%) and constant water / cement ratio (0.44).

Table 2 shows the characteristics of an admixture concrete with the admixture according to the invention compared to a concrete made with the same aggregates, the same cement at the same cement dosage but not containing an adjuvant.

Note the characteristics that the admixture gives to concrete:

reduction in the water / cement ratio for an identical initial rheology (after mixing for 3 minutes 30 seconds).

- maintenance of this rheology over time while there is a rapid stiffening for concrete containing no admixture or comprising PNS alone

- an improvement in resistance at all times, and particularly in the early ages

an increase, but without excess, of the occluded air.

Graph 3 shows the results of the rheological evolution of this concrete compared to that of the same concrete containing no admixture or PNS alone.

On the other hand, it is known that the characteristics of cements of the same type are not strictly the same from one plant to another, in particular their chemical composition and more especially their content of tricalcium aluroinate can vary, this being linked to the nature of the raw materials extracted from quarries.

As a result, an adjuvant does not always give as good results with cements of different origins.

We thus tested comparatively the maintenance of rheology with cements coming from four factories spread all over France.

The results which appear in Tables 3 to 5 show that the adjuvant which is the subject of the invention is effective with cements of different origins, having tricalcium aluminate contents varying from 2 to 10% by adapting its weight proportion (in active constituents) compared to cement.

This proportion will be between 0.1 and 2.5% compared to the cement.

The results in Tables 3 to 5 confirm the results obtained with the first cement on the various points examined:

- decrease in the W / C ratio with identical initial rheology,

- maintains rheology over time,

- improvement in resistance at early ages and improvement or maintenance of resistance at 28 days,

- increase in the occluded air without excess,

The results concerning the evolution of rheology over time compared with those of the concrete of the first example are plotted on graph 4.

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Claims

1. Adjuvant for cement-based products characterized in that it is obtained by the combination of at least three products belonging respectively to the following families:

- an anionic water reducing agent (agent A),

- a non-ionic surfactant and insoluble in water (agent B), of low molecular weight or not polymerized,

- a dispersible or water-soluble surfactant (agent C).

2. Adjuvant according to claim 1 characterized in that the water reducing agent belongs to one of the following families:

- polynapthalenes sulfonates (condensate of

naphthalene sulfonate and formalin in the form of Na, K, NH ₄ +, Ca, Mg ...) abbreviated PNS.

- lignosulfonates, purified or not

- melamine sulfonates (condensate of melanin sulfonate and formalin in the form of Na, K, NH ₄ +, Ca, Mg ... salts)

- salt of a polyhydroxylated acid such as gluconic acid, glucoheptonic acid.

3. Adjuvant according to claim 1 or 2 characterized in that the water reducer is used in a proportion by weight relative to the cement from 0.1% to 5%.

4. Adjuvant according to claim 1 characterized in that the nonionic surfactant (B) is insoluble in water is chosen from the following families:

polyoxyethylenated fatty alcohol having 2 or 3 ethylene oxides,

polyoxyethylene nonylphenol having 2 (NP2) or 3 ethylene oxides,

.the tributylphosphate,

.propylene glycol,

.acetyl enic diols such as "Surfinol

104 "sold by Air Products,

hydrophobic silicas such as "L300" from the company BEROL-NOBEL,

. hydrocarbons such as linseed oil,. fatty alcohols such as octyl alcohol,. salts of fatty acids such as cal cium, zinc stearate, etc.

. silicones such as "RHODORSIL 414" silicone from RHONE-POULENC.

5. Adjuvant according to any one of claims 1 or 4 characterized in that the surfactant (B) is used in a proportion of 0.01% to 0.5%

6. Adjuvant according to claim 1 characterized in that the surfactant (C) dispersible or soluble in water is chosen from the following families:

lauryl ether sulfate having 4 to 20 ethylene oxides,

polyoxyethylene nonylphenol having 4 to 20 ethylene oxides,

polyoxethylenated fatty alcohol having from 4 to 20 ethylene oxides,

.copolymers of ethylene oxide - propylene oxide, such as "SYNTHIONIC 80-20" from the company WITCO,

.esters and half esters of acid

sulfosuccinic,

organofluorines, such as

ATOCHEM company sold under the name "FORAFAC",

.alkyl sulfonates and alkylbenzene sulfonates.

7. Adjuvant according to any one of claims 1 to 8 characterized in that the surfactant (C) is used in a proportion of 0.001% to 0.5%.

8. Adjuvant according to claim 1,6 or 7 characterized in that the surfactant (C) is polyoxyethylenated nonylphenol with 6 ethylene oxides (NP6).

9. Adjuvant according to claims 2,4,9 characterized in that the 3 constituents are in the following proportions: PNS 55 parts

NP2 11 parts

NP6 4 parts

10. Adjuvant according to claims 1 to 9 characterized in that it is used in proportions by weight relative to the cement from 0.1% to 2.5%.

11. Adjuvant according to claim 1 characterized in that the three components are dissolved and / or dispersed in water.

12. Adjuvant according to claims 9 and 12 characterized in that the concentration of active products in water is less than or equal to 35%.

13. Grout, mortar or concrete characterized in that it is produced with the admixture according to any one of the preceding claims.

14. Adjuvant according to claim 1 characterized in that the three components are mixed in solid form.