Impact Printed Structures (2024-04)¶

The construction industry contributes significantly to environmental degradation through pollution, waste generation, and climbing greenhouse gas emissions, prompting the exploration of alternative materials with lighter environmental impact. The use of earth as a building material has been common in construction for centuries, offering advantages like high thermal inertia, moisture regulation, fire resistance, and acoustic insulation, which are ideally suited for construction. However, most traditional earth-building methods are formwork-dependent and labour-intensive, resulting in slow build rates and high costs. These shortcomings present a significant opportunity to leverage novel digital construction techniques for non-standard but sustainable materials such as raw earth. To address these challenges, this research presents the design and construction potentials of a novel robotic earth-building technique called ‘impact printing’ (IP). The robotic building process resembles a ‘shooting’ process from a close range, where discrete malleable parts of the material are deposited at controlled high velocities and frequencies by a custom mechanism, resulting in monolithic material structures. Like traditional adobe or cob construction, the IP process utilises a custom material mix in a plastic state that gradually gains mechanical strength as it dries. A custom low-carbon earth-based material is developed for the IP process using minimal hydraulic binders. This development aims to enhance and control the curing rate and boost the compressive strength of the structure. The high-payload IP mechanism is mounted on a bridge-like superstructure controlled by a 3-axis gantry. This configuration facilitates a free unrestricted movement of the mechanism in Cartesian space, achieved through the synchronous control of two external axes within a multi-axis robotic gantry system.