EP3152182A1

EP3152182A1 - Method for producing a calcium hydroxide-based construction material and resulting construction material

Info

Publication number: EP3152182A1
Application number: EP15736171.8A
Authority: EP
Inventors: Jordan WOLF; Jorgen HEMPEL
Original assignee: Hempel Familienstiftung
Current assignee: Hempel Familienstiftung
Priority date: 2014-06-04
Filing date: 2015-06-03
Publication date: 2017-04-12
Also published as: CH709733A1; US20170183264A1; WO2015184559A1; CH709733B1; US10266451B2

Abstract

The invention relates to a calcium hydroxide-based construction material in which the main component is calcium hydroxide, referred to as "hydrated lime", which is mixed with an organic and/or inorganic filler in order to produce a structural mass consisting of said basic component and said filler. A predetermined volume of water is added to said structural mass, which is calculated on the basis of the volume of said structural mass and is added in order to produce a paste that is workable and capable of hardening. To ensure that the mixture sets, an additive consisting of at least one powder made from volcanic natural materials is added. The filler is advantageously made from substance chips or fibres, preferably plant substances, such as hemp or wood, and the additive is preferably made of pozzolana. There are two alternative methods for providing said material: the main component, the filler and the additive are initially dry-mixed before the water is added, or the main component and the filler are dry-mixed, the water is added and then the additive is added.

Description

METHOD FOR MAKING A LIME-BASED CONSTRUCTION MATERIAL AND BUILDING MATERIAL OBTAINED

Technical area

The present invention relates to a process for the preparation of a building material based on lime, in which the main component is lime called "hydrated lime" to which is mixed a filler of organic and / or mineral origin to achieve a structural mass to which is added a determined volume of water calculated according to the volume of said structural mass to produce a curable and curable paste.

It also relates to a lime-based building material, in which the main component is lime called "hydrated lime" mixed with a filler of organic and / or mineral origin to produce a structural mass to which a determined volume is added. of water, this volume being calculated according to the mass of said structural mass to produce a curable and curable paste. Prior art

The construction of lime-based structures has taken on a certain magnitude since the builders have realized that this material has exceptional qualities in terms of both sound insulation and thermal insulation and concerning hydraulic exchanges. Lime and particle or fiber blends have been developed, including but not limited to wood chips and hemp fibers to make screeds, partitions, insulating liners for doubling existing walls, bulkhead fills for wooden frame houses. The results are indisputable, so that this material certainly has a secure future if we consider changing buildings to ecological solutions, looking for simple, natural methods to make recyclable products, promoting energy saving.

To date, a material known as hydraulic lime which contains substantially between 10 and 20% of clay and which is calcium carbonate which has been heated in an oven at a temperature of the order of 1200 ° C., is commonly used, and in any case less than 1500 ° C. However, some of the natural lime transformed into hydrated lime, however, has already been transformed into cement, known as Portland cement, during the process. As a result, the resulting material, whose setting is relatively fast, becomes partially inert and partially loses the desired characteristics, namely:

- that which allows it to become a hydraulic buffer by absorbing moisture and restoring it thereafter, thus playing the role of thermal regulator; and

- that which allows it to absorb carbon dioxide in relatively large amount so as to cause natural carbonation and progressive hardening over time.

In addition, it should be noted that hydraulic lime is a processed product that is commonly found only in industrialized countries and is indisputably more expensive than hydrated lime, almost natural worldwide, at low cost. The problem of hydrated lime is that of taking this material for its hardening. Currently this catch is very slow, which constitutes a handicap for the use of the material, in spite of the advantages that it presents elsewhere. As a result, it is almost unusable in practice.

German Patent No. 16753, of 1881, discloses a method of manufacturing a mass for the construction of parts of a building, including a fire blanket and a floor. The mixture of materials as described by this patent and in particular by the two claims 1 and 2 comprises inter alia in particular slaked lime and cement added components relatively disparate, minerals such as gypsum, chalk, sand and organic such as blood. The presence of cement has the advantage of accelerating the hardening of the mass, but a major disadvantage of preventing the natural carbonation of lime which has the advantage of being achieved through a natural and progressive absorption of carbon dioxide. As a result, the method described does not meet the problem solved by the present invention.

DISCLOSURE OF THE INVENTION The present invention proposes to overcome the aforementioned drawbacks by providing a method which makes it possible to solve the problem of the curing time of the construction material obtained, by accelerating the setting of the hydrated lime. The process makes this material advantageous for its hydraulic and thermal qualities, compatible with industrial use and allows it to retain the absorption capacity of carbon dioxide for natural carbonation.

This object is achieved by the process according to the invention as defined by the preamble, characterized in that an additive in the form of a mixture of mineral substances, comprising in its composition at least at least one composition, is added to said structural mass. a powder made from natural materials of volcanic origin.

In a preferential manner, said powder based on natural materials of volcanic origin contains at least pozzolan.

Advantageously, said powder based on natural materials of volcanic origin is finely ground and consists of particles between 10 μηη and 500 μηι and preferably between 10 m and 50 μιτι. According to a preferred embodiment said charge mixed with said main component comprises particles and / or plant fibers. The proportion of filler in the form of hemp chips is advantageously between 20% and 200% and preferably between 50% and 80% of the weight of the main component. The proportion of said powder based on natural materials of volcanic origin is advantageously between 5% and 25% and preferably between 10% and 20% of the weight of the main component.

The main component, the filler and the additive are advantageously initially mixed dry before the addition of water.

According to a particularly advantageous embodiment, the main component and the filler are mixed, then the water is added and finally the additive is added later.

The building material based on lime, according to the invention is characterized in that it comprises an additive composed of at least one powder based on natural materials of volcanic origin. Preferably, said powder based on natural materials of volcanic origin comprises at least pozzolan.

Said powder based on natural materials of volcanic origin is preferably finely ground and consists of particles of between 10 .mu.m and 500 .mu.m and preferably between 10 .mu.m and 50 .mu.m.

Said filler mixed with said main component advantageously comprises particles and / or plant fibers, in particular particles or vegetable fibers consist of products chosen from the group consisting of wood, hemp, kenaf, coconut, reeds.

According to a preferred embodiment, making it possible to produce an effective building material in terms of thermal and hydraulic qualities, economical and easy to implement, said charge mixed with said main component comprises hemp chips.

The proportion of filler in the form of hemp chips is advantageously between 20% and 200% and preferably between 50% and 80% of the weight of the main component.

The proportion of said powder based on natural materials of volcanic origin is advantageously between 5% and 25% and preferably between 10% and 20% of the weight of the main component.

The present invention and its advantages will be better understood on reading the detailed description of an embodiment of the method and preferred embodiments of the building material.

The construction of a building element using hard materials is often done using concrete. Concrete is an inert material that has very poor thermal insulation capabilities and is unable to absorb and then restore ambient moisture. With regard to thermal insulation, a wall, or any other element of construction intended for a concrete dwelling use, must necessarily be associated with at least one insulation layer reported on the building element. This dual realization is obviously costly in particular manpower and its effectiveness, particularly as regards the hydraulic characteristics to absorb and restore moisture and constitute a hydraulic buffer and thermal for regulating the temperature of a building, is completely ineffective.

It has been attempted to find this characteristic by replacing the concrete with a composition based on lime, mixed in particular with a mineral filler such as sand or vegetable such as for example fibers or chips of plant origin, such as hemp, kenaf, called Deccan hemp or even grass. The lime commonly used in this context is hydraulic lime obtained from calcium carbonate Ca 2 O 3, treated in a furnace. high temperature, between 1200 ° C and 1500 ° C. This treatment has the effect of mainly transforming calcium carbonate into hydraulic lime, but also produces a certain amount of Portland cement cement, which is obtained by a treatment of calcium carbonate in an oven at a temperature of the order of 1800 ° C. It is therefore a mixture of hydraulic lime and Portland cement that is usually used, resulting in some degradation of the hydraulic qualities of the lime, due to the presence of the inert material in the form of Portland cement. Due to the presence of cement the setting of the hydraulic lime mixture is relatively fast, so that the material obtained can be used substantially as concrete to make a screed or a facade cladding or the like. For example, a mixture made from hydraulic lime and chips or organic fibers such as hemp and used as a common construction material, has between 40 Kg and 70 Kg and preferably between 50 Kg and 60 Kg. hydraulic lime for an amount of organic elements of between 15 Kg and 25 Kg and preferably about 20 Kg. The specific gravity of this mixture is relatively high and its thermal insulation capacity is relatively low. For practical reasons, the use of hydraulic lime does not reduce the density and increase the insulating characteristics. In addition the use of hydraulic lime increases the cost of the building material. Finally, hydraulic lime, which is an inert material, does not have the absorption capacity of hydrated lime, namely that of absorbing large quantities of carbon dioxide and subjecting the material to natural carbonation while by storing the excess CO2 contained in the atmosphere.

When hydrated lime is used, the composition of the mixture is as follows: the main component is the hydrated lime, the filler in the form of inorganic or organic particles in the form of chips, in particular hemp chips and the additive in the form of powders based on natural materials of volcanic origin, including pozzolana. The proportion of The filler in the form of hemp chips is between 20% and 200% and preferably between 50% and 80% of the weight of the component, namely the hydrated lime. Said powder based on natural materials of volcanic origin is finely ground and consists of particles of between 10 .mu.m and 500 .mu.m and preferably between 10 .mu.m and 50 .mu.m. The proportion of said powder based on natural materials of volcanic origin is between 5% and 25% and preferably between 10% and 20% of the weight of the main component.

By way of example, the composition of the construction material according to the invention can be as follows: for 25 kg of hydrated lime to which approximately 20 kg of hemp and 3 kg to 5 kg of additives, for example pozzolan. The resulting building material has a reduced density, so that its weight is about 230 Kg / m ³ . Its thermal insulation qualities are increased, as well as its wettability and its ability to absorb moisture. The additive significantly increases the binding of hydrated lime particles, facilitates mixing during the preparation of the "dough" at the time of the addition of water. The mixture is more homogeneous and it is found that the formation of "pellets" which characterizes traditional preparations with hydraulic lime is not done in this case. The density of the material obtained is lower than that produced with hydraulic lime. The hardening is partially, but sufficiently thanks to the volcanic additive. The complete hardening is carried out over time, in the form of natural carbonation, by absorption of the carbon dioxide (CO2) contained in the atmosphere.

The object of the invention is to allow the use of hydrated lime, or slaked lime as a base of a building material with a setting time fast enough to allow industrial application. This speed is achieved thanks to the additive. In addition hydrated lime is an economical material and is found virtually worldwide, even in non-industrialized countries that are not equipped to manufacture cement. The qualities of the realized constructions are durable in time, because the carbonation hydrated lime occurs naturally thanks to natural exchanges and humidity. Volcanic powder is an economic material present on all ancient or active volcanic sites. Buildings are environmentally friendly because they are recyclable, gray energy is minimal, and they are economical because components can be found near construction sites.

The invention is not limited to the use of hemp and pozzolan, but can be extended to similar materials having the same characteristics.

Claims

claims

1. Process for the preparation of a building material based on lime, in which the main component is lime called "hydrated lime" to which a filler of organic and / or mineral origin is mixed to produce a structural mass to which adds a determined volume of water calculated as a function of the volume of said structural mass to produce a moldable and hardenable paste, characterized in that an additive composed of at least one powder based on natural materials is added to said structural mass; of volcanic origin.

2. Method according to claim 1, characterized in that said powder based on natural materials of volcanic origin comprises at least pozzolan.

3. Method according to claim 1 or 2, characterized in that said powder based on natural materials of volcanic origin is finely ground and consists of particles of between 10 .mu.m and 500 .mu.m and preferably between 10 .mu.m and 50 .mu.m. .

4. Method according to any one of the preceding claims, characterized in that said charge mixed with said main component comprises particles and / or plant fibers.

5. Method according to claim 4, characterized in that the proportion of said filler in the form of hemp chips is between 20% and 200% and preferably between 5% and 80% of the weight of the main component.

6. Method according to claim 4, characterized in that the proportion of said powder based on natural materials of volcanic origin is between 5% and 25% and preferably between 10% and 20% of the weight of the main component.

7. Method according to claim 1, characterized in that the main component, the filler and the additive are initially mixed dry before the addition of water.

8. Method according to claim 1, characterized in that the main component and the filler are mixed dry, in that the water is added and the additive is added later.

9. Building material based on lime, in which the main component is lime called "hydrated lime" mixed with a filler of organic and / or mineral origin to achieve a structural mass supplemented by a given volume of water, this volume being calculated as a function of the mass of said structural mass to produce a moldable and curable paste, characterized in that it comprises an additive composed of at least one powder based on natural materials of volcanic origin.

10. lime-based building material according to claim 9, characterized in that said powder based on natural materials of volcanic origin comprises at least pozzolan.

1. A lime-based building material according to claim 9, characterized in that said natural powder of volcanic origin is finely ground and consists of particles of between 10 μm and 500 μm and preferably between 10 μm and 50 μm.

12. Lime-based building material according to one of the preceding claims 9 to 11, characterized in that said filler mixed with said main component comprises particles or plant fibers, especially chosen from the group consisting of wood, hemp, kenaf, coconut, reeds.

13. lime-based building material according to claim 9, characterized in that the proportion of filler in the form of particles or plant fibers is between 20% and 200% and preferably between 5% and 80% by weight of the main component.

14. lime-based building material according to claim 9, characterized in that the proportion of said powder based on natural materials of volcanic origin is between 5% and 25% and preferably between 10% and 20% of the weight of the main component.