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Different rubble dry stack compositions made from the same rubble batch

What can you do with rubble?

​Rubble has found its way into architecture through various techniques. Some of them, like masonry techniques, require skill and experience, while others, like concrete casting, have an exact recipe. Some methods, such as drystone, use solely unprocessed rubble, while others, like rubble masonry and gabions, incorporate a secondary material as a binder or support structure. Some, like opus mixtum, work with various rubble types, whereas others, like brickwork, require pieces with specific dimensions and geometries. Overall, there is often a strong correlation between technique and material, which calls for a careful match.

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Prototype, slip-form

Categorizing the techniques

We gathered a range of rubble techniques, both historical and contemporary, architectural, and experimental, and divided them into two main categories based on how the material is handled during construction: pouring methods and placing methods. In pouring techniques, the material is handled in bulk, while in placing techniques, piece by piece. The techniques were sourced from books, magazines, and websites. The main selection criteria was that they had to include rubble itself or a material from which rubble is derived as the primary construction material.

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Technique overview. The pink circles mark the methods we tested in prototypes 
(First published in DMS 2024, Scalable Disruptors, p. 3–14, 2024 by Springer Nature.)

​Prototyping with unprocessed rubble​

While many recent research projects often use large-scale rubble pieces and focus on a single material group, few projects include the full range of rubble. We focused on techniques that require minimal to no material processing and facilitate the use of mixed, small pieces of rubble. The two material approaches were investigated in physical prototypes and experiments. We explored, for example, how traditional brickwork bonds could be adapted to brick rubble, how to dry-stack rubble, if slip-form masonry with mixed brick and concrete was faster and easier than other masonry techniques, if mycelium might be an alternative to mortar and if we could make stable building components by simply “backfilling” rubble into a container. The aim was to get first-hand experience with existing techniques while searching for methods that make sense to be adapted or further developed with digital technologies.

A full description of the technique exploration can be found in the paper: 

Wyller, M., Svatoš-Ražnjević, H., Schad, E., Menges, A. (2024). A Taxonomy of Techniques and Tools for Rubble. In: Eversmann, P., Gengnagel, C., Lienhard, J., Ramsgaard Thomsen, M., Wurm, J. (eds) Scalable Disruptors. DMS 2024. Springer, Cham. https://doi.org/10.1007/978-3-031-68275-9_1

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Prototyping

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Prototype of brickwork adapted to rubble

 

Prototype of dry stacking adapted to rubble

 

Prototype of gabions adapted to jammed rubble

 

Prototype of block casting adapted to rubble and mycelium

In-depth study: Jammed Rubble​

We explored the approach inspired by gabions and rubble’s granular behavior in-depth. In this method, rubble of different materials and sizes is sorted and poured into tailored, glass fiber mesh containers following a specific filling choreography. Although in its early development stages, the system has the potential to become a rapidly deployable, fully recyclable, and reusable building system used for temporary or permanent construction. The shape of the container can be sewn into various shapes – a column, a wall, a foundation, and the filling choreography adapted to include other parameters than the rubble sizes, such as its color.

A full description of the building system development can be found in the paper: Svatoš-Ražnjević, H., Wyller, M., Schad, E., & Menges, A. (2024). Jammed Rubble: A building system concept for granular architecture from mixed mineral waste. In O. Kontovourkis, M. C. Phocas, & G. Wurzer (Eds.), Proceedings of the 42nd Conference on Education and Research in Computer Aided Architectural Design in Europe. Data-Driven Intelligence. (Vol. 2, pp. 587–596). eCAADe, University of Cyprus, Department of Architecture.

How to jam rubble

We conducted a range of small to medium-scale physical experiments on distributing the rubble to achieve a stable component by maximizing the number of contact points between the pieces and minimizing gaps. Thirteen different strategies were tested at a small scale, and three of these were further explored on a large scale: (1) unsorted mixed rubble, (2) sorted horizontal, and (3) vertical layering. After completing the fabrication, we empirically evaluated the surface finish, the size, and quantity of gaps, as well as the rigidity of the filled container from the exterior. The most successful layering sequence was later adapted and tested in a full-scale prototype.

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Overview of filling strategies that we tested in small-scale prototypes. Number 13 was tested in a full-scale prototype 
(First published in eCAADe 2024, Data-Driven Intelligence, Vol. 2, p. 587 – 596, 2024 by eCAADe and University of Cyprus, Department of Architecture)

Compression tests​

​To test the capacity of the system to sustain forces at an architectural scale, we conducted a one-time uniaxial compression test on six prototypes at the University of Stuttgart. One prototype from each layering approach was tested, in addition to three prototypes with additional features: an external protective layer of mortar, a mycelium infill, and a triple-layered glass fiber mesh container. We recorded the load at the vertical displacement until we reached 5 cm displacement. The results of the tests show that the container and its tensile strength have the greatest impact on the performance. The improved container with a tripled glass fiber layer could withstand 350kN (3,5 tons) before reaching approximately 6 cm of vertical displacement and splitting at the seam. This was ten times more than any of the single container and crust samples and 4,5 times more than the mycelium sample.

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Before and after compression tests. 

(First published in eCAADe 2024, Data-Driven Intelligence, Vol. 2, p. 587 – 596, 2024 by eCAADe and University of Cyprus, Department of Architecture)

Full-scale prototyping​​

We tested the most successful layering sequence in a full-scale prototype of a 220 cm tall column with a diameter of 50cm. At this scale, we had to segment the container into four and iteratively sew them together during construction. The prototype was filled with approximately 800 kg of concrete and brick rubble. The rubble was collected and sorted into sizes in one day, while the column was assembled and disassembled in two days. 

Filling strategy

 

The most successful layering sequence: layers of large and medium pieces are placed in the center, small ones poured between the large and medium pieces, and the extra small ones poured along the container perimeter. (First published in eCAADe 2024, Data-Driven Intelligence, Vol. 2, p. 587 – 596, 2024 by eCAADe and University of Cyprus, Department of Architecture)

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1. Preparation, full- scale prototype: first segment of the fiber mesh container

 

2. The next segment is sewn onto the previous one

 

3. Filling the prototype

 

4. The prototype was disassembled and sorted back into four different rubble sizes

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Layering sequence: layers of large and medium pieces are placed in the center, small ones poured between the large and medium pieces, and the extra- small ones poured along the container perimeter

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The prototype consisted of four elements and had a final height of 220 cm and a diamenter of 50 cm

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