Large-sized load-bearing and insulating hempcrete blocks for the construction of structures

Abstract

The invention relates to a hempcrete block (1) comprising an aggregate (G) formed from hemp shives, water (E), and a rapid-setting binder (L), characterized in that the ratio between the masses of binder (L) and aggregate (G) is between 2.12 and 2.17, and in that the ratio between the masses of water (E) and binder (L) is between 0.85 and 0.88. (Fig. 2)

Description

Title of the invention: Large load-bearing and insulating concrete block HEMP FOR CONSTRUCTION STRUCTURES

[0001] The invention relates to the field of construction materials and is concerned, more particularly, with a large-dimension load-bearing and insulating block made of hempcrete intended for architecture for the design and construction of so-called "passive" buildings.

[0002] Currently, hempcrete blocks intended for construction are either small in size and intended mainly for wall insulation, from the outside or from the inside, or of equivalent size to a brick or a cinder block and intended to participate in the load-bearing structure of vertical walls but with restrictions of use to the field of individual houses, or buildings of modest size.

[0003] However, it turns out that existing prefabricated hempcrete elements have very low mechanical resistance to compression (less than or equal to 0.22 MPa), which greatly restricts their use as structural elements for the construction of works.

[0004] Due to its very good thermal conductivity, hemp straw (called "shives") is already used as aggregate in hempcrete, whether for the industrial production of prefabricated elements or for direct application on construction sites by formwork or spraying. However, this application is only advantageous if the proportion of hemp shives is very high in the mixture. The higher this proportion, the less mechanically resistant the hempcrete is, and it cannot then be used to form a load-bearing element.

[0005] In the field of construction, it has long been known to build structures using large, solid stone blocks. Indeed, stone offers high mechanical strength and good thermal inertia, but its thermal conductivity (X) is very low, necessitating the use of additional insulation. Thus, generally speaking, in conventional construction, a material is either load-bearing or insulating, and therefore does not possess both properties simultaneously.

[0006] In this problematic context, the invention sought a technical solution enabling hempcrete blocks to form walls that are both load-bearing and self-supporting over a great height while exhibiting resistance to the compression of plus or minus 2.5MPa and are, in addition, very thermally insulating while being able to be easily and quickly implemented on a construction site.

[0007] This goal is achieved, according to the invention, by means of a hempcrete block comprising an aggregate formed from hemp shives, water and a fast-setting binder, characterized in that the ratio between the masses of binder and aggregate is between 2.12 and 2.17, and in that the ratio between the masses of water and binder is between 0.85 and 0.88.

[0008] According to a preferred embodiment of the invention, the block has a length of 180 cm, a width between 40 cm and 70 cm and a height of 90 cm.

[0009] Preferably, the hemp concrete of the block of the invention contains a mass of aggregate between 115 Kg and 150 Kg, a mass of binder between 250 Kg and 320 Kg and a mass of water between 215 Kg and 280 Kg.

[0010] According to an advantageous feature of the block of the invention, the aggregate of the hemp concrete contains 90% to 100% hemp shives and 0 to 10% recycled hemp concrete.

[0011] According to another feature of the block of the invention, the binder (L) is chosen from the group consisting of a quick-setting cement, lime, clay cement or a mixture of at least two of them.

[0012] According to yet another characteristic, the hemp concrete block of the invention has a mechanical resistance to compression between 1.60 MPa and 3.00 MPa, a thermal conductivity between 0.08 W / mK and 0.1 W / mK, a thermal resistance between 4.0 m2K / W and 8.75 m2K / W.

[0013] According to a specific embodiment of the invention, the block includes reservations for the installation of connecting elements with blocks of the same type.

[0014] Another object of the invention is a method for machining a base block as defined above, characterized in that it comprises cutting said block to make recesses for assembly with adjacent blocks.

[0015] Yet another object of the invention is the use of a hempcrete block as defined above for the design and construction of passive structures.

[0016] The invention thus proposes blocks made from hemp shives, a healthy and bio-based material, binder, and water, which are both load-bearing and insulating. Such blocks not only comply with the strictest current standards but also exhibit environmental characteristics that far exceed them.

[0017] Thanks to their intrinsic properties resulting from the combination of the specific proportions of the different ingredients in the mixture and their unusual geometry, the blocks of the invention make it possible to design and construct load-bearing walls self-supporting, high-rise structures that are thermally insulating with relatively small thicknesses or widths and are suitable for all types of climates.

[0018] The installation of these blocks is much faster per square meter of facade (3 times faster) and per cubic meter of wall (6 times faster) than using blocks made of a conventional material of smaller dimensions, such as bricks or concrete blocks. Indeed, the blocks of the invention do not require the intervention of three successive trades (masonry, plastering, and painting), which also advantageously shortens the construction time.

[0019] The blocks of the invention also have an excellent carbon balance (1 hectare of planted hemp captures between 8 and 15 tonnes of CO2 in just 4 months), do not release any volatile organic compounds and have a very long life cycle (more than 100 years).

[0020] The industrial manufacture of these blocks consumes little energy because it requires neither cooking nor artificial drying in an oven and their transport is easy and economical by being compatible with conventional road or rail means.

[0021] Other features and advantages of the invention will become apparent from the description of the invention which will follow with reference to the figures explained below.

[0022] [Fig. 1] is a perspective view of a preferred embodiment of the hempcrete base block according to the invention.

[0023] [Fig.2] is an exploded perspective view of an assembly of two blocks of the [Fig.1] for the construction of a wall.

[0024] [Fig.3] is a perspective view of a second embodiment of a block in hemp concrete according to the invention after machining.

[0025] [Fig.4] is a perspective view of a third embodiment of a block in hemp concrete according to the invention after machining.

[0026] [Fig.5] is a perspective view of a fourth embodiment of a block in hemp concrete according to the invention after machining.

[0027] [Fig.6] is a perspective view of a fifth embodiment of a block in hemp concrete according to the invention during a machining operation.

[0028] For clarity, identical or similar elements are identified by identical reference signs in the description and throughout the figures.

[0029] Naturally, the embodiments of the block of the invention schematically illustrated by the figures shown above and described below are given only by way of non-limiting examples. It is explicitly provided for in the scope of the invention that different embodiments can be proposed and combined to create others.

[0030] The invention relates to the field of design and construction of structural works and is concerned, in particular, with a large hemp concrete block suitable and intended for the construction of so-called "passive" buildings.

[0031] Generally speaking, hempcrete is a material comprising an aggregate made of hemp straw (called hemp shives), water and a fast-setting binder.

[0032] The hempcrete base blocks that are the subject of the invention can be transformed after manufacturing and adapted according to their intended use by various machining methods. The machined profiles of these blocks are shown in Figures 3 to 6. The blocks of the invention are particularly self-supporting and thermally insulating, which opens up interesting applications for them in the field of modern building construction requiring compliance with very strict environmental standards.

[0033] To achieve this objective, the invention provides that the ratio in hemp concrete between the masses of binder (L) and aggregate (G) is between 2.12 and 2.17, and that the ratio between the masses of water (E) and binder (L) is between 0.85 and 0.88.

[0034] According to the invention and as illustrated by [Fig. 1], the basic hempcrete blocks 1 are generally parallelepiped in cross-section and of large dimensions (before machining). They initially have a length of 180 cm, a width between 40 cm and 70 cm and a height of 90 cm.

[0035] The hemp concrete used for the production of these blocks contains a mass of aggregate between 115 Kg and 150 Kg, a mass of binder between 250 Kg and 320 Kg and a mass of water between 215 Kg and 280 Kg.

[0036] Preferably, the aggregate G of the hempcrete contains 90% to 100% hemp shives and 0 to 10% recycled hempcrete.

[0037] The binder (L) is chosen from the group consisting of a rapid-setting cement, lime, clay cement, or a mixture of at least two of these ingredients. The characteristics of the hemp shives, whether calibrated or not, fibrous or not, have only a minor influence on the final properties of the hempcrete. On the other hand, the nature and formulation of the binder (Vicat-type rapid-setting cement (registered trademark) or other and / or lime and / or MCC1 Materrup clay cement (registered trademark)) are important parameters insofar as the rapid setting time is fundamental to the industrial process and the rate of block production.

[0038] A hemp concrete base block of the invention, having a length of 180 cm, a height of 90 cm and a width between 40 cm and 70 cm, has a mechanical resistance to compression between 1.60 MPa and 3.00 MPa, a thermal conductivity between 0.08 W / mK and 0.1 W / mK and a thermal resistance between 4.0 m2K / W and 8.75 m2K / W.

[0039] Preferably, and as illustrated in Figures 1 and 2, block 1 of the invention comprises recesses 10 for receiving connecting elements 2, preferably concrete and metal reinforcement A ([Fig. 2]), ensuring the bonding with blocks 1 of the same type to comply with DTU, standards and construction rules in force.

[0040] The blocks can preferably be machined directly in the factory or possibly, after delivery to the construction site, in order to produce, preferably by cutting, the reservations 10 and the recesses 11, lia, 11b allowing them to be adapted to the adjacent blocks to carry out their assembly in accordance with the envisaged architectural project, as illustrated by figures 3 to 6. Figure 6 illustrates the separation into two parts la, 1b of a basic block 1 by a cut.

[0041] The following table 1 shows the variations in compressive strength R c as a function of the quantities (by mass) of the various ingredients of the concrete (aggregate G based on hemp shives, binder L and water E), the ratios L / G and E / L as well as the density MV of the block, initial (MVi) and dry at 90 days (MVs).

[0042] [Tables 1] GLE MVi 100% MVs 75% 115 Kg 250 Kg 215 Kg 580 Kg 435 Kg L / G 2.17 E / L 0.86 1.60 < R c (Mpa) < 1.80 GLE MVi 100% MVs 75% 125 Kg 265 Kg 225 Kg 615 Kg 461.25 Kg L / G 2.12 E / L 0.85 1.80 < R c (Mpa) < 1.90 GLE MVi 100% MVs 75% 130 Kg 280 Kg 240 Kg 650 Kg 487.5 Kg L / G 2.15 E / L 0.86 2.30 < R c (Mpa) < 2.50 GLE MVi 100% MVs 75% 140 Kg 300 Kg 260 Kg 700 Kg 525 Kg L / G 2.14 E / L 0.87 2.60 < R c (Mpa) < 2.80 GLE 150 Kg 320 Kg 280 Kg L / G 2.13 E / L 0.88 MVi 100% MVs 75% 750 Kg 562.5 Kg 2.80 < R c (Mpa) < 3.00

[0043] The following table 2 shows the variations of the thermal resistance coefficient Rt as a function of the thermal conductivity X and the width e (or thickness) of the block.

[0044] [Tables2] Â (W / m K) e(m) Rt (m2 K / W) 0,080 0,40 5,00 0,45 5,63 0,50 6,25 0,55 6,88 0,60 7,50 0,65 8,13 0,70 8,75 0,085 0,40 4,71 0,45 5,29 0,50 5,88 0,55 6,47 0,60 7,06 0,65 7,65 0,70 8,24 0,090 0,40 4,44 0,50 5,56 0,55 6,11 0,60 6,67 0,65 7,22 0,70 7,78 0,095 0,40 4,21 0,45 4,74 0,50 5,26 0,55 5,79 0,60 6,32 0,65 6,84 0,70 7,37 0,100 0,40 4,00 0,45 4,50 0,50 5,00 0,55 5,50 0,60 6,00 0,65 6,50 0,70 7,00

Claims

Demands

1. Hempcrete block (1) comprising an aggregate (G) formed from hemp shives, water (E) and a fast-setting binder (L), characterized in that the ratio between the masses of binder (L) and aggregate (G) is between 2.12 and 2.17, and in that the ratio between the masses of water (E) and binder (L) is between 0.85 and 0.

88.

2. Block according to claim 1, characterized in that it has a length of 180 cm, a width between 40 cm and 70 cm and a height of 90 cm.

3. Block according to any one of the preceding claims, characterized in that the hemp concrete contains a mass of aggregate (G) between 115 Kg and 150 Kg, a mass of binder (L) between 250 Kg and 320 Kg and a mass of water (E) between 215 Kg and 280 Kg.

4. Block according to any one of the preceding claims, characterized in that the aggregate (G) of the hempcrete contains 90% to 100% hemp shives and 0 to 10% recycled hempcrete.

5. Block according to any one of the preceding claims, characterized in that the binder (L) is chosen from the group consisting of a quick-setting cement, lime, clay cement or a mixture of at least two of them.

6. Block according to any one of the preceding claims, characterized in that its mechanical resistance to compression (Rc) is between 1.60 MPa and 3.00 MPa, its thermal conductivity (X) between 0.08 W / mK and 0.1 W / mK, its thermal resistance (Rt) between 4.0 m2K / W and 8.75 m2K / W.

7. Block according to any one of the preceding claims, characterized in that it includes reservations (10) intended for the installation of connecting elements (2) with blocks of the same type.

8. A method for machining a basic block (1) made of hempcrete according to any one of the preceding claims, characterized in that it comprises cutting said block to make recesses (11, 1a, 11b) for assembly with adjacent blocks.

9. Use of a hempcrete block (1) according to any one of claims 1 to 7 for the design and construction of passive structures.