Portland cement (PC) is a widely used material in construction, essential for infrastructure, housing, and improving living standards. Its ability to harden quickly and perform well in various environments, including underwater, makes it highly versatile. However, the growing consumption of PC has raised significant concerns. Producing 1 ton of PC requires about 1.7 tons of raw materials and 4 GJ of energy. Globally, cement production consumes 7 billion tons of non-renewable materials annually (13 million tons in Portugal) and accounts for 2% of global primary energy use and 5% of industrial energy use. Despite these impacts, demand for cement is expected to increase by 12%-23% by 2050, with projections suggesting it could double by 2060. Cement-based materials are therefore essential for achieving the United Nations Sustainable Development Goals (SDGs), given their profound social, economic, and environmental impact.
To address the environmental footprint of cement production, innovative construction technologies and greener cement-based materials are gaining traction. Among these, digital fabrication processes, such as 3D printing of cement-based materials (3DPC), have shown transformative potential. This technology enables freeform architectural designs without formwork, enhances productivity, reduces costs, and improves
workplace safety. Furthermore, 3DPC can deliver environmental benefits, such as material savings and reduced waste generation. However, these advances also pose significant material challenges. Printable materials must simultaneously exhibit high flowability during extrusion and sufficient buildability to retain shape without collapse.
Achieving this requires mixture designs with fine materials (cement and supplementary cementitious materials) and chemical admixtures (e.g., superplasticizers, viscosity-
modifying agents), which can inadvertently increase CO₂ emissions and energy use compared to traditional concrete casting.
From a materials science perspective, 3DPC faces substantial hurdles. Ensuring optimal material flow while maintaining structural integrity necessitates sustainable and circular cementitious mixtures. DigiCrete, aims to address these challenges by developing cement-based materials that are suitable for 3D printing and also carbon efficient. The
approach focuses on i) using local materials (Portuguese market), ii) massive cement replacement by conventional and unconventional supplementary cementitious materials
and iii) an integrated mix design approach considering engineering and environmental requirements.