FR3055132A1 - COMPOSITION FOR AN INSULATING MORTAR SUCH AS HEMP MORTAR, AND CORRESPONDING MORTAR - Google Patents

Abstract

The invention relates to a mortar obtained by mixing with water a binder composition, comprising at least one inorganic binder, and insulating aggregates. According to the invention, said insulating aggregates comprise a mixture of insulating plant origin, such as hemp, and insulator of mineral origin in the form of perlite.

Description

(54) COMPOSITION FOR INSULATING MORTAR SUCH AS HEMP MORTAR, AND CORRESPONDING MORTAR.

(© The invention relates to a mortar obtained by mixing with water a binder composition, comprising at least one mineral binder, and insulating aggregates.

According to the invention, said insulating aggregates comprise a mixture of insulator of plant origin, such as hemp, and insulator of mineral origin in the form of perlite.

FR 3 055 132 - A1

Composition for an insulating mortar such as a hemp mortar, and corresponding mortar

1. Field of the invention

The present invention relates to the field of production of materials for construction and renovation.

More specifically, the invention relates to plasters and mortars for the building industry.

The invention applies in particular, but not exclusively, to hemp plasters and mortars for the insulation, inside and outside, of new or existing buildings.

2. Solutions and disadvantages of the prior art

The evolving needs for materials compatible with sustainable construction, consumer expectations and regulatory requirements are causing eco-materials to arouse more and more interest.

Among these eco-materials, hemp mortars have been known for a very long time, and even since ancient times, where the component of hemp (in particular the "cord") is used as an aggregate, in whole or in part, in preparations .

It is recalled that a mortar with plant or bio-sourced aggregates is constituted by a dry mixture of binder, such as lime, cement or the like, and aggregate (s), such as hemp, to which water is added. of mixing at the time of its application, for example by projection, on an exterior or interior surface of a building. Such a mortar can also contain additives and / or adjuvants in particular.

Such a mortar is used in construction to bond building elements (bricks or blocks) and / or as a coating to cover the building elements. By the term plaster is meant a mortar composition intended to be applied in a layer, in one or more passes, on an exterior or interior surface.

The interest of these plant aggregate mortars lies in good thermal and acoustic insulation, combined with very good mechanical resistance and an advantageous carbon balance.

However, progress remains to be made in terms of thermal insulation and fire resistance, in the case of these mortars and plasters.

3. Statement of the invention

In this context, the subject of the present invention is a mortar obtained by mixing with water a binder composition comprising at least one mineral binder and insulating aggregates (or granular elements), in which said insulating aggregates comprise a mixture of insulation of plant origin, such as hemp, and insulation of mineral origin in the form of perlite.

In the present description, the term “coating or mortar” is used to designate the mixture obtained after mixing with water a dry composition of binder and of insulating aggregates.

It is therefore proposed an insulating mortar comprising a mixture of insulating material of plant origin, such as hemp, and insulating material of mineral origin in the form of perlite.

Such a dry insulating mortar is intended to be mixed with mixing water at the time of its application, for example by spraying, onto an exterior or interior surface of a building.

The addition of insulating material of plant origin, such as hemp, makes it possible to reduce the quantities of CO ₂ released into the atmosphere. The use of such a material reduces the carbon footprint and the environmental impact of the mortar.

Perlite is in the form of granules and is made from crushed siliceous volcanic rocks then heated between 900 and 1200 ° C, an operation during which the water chemically bound to the ore is released, which causes an expansion of the matter from 10 to 20 times its initial volume.

Perlite, which is non-combustible by nature, coats hemp which is sensitive to fire and thus constitutes and optimizes the fire resistance of the mortar of the invention, which constitutes a fire-resistant material.

Perlite also has a low thermal conductivity (between 0.04 and 0.06 Wm ” ¹ ^” ¹ ) and a low density or density, which allows the mortar to be used for thermal and sound insulation. It is also light, hard, durable and ecological.

The mortar of the invention is characterized in that its coefficient of thermal conductivity is low and of the order of 0.04 to 0.10 Wm ^_1 -K ^_1

This coefficient of thermal conductivity is, for example, between 0.05 to 0.065 Wm ^ -K ¹ .

By way of comparison, the coefficient of thermal conductivity of a conventional mortar is of the order of 0.55 to 0.95 Wm ^_1 -K ^_1 .

Such a mortar can be applied manually or by projection to thermally and acoustically insulate a wall from the inside or from the outside, in a building of old or new construction.

It can be applied on vertical, horizontal and oblique walls.

According to a particular aspect of the invention, the perlite is a double cooking perlite, called overcooked.

The mortar of the invention can comprise a so-called classic perlite, an overcooked perlite or else a perlite which has been triple fired.

The cooking temperature for perlite double or triple cooking is about the same. However, the cooking / cooling cycles are multiple and faster in the case of overcooked perlite, the rapid cooling producing a stronger expansion of the aggregate and this all the more if the operation is repeated at short intervals. In addition, cycling increases the abrasion resistance of the external surface of the aggregates thus obtained.

According to a particular aspect of the invention, the apparent density (or apparent density) of the overcooked perlite is between 0.05 and 0.08 g.cm ' ³ .

According to a particular aspect of the invention, the particle size of the overcooked perlite is between 150 and 250 μm (micrometer).

According to a particular aspect of the invention, the thermal conductivity (λ) of the overcooked perlite is between 0.03 and 0.035 Wm ^_1 -K ^_1 .

According to a particular aspect of the invention, the insulator of plant origin comprises dusted hemp hemp seed aggregates.

An advantage linked to the use of dust-free hemp aggregates is that they can be coated with better efficiency and a lesser amount of binder in the dusted aggregate.

In an alternative, the insulation of plant origin consists of miscanthus straw, or rapeseed straw.

According to a particular aspect of the invention, the particle size of the dusted hemp hemp seed aggregates is between 0.2 and 12 mm.

According to a particular aspect of the invention, the proportion of the insulator of vegetable origin and the insulator of mineral origin in the mixture is between 30 and 70% by volume.

According to a particular aspect of the invention, the binder composition comprises at least one fluidization adjuvant for said at least one mineral binder and / or at least one deflocculation adjuvant for said at least one mineral binder.

According to a particular aspect of the invention, said fluidization adjuvant is a first hydrophilic silica airgel.

According to a particular aspect of the invention, said deflocculation adjuvant is a second hydrophobic silica airgel.

According to a particular aspect of the invention, the composition comprises an equal proportion by volume of hydrophilic silica airgel and hydrophobic silica airgel.

According to a particular aspect of the invention, the hydrophilic silica airgel and / or the hydrophobic silica airgel represents (s) between 2 and 20% by volume of the binder composition.

According to a particular aspect of the invention, the binder composition comprises by volume:

- between 50 and 60% of hydraulic binder (s);

- between 10 and 20% cement;

- between 5 and 10% pozzolans;

- between 5 and 10% limestone powder, and

- optionally between 0.5 and 2% of conventional additives, such as plasticizers and / or air entrainers.

According to a particular aspect of the invention, said at least one hydraulic binder is chosen from natural hydraulic lime, cements such as Portland cement, hydraulic binders based on lime, or a mixture of these.

According to a particular aspect of the invention, said fluidization adjuvant and said deflocculation adjuvant are chosen from ethylene glycol, diethylene glycol, sodium silicates, and calcium silicates.

According to a particular aspect of the invention, the mortar comprises in mass:

-15% perlite,

- 50% of a binder composition as described above, and

- 35% of vegetable aggregates, such as hemp aggregates.

According to a particular aspect of the invention, the mortar comprises in volume:

- 45% perlite,

-10% of a binder composition as described above, and

- 45% of vegetable aggregates, such as hemp aggregates.

According to a particular aspect of the invention, the thermal conductivity (λ) of the mortar is between 0.04 and 0.10 Wm ^_1 -K ^_1 .

4. Detailed description

The insulating mortar according to the invention is obtained by mixing with water a composition of binder and insulating aggregates (granular elements), in which the granular elements comprise a mixture of insulating material of plant origin, such as only hemp, and mineral insulation in the form of perlite.

In other words, the aggregate comprises two insulating parts, namely a mineral insulator offering excellent fire resistance and advantageous thermal properties, and a vegetable insulator offering a good carbon balance.

The mineral insulator and the plant insulator each represent between 30 and 70% by volume of the total volume of the aggregates depending on the cost objectives (economic) and the thermal performance targeted. By way of example, the mineral insulator and the plant insulator each represent 50% of the total volume of the aggregates.

The mineral insulation is a perlite which is preferably overcooked to optimize its mechanical resistance / hardening.

Thus, the perlite used in the mortar of the invention is a perlite which has undergone a double or even a triple baking. The overcooked perlite thus obtained is not as brittle as a conventional perlite.

The overcooked perlite has, for example, an apparent density (density) between 0.05 and 0.08 g.cm ' ³ , a particle size between 150 and 250 pm (micrometer), and a thermal conductivity between 0.03 and 0.035 Wm ^_1 -K ^_1 .

The plant insulator consists of hemp herringbone-type aggregates, with a particle size between 0.2 mm and 12 mm and a thermal conductivity of the order of 0.065 Wm ^_1 -K ^_1 . Advantageously, these aggregates of hemp hemp seed are dusted.

The overcooked perlite brings an anti-fire treatment to the hemp and makes it possible to optimize the fire resistance of the latter, and therefore of the mortar.

The fire classification of the mortar of the invention is therefore close to incombustibility, its higher calorific value (PCS in English) being less than 500.

Plant-based insulation, for example hemp, optimizes the carbon balance of the mortar obtained.

In summary, the combined use of an insulator of vegetable origin and an insulator of mineral origin gives the mortar fire and thermal properties very advantageous compared to the mortars existing on the market.

With regard to the mortar binder, its composition comprises at least one mineral binder, at least one fluidization adjuvant for said at least one mineral binder and / or at least one deflocculation adjuvant for said at least one mineral binder.

In a first embodiment, the fluidization adjuvant is a first hydrophilic silica airgel and the deflocculation adjuvant is a second hydrophobic silica airgel, the binder composition comprising an equal proportion by volume of hydrophilic silica airgel and hydrophobic silica airgel.

The hydrophilic silica airgel is intended to capture water to optimize the wettability of the mineral binder, while the hemp is subjected to the hydrophobic faction of the hydrophobic silica airgel. This thus prevents the uptake of water by the hemp component. For example, it does not take up any humidity or rainwater.

By way of example, the binder composition comprises proportions by volume as follows:

- between 50 and 60% hydraulic lime;

- between 10 and 20% cement;

- between 5 and 10% pozzolans;

- between 5 and 10% limestone powder;

between 2 and 20% hydrophilic silica airgel and hydrophobic silica airgel distributed in equal volume, and

- optionally between 0.5 and 2% of adjuvants and additives conferring particular properties can be added in the composition of the binder. They may, for example, be plasticizers, water retaining agents, air entraining agents, water reducing plasticizers, hydrophobicizing agents (to optimize the impermeability and therefore the resistance to bad weather for example), water repellents, setting accelerators and / or setting retarders.

It should also be noted that the volume content of binder in the mortar is low.

Thus, the mortar is made up in volume:

- from 5 to 25% of binder, preferably 10%, and

- from 75 to 95% of insulating aggregates, preferably 90%, including 45% of perlite and 45% of hemp.

The composition of the binder makes it possible to reduce the amount of binder relative to the plant aggregates and thus to increase the insulation coefficient, and therefore the thermal performance, of the mortar of the invention.

The mortar is made in mass:

- from 30 to 60% of binder (with adjuvants), preferably 50%, with in particular 0.8% of silica airgel (0.4% hydrophilic and 0.4% hydrophobic),

- from 10 to 25% of perlite, and

- from 30 to 45% of hemp aggregates (preferably 15% of perlite and 35% of hemp hemp seed).

The thermal conductivity λ of the mortar of the invention is between 0.04 and 0.10 Wm ^_1 -K ^_1 , for example between 0.05 and 0.065 Wm ^_1 -K ^_1 .

Other aspects and variants

Such a mortar is applicable as a layer on a wall, to thermally and acoustically insulate the latter, from the inside or the outside.

It can also be applied on the underside of a slab and constitute a fire-resistant insulation for a garage, for example.

It is particularly suitable for the thermal rehabilitation of old buildings, of a historical nature in particular, but also for new construction buildings.

It allows the production of an insulating coating, inside and outside, on vertical, horizontal and oblique walls.

The thickness of the mortar layer on a surface is, for example, between 30 and 100 mm, or even 120 mm, in successive passes of 30 to 40 mm.

The mortar according to the invention can be applied manually to a surface or else sprayed with any type of mixing machine / sprayer, of the type comprising a mixing screw for example.

It can advantageously constitute additional insulation in the case of constructions made using masonry of the hemp block type, for example, having a thermal conductivity λ between 0.12 and 0.15 Wm ^_1 -K ^_1 , by limiting the total thickness and optimizing the thermal efficiency of the wall by the interior / exterior choice.

The dry mortar according to the invention can be transported in bags of 50 to 100 liters, or in a big bag of one to two cubic meters

In implementation alternatives, the hydrophilic silica airgel and the hydrophobic silica airgel can be used alone (with reduced effectiveness, however) in the binder composition.

In a second embodiment, the fluidization adjuvant and the deflocculation adjuvant are chosen from ethylene glycol, diethylene glycol, sodium silicates, and calcium silicates.

These adjuvants can thus be combined or used alone in the binder composition.

Those skilled in the art will be able to envisage and adapt these various combinations, as a function of the specific application envisaged, of their general knowledge, of this description and possibly of a few simple routine tests.

Claims (19)

1. Mortar obtained by mixing with water a binder composition, comprising at least one mineral binder, and insulating aggregates, characterized in that said insulating aggregates comprise a mixture of insulator of plant origin, such only hemp, and mineral insulation in the form of perlite. 2. Mortar according to claim 1, characterized in that the perlite is a double cooking perlite, called overcooked. 3. Mortar according to claim 2, characterized in that the apparent density of the overcooked perlite is between 0.05 and 0.08 g.cm ' ³ . 4. Mortar according to claim 2 or 3, characterized in that the particle size of the overcooked perlite is between 150 and 250 micrometers. 5. Mortar according to one of claims 2 to 4, characterized in that the thermal conductivity (λ) of the overcooked perlite is between 0.03 and 0.035 Wm ^ -K ¹ . 6. Mortar according to one of claims 1 to 5, characterized in that the insulator of plant origin comprises aggregates of hemp hemp dusted. 7. Mortar according to claim 6, characterized in that the particle size of the dusted hemp chinevotte aggregates is between 0.2 and 12 mm. 8. Mortar according to one of claims 1 to 7, characterized in that the proportion of the insulator of vegetable origin and the insulator of mineral origin in the mixture is between 30 and 70% by volume. 9. Mortar according to one of claims 1 to 8, characterized in that the binder composition comprises at least one fluidization adjuvant of said at least one mineral binder and / or at least one deflocculation adjuvant of said at least one mineral binder. 10. Mortar according to claim 9, characterized in that said fluidization adjuvant is a first hydrophilic silica airgel. 11. Mortar according to claim 9 or 10, characterized in that said deflocculation adjuvant is a second hydrophobic silica airgel. 12. Mortar according to claim 10 or 11, characterized in that the composition comprises an equal proportion by volume of hydrophilic silica airgel and hydrophobic silica airgel. 13. Mortar according to one of claims 10 to 12, characterized in that the hydrophilic silica airgel and / or the hydrophobic silica airgel represents (s) between 2 and 20% by volume of the binder composition. 14. Mortar according to claim 13, characterized in that the binder composition comprises by volume: - between 50 and 60% of hydraulic binder (s); - between 10 and 20% cement; - between 5 and 10% pozzolans; - between 5 and 10% limestone powder, and - optionally between 0.5 and 2% of conventional additives, such as plasticizers and / or air entrainers. 15. Mortar according to claim 14, characterized in that said at least one hydraulic binder is chosen from natural hydraulic lime, cements such as Portland cement, hydraulic binders based on lime, or a mixture of these . 16. Mortar according to claim 9, characterized in that said fluidization adjuvant and said deflocculation adjuvant are chosen from ethylene glycol, diethylene glycol, sodium silicates, and calcium silicates. 17. Mortar according to one of claims 1 to 16, characterized in that it comprises in mass: -15% periitis, - 50% of a binder composition according to one of claims 9 to 16, and - 35% of vegetable aggregates, such as hemp aggregates. 18. Mortar according to one of claims 1 to 17, characterized in that it comprises in volume: - 45% peri ite, -10% of a binder composition according to one of claims 9 to 16, and - 45% of vegetable aggregates, such as hemp aggregates. 19. Mortar according to one of claims 1 to 18, characterized in that its thermal conductivity (λ) is between 0.04 and 0.10 Wm ^_1 -K ^_1 .