Abstract:
The invention relates to a brick ( 1 ) made from a material comprising vegetable fibres agglomerated using a binder (such as hemp concrete), said brick being provided with a groove ( 9, 11 ) and a tongue ( 5, 7 ) allowing the dry-joint connection of bricks. The invention also relates to a method for constructing a building using such bricks.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to the field of construction. More specifically, it relates to a method for making a building from prefabricated and interlocking elementary bricks, made from a material comprising plant fibers (hemp, straw, flax, etc.) agglomerated using a binder (in particular dirt, non-hydraulic or hydraulic lime). 
       BRIEF DESCRIPTION OF RELATED ART 
       [0002]    The use of plant fibers to construct buildings, and more specifically to produce walls and partitions, has been known for some time. Examples include laterite mud, made up of a matrix of clay (or more generally dirt) and agglomerated plant fibers (in particular straw). 
         [0003]    Hemp fibers have also been used in construction. One traditional technique consists of preparing a concrete (commonly, although wrongly, called hemp “concrete”) in situ from a plant aggregate (hemp chaff) and a binder (non-hydraulic or hydraulic lime), and filling a wooden framework wall using such a concrete. 
         [0004]    Hemp concrete may also be used to produce concrete slabs, insulating coats, or insulation per se, which is for example poured into the rakes of a roof before placing a cover. 
         [0005]    A number of recipes and applications exist for hemp concrete. The  Association Construire en Chanvre  specifically defined hemp concrete and formulated professional rules for building with hemp concrete. These rules were published in a volume entitled  Construire en Chanvre  (ISBN 978-2-915162-92-9). For an exhaustive list of works, articles and publications relative to hemp-based construction, see the bibliography published on the Association&#39;s website: http://www.construction-chanvre.asso.fr/. 
         [0006]    While the ordinary techniques, today offered by several companies (including the company BCB, which offers hemp concrete under the Tradical registered trademark), may be deemed satisfactory in terms of mechanical, acoustic and thermal performance (greater than or equal to that of ordinary quarry stone constructions), they are nevertheless flawed by a high degree of technicality and difficult implementation, which limit their use to building professionals. 
         [0007]    Techniques have been proposed to resolve these drawbacks and democratize the use of hemp in construction. One of these techniques, described in French patent application FR 2 871 487 in the name of the company Développement Construction Ecologique (see also the American equivalent US 2008/272270), consists of making a wall from prefabricated blocks that are assembled in situ. These blocks are provided with vertical shafts in which wooden posts are inserted to form a framework. The shafts are then sealed in the blocks using a filler, such as a binder of the lime milk type. 
         [0008]    It is true that the use of prefabricated blocks makes it possible to save on the on-site preparation of the hemp concrete. However, the savings are marginal, since the insertion, then sealing of many posts in the shafts of the blocks are lengthy and tedious operations, which also require the in situ preparation of a large quantity of binder. 
         [0009]    Due to the aforementioned drawbacks of the known techniques, including the most recent, the share of hemp concrete in construction is progressing little if at all, traditional quarry stone construction continuing to represent the vast majority of the market. 
       BRIEF SUMMARY 
       [0010]    The invention aims to improve the use of plant fibers (in particular hemp) in construction, by proposing an implementation that is both simple and fast, capable of equaling or even surpassing the ordinary construction techniques (in particular terra cotta bricks or cement concrete quarry stone). 
         [0011]    To that end, the invention first proposes a method for constructing a building using prefabricated bricks made from a material (such as hemp concrete) comprising plant fibers agglomerated using a binder, provided with grooves and tongues allowing the dry-joint connection thereof. 
         [0012]    According to one embodiment, this method comprises the combined placement of solid base bricks, provided with a groove and a tongue that can be joined together, and honeycomb stiffening bricks, provided with a groove and a tongue, that can be joined together as well as a cell with the passage of a reinforcing post. 
         [0013]    The following operations may be provided:
       producing a mortar base;   placing a series of posts in the base;   placing stiffening bricks at the posts, with insertions of said posts into the cells of the stiffening bricks;   placing base bricks between the stiffening bricks.       
 
         [0018]    Each post for example comprises a metal framework embedded in (cement) concrete. 
         [0019]    It is also possible to provide an operation for placing, at a post and above the stiffening brick, a half-stiffening brick, provided with a tongue to allow it to be joint-connected on the stiffening brick and a cell for the passage of the post, and having a length equal to half the length of the stiffening brick. 
         [0020]    The following operations may also be provided:
       placing linking bricks comprising a tongue allowing them to be joint-connected in the grooves of other bricks, and a central cavity delimiting two side walls and a bottom;   placing a metal framework in the cavity;   filling in the cavity using concrete.       
 
         [0024]    Likewise, the following operations may be provided:
       placing linking bricks comprising a tongue allowing them to be joint-connected in the grooves of other bricks, and a central cavity delimiting two side walls and a bottom;   cutting out side walls;   placing a slab resting directly on the bottom of the linking bricks.       
 
         [0028]    The invention secondly proposes, for the implementation of the aforementioned method, a hemp concrete brick, provided with a tongue designed to be joint-connected in a groove, said tongue having a protrusion whereof the ratio to an effective height or effective width of the brick is comprised between 1/10 and 1/4, preferably approximately 1/5. 
         [0029]    According to one embodiment, the tongue also has a width whereof the ratio to an effective width of the brick is comprised between 1/4 and 1/2, preferably approximately equal to 1/3. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Other aims of advantages of the invention will appear in light of the following description, done in reference to the appended drawings, in which: 
           [0031]      FIG. 1  is a perspective view of a first type of hemp concrete brick; 
           [0032]      FIG. 2  is a side view of the brick of  FIG. 1 ; 
           [0033]      FIG. 3  is a top view of the brick of  FIG. 1 ; 
           [0034]      FIG. 4  is a perspective view of a second type of hemp concrete brick; 
           [0035]      FIG. 5  is a side view of the brick of  FIG. 4 ; 
           [0036]      FIG. 6  is a top view of the brick of  FIG. 4 ; 
           [0037]      FIG. 7  is a perspective view of a third type of hemp concrete brick; 
           [0038]      FIG. 8  is a side view of the brick of  FIG. 7 ; 
           [0039]      FIG. 9  is a top view of the brick of  FIG. 7 ; 
           [0040]      FIG. 10  is a perspective view of a fourth type of hemp concrete brick; 
           [0041]      FIG. 11  is a side view of the brick of  FIG. 10 ; 
           [0042]      FIG. 12  is a top view of the brick of  FIG. 10 ; 
           [0043]      FIGS. 13 to 19  are perspective views showing different successive steps for producing a building from the bricks of  FIGS. 1 to 12 ; 
           [0044]      FIGS. 20 and 21  are perspective views showing two successive steps for producing a corner wall from the bricks of  FIGS. 1 to 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0045]      FIGS. 1 to 12  show four different types of prefabricated hemp concrete elementary bricks. The concrete is prepared from hemp or hemp chaff aggregate, which is the fragmented inner part of the hemp stalk. The hemp chaff used meets the recommendations of hemp producers for use in construction, cf. the aforementioned volume Construire en Chanvre. The density of the dry hemp chaff used is approximately 100 kg/m 3  bulked (i.e. not tamped). The binder used may comprise non-hydraulic or hydraulic lime (standard NF EN 459-1 to 3), potentially with added pozzolana (standard NF P 18-308), but in the case at hand is preferable to use pure non-hydraulic lime. The composition also comprises quick-setting cement and mixing water (meeting the stipulations of standard NF EN 1008). 
         [0046]    The proportions by volume of the preferred composition are as follows: hemp chaff 73%; non-hydraulic lime 8%; quick-setting cement 4%; water 15%, i.e., for 100 l (10 kg) of hemp chaff, approximately 11 l of non-hydraulic lime, 5.5 l of quick setting cement and 20 l of water. 
         [0047]    After mixing and stirring of the composition, each type of brick is made by pressurized molding (the pressure is done by compaction of the still-wet composition). Once folded, each brick is stripped, then undergoes air drying for several weeks, or may be placed in a drying oven for accelerated drying. 
         [0048]    A first type of brick  1  is illustrated in  FIGS. 1 to 3 . This brick  1 , called a base brick, is solid. It has an effective length  2  of 600 mm, an effective width  3  of 300 mm, and an effective height  4  of 300 mm. 
         [0049]    The base brick  1  comprises:
       a lower tongue  5  protruding on a lower surface  6 ;   a front tongue  7  protruding on a front surface  8 ,   an upper central groove  9  hollowed in an upper surface  10  of the brick  1  and that runs over the entire length thereof, including on the front tongue  7 ;   a rear groove  11  hollowed in a rear surface  12  of the brick  1  and that runs over the entire height thereof, including over the lower tongue  5 .       
 
         [0054]    The tongues  5 ,  7  have a (protruding) height  13  of 50 mm and a width  14  of 100 mm. The grooves  9 ,  10  have a depth  13  of 50 mm and a width  14  of 100 mm. 
         [0055]    A second type of brick  15  is illustrated in  FIGS. 4 to 6 . This brick  15 , called a stiffener, has a cellular structure. Like the base brick  1 , it has an effective length  2  of 600 mm, an effective width  3  of 300 mm, and an effective height  4  of 300 mm. 
         [0056]    The stiffener  15  comprises a cell  16  with a square section pierced over the entire height thereof, the sides of which measure 150 mm and are spaced apart from the side  17  and rear  18  surfaces of the stiffener  15  by 75 mm. 
         [0057]    The stiffener  15  comprises:
       A lower tongue  19  protruding on a lower surface  20 , which is interrupted at the boundary of the cell  16  (cf.  FIG. 5 );   A front groove  21  hollowed in a front surface  22 , which runs over the entire height of the brick  15 , including over the lower tongue  19 ;   An upper central groove  23  hollowed in an upper surface  24  of the brick  15  and which extends forward as far as the front groove  21  and is interrupted toward the back at a distance of 75 mm from the cell  16 .       
 
         [0061]    The lower tongue  19  has a protruding height  13  of 50 mm and a width  14  of 100 mm; the grooves  21 ,  23  have a depth  13  of 50 mm and a width  14  of 100 mm. 
         [0062]    A third type of brick  25  is illustrated in  FIGS. 7 to 9 . This brick  25 , called a half-stiffener, has a cellular structure. It has a generally cubic shape with an equal effective length  26 , width  3  and height  4  of 300 mm. In this way, the effective length  26  of the half-stiffener  25  is equal to half the effective length  2  of the base brick  1  and the stiffener  15 . The half-stiffener  25  comprises a cell  16  with a square section pierced over the entire height thereof, the sides of which measure 150 mm and are spaced apart from the four side surfaces of the half-stiffener  25  by an equal distance of 75 mm. The half-stiffener  25  comprises:
       a front tongue  27  protruding on a front surface  28 , which is interrupted toward the top at a distance of 50 mm from an upper surface  29  of the brick  25 , and is extended downward beyond a lower surface  30  of the brick  25  over a distance of 50 mm;   a central lower tongue  31 , which protrudes over the lower surface  30  of the brick  25 , is interrupted toward the rear at the boundary of the cell  16 , and extends forward beyond the front surface  28  to form a block with an L-shaped profile with the front tongue  27 .       
 
         [0065]    The tongues  27 ,  31  have a protruding height  13  of 50 mm and a width  14  of 100 mm. 
         [0066]    A fourth type of brick  32  is illustrated in  FIGS. 10 to 12 . This brick  32 , called a linking brick, is hollow and has a U-shaped profile in transverse section. It has an effective length  2  of 600 mm, an effective width  3  of 300 mm, and an effective height  4  of 300 mm. These sides are identical to those of the base brick  1  and those of the stiffener  15 . 
         [0067]    The linking brick  32  comprises:
       a central cavity  33 , hollowed out over the entire length of the brick  32 , over a height  34  of 200 mm from an upper surface  35 , and over a width  36  of 150 mm, the central cavity  33  thus delimiting two sidewalls  37  with a same thickness (75 mm) spaced apart from the width  36  of the cavity  33 , and a bottom  38  with a thickness of 100 mm;   a central lower tongue  39 , which protrudes over a lower surface  40  of the brick, is interrupted toward the back at a distance of 50 mm from a rear surface  41  of the brick  32 , and extends toward the front beyond a front surface  42  of the brick  32 , over a distance of 50 mm;   a front tongue  43  that protrudes from the front surface  42  of the brick  32  in the extension of the lower tongue  39  and is interrupted toward the top at the central cavity  33 ;   a rear groove  44  hollowed in the bottom  38 , and which extends over the height of the lower tongue  39 .       
 
         [0072]    The tongues  39 ,  43  have a protruding height  13  of 50 mm and a width  14  of 100 mm. 
         [0073]    The four types of prefabricated elementary bricks that have just been described make it possible to produce any masonry construction, and in particular to build walls and partitions. 
         [0074]    To that end, the bricks  1 ,  15 ,  25 ,  32  may be combined with each other. They are in fact designed to fit together both horizontally and vertically. Thus:
       the lower tongue  5  of each base brick  1  may fit into the upper groove  9  of another base brick  1 , in the upper groove  23  of a stiffener  15 , or in the cavity  33  of the linking brick  32  (the difference in width being able to be filled in with concrete);   the front tongue  7  of each base brick  1  can fit into the rear groove  11  of another base brick  1 , in the front groove  21  of a stiffener  15 , or in the rear groove  44  of a linking brick  32 ;   the lower tongue  19  of the stiffener  15  can fit into the upper groove  9  of the base brick  1 , in the upper groove  23  of another stiffener  15 , or in the cavity  33  of a linking brick  32  (the difference in width being able to be filled in with concrete);   the lower tongue  31  of a half-stiffener  25  can fit into the upper groove  9  of the base brick  1 , in the upper groove  23  of another stiffener  15 , or in the cavity  33  of a linking brick  32  (the difference in width being able to be filled in with concrete;   the front tongue  27  of a half-stiffener  25  can fit into the rear groove  11  of the base brick  1 , in the front groove  21  of the stiffener  15 , or in the rear groove  44  of a linking brick  32 ;   the lower tongue  39  of a linking brick  32  can fit into the upper groove  9  of the base brick  1 , in the upper groove  23  of a stiffener  15 , or in the cavity  33  of another linking brick  32  (the difference in width being able to be filled in with concrete, as will be illustrated hereafter);   the front tongue  43  of a linking brick  32  may fit into the rear groove  44  of another linking brick  32 , in the rear groove  11  of the base brick  1 , or in the front groove  21  of the stiffener  15 .       
 
         [0082]    As will be seen below, these fittings may be done as dry-joint connections (i.e. without jointing mortar), without harming the stability of the construction one wishes to make, owing to the size ratios between the sides (height and width) of the grooves and tongues, and the effective size ratios of the bricks. 
         [0083]    In this way, the ratio between the width  14  of the tongues  5 ,  7 ,  19 ,  27 ,  31 ,  39 ,  43  (equal to that of the grooves  9 ,  10 ,  21 ,  23 ,  44 ) and the effective width  3  of the bricks  1 ,  15 ,  25 ,  32  is preferably comprised between 1/4 and 1/2. A ratio of approximately 1/3, which corresponds to the quoted values provided above, is a good compromise between good shearing strength of the tongues  5 ,  7 ,  19 ,  27 ,  31 ,  39 ,  43 , which guarantees good strengths of the walls with respect to forces in the orthogonal direction (in particular wind and bearing forces) on the one hand, and a sufficient bearing surface of the bricks  1 ,  15 ,  25 ,  32  on one another, on either side of the tongues  5 ,  7 ,  19 ,  27 ,  31 ,  39 ,  43 , guaranteeing good stability of the walls, on the other hand. 
         [0084]    Furthermore, the ratio between the height of the tongues  5 ,  7 ,  19 ,  27 ,  31 ,  39 ,  43  (equal to the depth of the grooves  9 ,  10 ,  21 ,  23 ,  44 ) and the effective height (or the effective width, equal to the effective height) of the bricks  1 ,  15 ,  25 ,  32  is preferably comprised between 1/10 and 1/4. A ratio of approximately 1/6, which corresponds to the quoted values provided above, is a good compromise between a certain ease of assembly on the one hand, and the need to maximize the contact surfaces between the bricks  1 ,  15 ,  25 ,  32  (i.e. the friction therebetween), so as to stiffen the structure, on the other hand. 
         [0085]      FIGS. 13 to 19  show different successive steps in the construction of a structure comprising a straight wall  45 , provided with an opening  46  (in this case a window) and topped by a slab  47 . 
         [0086]    The wall  45  is built on a base  48  (forming a compression slab) made from water-repellent cement mortar, which is poured on a concrete foundation  49  situated below ground level as defined by a finished (i.e. tamped) outside terrain  50 . As shown in  FIG. 13 , the base  48  is partially buried in the ground  50 , and has a protruding upper portion in which a groove  51  is followed with a width and depth respectively equal to the width and the depth of the grooves of the bricks. Thus, in this case, the groove  51  has a width of 100 mm and a depth of 50 mm. 
         [0087]    In anticipation of the production of the opening  46  on the one hand, and to consolidate the wall  45  on the other hand, two metal frameworks  52  with a square section are vertically implanted in the base  48  for the subsequent production of reinforcing posts  53 , while being spaced apart by a predefined value corresponding to three brick lengths (i.e. 1800 mm), this measurement being done on the central axis of the frameworks  52 . The frameworks  52  are preferably pre-positioned during pouring of the base  48 , so as to be embedded therein, but it is also possible to consider making the base  48  first, then later drilling housings as a function of the desired positioning of the frameworks  52 , in the scenario where that positioning is not known when the base  48  is poured. 
         [0088]    The wall  45  is then erected through the successive stacking of rows of bricks fitted into each other both horizontally and vertically.  FIG. 13  illustrates the placement of a first row of bricks, the lower tongues of which are fitted into the groove  51  of the base  48 . This first row alternates between base bricks  1 , fitted into the base  48  at locations with no frameworks  52 , and stiffeners  15  fitted into the base  48  at the frameworks  52 . More specifically, as shown in  FIG. 13 , the stiffeners  15  are positioned such that the frameworks  52  extend through their cells  16 . From a practical perspective, in the case where the frameworks  52  are pre-positioned in the base  48 , the stiffeners  15  are simply slipped through the top on the frameworks  52 , to then fit into the groove  51  of the base  48 . 
         [0089]    The base bricks  1  are all oriented in the same direction (their rear surface  12  here turned toward the back in  FIG. 13 ). The stiffeners  15  are also oriented in the same direction, but opposite the base bricks  1 . In this way, each stiffener  15  is framed by two base bricks  1 : a first whereof the rear surface  12  is simply pressed against the rear surface  18  of the stiffener  15 , and a second whereof the front tab  7  is fitted into the front groove  21  of the stiffener  15 . 
         [0090]    This first row is placed dry, without mortar joints, by simple fitting of the bricks  1 ,  15  into the base  48 . Given the identical quoted values (for the height and width) of the groove  51  of the base  48  and the tongues  5 ,  7 ,  19  of the bricks  1 ,  15 , there is no functional play between the groove  51  and the tongues  5 ,  7 ,  19 . This lack of play does not, however, prevent the fitting, due to the relative elasticity of the material of the bricks  1 ,  15  (unlike cement concrete, for example, which is extremely rigid). 
         [0091]    Before placing the second row of bricks, the following two operations are carried out:
       filling in, preferably using hemp concrete, a gap  54  existing between the rear surface  18  of each stiffener  15  and the rear groove  11  of the adjacent base bricks  1 ;   producing a cutout  55  in the front surface  24  of each stiffener  15 , on the side of its rear surface  18 , to extend the upper groove  9  of the adjacent base bricks  1  as far as the cells  16  and thereby allow the unencumbered placement of the higher row of bricks.       
 
         [0094]    The second row of bricks can then be placed. As shown in  FIG. 14 , the bricks of that second row are turned opposite the bricks of the first row, so as to arrange the bricks in staggered rows from one row to the next. Owing to the cutout  55  made in the upper surface  24  of the stiffeners  15  of the first row, each stiffener  15  of the second row can fit without obstacle, straddling the stiffener  15  of the first row and the adjacent base brick  1 , on the side of its rear surface  12 . As for the first row, the second row (and subsequent rows) is placed dry, without mortar joints, by simple fitting of the bricks of the second row into one another and into the bricks of the first row. In light of the identical quoted values (in terms of projection and width) of the grooves and the tongues, there is no functional play in the fittings, which does not hinder the placement due to the relative elasticity of the hemp concrete. The lack of joints has three advantages:
       the placement time is considerably reduced as a result;   a large quantity of material (water, cement, aggregate) is saved, benefiting the costs of the construction and its environmental qualities;   the wall thus erected has few or no thermal bridges, its thermal and acoustic insulation capacities thus being increased.       
 
         [0098]    Once the second row of bricks is placed, the same filling in and cutting out operations are carried out in the stiffeners  15  of the second row as those done in the stiffeners  15  of the first row, so as to allow the placement of the third row. The third row is then placed, the base bricks  1  and the stiffeners  15  being oriented in the same direction as those of the first row (and therefore opposite those of the second). As before, the fitting is simple, with no mortar joints. 
         [0099]    The cells  16  of the stiffeners  15  can then be filled in using a cement concrete, thereby embedding the frameworks  52  and forming reinforced posts  53  that vertically stiffen the wall  45  and form a reveal for the window  46 . 
         [0100]    The third row delimiting a support for the window  46 , no fourth row bricks are placed between the frameworks  52 . However, to horizontally stiffen the frame of the window, the following operations are carried out:
       a cutout  55  is made in the upper surface  24  of each stiffener  15 , to extend the upper groove  9 ,  23  of the bricks of the third row between the frameworks  52  on either side as far as the cells  16  ( FIG. 15 );   a horizontal metal framework  56  is placed in said groove  9 ,  23  and extends from one vertical framework  52  to the other ( FIG. 15 );   the groove  9 ,  23  is filled in using a cement concrete to embed that the horizontal framework  56  and thereby produce a reinforcing beam to support the window ( FIG. 16 ).       
 
         [0104]    In order to allow the stiffeners  15  of the subsequent row to be fitted, as before, cutouts  55  are made in the upper surfaces  24  of each stiffener  15 . The bricks of the following row are then placed (the fourth, in the illustrated example). As shown in  FIG. 16 , in order to continue erecting the wall  45  with a distribution of the bricks in staggered rows, a half-stiffener  25  is fitted on the stiffener  15  of the third row turned opposite the opening  46 , with its front tongue  27  turned opposite the opening  46 . A base brick  1  is then horizontally fitted on the half-stiffener  25 . Stiffeners  15  and half-stiffeners  25  of this row and the following rows together form a reveal for the window  46  thus delimited. 
         [0105]    As shown on the right in  FIG. 17 , and on the left in an exploded view in  FIG. 18 , stiffeners  15  and half-stiffeners  25  are alternated in each successive row to mount the reveal for the window  46  while preserving the staggered rows. As before, cutouts are made in the upper surfaces of the stiffeners  15  and half-stiffeners  25  to allow the fitting of each higher row. 
         [0106]    Once the reveal for the window  46  has reached the desired height (which in this case corresponds to four rows of bricks, or a height of 1200 mm), an additional row of linking bricks  32  is placed that will participate in producing a lintel for the window  46 . 
         [0107]    As shown in  FIG. 18 , the linking bricks  32 , simply fitted together vertically in the groove  9 ,  27  of the bricks of the lower row, and horizontally into each other, are horizontally stiffened using a metal framework  57  lying in the central cavity  33 , which is then filled in using a cement concrete that will embed the framework  57  and thereby form a lintel beam  58  for the window  46 . As shown in  FIG. 19 , the lintel beam  58  is nevertheless hollowed out (for example using a furring that is removed once the cement has set) by a groove  59  with the dimensions (same depth, same width) of the tongues  39 , so as to allow fitting of the upper row (see below). 
         [0108]    In order to allow the passage of the vertical frameworks  52 , the bottom  38  of the linking bricks  32  placed overhanging the reveal for the window  46  are also cut out with an opening  60  with a square section, said opening  60  being filled in using a cement concrete to complete the vertical reinforcing post  53  of the wall  45  (and the window  46 ). 
         [0109]    As illustrated in  FIG. 19 , the following row is made up of linking bricks  32  vertically fitted into the grooves  9  of the base bricks  1  of the preceding row and in the groove  59  hollowed out in the lintel beam  59 . 
         [0110]    Furthermore, in order to allow the placement of the slab  47  resting on that last row of bricks  32 , side walls  37  are cut out (in this case by complete leveling) on an inner side of the linking bricks  32 . As shown in  FIG. 19 , the slab  47  comprises profiled girders  61  (for example with a T-shaped transverse section, as illustrated), one end  62  of which is placed directly on the bottom  38  of the linking bricks  32 , owing to the cutout made. The girders  61  do not, however, extend as far as the side opposite side walls  37  of the linking bricks  32 : they are in fact spaced to allow the placement, between the side walls  37  and the end  62  of the girders, of a metal framework  57  for reinforcing the border of the slab  47 , which will subsequently be embedded in a cement concrete. 
         [0111]    As also shown in  FIG. 19 , the vertical metal frameworks  52  extend as far as the slab  47 , through square openings  60  cut in the bottoms  38  of the linking bricks  32  situated overhanging the reveal for the window  46  and filled in with a cement concrete completing the vertical reinforcing posts  53 . 
         [0112]    The subsequent fastening of jambs (doors, windows) is done directly in the posts, supports, reveals and lintels of the openings. To access them, one need only form mortises in the bricks to allow the passage of fastening tongues of the jambs. 
         [0113]      FIGS. 20 and 21  show, as an illustrative example, the production of a corner wall  63  using base bricks  1 , stiffeners  15  and half-stiffeners  25 . Only the placement of a first and second row of bricks are illustrated, the subsequent rows being done identically alternating between the first two rows. 
         [0114]    As previously described, the corner wall  63  rests on a base  48  provided with a groove  51  hollowed on an upper surface, and poured over a foundation (not shown) situated below the ground level of the finished terrain. The wall  63  is made up of two wall faces  64 ,  65  (which are arbitrarily called left face  64  and right face  65 , in reference to the orientation chosen for  FIG. 20 ) forming an angle (a right angle in the case at hand), and comprises at least one corner post  53  stiffened by a metal framework  52  vertically implanted in the base  48 . In the illustrated example, two other frameworks  52  are each implanted in a base face  48 , at predetermined equal distances ( 1800  mm) from the corner framework  52 . 
         [0115]    The first row of bricks comprises a first stiffener  15  fitted on the base in the corner of the wall  63 , with the metal corner framework  52  slipped into the cell  16  of the stiffener  15 . This first stiffener  15  may be oriented differently along either of the wall faces  64 ,  65 . In the drawing of  FIG. 20 , we have arbitrarily chosen to orient the stiffener  15  along the left face  64 . 
         [0116]    The first row of bricks also comprises several (two in the case at hand) base bricks  1 , fitted on the base  48  in each face. In the left face  64 , where the corner stiffener  15  extends, the base bricks  1  are oriented toward the corner, the front tongue  7  of the base brick  1  adjacent to the corner stiffener  15  fitting into the front groove  21  thereof. As illustrated, a half-stiffener  25  is fitted on the base  48  at the framework  52  of the left face  64 , which is slipped in its cell  16 . The half-stiffener  25  is oriented toward the corner, such that its front tongue  27  fits into the rear groove  11  of the adjacent base bricks  1 . 
         [0117]    In the right face  65 , the (two) base bricks  1  are oriented opposite the corner, the rear surface  12  of the base brick  1  adjacent to the corner stiffener  15  being pressed flat against a side surface  17  thereof. As also illustrated, a stiffener  15  is fitted on the base  48  at the framework  52  of the right face  65 , which is slipped into its cell  16 . The stiffener  15  is oriented toward the corner, such that the front tongue  7  of the adjacent base brick  1  fits into the front groove  21  of the stiffener  15 . 
         [0118]    As in the example described in reference to  FIGS. 13 to 19 , the bricks are simply fitted into the base  48  and into one another, no mortar joints being used. 
         [0119]    Once the first row is placed, the following two preparatory operations are carried out in anticipation of the placement of the second row:
       the gap  54  between the side surface  17  of the corner stiffener  15  and the rear groove  11  of the base brick  1  adjacent to the right face  65  is preferably filled in, preferably using hemp concrete;   a cutout  55  is made in the upper surface  24  of the corner stiffener  15 , on the side of the base brick  1  adjacent to the right face  65 , to extend the upper groove  9  of the base brick  1  as far as the cell  16  and thereby allow the unencumbered placement of the second row of bricks;   a cutout  55  is made in the upper surface  29  of the half-stiffener  25  of the left face  64 , on the side of the adjacent base brick  1 , to extend the upper groove  9  of the base brick  1  as far as the cell  16  and thereby allow the unencumbered placement of the second row of bricks;   a cutout  55  is made in the upper surface  24  of the stiffener  15  of the right face  65 , on the side of the adjacent base brick  1 , to extend the upper groove  23  of stiffener  15  as far as the cell  16  and thereby allow the unencumbered placement of the second row of bricks.       
 
         [0124]    It is then possible to place the bricks of the second row, as illustrated in  FIG. 21 . As shown in the figure, in that second row, the bricks are oriented opposite those of the first row. In this way, the second row comprises an angularly offset corner stiffener  15  (in this case at a right angle) relative to the corner stiffener  15  of the first row, and is fitted overlapping thereon and on the adjacent base brick  1  of the right face  65 . The base bricks  1  of the right face  65  are oriented toward the corner of the wall  63 , and a half-stiffener  25  is placed at the framework  52  of the right face  65 , also oriented toward the corner, its front tongue  27  fitting into the rear groove  11  of the adjacent base brick  1 . 
         [0125]    Likewise, the base bricks  1  of the left face  64  of the second row are oriented opposite the corner, and a stiffener  15  is placed at the framework  52  of the left face  64 , such that the front tongue  7  of the adjacent base brick  1  fits into the front groove  21  of the stiffener  15 . No mortar joint is used between the bricks. As shown in  FIG. 21 , the cells  16  of the stiffeners  15  and half-stiffeners  25  may be filled with cement concrete for placement of the second row. This filling may nevertheless be done at a later time, after the placement of the second row or even higher rows, to form the reinforced vertical posts  53 . 
         [0126]    One can see that, irrespective of the configuration of the construction to be built, the use of the hemp bricks described above allows an easy and rapid construction, in particular owing to the absence of jointing, which allows considerable savings in terms of time and material. As an example, the construction of a traditional building with a ground surface area of 150 m 2 , which requires approximately 1000 bricks (in all), of the various described types, may be completed (excluding light work) in one week with one single person on the worksite, i.e. time savings of more than 50% relative to the known methods, or ordinary quarry stone-based masonry, or hemp-based masonry set on a wooden frame, or hemp concrete block-based masonry jointed and placed on a wooden frame. 
         [0127]    By using a reinforced concrete frame to produce the posts (which may also serve as a rigid frame for the openings) and slabs, the erection, from the hemp bricks described above, of a multi-floor construction does not suffer any restrictions, whereas the professional rules regarding hemp concrete constructions made traditionally on a wooden frame limit the height of the structures to two floors (ground floor with one upper four). 
         [0128]    The combination of solid base bricks and cellular stiffener bricks for the erection of the walls limits the number of reinforcing posts and avoids the use of a frame requiring the intervention of a specialized carpenter, while the quantity of cement concrete is nevertheless limited and the environmental qualities of the construction are preserved. However, it is fully possible to consider replacing the reinforced concrete posts with wooden pillars or non-reinforced lime concrete, just as it is possible to consider replacing the support and lintel reinforcements of the openings made from reinforced concrete with wooden beams or non-reinforced lime concrete.