FR2633552A1 - Process for the manufacture of stabilised wood aggregates and stabilised wood aggregates thus manufactured - Google Patents

Abstract

The process is characterised in that the wood aggregates are treated with a suspension or a colloid of a salt or of a mixture of salts of aliphatic organic acids chosen from those whose chain is solely hydrocarbon-containing, simple or branched, saturated or unsaturated.

Description

The present invention relates to a method for manufacturing stabilized wood aggregates.

It also relates to wood aggregates stabilized and manufactured according to the process.

The stabilized wood aggregates, forming part of the present invention, are to be used for the manufacture of lightweight concrete,
This concrete can be used to make building elements either interior or exterior.

Lightweight wood concrete is currently used successfully for interior building components, but with much less success for exterior building components.

Indeed, the essential problem of concrete lightened to wood and exposed to external humidity is the swelling of the wood aggregates contained in said concrete.

This subjects the concrete to internal stresses and causes microcracks.

The patent FR 2 567 119 is known according to which the wood aggregates are first subjected to the following two waterings 1 / watering with a calcium solution, 2 / watering with a soluble silicate solution containing
suspension of silicon dioxide (insulation).

Once these two treatment steps have been carried out, the wood aggregates are plasticized and then subjected to a mixing bath with mixing (quicklime, blast furnace slag and silicon dioxide) to improve the ability to bind with hydraulic binders. .

The disadvantages of this process are as follows 1 / The insulation made by the second watering is not sufficient
fisante, which explains the plasticization.

2 / The thin plastic film can tear
during the squeezing and mixing, this exposes again
wood in the outside environment.

3 / Hanging of bathing products on the pelli
plastic material is poor.

4 / The risk of wood mold due to the lack of product to prevent it.

5 / The manufacturing cost is high given the number of operations to
carry out.

We also know the practice of treating wood aggregates which consists of spraying them with aluminum sulphate.

This treatment prevents wood from becoming moldy, but does not solve the swelling problem.

For these reasons, the present invention provides a simple process which definitively prevents the reactions of wood with respect to humidity while ensuring good adhesion of the aggregates treated with hydraulic binders.

To this end, the process forming part of the present invention consists in spraying the wood aggregates with a suspension or colloidal of salt or mixture of salts insoluble in cold water of organic acids chosen from those whose chain is only hydrocarbon, simple or branched, saturated or unsaturated.

The present invention will be better understood on reading the detailed description given below
As stated above, the process, which is part of the present invention, consists in treating the wood aggregates, in order to stabilize them, by a suspension or by a colloid of salt or mixture of salts insoluble in water. cold of aliphatic organic acids chosen from those the chain of which is solely hydraucarbonated, simple or branched, saturated or unsaturated.

The salt (s) to choose are those which are very lubricating to the touch, these insoluble salts in cold water can be of a mono or bivalent metal of aliphatic organic acids whose number of carbons is very variable ; in fact, the choice of this (these) salt (s) is based essentially on their physical characteristics, namely insolubility and touch.

These salts have the general formula (CnHmC02) 1M
where m - 2n-1, 2n or 2n41 and 1 is the valence of the metal M.

Our experiences have shown that stearic acid is very suitable.

These same experiments have also shown that the most suitable salts of this acid are
Calcium stearate: (CH3- (CH2) 16C02) 2Ca "
Zinc stearate s "(CH3- (CH2) 16-C02) 2-Zn" and
Cesium stearate: "CH3- (CH2) l6-Co2-CS-
According to the process forming part of the present invention, the wood aggregates can be treated with a suspension or with a colloid, of one of these three salts.

They can also be treated with a mixture of these salts in the form of a water-salt suspension or colloid.

 It should be noted that in the present description the terms "suspension" and "colloid" must always be understood as a "water-salt (s)" suspension and a "water-salt (s)" colloid.

According to the present process, the colloidal form is preferred because the particles of the salt (s) are much finer than those of the form of a suspension.

Our experiments have shown that a mixture of these three salts gives very satisfactory results, namely perfect sealing of wood aggregates preventing their swelling in a humid environment.

It should be noted that before the treatment of the wood aggregates, these are dried to reduce their relative humidity to a rate lower than 15 8 but preferably from 5 to 10%: this to increase their absorption power during the treatment.

An absorption made under these conditions causes the deposition of the salt (s) contained in the colloid or in the suspension to increase not only on the surface of the aggregates but also in the mass of said aggregates.

Once the treatment is done, the humidity of these aggregates is again reduced to its value before the treatment.

The term relative humidity "means the percentage of existing humidity in relation to the maximum humidity (100%) that these aggregates can reach.

According to the present process, it is preferable that these aggregates are treated beforehand with a product which prevents their organic degradation such as for example aluminum sulphate
A12 (S04) 3 commonly used for this purpose.

In the following we give an example of treatment of wood aggregates as a demonstration
EXAMPLE
The wood used is crushed, refined to have aggregates whose approximate dimensions are - length from 10 to 30 mm, - width from 3 to 10 mm, - thickness from 1 to 6 mm.

1 / The aggregates are dried to bring back their relative humidity
at a lower rate of 15% and preferably 5 to 10%.

One cubic meter of dried aggregate, of ordinary wood used
in this area weighs approximately 170 kg.

2 / The aggregates (1 cubic meter) are sprayed hot, i.e.
say at the end of drying with a sulfate solution
3.6 kg aluminum in 20 liters of water.

3 / The aggregates are dried again to remove the water used
used as solvent in step 2.

4 / These aggregates are sprayed again with a suspension
or a colloid containing
- 190 to 500 g and preferably 300 to 400 g of calcium stearate,
- 190 to 500 g and preferably 300 to 400 g of zinc stearate,
- 375 to 750 g and preferably 500 to 600 g of cesium stearate,
- 8 to 26 1 and preferably 12 to 20 l. Of water.

5 / The aggregates are dried again, to remove the water
used, in step (4), as a suspension or
colloid.

The aggregates produced according to the preceding stages are ready for use, that is to say to be mixed with the usual components (cement, gravel, water, additives, etc.) for the manufacture of concrete.

Concrete produced in this way has better thermal and sound insulation.

The incorporation of wood aggregates, manufactured according to the process forming part of the present invention, does not alter the mechanical characteristics of the concrete given the absence of swelling, this allows said concrete to be used as a support support.

An experiment was made with respect to the visible part of concrete aggregates, a flame was directed towards the concrete, it was found that the visible aggregates turn red without igniting when the temperature of the concrete surface reaches 1300C .

The stabilized wood aggregates, also forming part of the present invention, are characterized in that they are produced according to the present process.

Claims (5)

 1. A method of manufacturing stabilized wood aggregates characterized in that the wood aggregates are treated with a suspension or with a salt colloid or mixture of salts insoluble in cold water of aliphatic organic acids chosen from those whose chain is only hydrocarbon, simple or branched, saturated or unsaturated.  2. Manufacturing process according to R1 characterized in that the salt (s) used for said treatment is (are) one or a mixture of the following salts - calcium stearate, - zinc stearate , - cesium stearate.  3. Method according to R2 characterized in that a mixture of these three salts, in suspension or in colloidal state in water is used in the said treatment and in that the said mixture contains these salts in the following weight proportions - calcium stearate from 15 to 40%, - zinc stearate from 15 to 40%, - cesium stearate from 30 to 60%.  4. Method according to R3 according to which the wood aggregates are crushed, refined, dried and pulverized with an aluminum sulphate solution, method being characterized in that - the aggregates are dried to reach a moisture content  relatively less than 15 *, - the aggregates are sprayed with a suspension or a neck  bide containing  - 190 to 500 g of calcium stearate,  - 190 to 500 g of zinc stearate,  - 375 to 750 g of cesium stearate,  - 12 to 26 1 of water, this for each cubic meter of wood aggregates whose dimensions are approximately  - length from 10 to 30 mm,  - width from 3 to 10 mm,  - thickness from 1 to 6 mm,  - the aggregates are dried to remove the water used  as a suspension or colloid medium.  5. Stabilized wood aggregates, characterized in that they are manufactured according to any one of claims 1 to 4.