Natural construction materials

Constructible ground

It is a mixture of Sable S, Silt and Argile S in the approximate proportions of ½, 1/3, 1/6, of Humus and Colloïde S other than clay; the ideal mixture is a structure of large granules, increasingly small spaces being filled of granules. The whole is bound thanks to a thin layer of clay and water on each granule. The presence of gravel S will be more or less important according to the use considered, of the gravels being acceptable in a paving stone in beaten Ground (often built on a Hérisson makes of a bed of large gravels without filling).

Sands

They are granules of Silice or of quartz, with sometimes of the pulverized calcic rocks, measuring between 5 mm and 0,06 Misters the grains are visible with the naked eye. The sand of Sea, being round, is useful for the Maçonnerie, but on the other hand it is not good for the Enduit S. the stream sand is pointed and offers in its open structures space for the silt and clay to contribute to cohesion. The structure of sands thus stabilized can resist the compressive forces well.

Silt

It is the muddy part, especially made up of particles of silica or of quartz of diameter ranging between 0,06 mm and 0,002 Misters Cela is presented in the form of a layer of too fine particles to be seen separately. Its contribution to the stability of a ground is due to its internal friction by filling the openings in sands. In excess, it increases the permeability of the ground.

Clays

They are particles (or Micelle S) of Aluminosilicate S hydrated of size <2µ (0,002 mm). They have a surface specific infinitely larger than those of coarse particles going from 10 to 800 m ² /g. We can consider 2 groups of clays. Those which do not inflate much with water, rather represented by the kaolinites, and those which inflate, represented in our area rather by argilo-limestones or Montmorillonite S and Illite S. the presence of inflating the disorder water where they are dispersed during more than 10 minutes. For construction we need stable materials; we thus seek a maximum of Kaolinite S.

The electrostatic forces which bind clay micelles ensure the cohesion of the ground mainly.

Water

The reactions between the Water and the matters which constitute the ground, including the possible impurities present in the ground, explain all qualities and imperfections which we can detect.

The water of Pluie is better since it utilizes Ion S OH-- in the bonds between clay micelles which become more sticking. This effect can be obtained by adding Défloculant S, such as the Soude and the Sodium silicate at a rate of 0,1 to clay 0,4%, or by replacing water completely with humic Acide, Tannic acid or Urine of Cheval. These substances make it possible to employ less water, gives less withdrawal and a faster drying. The act of malaxation more or less also distributes clay micelles in the mixture. This penetration takes a certain time, which can be reduced by a fine grinding. Dry clay is rigid like concrete. The addition of water provides a plastic material which one calls Torchis. More water gives a barbotine less and less sticking up to the point of saturation where that becomes turbid water.

Until saturation, the addition of water to sand makes it more cohesive. The silt reacts in the same way. This reaction, with that of the clay which returns it slipping more, gives consistency to the mortar. The combination of a ground barbotine or clay, sands and silt gives us a mortar. The moisture of sand and water in barbotine must be taken into account to obtain a mortar having the good proportions and a good consistency.

Salts in water or the ground can involve efflorescences which will damage coatings in Chaux, Ciment or Plâtre in contact with the ground but not the coatings out of ground.

Implementation

Stabilization

Stabilization is not an obligation but it can be useful in difficult circumstances. It can offer an improvement of the strength to erosion, the distortion or moisture. We can add 20 to 30 kg of fibers to m3 of ground. The Dung of the animals, the Blood of Ox, the Flour of Rye, the Sap S of plants, the oxidizing Oil S, are some of the products used like stabilizing. The use of stabilizing mineral such as lime and cement is effective only in particular cases but they are absorbent, which attracts moisture and they are colder with the touch than the ground. Moreover they even limit remove the fact that the ground is a material entirely which can be recycled.

Cob

Cob is the rough constructible ground mixed with water until obtaining a flexible consistency, handled with the hand or the feet. It was traditionally mixed with a little Paille or envelope (the ball) of cereals and filled the Colombage S or of the moulds of bricks adobe.

The rough ground is improved by the addition of sand or clay to obtain the optimal proportions (1/2 sand, 1/3 silt, 1/6 clay).

sand that François found at the edge of the river was rather well proportioned out of clay to use it in the state for its coating.

All the fibers good are once dried. One adds some from 5 to 10% to the ground to stabilize cob. The optimal length is around the thickness of the place of employment.

Cob is manufactured in pit or in a kneader or a specialized mixer. It is too firm to be made in a concrete-mixer. It has a good resistance in compression. It is little Isolant, like full stones or cooked bricks, but it constitutes a good thermal mass.

Adding water to cob it becomes mortar which can be made in a concrete-mixer and applies to the Truelle. With sand round one poses bricks, stones and tiles. With pointed sand, it is for the coatings.

reference: Treaty of Construction out of Ground - CRATerre - Brackets

Mix ground-chips

The ground-chips mixture is a composite which contains much load, granules, sheets or fibers; bituminous mix of little ground (clay), typically 90%. The chips come from waste of the wood work. It can be sold in prefabricated panels (see http://www.akterre.com/), or get busy to make the puddled earth reduced.

The ground-straw is a mixture traditionally employed in Normandy, manufactured with long straws coated with ground barbotine. It is mixed with the fork or with a specialized mixer.

The ground-chips mixtures can be made in a concrete-mixer. They are not very resistant mechanically. They are very insulating but they contribute little to thermal inertia. They have good qualities of insulation Acoustique and research suggests that the size of the chips and the ground mass employed influence the frequency of the sounds which are reduced.

Fiber addition

The fibers employed in ground construction are of all kinds. The straw, the hay, the grass of the Pampa, the ball, the cluster of flax or hemp, the nettles and the shavings all are useful. They bring the flexibility and resistance to the composite which contains them (see below).

As opposed to what one believes, the fibers contribute only seldom by their resistance to the stretching; they are the weak bonds between the fibers and stamps it (ground), which oblige the microscopic cracks to go in all the directions when the material undergoes external forces. The microscopic cracks absorb the energy which would have caused a large crack. The mass does not fissure right through.

The weakness gives the flexibility which resists better.

The straw slips, the grass of the pampa clings

This paradox is explained in mechanics by the transition from the elastic state towards the plastic state. It is the principle of all composite materials including cob.

Cob, wood, the Os and the Cuir are among the most powerful composites, and they are renewable.

Use of the wood of coppice

The coppice is a practice of culture of the trees which was known by Romans. There are coppices in Europe which are collected since the Moyen-âge. The ripe trees are cut and the remaining stocks give the rejections which are collected (each year for the wickers but on 20 to 35 years for the wood of Charpente). The rejections are managed to obtain a small number of beautiful bits. This cycle of production has been maintained for at least 800 years without negative effect, neither on harvest, nor on the environment. The mineralization of the ground increases year by year by the mineral contribution concentrated in the sheets, drawn increasingly deep by the roots. The unhewn timber thus collected pre-is sawn with a Band saw and so desired cut with the Herminette or the Doloire. It provides the bars from 10 to 20 cm square, often with its curved form in a plan, but right in the other.

reference: the Chestnut, a tree, a wood - Catherine Bourgeois - IDF

Random links: