FR2590249A1 - Activator intended to be incorporated into a mixture comprising at least one sand and a binder such as granulated slag - Google Patents

Abstract

An activator intended to accelerate the setting of a mixture comprising at least one sand and a binder. According to the invention the gypsum-based activator to which sodium sulphate and lime have been added is characterised by the addition of a deflocculating product itself consisting of two agents known per se by the trade names Deflopan No. 55 and Deflopan No. 56. The graph illustrated in the figure shows that, when compared with a reference curve A, a mixture comprising an activator according to the invention exhibits markedly superior tensile strength characteristics. Application: construction of all works such as roads, buildings or the like.

Description

"Activant intended to be incorporated into a mixture comprising
at least one sand, and a binder such as granulated slag "
The present invention generally relates to mixtures of the kind consisting of at least one sand and of a binder such as granulated blast furnace slag commonly used in construction for producing any works, and in which a activating proper to accelerate the setting of the binder.

 French patent No. 2,191,550 of June 26, 1972 has already been proposed, in the name of the applicant, a mixture based on sand and a binder such as granulated blast furnace slag, a mixture in which an activating agent is incorporated. setting catalyst, said activator being composed of caustic soda dispersed in finely divided gypsum at a rate of 5 to 10% relative to the gypsum.

In the French patent No 2 428 629 of June 12, 1978 also
Lement in the name of the applicant, there has been described a process for preparing an activator, according to which instead of caustic soda, is incorporated into the finely divided gypsum, 10 to
24% sodium sulphate, 3.7 to 9% lime counted with CaO compared to gypsum.

In French Patent No. 2,390,392, a
another activator to accelerate the setting of the aforementioned mixture, such an activator consisting of a composition of gypsum and lime used in an amount of 6 to 15% relative to the gypsum.

 In all of these documents, the activators developed to accelerate setting give rise to hydraulic mixtures whose mechanical resistance characteristics, for an equivalent period of time, are not very far from each other.

In addition, in mixtures comprising crushed (fine) sands, it is known that the incorporation of these in an appropriate quantity improves the stability of the mixtures (ease of movement of vehicles and other vehicles) or their trafficability - before setting. , but also mechanical characteristics compressive strengths and tensile strength - after setting. However, when fines are introduced into a mixture. We are not absolutely certain that the arran
management of fine particles, is done properly; the finest elements filling the voids left by the coarsest elements. From a certain dimension the fine particles remain agglomerated, so that the accumulations of fines no longer serve to improve the stability of the mixture (increase in friction angle
internal and cohesion) because they can no longer enter voids that have become too small for them.

 These clumps of fines are even harmful because they are more fragile than grains of sand of the same size. In order to remedy the random nature of incorporation of fines in the mixtures, it has been proposed to incorporate deflocculating agents, dispersants, which are capable of destroying these clumps of fines. These agents are anionic tension-active agents. Their negative polarity plays an essential role in the deflocculation and dispersion phenomenon of clumps of fines (grain repulsion).

 In addition, these adjuvants, by their constitution allow to lower the interfacial tension which prevails between liquid phase and solid surfaces of the materials thus ensuring a better wettability of these and in particular of the binder. So its "reactivity" (hydration) is improved.

 These deflocculating, dispersing and wetting properties therefore lead to better organizing the "voids" of the material.

 Ùe more, these allow the plasticity (viscosity) equal to the initial fresh mixture, to significantly decrease (-5% to -8%) the amount of water used, It is known that 1 lowering the water ratio -binder, increases the mechanical resistance of the material (knowing that in any event, the amount of water used always remains above the theoretical amount of water necessary for the hydration of the binder).

 All of these properties, by synergy, converge towards improving the final characteristics of the material.

 Continuing this research in the area in question, (activator for mixtures based on sand, dairy or other pozzolanic materials) the Applicant has developed a new activator for accelerating the setting of the mixtures, which significantly improves the mechanical characteristics of the mixtures at issue compared to mixtures of the kind described in the aforementioned patents.

 The activator to accelerate the setting of a mixture based on sand and a binder such as granulated blast furnace slag or other pozzolanic material, said activator being of the type comprising a mixture of gypsum, optionally added, sodium sulphate, of lime, is characterized by the fact that a deflocculating product itself is added to it, consisting of at least one, but preferably two dispersing agents, wetting agents, of a type known as a fool.

 Advantageously, the deflocculating product added to the active ingredient comprises two dispersing and wetting agents known under the trade names DEFLOPAN NO 55 and DEFLOPAN NO 56 at a rate of 2 to 6% by weight relative to the activator.

 It is noted that the dispersing agents, wetting agents, are intimately mixed in proportions which will be indicated below in the activating gypsum sulphate of soda and lime, before the incorporation of the latter into the sand + slag mixtures.

Other characteristics and advantages of the invention will also emerge from the description which follows, given by way of example, without limitation, with reference to the appended drawings in which
FIG. 1 shows a series of curves illustrating the mechanical characteristics of tensile strength of a mixture in which an activator has been incorporated according to the invention, each curve relating to a particular composition of an activator;
Figure 2 is a view similar to the previous, but in which the curves give a compressive strength of a mixture comprising an activator according to the invention.

 It is specified that the deflocculating product preferably comprises two dispersing and wetting agents, as mentioned above, chosen from the following products used alone or as a mixture.

1. Llgnosulfonates: soluble salts of sodium, calcium, ammonium, lithium, ethanolamines, etc ... of lignosul fungal acids resulting from hot attack in acidic medium, bowls using bisulfite. These agents are mixtures of lignosulfonates which correspond to the following general formula:

 2. Polynaphthalene sulfonates: in the form of soluble salts of sodium, calcium, ammonium, lithium, ethanolamine, etc.

meeting the following general formula

 Other sulfonate polymers such as polymelamine formalin sulfonate, or polystyrene indene sulfonate or poly coumarone Indene sulfonate, etc.

 It is understood that the agent NO 55 corresponds to a lignosulfonate, calcium salt with an average molecular weight of 6,000 which is in the form of an anhydrous powder which is endowed with remarkable deflocculating and dispersing properties.

 Similarly, the agent NO 56 corresponds to a polynaphthalene sulfonate, in the form of the sodium salt (n = number of basic units comprised between 5 and 10), it is an anlonic surfactant sulfonate polymer endowed with deflocculating properties, dispersing and fluidifying.

 The deflocculating product (mixture of the two agents NO 55 and NO 56 mentioned above? Inserted into the activator to accelerate the setting of the mixtures, with the appearance of a powder easy to handle, so that the insertion into the activator is worked out.

 The deflocculating product resulting from the mixture of the two aforementioned agents (NO 55 + N 56) is advantageously used at a rate of 2 to 6% of the weight of the activator, which is itself used at a dosage comprised substantially between 0.5 and 1.5% of the total weight of the sand + slag + activator mixture.

Preferably, the deflocculating product inserted into the new activator according to the invention consists of 3/4 of agent
N 55 and 1/4 of agent N 56, and the product thus obtained is
Inserted at a rate of 2% to 6% in 94 to 98% of any activator mentioned above.

 Preferably, the deflocculating product obtained is used in an amount of 2% in 98% of any activator to thereby form a new activator to accelerate the setting of hydraulic binders, and this new activator is itself advantageously used in an amount of 0 , 8 to 1.2% in mixtures based on sands and a binder such as slag, artificial or natural pozzolans.

 On examination of the graphs illustrated in FIG. 1, recording the tests carried out in the laboratory, relating to the tensile strength, it is observed that the mechanical characteristics of the mixtures comprising an activator with deflocculating product are clearly superior both as regards the compressive strength, and tensile strength as those minted by the reference curve indicated by A, it being understood that the sand-slag granulated blast furnace mixtures, are similar to those described in French patent No 2,535,709 in the name from the applicant the mixture comprising for example 12% of granulated blast furnace slag.

 In FIG. 2, curves B, C, D and E respectively indicate the evolution of the characteristics of mechanical resistance to compression of a mixture up to 180 days, with an activator in which a mixture of the two NO agents has been incorporated. 55 and NO 56 at the rate of: 6% for curve B, 4% for curve D, 6% for curve E. For curve B the mixture of agents NO 55 and NO 56 was carried out at the rate of 1 / 3 for NO 56 and 2/3 for NO 55. For curve C, the agents were mixed at a rate of 1/3 for the NO 56 agent and 2/3 for the NO 55 agent; with regard to curve D, the agents were mixed at a rate of 1/4 for NO 56 and 3/4 for NO 55; and, finally, with regard to curve E, the mixture of agents NO 55 and NO 56 was carried out at a rate of 1/4 for NO 56 and 3/4 for NO 55.

 The curves shown in FIG. 2 indicate the characteristics of mechanical resistance, with of course mixing compositions identical to those indicated above, whether these are sand-granulated slag mixtures activating setting according to the invention, curve A being as in figure 1 the reference curve.

 Here too, it can be seen that the characteristics of mechanical resistance to compression are clearly improved compared to the reference curve A.

 It goes without saying that the invention is not limited to the embodiments described, but is on the contrary, susceptible of variant, without departing from the scope of the present Inventlon.

Claims (6)

 1. Activator intended to be incorporated into a mixture comprising at least one sand, and a binder such as granulated blast furnace slag or other pozzolanic material, to accelerate the setting of the binder, such an activator being based on gypsum possibly added with sulphate soda, lime, characterized by the fact of incorporating in said activator a deflocculating product itself advantageously constituted by at least two agents having dispersing and wetting properties of types known in soil.  2. Activating agent according to Claim 1, characterized in that the deflocculating product which it comprises is incorporated according to a range of 2 to 6%.  3. Activator according to any one of the preceding claims, characterized in that the deflocculating product is preferably incorporated at a rate of 2 to 6% of the weight of the activator and at a rate of 0.8 to 1.2% of the weight total of the mixture.  4. Activator according to any one of the preceding claims, characterized in that the deflocculant is chosen by the sulphate products used alone or as a mixture.  - Llgnosulfonates soluble sodium salts, calcium am monlum, lithium, ethanolamine, etc.  - Polynaphthalenes sulfonates soluble salts of sodium, calcium, ammonium, lithium, ethanolamines, etc ...  - Other synthetic polymers such as polymelamine formalin sulfonate, polystyrene indene sulfonate or poly coumarone Indene sulfonate.  5. Activator according to any one of the preceding claims, characterized in that the deflocculating agent consists of two adjuvants known in soil under the trade names DEFLOPAN NO 55 and DEFLOPAN NO 56.  6. Hydraulic binder of the type comprising at least one sand, and granulated slag from a blast furnace, or other pozzolans, characterized in that it comprises an activator obtained according to any one of the preceding claims.