FR3064000A1 - CURE AGENT FOR CEMENTITIOUS FORMULATION - Google Patents

Abstract

The invention relates to a cementitious formulation comprising a hydraulic binder, aggregates, water and a polymer having a molecular weight in the range of about 50,000 g / mol to about 6,000,000 g / mol.

Description

Holder (s): FRENCH INSTITUTE OF SCIENCES AND TECHNOLOGIES OF TRANSPORTATION, PLANNING AND NETWORKS Public establishment.

Extension request (s): Polynesia-Fr

Agent (s): CABINET BEAU DE LOMENIE.

(54) CURE AGENT FOR CEMENT FORMULATION.

(5j) The invention relates to a cementitious formulation comprising a hydraulic binder, aggregates, water and a polymer having a molar mass in the range from about 50,000 g / mol to about 6,000,000 g / mol.

FR 3,064,000 - A1

i

Curing agent for cement formulation

Technical field of the invention

The present invention finds application in the field of building and construction. More particularly, the invention relates to cementitious preparations incorporating a curing agent making it possible to reduce the loss of water by evaporation of said preparations.

Technological background

The problem of curing concrete has always been a limitation in construction starts. It is particularly critical in situations of high water loss before setting, and for slow hydration concretes, which concerns a certain number of “environmental” formulas; the remaining water allowing the chemical reactions is then reduced. In addition, the loss of water can cause cracks. In practice, mortar screeds as well as large area constructions (road type, bridge deck, paving) need to be protected against excessive water evaporation before setting.

There are currently three main methods used to limit the evaporation of water in a cement or mortar:

- regularly water the surface with water, the amount of water in the material remaining constant despite the amount of water that evaporates;

- spray a curing agent on the surface to form a protective film and limit water exchange;

- cover the surface with protection (tarpaulin, fabric, etc.), which limits water exchange.

US Patent 5143780 describes a cement or concrete composite comprising a layer of cement or concrete and at least one outer layer consisting of a curing composition comprising cellulose fibers, water, a viscosity improving polymer and a hygroscopic blowing agent.

US patent 8404040 describes a process for curing a cement or a concrete which consists in applying to the surface of the cement or the concrete an emulsion comprising, inter alia, a hydrocarbon wax of paraffin and a saponifiable wax.

Patent application FR-A-2726264 describes a curing agent for a cement-based composition, essentially comprising a water-soluble polyalkylene oxide and a super-absorbent material. According to the only example of this patent application, a curing agent comprising 0.56% by mass of polyethylene oxide of molecular weight 4,000,000 is incorporated into a cement at a rate of at most 1.5% by cement mass, with a water / cement ratio equal to 0.5 or 0.54. The mass of polyethylene oxide relative to the mass of water present in the cement is therefore at most 0.017%.

Patent application FR-A-2 975 096 describes a process for curing a concrete element, comprising at least partial covering of the concrete element with a curing composition comprising from 40% to 99.9% in mass of a solvent and 0.1% to 5% by mass, expressed as dry extract, of a thickening agent (typically a gelling agent), which is insoluble in the solvent for a pH greater than 12 and which is soluble in the solvent for a pH range having an upper limit which is less than 11.

Description of the invention

It has now been discovered, and this is the basis of the invention, that it is possible to reduce the evaporation of water from a cement formulation, in particular a mortar or concrete formulation, before setting. this by incorporating a specific molecular weight polymer therein.

The invention therefore relates, according to a first object, to a cement formulation comprising:

(a) a hydraulic binder consisting of a cement and optionally of one or more mineral additions;

(b) aggregates;

(c) water;

(d) about 0.1% to about 10% by mass, based on the mass of water of the cement formulation, of a polymer having a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol, chosen from a polyethylene oxide, a cellulose derivative, a polyvinyl alcohol, or a mixture of these compounds.

The hydraulic binder used in the context of the present invention is a finely ground mineral material comprising a cement and possibly one or more mineral additions and which, mixed with water, hardens as a result of reactions and hydration processes. The hydraulic binder is advantageously in pulverulent form with a particle size such that at least 90% of the particles pass through a sieve of 200 μm (D ₉₀ <200 μm). In one embodiment of the invention, the cementitious formulation comprises from approximately 100 kg to approximately 800 kg, preferably from approximately 100 kg to approximately 300 kg, more preferably from approximately 150 kg to approximately 300 kg of hydraulic binder per cubic meter of cement formulation.

The cement is typically a Portland clinker cement such as those defined in standard EN 197-1.

The mineral additions may be granulated blast furnace slag such as those defined in standard EN 15167-1, fly ash for concrete such as those defined in standard EN 450-1, silica fumes for concrete such as those defined in standard EN 13263-1, metakaolins for concrete such as those defined in the draft standard NF P 18-513, limestone additions such as those defined in standard NF P 18-508, siliceous additions such as those defined in standard NF P 18-509, any other finely divided mineral compound having binding properties in the cement formulation of the invention, or any mixture of the aforementioned constituents.

When they are present in the hydraulic binder, the mineral additions are used in proportions such that their mass ratio to the cement is advantageously between approximately 0.1 / 1 and approximately 4/1, preferably between approximately 0.1 / 1 and about 3/1.

The aggregates used in the context of the present invention are natural, artificial or recycled granular materials of mineral origin, as defined in standard (s) EN 12620 and / or EN 13055-1; these are typically sands or gravel, the diameter of the largest aggregate of which is less than 25 mm. In one embodiment of the invention, the cement formulation comprises from approximately 500 kg to approximately 2000 kg, preferably from approximately 1000 kg to approximately 2000 kg, of aggregates per cubic meter of cement formulation.

The polymer used in the context of the present invention has a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol, preferably in the range of about 100,000 g / mol to about 5,000,000 g / mol, more preferably in the range of about 100,000 g / mol to about 4,000,000 g / mol, more preferably in the range of about 100,000 g / mol to about 3,000,000 g / mol, more preferably in the range of about 100,000 g / mol to about 1,000,000 g / mol. The cementitious formulation comprises from approximately 0.1% to approximately 10% by mass, preferably from approximately 0.1% to approximately 5% by mass, more preferably from approximately 0.5% to approximately 5% by mass , more preferably from about 1% to about 5% by mass, of polymer relative to the mass of water. In one embodiment of the invention, the polymer is a mixture of one or more of the above-mentioned compounds (polyethylene oxide, cellulose derivative, polyvinyl alcohol); in this embodiment, the total amount of polymers used should be within the above range (about 0.1% to about 10% by mass of the mass of water). In another embodiment of the invention, the cellulose derivative is hydroxypropylmethylcellulose.

In the context of the invention, "cement formulation" means a fresh cement formulation, that is to say a formulation as obtained after mixing the various constituents making it up, before drying and / or setting.

In one embodiment of the invention, the cementitious formulation can also comprise one or more additives, in particular fibers and / or organic compounds making it possible to modify the consistency of the formulation, such as viscosity agents (XP P 18- 340), setting or hardening accelerators, setting retarders, plasticizers or superplasticizers. These can be defined in standard EN 934-2. The superplasticizers can in particular be from the family of polycarboxylates, polynaphthalenes sulfonates, melamines sulfonates or lignosulfonates. As examples of superplasticizer, mention may be made of those sold under the name GLENIUM®, the name CHRYSOFLUID®, the name VISCOCRETE® or the name MAPEFLUID®. Viscosity agents are colloidal compounds made up of long chains of polymers which adhere to the periphery of water molecules and adsorb part of this water. As examples of viscosity agent, mention may be made of those sold under the name RHEOMAC®, the name CHRYSO®Plast V90, the name V-MAR® 3 or even the name VISCOSTAR 3K. The fibers which can be used in the context of the present invention are steel fibers or polymer fibers such as those defined in standards EN 14889-1 and EN 14889-2. The mass proportion of additives, relative to the hydraulic binder, is preferably at most equal to around 10%, and is preferably in the range from around 1% to around 5%.

The cementitious formulation in accordance with the invention can be manufactured in a conventional manner by mixing the various constituents using a mixer provided for this purpose.

The constituents necessary for the preparation of the cementitious formulation according to the invention can also be in the form of a dry premix to which water will be added on site.

Thus, according to a second aspect, the invention relates to a dry premix for cementitious formulation, composed of a hydraulic binder, of aggregates, of a polymer having a molar mass included in the range of approximately 50,000 g / mol at around 6,000,000 g / mol, and possibly additives. The various constituents of the premix are as defined above with reference to the cement formulation, and are used in the proportions necessary for producing a cement formulation according to the invention after addition of water.

The use of the above-mentioned polymer makes it possible to reduce the amount of water which evaporates between the placement and the setting of the cement formulation. This simplifies and makes the installation of construction materials easier and more reliable. The advantages of this simplification include the following:

- a processing step is saved (staff and time savings);

- there is no delay between placing and protecting the material;

- the protection against drying is complete even in situations where it is impossible to spray a liquid on the surface;

- a non-toxic / dangerous material (the polymer) is used;

- the cementitious formulation, in particular concrete, can be applied on vertical surfaces (wall).

Thus, according to a third aspect, the invention relates to the use of a polymer having a molar mass included in the range of approximately 50,000 g / mol to approximately 6,000,000 g / mol, chosen from a polyethylene oxide, a cellulose derivative, a polyvinyl alcohol or a mixture of these compounds, as a curing agent for a cement formulation comprising a hydraulic binder consisting of a cement and optionally of one or more mineral additions, aggregates and water, said polymer being used at a rate of approximately 0.1% to approximately 10% by mass relative to the mass of water in the cement formulation.

According to a fourth aspect, the invention relates to the use of a polymer having a molar mass comprised in the range of approximately 50,000 g / mol to approximately 6,000,000 g / mol, chosen from a polyethylene oxide, a derivative cellulosic, a polyvinyl alcohol or a mixture of these compounds, as an agent for reducing the water loss of a cement formulation comprising a hydraulic binder consisting of a cement and optionally of one or more mineral additions, aggregates and water, said polymer being used at a rate of approximately 0.1% to approximately 10% by mass relative to the mass of water in the cement formulation.

In these last two aspects of the invention, the various constituents of the cement formulation are as defined above with reference to the first aspect of the invention, and are used in the same proportions.

The invention will be better understood using the examples below given by way of illustration.

Example 1

Different mortars of the composition indicated in Table 1 below were prepared by mixing an aqueous polymer solution with water in sufficient quantity to have a W / C ratio = 0.4, then adding the cement to the liquid as well. obtained and mixing everything for about 1 min in a kneader, and finally by gradually adding the sand in the kneader (in about 30s), the kneading being continued for about 1 min. The aqueous polymer solution was previously prepared by dispersing said polymer in water, with stirring, for approximately 24 h. The reference mortar was prepared by mixing water, sand and cement in a mixer.

The amounts indicated in table 1 are percentages by mass (except of course the polymer / water ratio). The sand used is a sand with a particle size of 1-4 mm (Sablière Palvadeau Les Douemes). The cement used is a Portland cement equivalent to a NF EN 197-1 type 1 cement (St Vigor-Le Havre). The polymers used are as follows:

PEO = polyethylene oxide (with molar mass in g / mol) sold by Sigma Aldrich

HPMC = hydroxypropylmethylcellulose (with molar mass in g / mol) sold by Dow Chemical Company

PVA = polyvinyl alcohol (with molar mass in g / mol) sold by Sigma Aldrich.

Table 1

Ref. 1 2 3 4 5 6 7 8 Comp. sand 62.28 62.36 62.36 62.36 62.36 62.20 61.51 62.42 62.42 62,465 cement 26.95 26.86 26.86 26.86 26.86 26.86 26.86 26.86 26.86 26.86 water 10.77 10.67 10.67 10.67 10.67 10.67 10.67 10.67 10.67 10.67 PEO (5.00 E + 06) 0.11 PEO (4.00 E + 06) - - 0.11 - - - - - - - PEO (6.00 E + 05) 0.11 0.005 PEO (1.00 E + 05) - - - - 0.11 - - - - - PEO (6.00 E + 05) 0.27 PEO (1.00 E + 05) - - - - - - 0.96 - - - HPMC (5.76 E + 05) 0.05 PVA (1,30 E + 05) 0.05 Polymer / water - 1.0 1.0 1.0 1.0 2.50 9.0 0.5 0.5 0.05

Example 2

The water loss at 12 o'clock was measured from the mortars prepared in Example 1 according to the protocol below.

A cylinder 7 cm high and 4 cm in diameter was manually filled with the various prepared mortars. Light manual shocks were enough to cause the bubbles to rise. The cylinder was placed on a weigh scale which records the mass every minute. To ensure constant drying conditions during mass monitoring, the assembly (sample and balance) was placed in a 50x70cm section channel supplied by one side with dry air at a fixed flow rate of 40 liters / minute. The water loss was noted at 12 noon. The results are collated in Table 2.

Table 2

Water loss at 12 p.m. (g) % reduction evaporation by compared to the reference Reference 7.05 - 1 3.03 57.02 2 4.33 38.58 3 4.54 35.60 4 4.26 39.57 5 2.93 58.44 6 1.98 71.91 7 4.05 42.55 8 2.65 62.41 Comp. 6.70 4.96

As can be seen, the water loss is reduced significantly with the mortar of the invention compared to the reference mortar and the comparative mortar, the latter comprising 0.05% by mass of polymer relative to the mass of water.

Claims (15)

1. Cement formulation including: (a) a hydraulic binder consisting of a cement and optionally of one or more mineral additions; (b) aggregates; (c) water (d) about 0.1% to about 10% by mass, based on the mass of water of the cement formulation, of a polymer having a molecular weight in the range of about 50,000 g / mol to approximately 6,000,000 g / mol, chosen from a polyethylene oxide, a cellulose derivative, a polyvinyl alcohol or a mixture of these compounds. 2. Cement formulation according to claim 1, in which the cement is a Portland clinker. 3. Cement formulation according to claim 1 or claim 2, wherein the cellulosic derivative is hydroxypropylmethylcellulose. 4. Cement formulation according to one of claims 1 to 3, wherein the polymer has a molecular weight in the range of about 100,000 g / mol to about 5,000,000 g / mol, preferably in the range of about 100,000 g / mol to about 3,000,000 g / mol. 5. Cement formulation according to one of claims 1 to 4, which comprises from about 100 kg to about 800 kg of hydraulic binder per cubic meter of cement formulation. 6. Cement formulation according to one of claims 1 to 5, which comprises from approximately 500 kg to approximately 2000 kg of aggregates per cubic meter of cement formulation. 7. Cement formulation according to one of claims 1 to 6, which is a mortar. 8. Cement formulation according to one of claims 1 to 6, which is a concrete. 9. Use of a polymer having a molar mass in the range of approximately 50,000 g / mol to approximately 6,000,000 g / mol, chosen from a polyethylene oxide, a cellulose derivative, a polyvinyl alcohol or a mixture of these compounds, as a curing agent for a cementitious formulation comprising a hydraulic binder consisting of a cement and optionally of one or more mineral additions, aggregates and water, said polymer being used at a rate of approximately 0, 1% to about 10% by mass relative to the mass of water in the cement formulation. 10. Use of a polymer having a molar mass in the range of approximately 50,000 g / mol to approximately 6,000,000 g / mol, chosen from a polyethylene oxide, a cellulose derivative, a polyvinyl alcohol or a mixture of these compounds, as an agent for reducing the water loss of a cement formulation comprising a hydraulic binder consisting of a cement and optionally of one or more mineral additions, aggregates and water, said polymer being used for about 0.1% to about 10% by mass based on the mass of water in the cement formulation. 11. Use according to claim 9 or claim 10, in which the cement of the cement formulation is a Portland clinker. 12. Use according to one of claims 9 to 11, in which the cellulose derivative is hydroxypropylmethylcellulose. 13. Use according to one of claims 9 to 12, wherein the polymer has a molar mass in the range of about 100,000 g / mol to about 5,000,000 g / mol, preferably in the range of about 100,000 g / mol to approximately 3,000,000 g / mol. 14. Use according to one of claims 9 to 13, wherein the cement formulation is a mortar. 15. Use according to one of claims 9 to 13, in which the cement formulation is a concrete.