FR2578187A1 - Use of tree bark, in the composition of novel construction materials, manufacturing methods and products obtained - Google Patents

Abstract

Novel construction materials containing bark. The invention relates to the composition of lightweight novel materials, containing a significant percentage of resinous or foliaceous bark, bound by an inorganic-based, air-cured or hydraulic binder, which exclusively provides cohesion thereof. This invention creates a novel outlet for the forestry industry, confronted with the problem of bark, a valueless and bulky waste product. At the same time it provides manufacturers of construction materials with quality products at a very competitive price, for acoustic, thermal and hygrometric insulation. The manufacture of these novel materials may be a manual cottage industry, or mechanical and industrial.

Description

USE OF TREE SKINS IN THE COMPOSITION OF NEW PRODUCTS
CONSTRUCTION MATERIALS. MANUFACTURING METHODS AND PRODUCTS
SO OBTAINED.

 The present invention relates to the composition of new materials, intended for the construction or maintenance of buildings. These materials having properties specifically sought and obtained, by incorporating, during their manufacture, a certain percentage of tree bark, crushed to various grinds.

The bark is defined as the outer part of the tree, which includes from outside to inside the barrel, what botanists call suber, periderm, liber and cam-bium.It constitutes 7 at 20% of the weight of the tree.

Wood utilization or processing industries: large sawmills, paper and cardboard mills, or cellulose and cellulose derivatives, are confronted with the problem of the accumulation of tree bark that they consume. This unavoidable by-product is considered to be a cumbersome waste, the disposal or disposal of which is expensive. The importance of this problem will be better understood, when it will be known, that in France, some factories produce more than 500 tons per month, stripped, and no recent estimate estimates to seven million tons the production of Ganada, and to more than five million tons that of the western United States.

Bark production remains constant according to volumes of treated wood. They must be collected and stored in huge heaps, which in some areas are reminiscent of the slag heaps of the mining countries.

For a long time, we have been looking for, not a solution, but solutions to this worrying problem. So far we have been able to use: as fuel, because in theory their calorific value is interesting, but there are serious disadvantages in practice. The bark being exposed to the weather, their moisture content is often very high (about 30% water). Their combustion causes the emission of abundant fumes, which cause fine particules, polluting the atmosphere in a large radius. The sulfur content of bark is not less than that of other fuels, and for all these reasons, specially designed boilers must be provided.

Their savage destruction, which consists in burning them in the open air, in vain, will not be tolerated very long, because of the pollution of the air and the ensuing water.

Either as compost, or as growing media, mixed with other products, after various treatments,
Either as a soil stabilizer or as a road stabilizer,
As litter, for poultry or livestock,
As an effluent treatment agent, thanks to their high adsorbent capacity,
Or, as panels in construction, furnishing or decoration.

But all the types of panels described in the literature to date, are presented as associations, between barks and - wood fibers, or sawdust to get to
variants / wood chipboards or dtagglo
-mere well known, - plastics (polyethylene, polypropylene, poly
-styrene, ...) to obtain injec molded plates
or pressed, - various synthetic resins or adhesives: phenolic acrylic, vinyl, cellulose, ......

cyclized or non-cyclic aldehydes (formaldehyde, trioxane, etc.),
which react hot, between 2000 and 3000C, and under strong
pressure, to give with the polyphenols contained in the
lignin bark, a natural binder, more or less accepted
-ble, formed "in stu".

- fiberglass, rockwool, felt, ....
all hot pressed.

The present invention will make it possible to use, as a raw material, important tonnages of decorations, to manufacture materials of entirely new design.

Indeed, it will never question employing binders or organic materials (resins, plastics, glues, ....) in the manufacturing processes that we will describe.

 There will never be any question of using wood, wood fiber, sawdust or flour, heart or beet waste, chips, celluloses or cellulosic derivatives, which many inventors have advocated or used in the past. construction, in combination with crushed bark, or as adjuvants of hydraulic mineral binders - or aerial.

The bark of trees, by their physical nature, and by their chemical composition, very different, products li -gneux constituants wood.

When lton wants to agglomerate bark to make panels, their lack of fibrous materials, makes their modulus of rupture low, and their cohesion random. On the other hand, their very high absorbency requires the use of very high percentages of resins or glues to obtain acceptable cohesion. They must also be treated to rid them of unacceptable impurities (earth, sand, foams, ...) and especially to dry them to make them compatible with the auxiliary solvents, or the diluents of the resins used.

These preparation and drying costs largely offset the advantage of their low price initially.

On the other hand, the bark has very interesting properties: - Thermal conductivity much lower than that of wood (this outer fabric of the tree has the role of protecting and isolating the wood), so excellent product iso -lant . (Example of a particular bark: cork.)
- Indifference to humidity, the barks are not hygroscopic like wood,
- Density lower than that of wood, lightening structures or incorporating them.

The present invention therefore seeks to use the bark to benefit from their excessively expensive cost price, and the specific qualities outlined above, while overcoming the deterrent disadvantage, that is their lack of cohesion.

It will not be necessary to clean, de-sand or even dry the bark, which may be used raw, in the processes described in the present invention.
PRINCIPLE: Moist barks (the percentage of water as such, may vary independently from 10 to 30%), gross (net -washed or not), crushed or crushed with variable grinding will be brought into contact with an aerial or hydraulic mineral binder in the presence of a quantity of make-up water, representing the difference, between the quantity of water necessary for the good setting of the binder, and the quantity of water provided by the humidity of the barks used.

The set: bark - mineral binder - make-up water, being properly mixed by mechanical means, then poured before setting; or appropriately squeezed to obtain plates or panels.

The inorganic binders selected in the present invention may be structural plasters, plaster casts or fine plasters of type T.H.D., as they are defined for example, in standards B of AFNOR.

The inorganic binders retained in the present invention may also be cements: various hydraulic binders such as Portland cements; blast furnace cements, slag cements, and generally the binders defined in the AFNOR standards, or the natural or artificial hydraulic lime defined in these same standards.

These binders may be used in the presence of other inorganic materials commonly used with them, such as sand (silica), silicates (talc, kaolin, etc.), calcium carbonate, titanium oxide. .......

The bark may come from deposits of bark of resi -neux (fir, Scots pine, Oregon pine, spruce, maritime pine, ...) or hardwood (oak, beech, chestnut, cherry, ...

We will describe below, by way of illustrative and non-limiting examples, preparations of materials made in the laboratory or semi-industrial, according to the invention.

A - EXAMPLE ACCORDING TO WHICH THE MATERIAL IS PREPARED WITH A
PLASTER TO MOLD LIKE BINDER. AFNOR NF B 12-302.

To facilitate the calculations, we will reduce the data to an implementation of: 1 kg of plaster.It is plaster MOLDA 3 NORMAL, with which a manufacture-control, will be carried out, under the same conditions, for comparison practical Tempering rates: Plaster / water being 1000/700 # 1.4. The dried and crushed bark is maritime pine.

Implementation: Witness. Example A.

Plaster Molda 3 Normal: 1.000, - g. . f, 000 g.

Water from the city: 700, - g. . 700, - g.

Bark. :. 250, - g.

Volume of the dry material: 1,000, - cc. . 1.410, - cc.

Weight of the dry material: 1.150, - g. . 1.270, - g.

Density obtained: 1.15. 0.90
Gain in volume: 410, - cc.

In this example the use of 250 g. dried bark, causes a volume gain of 410 cc. of material. According to the test, 410 g should have been used. additional plaster to achieve the same result.

One can establish a practical relation, saying that: 1 Kg.

 decors occupy a volume of: 410 x 1000/250 = 1.640 cc.

which corresponds to 1.640 g. plaster.

Bark weight (dry) in the material: 250 x 100 / 1.270 #i 19.7- g% g.

Tests performed by manual mixing, trowel.

B - EXAMPLE ON WHICH THE MATERIAL IS PREPARED WITH A
PLATE END OF CONSTRUCTION PFC 2. AFNOR NF B 12-301.

One kg of plaster, above, will be used with a water weight of: 800 g. Plaster / water mixing rate being: -1000/800 = 1.25.

This water will be constituted, at the same time, by batten coming from the barks used in the wet state, and by make-up water.

Implementation of 500 g. of fir bark of the Vosges at 22.4g% g. measured humidity. Either: 22.4 x 500/100 = 112 g of water from the bark and: 800 - 112 = 688 (## 700 g.) Extra fill.

This charge is mixed: 500 g. bark at 22.4% moisture plus 700 g. of water, plus 1,000 g. of plaster PFC 2, using an electric mixer, to obtain a paste of appearance and homogeneous consistency. The paste is cast on a glass plate, between steel rods, constituting a 2 cm mold. dtépaisseur. We make a plate of: 30 x 30 x 2 cm is: 1.800 cc. After drying at constant weight, the plate weighs 1.435 g. for a density of: 0.80. Weight of bark (dry) in the material: 500 - 112 = 388 x 100 / 1.435 = 27 g.
C - EXAMPLE ON WHICH THE MATERIAL IS PREPARED WITH A
PLATTER THD AFNOR NF B 12-303.

A plaster Kg. Above will be implemented as follows. Plaster / water mixing rate: 1000/600 = 1.66. Mixture of Scots pine (Massif Central) and maritime pine (Landes) bark, pre-conditioned for optimum moisture content: 31%, and finely crushed without grinding, with a sieve of 2 , 5 mm. (NF X 11-501).

The following charge is mixed in a mechanical kneader: 2,000 g. bark above and 1,000 g. of plaster above.

The plaster being sprinkled on the barks placed in the blaster. The whole is then emptied in a steel mold, and pressed, to give a plate of: 25 x 40 x 3.5 cm., A volume of: 3,500 cc.The water necessary for the setting of the plaster is exclusively from moisture barks: 31 x 2000/100 is: 620 g. theoretical. After drying at a constant weight, the above plate weighs: 2.555 g., For a density of 2555/3500, ie: 0.73, and a scouring rate (in seconds) of: 2000 - 620 = 138) x 100/2555 = 54 g,% g.

These three non-limiting examples show how a plaster of current quality, can be used as a binder, to cons-state, with tree bark as aggregates, a new lightened material. A pre-mixed product, consisting of plaster, was already known for at least 66% (expressed as S04Ca 1/2 H2O) and wood fibers, obtained from clean dry chips calibrated under the name "Gypsum wood". -fibered plaster "or Gypsum concrete", which could be translated as "plaster to wood fiber and plaster" This product is defined in the American standards ASTMC 28 and C 317, but it does not contain tree decorations , which we have seen, have properties and behavior very significantly different from those of wood fiber.

Other examples which follow, show in a nonlimiting way, how it is possible to use bark as aggregates, with hydraulic binders, to access pro-products homologous to those which have been prepared with plasters, in examples A, B, and C.

D - EXAMPLES ACCORDING TO WHICH THE MATERIAL IS PREPARED WITH A
HYDRAULIC BINDER. Defined by AFNOR NF P 15 standards.

A normal mortar is prepared: Standard NF P 15-403. Let Binder type CPA 55: 500 g. Dry normal sand (x3): 1,500 g. Mixing water (x0.5): 250 g. To this mortar, add, during three successive operations, and during mixing, the quantities of oak, crushed and dried, according to table
Surgery. Weight of scraps. . % bark / sec. Density material
Witness. O. 0. 2.14 (sec) n 1. 250 g (x 0.5 binder). 10%. 1.70 (sec) n 2. 500 g (x 1 binder). 19%. 1.55 (sec) n0 3. 750 g (x 1q5 binder). 26%. 1.25 (dry)
Thus, materials which after a setting, undisturbed by the presence of bark, show good cohesion, and good homogeneity of appearance, with a decrease in density, which is a function of the bark content in the dry material.

E - EXAMPLE ACCORDING TO WHICH THE MATERIAL IS PREPARED WITH LIME AS A HYDRAULIC BINDER. Lime slag cement CLX
Standard NF P 15-306. A mortar is prepared in the kneader in which wet bark of chestnut from the Pyrenees (17% of water) is introduced during mixing, so as to be in a ratio of 20% of dried bark for 80% binder as it is. A lightened material with a density of 1.30 is obtained and whose compressive strength after one month is close to 100 kg / cm 2.

This illustrative example was chosen from among others made with XHN natural hydraulic lime and XHA artificial hydrated lime, which give similar results.

F - EXAMPLE ON WHICH THE MATERIAL IS PREPARED WITH
COMPOUND MINERAL BINDERS, WITH AIR TAKING.

Sea pine barks, at 14% humidity, passing through a 2.5 mm sieve, are mixed with the mixer with Durcal OMYA-type calci-carbon carbonate, hydrated lime for masonry, (ASTM C 207 type). ), and wetted with a solution of sodium siliconate. A calcium siliconate gel is formed which has been adsorbed by the barks, and after pressing and drying the product in the air, it is possible to obtain hard-wearing plates which are perfectly hydrofugal. It can also keep this dough away from the air, and serve as waterproof mastic, to fill cracks, crevices, or cracks outside or inside buildings: ceilings, terraces, floors, walls, .... ..

The percentage bark (dry) can reach 10%, and form a tenuous structure, water repellent mass.

The products obtained, according to the invention, in the examples above, which are in no way limiting, may give rise to any desirable modification, by addition of semi-ordinary materials, the use of which is authorized and common in the building or construction. .

For example: addition of vermiculite or perlite in plaster, dolomites, calcites, dtalumines, pozzolans> silicas, insoluble silicates (talcs, kaolins, ...) in lime; accelerators or set retarders in cements (calcium chloride); white or colored mineral pigments (oxides, chromates) in all binders.

Claims (12)

 1) Composition of new construction materials, or maintenance of buildings, characterized by the fact that it contains a significant percentage of deciduous trees or deciduous trees in an aerial or hydraulic mineral binder excluding wood fibers and binders or organic glues that would ensure cohesion.  2) Composition according to claim 1, characterized in that the weight percentage of tree bark in the finished product is between 5 and 60 g% g. Value expressed in dry organic matter from bark.  3) Composition according to claim 1, characterized in that the barks are crushed and sieved after drying, for calibration mesh NF X 11-501, preferably between 12.5 mm and 2 mm.  4) Composition according to claim 1, characterized in that the barks are used raw, as they are on the deposit, wet and unsized.  5) Composition according to claims 1 to 4, charac-terized by the fact that the binder is plaster. Product defined by standards NF B 12 and ASTM Gypsum plastes.  6) Composition according to claims 1 to 4, charac-terized in that the binder is a hydraulic binder defined by standards NF P 15 and ASTM "Cements't.  7) Composition according to claims 1 to 4, charac-terized in that the binder is lime, defined by standards NF P 15 and ASTM "Llmes.  8) Composition according to claims 5,6,7, charac-terized by the fact that the binders can be used in combination with inorganic fillers normally allowed in the building: dolomites, calcites, aluminas, pozzolans, silicas, insoluble silicates ( kaolins, tales, clays, ...), vermiculite, perlite, pigments (oxides, chromates, ...), accelerators or retarders of setting, ...  9) Composition according to claims 1 to 8, characterized in that the manufacture is performed manually, trowel, from a bag containing the premixed conditioning, decorations and binder.  10) Composition according to claims 1 to 8, characterized in that its manufacture is carried out by mechanical mixing, pouring the product continuously on a conveyor belt, or discontinuously in molds.  11) Composition according to claims 1 to 8, characterized by the fact, that its manufacture is carried out by dusting the dry binder, in powder, on the wet barks; liteau contained in the barks used exclusively, the good setting of the binder, the assembly being molded and formed by a suitable pressing.  12) Composition according to claims 7 and 8, charac-terized by the fact that the barks are wetted with a solution of sodium or potassium siliconate, in the presence of free lime, to give-after pressing and air drying a water-repellent product, or to provide air-tight sealant for cracks and crevices.