Printed concrete column against the sky, School 08, Doha

3D concrete printing

Advantages

No formwork

The shape comes from the toolpath, so curved and leaning walls and columns are printed without formwork or moulds. Each wall is printed in one piece, with fewer seams, and service channels are cut into the wet material. The printed wall stays in place as the permanent formwork and the finished façade.

A printed column at School 08 beside a steel reinforcement cage

A tall printed column with a curved, leaning face at School 08

A row of tapered printed columns beside the scaffold at School 08

Printed columns and wall ends at School 08, with reinforcing bars standing ready beside them

Prints on upper floors

The printer weighs 2,700 kg, spread across four deployable legs, so it needs no foundation and works on suspended slabs. It is lifted by crane onto the floor above, then unfolds and starts printing in 30 minutes.

Two 3D printers standing on their legs on the roof slab at School 08, Doha

What 3D concrete
printing is

3D concrete printing is concrete that is extruded layer by layer and shaped by a nozzle instead of a mould. It is used for structural and non-structural elements.

01
Dry mix
Delivered to site in bags.
02
Mixer-pump
Mixed with water in the mixer-pump.
03
Hose
Pumped through a hose along the arm.
04
Nozzle
Extruded through the nozzle, layer by layer.

Gantry and
mobile printers

A gantry printer carries its print head on a beam over a fixed frame, which needs a level, load-bearing foundation. It covers the whole build area from one position, but it is slow to set up, and the frame is dismantled and re-erected for each part of the project.

GGI uses a mobile printer: a crane arm on a tracked chassis with deployable legs. It needs no foundation, sets up quickly, folds through doorways and drives itself from one part of the project to the next.

Illustration to scale: a gantry printer with its batching plant beside a mobile printer with its pump tent

The printer

Size	3.15 m long, 1.99 m tall and 0.85 m wide: it drives through doors and along corridors on its own tracks, and fits in a standard 20-foot container
Weight	2,700 kg across four legs
Footprint	5 m diameter
Reach	13.8 m diameter at 3.85 m height
Print height	Up to 6 m, at reduced reach
Vertical tolerance	1 cm per metre at most
Printing speed	Up to 160 mm/s

Our crews are certified on these machines.

Illustration of the printer's reach: the machine in the middle of a 13.8 m circle, inside a printed wall 3.85 m high

The printing
material

The dry mix is sourced and blended at an off-site factory and delivered to site in jumbo bags. Water is added at an automatic pump with a 15 m hose. Quality is controlled at the factory, and the fresh material is checked on site with a vane shear test.

Property	Value	What it means
Compressive strength, 1 day	≥ 10 MPa	Reaches over a quarter of its 28-day strength in one day, so work on the wall can continue the next day.
Compressive strength, 28 days	≥ 35 MPa	In the range of ordinary structural concrete, and 7 to 10 times stronger than AAC (3.5 to 5.0 MPa).
Tensile splitting strength, 28 days	≥ 3.5 MPa	About one-tenth of its crushing strength. Concrete resists pushing far better than pulling, so walls still need steel reinforcement.
Density	1,900–2,100 kg/m³	A little lighter than ordinary concrete, which is about 2,400 kg/m³.
Thermal conductivity	1.8–2.0 W/(m·K)	Insulation comes from filling the wall cavities with polystyrene beads.
Shrinkage	≤ 0.7 mm per metre	The joint between printed and AAC walls is detailed to allow movement.

Custom layers

We can customise the layer width and height to meet your requirements.

A small rectangular test print in clay, its layers laid by the printer nozzle

What we
print

Six applications, all printed with the same machine, material and crew. Each has its own brochure, sent on request. The villa, majlis, heritage, defence and municipal images are design concepts.

01 Education

Schools with printed outer walls and AAC inside, delivered at School 08 of Ashghal's PPP programme.
02 Villas

G+1 villas with printed outer walls and AAC inside, in four printed finishes with optional sculpted elements.
03 Majlis

Curved printed walls and a glazed front: Desert Rose, Pavilion, Arabesque or Modern.
04 Heritage

Design concepts based on landmarks in Qatar and Saudi Arabia, reworked as printed buildings for new uses.
05 Defence

Blast walls, bunkers, guard posts and barriers for armed forces and critical infrastructure.
06 Municipality

Benches, bin enclosures, bus shelters and shade for municipalities, printed in Qatar.