BAM is working with Weber Beamix to combine their experience and push what can achieved in construction with 3D printing concrete elements. BAM has a sustained relationship with the concrete printing experts, previously creating the world’s longest 3D concrete printed bridge with them in 2019 in Nijmegen, Netherlands.

The printer uses 3D geometric designs to make elements that can be combined into structures such as bridges, retaining walls, outlet details, street furniture and even skate ramps.

The chosen design is printed using a concrete mortar mix, which is driven through a printing nozzle from a concrete pump that is affixed to a robotic arm by a hose. The arm delivers layer upon layer of mortar approximately 5mm thick to build up the 3D element. Between each layer we can include a fine metal wire to increase durability and prevent cracking.

The printer uses a unique mortar mix, which remains fluid until it stops moving. Once laid out it solidifies until the subsequent layer introduces energy and bonds both layers as a fluid. Each layer must be laid within 10 min of each other. This means it is as strong as normal cast in place monolithic elements and has a similar performance without delamination.

The concrete takes 28 days to reach full strength but elements are usually moved within a day from the print bed to allow others to be made.

Earlier this year, BAM has become the first contractor in Scotland to make use of 3D concrete printing – installing a printed staircase which will provide access to the new M8 Sighthill bridge. It is believed to be largest printed concrete construction in the UK to date.

When complete, the iconic new pedestrian and cycle bridge will connect Glasgow City Centre to the Sighthill area in a new sustainable transport corridor.

Partners:

Saint- Germain Weber Beamix.

Weber Beamix solution uses the unique characteristics of rheological (thixotropic) materials, unlike traditional mortar.

When mixed, the mortar acts like a fluid. When static, the mortar stiffens and strengthens, to hold subsequent layers, forming monolithic concrete structures. Timings for the chemical reaction are critical, to guarantee the safety of printed structures for the entire lifespan.

Purpose:

BAM is actively engaging with proactive clients to explore how 3D concrete printing can be implemented on future schemes. Our approach focuses on how project outcomes, innovation and alternative solutions can be fully embraced. Re-evaluating how whole-life costs and sustainability can impact traditional processes and materials.

3D concrete printing provides the following benefits on a cost neutral basis:

• People reduced their working time by up to 80%

• 60% reduction in lead in time.

• Material only placed where it is required saving up to 50% on material

• Significant reduction in CO2

• Improved H&S and Quality control through a factory process

• Digital delivery – Right first time

• Parametric design – one design but complete flexibility with bespoke versions at no additional cost