Hempcrete – CO ₂ Neutral Wall Solutions for 3D Printing

Abstract

Abstract Hempcrete is a bio-based self-bearing envelope and thermal insulation building material that is becoming more popular nowadays and has a low environmental impact, especially CO 2 emissions. This study looks for solutions for hempcrete printing using a custom-built gantry type 3D printer typically used for concrete 3D printing. Preliminary research shows that hempcrete can be printed at a relatively low density of 660 kg/m 3 and achieve an adequate buildability and compressive strength for printing individual wall elements. At this density, hempcrete has a thermal conductivity of 0.133 W/(m·K), unable to provide the adequate thermal resistance at average wall thickness, so high-density hempcrete should be printed as an outer wall shell (similar to Contour Crafting) and the middle filled with lower density thermal insulation hempcrete. By calculating the CO 2 emissions of such printed 400–620 mm thick walls, it was found that they absorb from 1.21 to 16.7 kg of CO 2 per m 2 , thus, such material could reduce the negative environmental impact of the construction industry while improving its productivity through 3D printing.