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Title:
STABILIZED BLOCK OF COMPRESSED EARTH
Document Type and Number:
WIPO Patent Application WO/2017/013484
Kind Code:
A1
Abstract:
The present invention refers to a stabilized block of com¬ pressed earth (1) for constructing a wall (100) of a building comprising : - a first layer (L1) comprising a mixture (M) of earth (E) and cement (C), said mixture (M) exhibiting a first pro- portion by weight (Tl) of cement (C) based on the weight of the mixture (M), - a second layer (L2) intended to form a superficial face (F) of the earth block (1), said second layer (L2) exhibiting a second proportion by weight (T2) of cement (C), greater than the first proportion by weight (T2) of cement (C) of the mixture (M). The present invention also relates to a method of making such an earth block as well as a wall comprising a plurality of such earth blocks (1).

Inventors:
LECOMET GILLES (FR)
GAGEY FABRICE (FR)
SERCLERAT IVAN (FR)
Application Number:
PCT/IB2016/001032
Publication Date:
January 26, 2017
Filing Date:
July 21, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
LAFARGE SA (FR)
International Classes:
E04C1/40
Domestic Patent References:
WO2008062299A22008-05-29
Foreign References:
FR493005A1919-07-29
FR535789A1922-04-21
FR967174A1950-10-27
EP1525967A12005-04-27
FR2638187A11990-04-27
BE347083A
Other References:
None
Attorney, Agent or Firm:
KESCHMANN, Marc (AT)
Download PDF:
Claims:
Claims :

1. A stabilized block of compressed earth (1) for the construction of a wall (100) of a building comprising:

- a first layer (LI) comprising a mixture (M) of earth (E) and cement (C) , said mixture (M) presenting a first proportion by weight (Tl) of cement (C) based on the weight of the mixture (M) ,

- a second layer (L2) intended to form a superficial face (F) of the earth block (1), said second layer (L2) exhibiting a second proportion by weight (T2) of cement (C) , greater than the first proportion by weight (Tl) of cement (C) of the mixture (M) .

2. The earth block (1) according to claim 1, in which the first proportion by weight (Tl) of cement (C) is between 2 and 12%, preferably from 5 to 8%.

3. The earth block (1) according to claim 1 or 2, in which the second layer (L2) only comprises cement (C) .

4. The earth block (1) according to claim 3, in which the second layer (L2) exhibits a maximum thickness of less than 2 mm.

5. The earth block (1) according to anyone of claims 1 to 4, in which the cement (C) of the second layer (L2) comprises a waterproofing agent.

6. A method of making an earth block (1) comprising the following steps:

(i) providing a mold (10) , (ii) forming in the mold (10) a first layer (LI) com¬ prising a mixture ( ) of dampened earth (E) and cement (C) , said mixture (M) presenting a first proportion by weight (Tl) of cement (C) based on the weight of the mixture (M) ,

(iii) covering an apparent surface (S) of the mixture (M) in the mold (10) with a second layer (L2) intended to form a superficial face (F) of the earth block (1), said second layer (L2) exhibiting a second proportion by weight (T2) of cement (C) , greater than the first proportion by weight (Tl) of cement (C) of the mixture (M) ,

(iv) pressing the earth block (1) inside the mold

(10).

7. The method according to claim 6, in which the apparent surface (S) of the first layer (LI) is leveled in the mold (10) .

8. The method according to claim 6 or 7, in which the second layer (L2) is distributed homogeneously on the surface of the first layer (Ll) .

9. The method according to anyone of claims 6 to 8, in which the earth block (1) is cured in wet atmosphere.

10. A wall (100) comprising a plurality of earth blocks (1) according to anyone of claims 1 to 5, all of the superficial faces (F) of the second layer (L2) of said plurality of earth blocks (1) being orientated on the same side (0) of the wall (100) .

Description:
STABILIZED BLOCK OF COMPRESSED EARTH

The present invention relates to the technical field of construction and more specifically to a stabilized block of compressed earth as well as a method for making such an earth block.

Earth is still widely used in certain locations of the world as constructing material for dwellings.

One of the most commonly used methods consists of molding wet soil to form blocks of earth and then drying these blocks in the sun.

These blocks are inexpensive and allow do-it-yourself construction .

However, these earth blocks present irregularities in their shape as well as limited durability due to their inability to prevent the earth from absorbing water, thus transforming the earth into mud.

This results in the construction of poor-quality dwellings, which suffer from severe damage in the event of rain, flooding and seismic events.

One of the solutions to this problem consists of adding a low proportion of cement to the soil, compacting the mixture in a press to ensure a controlled geometry and then curing the block under wet conditions to enable the cement to hydrate. These blocks, known as "Compacted Stabilized Earth Blocks," or CSEB, present more uniform shapes and greater durability than simple blocks of earth.

In particular, the part of the block in contact with water no longer turns into mud.

However, these compacted stabilized earth blocks become wet when in contact with water, which reduces their durability.

The usual solutions for reinforcing the surface of these blocks use varnish or organic waterproofing agents.

These solutions are expensive and have to be repeated periodically.

The present invention aims to resolve the disadvantages mentioned above either partially or completely.

For this purpose, the present invention refers to an earth block for constructing a wall of a building comprising:

- a first layer comprising a mixture of earth and cement, said mixture exhibiting a first proportion by weight of cement based on the weight of the mixture,

- a second layer intended to form a superficial face of the earth block, said second layer exhibiting a second proportion by weight of cement greater than the first proportion by weight of cement of the mixture.

This second layer considerably reduces the water absorption capacity of the superficial face of the earth block.

Thus, by placing the earth block in the wall such that the superficial face of the earth block is orientated towards the outside of the building, it is possible to considerably reduce the earth block's water absorption capacity, particularly during bad weather or flooding, and to thus keep most of the block dry, which contributes to solving the problem of unsanitary conditions inside the building.

According to one preferred embodiment of the invention, the first proportion by weight of cement is between 2 and 12%, preferably from 5 to 8%.

According to another preferred embodiment of the invention, the second layer only comprises cement.

This arrangement further reduces the earth block' s water absorption capacity by the superficial face of the second layer .

According to another preferred embodiment of the invention, the second layer exhibits a maximum thickness of less than 2 mm.

This arrangement enables a minimum amount of cement to be used to form the second layer so as to not significantly increase the costs of making earth blocks.

According to another preferred embodiment of the invention, the cement of the second layer comprises a waterproofing agent .

This arrangement further reduces the earth block' s water absorption capacity by the superficial face of the second layer . Another object of the present invention is a method of mak ¬ ing an earth block comprising the following steps:

- providing a mold,

- forming a first layer in the mold comprising a mix ¬ ture of dampened earth and cement, said mixture exhibiting a first proportion by weight of cement based on the weight of the mixture,

- covering an apparent surface of the mixture in the mold with a second layer intended to form a superficial face of the earth block, said second layer presenting a second proportion by weight of cement greater than the first proportion by weight of cement of the mixture,

- pressing the earth block inside the mold.

The mixture of dampened earth and cement of the first layer is the result of a mechanical blending of earth with cement .

According to one preferred embodiment of the method, the apparent surface of the first layer is leveled in the mold.

According to another preferred embodiment of the method, the second layer is distributed homogeneously on the surface of the first layer.

According to another preferred embodiment of the method, the earth block is cured in wet atmosphere.

Another object of the present invention is a wall comprising a plurality of earth blocks as described previously, all of the superficial faces of the second layer of said plurality of earth blocks being orientated on the same side of the wall. In any case, the invention will be better understood using the following description, with reference to the attached schematic drawing representing, by way of non-limiting example, an example of an earth block according to the invention.

Figure 1 is a schematic cross-sectional view of an earth block according to the invention.

Figure 2 represents the different steps of a method of making an earth block according to a preferred embodiment of the invention.

Figure 3 represents a cross sectional view of a wall according to the invention.

As illustrated in Figure 1, an earth block 1 for constructing a wall 100 of a building according to the invention preferably presents a substantially parallelepiped shape and comprises a first layer LI and a second layer L2 of materials .

The first layer LI is different from the second layer L2.

The first layer LI extends over a large part of the height of earth block 1 and comprises a mixture M of earth E and cement C.

This mixture M exhibits a first proportion by weight Tl of cement C based on the weight of the mixture M.

The first proportion by weight Tl of cement is between 2 and 12%, preferably from 5 to 8%. This first proportion by weight Tl of cement depends on the nature of the earth used to make earth block 1.

The best results are obtained with earth containing both a clay fraction and a sandy fraction.

In one embodiment, the second layer L2 of earth block 1 only comprises cement C. The second proportion by weight T2 of cement C is then equal to 100%.

In this embodiment, the second layer L2 extends over a small part of the height of earth block 1, typically less than 2 mm.

In the case where the second layer L2 also comprises earth, the thickness of this second layer L2 can be in the centimeter range.

The second layer L2 can also comprise a waterproofing agent .

This second layer L2 is intended to form a superficial face F of earth block 1.

As illustrated in Figure 3, in a wall 100 comprising a plurality of earth blocks 1 according to the invention, all of the superficial faces F of the second layer L2 of this plurality of earth blocks 1 are orientated on the same side of the wall, this side corresponding to the outer side 0 of wall 100 of a dwelling, this outer side 0 being opposite to the inner side I of the dwelling wall. Each of these superficial faces F forms a water barrier by limiting the earth blocks' capacity to absorb water through these superficial faces F and through the second layer L2.

The present invention also relates to a method of making an earth block 1.

As illustrated in Figure 2, in a preferred embodiment of the method, the method comprises several well-defined steps .

In a first step (i) , a mold 10 is required to give the earth block 1 the desired shape and to ensure reproducibility of the shape of earth block 1.

In a second step (ii) a determined weight of a mixture of dampened earth T and cement C is introduced in mold 10 so as to form a first layer LI of materials for earth block 1.

This mixture M presents a first proportion by weight Tl of cement C based on the weight of the mixture M.

This mixture M is deposited in mold 100 so as to give a certain flatness to the apparent surface S of mixture M.

In a third step (iii) , the apparent surface S of mixture M in mold 10 is covered with a second layer L2 intended to form a superficial face S of earth block 1.

This second layer L2 exhibits a second proportion by weight T2 of cement greater than the first proportion by weight Tl of cement C of mixture M. In a fourth step (iv), earth block 1 is pressed inside mold 10 by using a press.11.

In a subsequent step, earth block 1 is removed from mold 10 and cured in wet atmosphere.

In the case where the second layer L2 only comprises cement, the humidity of the mixture used to make earth layer LI is enough to hydrate the cement used in the first layer LI and in the second layer L2.

The cement thus hydrated and hardened gives the material its water resistant properties.

The method is repeated as many times as necessary to create a sufficient quantity of blocks 1 to erect the wall 100.

Although the invention has been described in connection to particular examples of embodiment, it is obvious that it is not limited to these examples and that the invention, comprises all technical equivalents of the means described as well as their combinations.