METHOD FOR PRODUCING A CALCIUM HYDROXIDE-BASED CONSTRUCTION MATERIAL AND RESULTING CONSTRUCTION MATERIAL

Abstract

A budding material based on calcium hydroxide, in which the main component is lime of the type known as hydrated lime, which is mixed a filler of organic and/or mineral origin to produce a structural mass comprising of the basic component and the filler. A defined volume of water, calculated as a function of the volume of the structural mass, is added thereto to produce a paste that can be worked and is capable of hardening. To ensure setting of the material, an additive comprising at least one powder based on natural materials of volcanic origin is added to the pasty structural mass. The additive is preferably pozzolana and the filler advantageously comprises shavings or fibers of substances, preferably of vegetable origin such as hemp or wood.

Claims

1-14. (canceled)

15. A process for preparation of a building material based on calcium hydroxide, in which a main component is lime (hydrated lime), the process comprising: mixing a filler of at least one of organic origin and inorganic origin with the main component to produce a structural mass; adding to the structural mass a defined volume of water calculated as a function of a volume of the structural mass to produce a paste that can be worked and is capable of hardening; and adding an additive, comprising at least one powder based on natural materials of volcanic origin, to the structural mass.

16. The process according to claim 15, further comprising including at least pozzolana in the powder based on natural materials of volcanic origin.

17. The process according to claim 15, further comprising finely crushing the powder based on natural materials of volcanic origin into particles between 10 m and 500 m.

18. The process according to claim 15, further comprising including at least one of particles and fibers of vegetable origin in the filler mixed with the main component.

19. The process according to claim 18, further comprising including a proportion of the filler, in the form of hemp shavings, of between 20% and 200% of a weight of the main component.

20. The process according to claim 18, further comprising including a proportion of the powder based on natural materials of volcanic origin of between 5% and 25% of a weight of the main component.

21. The process according to claim 15, further comprising initially dry-mixing the main component, the filler and the additive before the water is added.

22. The process according to claim 15, further comprising dry-mixing the main component and the filler, then adding the water, and subsequently adding the additive.

23. A building material based on calcium hydroxide, the building material comprising: a main component of lime, and the lime being a hydrated lime; a filler of at least one of organic and mineral origin which is mixed with the main component to produce a structural mass which is completed with a defined volume of water, and that volume of water being calculated as a function of a mass of the structural mass to produce a paste that can be worked and that is capable of hardening; and an additive consisting of at east one powder based on natural materials of volcanic origin.

24. The building material based on calcium hydroxide according to claim 23, wherein the powder based on natural materials of volcanic origin contains at least pozzolana.

25. The building material based on calcium hydroxide according to claim 23, wherein the powder based on natural materials of volcanic origin is finely crushed and comprises particles of between 10 m and 500 m.

26. The building material based on calcium hydroxide according to claim 23, wherein the filler mixed with the main component contains either particles or fibers of vegetable origin.

27. The building material based on calcium hydroxide according to claim 23, wherein a proportion of the filler, which are in a form of either particles or fibers of vegetable origin, is between 20% and 200% of a weight of the main component.

28. The building material based on calcium hydroxide according to claim 23, wherein a proportion of the powder based on natural materials of volcanic origin is between 5% and 25% of a weight of the main component.

29. The building material based on calcium hydroxide according to claim 26, wherein the particles or fibers of vegetable origin are selected from the group consisting of hemp, kenaf, coconut and reeds.

30. A process of preparing a building material based on calcium hydroxide, the process comprising: dry mixing a main component and a filler, the main component being hydrated lime and the filler being at least one of organic and mineral origin to produce a structural mass; adding a defined volume of water to the structural mass to produce a paste that can be worked and is capable of hardening, and the defined volume of water being calculated as a function of a volume of the structural mass; and adding an additive, comprising natural materials of volcanic origin which have been crushed into a powder, to either the structural mass or the paste.

31. The process according to claim 30, further comprising crushing the natural materials of volcanic origin to a powder consisting of particles between approximately 10 m and 50 m in size.

32. The process according to claim 30, further comprising mixing the main component and the filler in a proportion of the filler being 50%-80% of a weight of the main component, and the filler being at least one of particles and fibers of vegetable origin

33. The process according to claim 30, further comprising adding the additive such that a proportion of the additive is 10%-20% of a weight of the main component, and the natural materials of volcanic origin comprises at least pozzolana.

34. The process according to claim 32, further comprising adding the additive such that a proportion of the additive is 10%-20% of the weight of the main component, and the natural materials of volcanic origin comprise at least pozzolana; and crushing the natural materials of volcanic origin to a powder comprising particles approximately between 10 m and 50 m in size.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention and its advantages will be better understood after reading the following detailed description of a method of carrying out the process, and of preferred embodiments of the building material.

[0027] Producing a building element by means of hard materials is often done using concrete. Concrete is an inert material which has very poor thermal insulation properties and which is incapable of absorbing and then releasing ambient humidity. As regards thermal insulation, a wall or any other building element intended for use in dwellings made of concrete must be associated with at least one insulation layer applied to the building element. This double production process is clearly expensive, mainly because of the labor involved, and its effectiveness is quite inadequate, particularly as regards its hydraulic characteristics for absorbing and releasing humidity and for constituting an absorber of moisture and heat with a view to regulating the temperature of a building.

[0028] It has been attempted to produce these characteristics by replacing the concrete with a composition based on calcium hydroxide, in particular mixed with a mineral filler such as sand, or an organic filler such as fibers or shavings of vegetable origin such as hemp, kenafknown as Deccan hempor even grass. The calcium hydroxide currently used in this context is hydraulic lime obtained from calcium carbonate Ca.sub.2O.sub.3, by calcining in a furnace at a high temperature between 1200 C. and 1500 C. The result of this treatment is to transform most of the calcium carbonate into hydraulic lime, but it also produces a certain amount of cement, called Portland cement, which is obtained by calcining calcium carbonate in a furnace at a temperature of the order of 1800 C. It is therefore a mixture of hydraulic lime and Portland cement which is usually used, which entails some degradation of the hydraulic properties of the lime due to the presence of the inert material in the form of Portland cement.

[0029] Owing to the presence of cement the setting of the mixture based on hydraulic lime is relatively rapid, so the material obtained can be used in essence like concrete to produce a screed or a faade cladding or the like. For example, a mixture made from hydraulic lime and organic shavings or fibers such as hemp is used as a fairly common building material and comprises between 40 and 70 Kg and preferably between 50 and 60 Kg of hydraulic lime for a quantity of organic constituents between 15 Kg and 25 Kg and preferably about 20 Kg. The specific mass of this mixture is relatively high and its thermal insulation capacity is relatively poor. For practical reasons the fact that hydraulic lime is used does not enable the density to be reduced and the insulating properties to be improved. Furthermore, 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 that hydrated lime possesses, namely the ability to absorb large amounts of carbon dioxide and thereby enabling the material to undergo natural carbonization by storing the excess CO.sub.2 in the atmosphere.

[0030] When hydrated lime is used the composition of the mixture is as follows: the main component is hydrated lime, the filler is in the form of mineral or organic particles in the form of shavings, in particular hemp shavings, and the additive is in the form of powders based on natural materials of volcanic origin, in particular pozzolana. The proportion of filler in the form of hemp shavings is between 20% and 200%, preferably between 50% and 80% of the weight of the main component, namely the hydrated lime. The said powder based on natural materials of volcanic origin is finely crushed and consists of particles between 10 m and 500 m and preferably between 10 m and 50 m. The proportion of the 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.

[0031] As an example, the composition of the building material according to the invention can be as follows; to 25 Kg of hydrated lime are added about 20 Kg of hemp and 3 Kg to 5 Kg of additives, for example pozzolana. The building material obtained has a lower density such that its specific weight is around 230 Kg/m.sup.3. Its heat insulating properties are improved, as also is its wettability and capacity for absorbing humidity. The additive considerably increases the bonding of the particles of hydrated lime and facilitates mixing during the preparation of the paste when the water is added. The mixture is more homogeneous and it is found that the formation of lumps that characterizes traditional preparations with hydrated lime does not take place in this case. The density of the material obtained is lower than when hydraulic lime is used. Hardening takes place partially, but sufficiently thanks to the volcanic additive. Complete hardening takes place in the course of time, in the form of natural carbonization by absorption of the carbon dioxide (CO.sub.2) present in the atmosphere.

[0032] The purpose of the present invention is to enable the use of hydrated lime or slaked lime as the basis for a building material with a sufficiently rapid setting time to enable industrial application. That rapidity is achieved thanks to the additive. Furthermore, hydrated lime is a cheap material found almost all over the world, even in non-industrialized countries which are not equipped for the production of cement. The buildings constructed are durable over time, because the carbonization of the hydrated lime takes place naturally thanks to natural exchanges and to the ambient humidity. The volcanic powder is a cheap material available at any volcanic location, whether extinct or active. The buildings are ecological, since they can be recycled, the gray energy is minimal and they are economical since the components can be found close to the building sites.

[0033] The invention is not limited to the use of hemp and pozzolana, but can be extended to similar materials that have the same characteristics.