The 3D Printing Material: A Solution for Reducing Carbon Footprint – Estelle Hynek

The 3D printing material, a solution for reducing the carbon footprint - Estelle Hynek

In this article, we focus on the development of low-carbon printable micro-concrete, an innovation led by the Constructions-3D team through the Termix-3D factory. Estelle Hynek, a research engineer at Constructions-3D, shares her insights on the creation of this unique material and the challenges faced in adapting traditional concrete for 3D printing.

The inks used for 3D printing are significantly different from the traditional concrete used in conventional construction methods. These inks must specifically meet certain criteria to be suitable for additive manufacturing technology. Unlike traditional concrete, which is poured into molds, the printable material must transition from a fluid state to a solid state in a very short time to allow for layer-by-layer deposition. These properties require a precise formulation tailored to each project.

The main differences between traditional concrete and 3D printing ink lie in the composition and behavior of the materials:

• 1

  Particle Size:

  The printed ink has a finer particle size than traditional concrete, allowing for optimal extrudability.

• 2

  Binder:

  The binders used in a printable material and in traditional concrete are not necessarily different. In 3D printing, many of the binders used are similar to those in traditional concrete.

• 3

  Admixtures:

  Specific admixtures are added to improve aspects such as fluidity, adjust the setting speed according to the project's needs, or enhance mechanical properties. For 3D printing material, the main difference lies in the use of powdered admixtures, and the process utilizes the material in the form of a premix.

3D concrete printing offers significant advantages for the construction sector, particularly in terms of cost reduction and resource optimization:

The development of low-carbon printable mortar at Constructions-3D addresses a growing demand for more sustainable and environmentally friendly materials. The carbon footprint of these materials is reduced by substituting Portland cement with alternative binders. Traditionally, the production of Portland cement generates a significant amount of CO2. Additionally, incorporating local materials into the formulations minimizes the environmental impact associated with transporting raw materials. The Termix-3D factory, located near Constructions-3D, plays a key role by enabling local production of 3D printing materials, thus reducing the supply chain and the overall environmental impact of the project.

The development of 3D printable ink presents complex technical challenges. Unlike traditional concrete, which is designed to be poured into molds, the printable ink must both:

• 1

  Be fluid enough to be pumped and extruded through a nozzle.

• 2

  Set quickly to allow for the layering of materials without collapsing or deforming.

This duality requires precise adjustments in terms of composition, including the addition of fibers or specific admixtures to control the setting and hardening of the material and ensure its mechanical strength. Additionally, the formulation must adapt to climatic conditions and project requirements, such as printing speed or the height of the structures.

Compared to traditional concrete, the difference lies mainly in its rheology: the behavior of the material must be specific and tailored to control the setting speed according to the layer printing time and the length of the hose. Depending on these factors, one can use:Compared to traditional concrete, the difference lies mainly in its rheology: the behavior of the material must be specific and tailored to control the setting speed according to the layer printing time and the length of the hose. Depending on these factors, one can use:

• 1

  Retarders for hot climates, to slow down the setting speed and prevent the mortar from hardening too quickly.

• 2

  Accelerators for cold climates, to ensure faster setting despite low temperatures.

Each formulation is unique and must be tailored to the specific application and site conditions.

In 2019, Constructions-3D initiated a partnership with IMT Nord-Europe to develop a low-carbon printable ink. This research project, conducted as part of a doctoral thesis, enabled the design of innovative materials with a low environmental impact, while incorporating local materials from the Hauts-de-France region.

The development process was methodical:

Through this approach, Constructions-3D not only developed a high-performance printable material but also established a formulation methodology adaptable to various projects.

The material developed by Constructions-3D contains a significant proportion of local, low-carbon materials, with 70% of the traditional cement replaced by alternative binders. These materials, combined with specific admixtures, offer high performance while reducing the material's carbon footprint. For example, the mechanical strengths achieved with such materials exceed 30 MPa (Mega Pascal), which is more than sufficient for most construction projects.

The future of Termix-3D and Constructions-3D relies on the expansion of local production of 3D printing material, particularly through the introduction of mobile factories and the C3D Lab mobile laboratory.

These innovations will enable Constructions-3D to further its approach to local and sustainable production. The mobile factories will facilitate the on-site production of materials, thereby reducing transportation costs and CO2 emissions. The C3D Lab mobile laboratory will provide the ability to formulate customized inks tailored to the specific conditions of the project and the local environment. The C3D Lab will also serve to conduct on-site quality control during construction printing.

Termix-3D, in collaboration with Constructions-3D, has the potential to transform the construction industry. The continuous development of low-carbon materials, combined with the use of mobile factories, will provide the construction sector with more eco-friendly and cost-effective solutions while enhancing the durability of printed structures.

The development of low-carbon printable ink at Constructions-3D, in partnership with Termix-3D, marks a significant step forward in innovation for more sustainable construction. With solutions such as the mobile factory and the C3D Lab, the future of 3D concrete printing looks promising, and Constructions-3D is positioning itself as a key player in the revolution of sustainable construction.