Method for casting a construction element

1. A method for casting building material to form a construction element using a computer-controlled apparatus, the apparatus having a material deposition head in communication with a reservoir of formwork material and being movable within a build volume of greater than 1 m 3 responsive to computer instructions, the method comprising the sequential steps of:

(a) receiving, by the apparatus, computer instructions relating to a formwork geometry;

(b) responsive to receiving the computer instructions, moving the material deposition head within the build volume and depositing the formwork material, from the deposition head, in specific locations defined by the computer instructions to progressively build up a formwork corresponding with the formwork geometry, such that the formwork defines a shell at least partially covering a scaffold structure, the scaffold structure comprising a plurality of interconnected braces defining a plurality of voids, and the shell defining a three-dimensional casting surface;

(c) applying one or more portions of composite material to the formwork in specific locations, defined by the computer instructions, to at least partially cover the casting surface;

(d) at least partially covering the casting surface and/or the one or more portions of composite material with the building material;

(e) at least partially curing the building material in contact with the casting surface so that the at least partially cured building material bonds to the one or more portions of the composite material and forms the construction element;

(f) removing at least a portion of the formwork from the construction element; and then

(g) collecting the formwork material removed from the construction element and recirculating the removed formwork material to the reservoir to allow the removed formwork material to be re-used, by the computer-controlled apparatus, to fabricate a further formwork.

2. The method for casting building material to form a construction element according to claim 1 , wherein the step of removing the at least a portion of the formwork comprises heating the construction element and the at least a portion of the formwork to a temperature above the melting point of the formwork material, thereby melting the at least a portion of the formwork.

3. The method for casting building material to form a construction element according to claim 2 , wherein the building material is concrete and the step of heating the construction element and the at least a portion of the formwork to the temperature above the melting point of the formwork material comprises heating the construction element and the at least a portion of the formwork to less than 70° C.

4. The method for casting building material to form a construction element according to claim 2 , wherein the formwork material is a wax compound.

5. The method for casting building material to form a construction element according to claim 1 , further comprising the step of applying one or more materials to the formwork in specific locations in order to affect a surface finish of the construction element.

6. The method for casting building material to form a construction element according to claim 5 , wherein one of more the materials used to affect the surface finish of the construction element comprise at least one of an acid, a pigment, paint, or masking.

7. The method for casting building material to form a construction element according to claim 1 , further comprising the steps of:

before pouring the building material, applying a retarder to the formwork in specific locations; and

after the at least a portion of the formwork is removed from the construction element, removing uncured building material from the construction element by mechanical means.

8. The method for casting building material to form a construction element according to claim 1 , wherein the apparatus further has a milling head movable within the build volume responsive to computer instructions, and the method further comprises the step of, before pouring the building material, operating the milling head to mill the formwork in specific locations.

9. The method for casting building material to form a construction element according to claim 1 , wherein the scaffold structure defines at least one conduit arrange to allow a fluid to pass through the formwork.

10. The method for casting building material to form a construction element according to claim 1 , wherein the step of depositing the formwork material to fabricate the formwork further comprises heating or cooling at least a portion of the build volume.

11. The method for casting building material to form a construction element according to claim 1 , wherein the step of applying the one or more portions of composite material to the formwork further comprises curing the one or more portions of composite material.