Construction materials and techniques have witnessed major advancements due to the application of digital tools in the design and fabrication processes, leading to a wide array of possibilities, especially in additive digital manufacturing tools and 3D printing techniques, scales, and materials. However, possibilities carry responsibilities with them and raise the question of the sustainability of 3D printing applications in the built environment in terms of material consumption and construction processes: how should one use digital design and 3D printing to achieve minimum material use, minimum production processes, and optimized application in the built environment? In this work, we propose an optimized formal design of “Biodigital Barcelona Clay Bricks” to achieve sustainability in the use of materials. These were achieved by using a bottom-up methodology of biolearning to extract the formal grammar of the bricks that is suitable for their various applications in the built environment as building units, thereby realizing the concept of formal physiology, as well as employing the concept of fractality or pixilation by using 3D printing to create the bricks as building units on an architectural scale. This enables the adoption of this method as an alternative construction procedure instead of conventional clay brick and full-scale 3D printing of architecture on a wider and more democratic scale, avoiding the high costs of 3D printing machines and lengthy processes of the one-step, 3D-printed, full-scale architecture, while also guaranteeing minimum material consumption and maximum forma–function coherency. The “Biodigital Barcelona Clay Bricks” were developed using Rhinoceros 3D and Grasshopper 3D + Plugins (Anemone and Kangaroo) and were 3D printed in clay.

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In a previously published study, the authors explained the formal design efficiency of the 3D-printed biodigital clay bricks 3DPBDCB: a project that aimed to change the conventional methods of clay brick design and mass production. This was achieved by employing the behavioural algorithms of reaction-diffusion and the shortest path that were extracted from the exact material physical properties and hydrophilic behaviours of clay and controlled material deposition 3D printing to create sustainable clay bricks. Sustainability in their use in the built environment and their production processes, with full potential sustainability aspects such as passive cooling, thermal and acoustical insulation, and bio receptivity. The current work studies the mechanical properties of the 3D-printed biodigital clay bricks as elastic and durable clay bricks whose properties depend mainly on their geometrical composition and form. Each of the three families of the 3D-printed biodigital clay bricks (V1, V2, V3) includes the linear model of a double line of 0.5 cm thickness and a bulk model of 55% density were tested for compression and elasticity and compared to models of standard industrial clay bricks. The results revealed that the best elasticity pre-cracking was achieved by the V2 linear model, followed by the V3 linear model, which also achieved the highest post-cracking elasticity—enduring until 150 kN pre-cracking and 200 kN post-cracking, which makes the V3 linear model eligible for potential application in earthquake-resistant buildings. While the same model V3-linear achieved the second-best compressive strength enduring until 170 kN. The best compressive strength was recorded by the V1 linear and bulk model enduring up to 240 kN without collapsing, exceeding the strength and resistance of the industrial clay bricks with both models, where the bulk and the perforated collapsed at 200 kN and 140 kN, respectively. Thus, the mass production and integration of the V1 bulk and linear model and the V3 linear model are recommended for the construction industry and the architectural built environment for their multi-aspect sustainability and enhanced mechanical properties.