EP3596025A1

EP3596025A1 - Curing agent for a cementitious formulation

Info

Publication number: EP3596025A1
Application number: EP18714574.3A
Authority: EP
Inventors: Emmanuel KEITA; Nicolas Roussel; Patrick Belin
Original assignee: Institut Francais des Sciences et Technologirs des Transports de lAmenagement et des Reseaux
Current assignee: Universite Gustave Eiffel
Priority date: 2017-03-15
Filing date: 2018-03-14
Publication date: 2020-01-22
Also published as: FR3064000B1; WO2018167425A1; FR3064000A1

Abstract

The invention relates to a cementitious formulation comprising a hydraulic binder, aggregates, water and a polymer having a molar mass within the range from approximately 50,000 g/mol to approximately 6,000,000 g/mol.

Description

Curing agent for cementitious 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 for reducing the water loss 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, loss of water can cause cracks. In practice, mortar screeds as well as large-surface constructions (road type, bridge deck, pavement) need to be protected against excessive evaporation of water before setting.

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

- Water regularly 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 of a protection (tarpaulin, fabric ..), which limits the water exchanges.

US Patent 5143780 discloses 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 swelling agent.

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

FR-A-2726264 discloses a curing agent for a cementitious composition, essentially comprising a water-soluble polyalkylene oxide and a superabsorbent material. According to the sole example of this patent application, a curing agent comprising 0.56% by weight of polyethylene oxide of molecular weight 4 000 000 is incorporated in a cement at a rate of not more than 1.5% by weight of the cement, 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%.

The patent application FR-A-2 975 096 describes a method for curing a concrete element, comprising at least partially covering the concrete element with a curing composition comprising from 40% to 99.9% by weight. mass of a solvent and from 0.1% to 5% by weight, expressed as solids, 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 cementitious formulation, in particular a mortar or concrete formulation, before making this by incorporating a polymer of specific molecular weight.

The invention thus relates, in a first aspect, to the use of a polymer having a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol, selected from polyethylene oxide, a cellulosic derivative, a polyvinyl alcohol or a mixture of these compounds, as a water evaporation reducing agent of a cementitious formulation comprising a hydraulic binder consisting of a cement and optionally one or more mineral additions, aggregates and water, said polymer being used in a proportion of about 0.1% to about 10% by weight relative to the water body of the cementitious formulation.

The invention also relates, in another aspect, to a cementitious formulation comprising:

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

(b) aggregates;

(c) water;

(d) from about 0.1% to about 10% by weight, based on the weight of water of the cementitious formulation, of a polyvinyl alcohol having a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol. The hydraulic binder used in the context of the present invention is a finely ground mineral material comprising a cement and optionally 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 about 100 kg to about 800 kg, preferably from about 100 kg to about 300 kg, more preferably from about 150 kg to about 300 kg of hydraulic binder per cubic meter of cementitious formulation.

The cement is typically a cement based on Portland clinker such as those defined in the EN 197-1 standard, or a sulfo-aluminous cement.

The mineral additions may be ground granulated blast furnace slags such as those defined in the EN 15167-1 standard, fly ash for concrete such as those defined in the EN 450-1 standard, silica fumes for concrete such as those defined in the EN 13263-1 standard, 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 NF P 18-509, any other finely divided mineral compound having binding properties in the cementitious 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 about 0.1 / 1 and about 4/1, preferably between about 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 the standard (s) EN 12620 and / or EN 13055-1; these are typically sands or chippings, whose diameter of the largest granulate is less than 25 mm. In one embodiment of the invention, the cementitious formulation comprises from about 500 kg to about 2000 kg, preferably from about 1000 kg to about 2000 kg, granules per cubic meter of cementitious 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, of 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 range from about 100,000 g / mol to about 1,000,000 g / mol. The cementitious formulation comprises from about 0.1% to about 10% by weight, preferably from about 0.1% to about 5% by weight, more preferably from about 0.5% to about 5% by weight. more preferably from about 1% to about 5% by weight of polymer relative to the weight 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 in the above range (about 0.1% to about 10% by weight of the water body). In another embodiment of the invention, the polymer is a polyvinyl alcohol. In another embodiment of the invention, the cellulose derivative is hydroxypropyl methylcellulose.

In the context of the invention, the term "cementitious formulation" means a fresh cementitious formulation, that is to say a formulation such as obtained after mixing the various constituents of the component, before drying and / or setting.

In one embodiment of the invention, the cementitious formulation may 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 EN 934-2. Superplasticizers may especially be of the family of polycarboxylates, polynaphthalenesulphonates, melamine sulphonates or lignosulphonates. As examples of superplasticizer, mention may be made of those sold under the name GLENIU®, the name CHRYSOFLUID®, the name VISCOCRETE® or the name MAPEFLUID®. Viscosity agents are colloidal compounds consisting of long chains of polymers that adhere to the periphery of water molecules and adsorb some 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-AR® 3 or the name VISCOSTAR 3K. The fibers that can be used in the context of the present invention are steel fibers or polymer fibers such as those defined in the standards EN 14889-1 and EN 14889-2. The mass proportion of additives, relative to the hydraulic binder, is preferably at most about 10%, and is preferably in the range of about 1% to about 5%.

The cementitious formulation according to the invention can be manufactured in a conventional manner by mixing the various constituents with the aid of a kneader provided for this purpose.

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

Thus, according to a second aspect, the invention relates to a dry premix for cementitious formulation, composed of a hydraulic binder, granulates, a polymer having a molar mass in the range of about 50,000 g / mol at about 6,000,000 g / mol, and possibly additives. The various constituents of the premix are as defined above with reference to the cementitious formulation, and are used in the proportions necessary for the production of a cementitious 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 that evaporates between setting up and setting the cementitious formulation. This makes it easier and more reliable to install construction materials on site. The benefits of this simplification include:

- we save a processing step (staff and time savings);

- there is no delay between the installation and the protection of 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, especially concrete, can be applied on vertical surfaces (wall).

The invention will be better understood with the aid of the following examples given by way of illustration. Example 1

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

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

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

HPMC = hydroxypropyl methylcellulose (with molar mass in g / mol) marketed by Dow Chemical Company

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

Table 1

Example 2

The percentage of evaporation of water at 12h was calculated from the mortars prepared in Example 1 by measuring the water loss of these mortars according to the protocol below. A cylinder 7 cm high and 4 cm in diameter was filled manually with the various prepared mortars. Light manual shocks were enough to make to go up the bubbles. The cylinder has been placed on a weigh scale which records the mass every minute. To ensure constant drying conditions during mass tracking, the assembly (sample and balance) was placed in a 50x70cm section channel fed by a dry air face at a fixed flow rate of 40 liters / minute. The loss of water was noted at 12h. The results are collated in Table 2.

Table 2

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

Example 3

Various mortars of composition indicated in Table 3 below were prepared according to the protocol of Example 1.

The amounts shown in Table 3 are percentages by weight (except of course the polymer / water ratio). The sand used is a sand of granulometry 1-4 mm (Sablière Palvadeau Les Douemes). The cement used is a sulfo-aluminous cement marketed by Vicat under the name Alpenat ™. The polymer used is a polyvinyl alcohol (PVA), with molar mass in g / mol, marketed by Sigma Aldrich.

The percentage of water evaporation reduction at 12 h was calculated from the mortars by measuring the water loss of these mortars, according to the protocol described in Example 2; the results are shown in Table 3.

Table 3

As can be seen, the evaporation of water is significantly reduced with the mortars of the invention compared to the reference mortar.

Claims

A cementitious formulation comprising:

(b) aggregates;

(c) water

(d) from about 0.1% to about 10% by weight, based on the weight of water of the cementitious formulation, of a polyvinyl alcohol having a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol.

The cementitious formulation of claim 1, wherein the cement is a Portland clinker or a sulfo-alumina cement.

The cementitious formulation according to one of claims 1 to 2, wherein the polyvinyl alcohol 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 from about 100,000 g / mol to about 3,000,000 g / mol.

4. Cementitious formulation according to one of claims 1 to 3, which comprises from about 100 kg to about 800 kg of hydraulic binder per cubic meter of cementitious formulation.

5. Cementitious formulation according to one of claims 1 to 4, which comprises from about 500 kg to about 2000 kg of aggregates per cubic meter of cementitious formulation.

6. Cementitious formulation according to one of claims 1 to 5, which is a mortar.

7. Cementitious formulation according to one of claims 1 to 5, which is a concrete.

8. Use of a polymer having a molar mass in the range of about 50,000 g / mol to about 6,000,000 g / mol, selected from polyethylene, a cellulose derivative, a polyvinyl alcohol or a mixture of these compounds, as a water evaporation reducing agent of a cementitious formulation comprising a hydraulic binder consisting of a cement and optionally one or more mineral additions , aggregates and water, said polymer being used in a proportion of about 0.1% to about 10% by weight relative to the water body of the cementitious formulation.

9. Use according to claim 8, wherein the cement of the cementitious formulation is a Portland clinker or a sulfo-aluminous cement.

10. Use according to one of claims 8 to 9, wherein the cellulose derivative is hydroxypropylmethylcellulose.

11. Use according to one of claims 8 to 9, wherein the polymer is a polyvinyl alcohol.

The use according to one of claims 8 to 11, 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 about 3,000,000 g / mol.

13. Use according to one of claims 8 to 12, wherein the cementitious formulation comprises from about 100 kg to about 800 kg of hydraulic binder per cubic meter of cementitious formulation.

14. Use according to one of claims 8 to 13, wherein the cementitious formulation comprises from about 500 kg to about 2000 kg of aggregates per cubic meter of cementitious formulation.

15. Use according to one of claims 8 to 14, wherein the cementitious formulation is a mortar.

16. Use according to one of claims 8 to 14, wherein the cementitious formulation is a concrete.