Rubble Works: Leveraging digital technologies for design and construction with mixed mineral construction and demolition waste

Abstract

This report presents the results of the research project Robots//Reuse, funded by the Research Initiative Zukunft Bau. In this research project, David Chipperfield Architects Berlin and the Institute for Computational Design and Construction at the University of Stuttgart explored the reuse of rubble by looking at how material, techniques, and digital technologies can be combined to make construction and demolition waste relevant to contemporary architecture. Construction and demolition waste (CDW) is Europe’s largest waste stream and a major global problem. Despite an emergent interest and focus in the material group, it does not find its way back into architecture to a sufficient extent as the most widely currently applied recycling practice for CDW is crushing to secondary aggregates. Achieving a circular use of building materials requires both the development of cost-effective and time-efficient technologies that enable the reuse, and an architectural aesthetic that attracts users, investors, and architects to choose to build with it. In the past, the reuse of building materials was common practice, and many renowned architectural projects were built from, for example, reused wood, stones, and brick. These projects showcase both the large and varied aes-thetic potential of reuse. Yet, common for all of them is the dependence on manual labor. Skilled craftspeople would select, adapt and carefully implement found or taken building components and elements into new architecture. Today, the scale of both the mass manufacturing industry and the CDW problem overgoes the scale at which a craftsperson works. The high costs associated with the processing of non-standardized and irregular materials are, next to barri-ers relating to material quality, building code and logistics, one of the greatest barriers to the reuse of CDW in architecture. However, recent advances in robotics and scanning allow us to disassociate the technique from the manual effort and open up new design possibilities. The evolution of manufacturing—from traditional craft production to mass production and then to mass customization—points towards a future of flexible automation. Here, complex fabrication and assembly processes involving non-standardized materials are as efficient in terms of time, cost, and energy-consumption as the production of new materials. Beyond automating existing techniques, digital technologies also offer the chance to develop entirely new ones. While the potential of matching CDW with new building technology has already been explored in other research projects, there seems to be little research compared to the large amount of this type of waste and the research project tend to focus on larger pieces. The aim of the project is through a combined expertise from both practice and academia to explore how a synergy between material, tools and aesthetics can be achieved in the light of four overarching research questions: What are the current limitations of computer-based design and digital fabrication processes used to process and assemble non-standardized building materials? Which digital design processes could be suitable for building with reused building materials? How can the use of computer-based design and digital fabrication methods make the reuse of building materials attractive to architects, companies and users in terms of aesthetics, scalability and efficiency? How can we bridge the gap between architectural design practice and current academic research on the reuse of building materials? Inspired by both traditional crafts and new technologies, these research questions and new potentials for designing with reclaimed materials were explored on a both theoretical and practical level. The project was split into a historical pre-study of reuse in architecture, and a case study focused specifically on rubble. Through methods ranging from an analysis of traditional and contemporary reuse and masonry-related techniques, to material classification and prototyping, we developed different approaches to how to think about, handle and design with rubble. One direction, jammed rubble, was explored in depth along with concepts for robotic rubble placement and pouring. The project is a conceptual, basic research project and although it is out of the project’s scope to develop finished solutions, certifiable building systems, or complete robotic workflows, it provides a starting point for rediscovering the potential of reuse of reclaimed materials through digital tools. The overall outcome of the project is a series of rubble works that, rather than offering a definitive solution to rubble’s challenges, provide a starting point for rediscovering its potential.