Peat is a type of soil consisting partly of transformed plant residues, and is found in wet areas such as bogs. Almost all peat is formed in acid conditions under water. The transformation itself of organic material into peat happens very slowly. The properties of the peat will to a great degree be determined by the plants which used to grow at the place. Usually peat is found in the tempered zone on the Northern hemisphere. Best known is the use of peat for roofing, or as a fuel after the peat is dried.

Peat provides a light, porous material when its moisture has been removed. Of course, dry peat will have properties which basically makes it suitable for many purposes, as building material among other things. As far as the applicant knows,

known trials of producing fibre boards and building insulation from peat have not proved particularly successful.

One reason is probably that it has not been possible to prevent such building materials of peat from absorbing moisture from the surroundings later.

The main object of the present invention is to provide an adequate building material from peat. This is realized by the present method of manufacturing building material such as an insulating material from peat. The peat used is preferably taken directly from the bog occurence. The novelty and particularity of the invention is that the peat is first converted into peat pellets/peat balls, the converted peat pellets/peat balls then being dehydrated until the remaining moisture is maximum 12 %, preferably 10-12 %. What happens next, is that the dehydrated peat pellets/peat balls are impregnated, whereafter the peat pellets/peat balls are dried. Thereby is avoided that the building material will absorb moisture from the surroundings later. Finally, impregnated and dried peat pellets/peat balls are glued together to the shape and size that the completed building material is supposed to have. Other advantageous details of the invention appear from the dependent claims and the following part of the specification.

One of the advantages of the invention is that the peat is first converted into peat pellets/peat balls, so that the building material, consisting of peat pellets/peat balls glued together, is only connected at points of contact between adjacent peat pellets/peat balls. Thereby the building material achieves increased porosity, becomes lighter and achieves a greater ability to resist the movements normally occurring in the construction in which the

building material is incorporated. Another and not less important advantage is that the peat pellets/peat balls are impregnated. This results in the building material not absorbing moisture from the surroundings later. Moreover, the quality of the impregnation will be a lot higher because of its taking place before the building material receives its final form and size in the gluing together. By selecting a convenient impregnation the building material may be provided with properties making the building material fire retarding, tight to diffusion, water-repellent, fungicidal etc.

In the following part of the specification it will be explained briefly how the building material in question is manufactured. Preferably the peat is taken directly from the bog occurence. It will not be explained in any further detail how this is done, since it is not part of the present invention. The present method starts by the peat first being converted into peat pellets/peat balls. This is done the most conveniently by the peat first being extruded to a peat string which preferably has a circular cross-section of a diameter of 2-10 mm. The peat string is then cut into peat cubes of lengths of 2-10 mm, whereafter the peat cubes are reshaped into peat pellets/peat balls by being passed through a rotating pipe. The pipe may for example have double rotation. The next thing to happen is that the converted peat pellets/peat balls are dehydrated until the remaining moisture is maximum 12 %, preferably 10-12 %. The dehydrating itself may be carried through in any suitable manner, such as by mechanical air-drying by ordinary air and by heated air.

It is also possible to dehydrate the peat pellets/peat balls during the above rotation in pipes by supply of heated air.

To prevent the building material from absorbing moisture from the surroundings later, the dehydrated peat pellets/peat

balls are impregnated by for example a wax emulsion of an suitable type. After application of the wax emulsion, the peat pellets/peat balls are dried in a micro wave oven for example. It all ends by impregnated and dried peat pellets/peat balls being glued together with an adhesive mixture suitable therefore, so that a building material of desired shape and thickness may be formed. In addition the impregnation may be such that the building material is fire retarding, tight to diffusion, water repellent, fungicidal, etc.

In this manner is provided an adequate building material which is meant, first and foremost, to be used as an insulating material. The building material may be used with advantage in co-operation with other building materials, such as wood and steel, to form carrying sandwich constructions such as wall and deck elements. In the production of sandwich construction peat pellets are glued together with the other comprised materials. The building material may also be used for the formation of wall and ceiling boards.