On December 13th, 2024, Daria Kovaleva defended her doctoral research titled "Zero-waste sand formworks for lightweight concrete structures" in front of the doctoral committee. The doctoral committee consisted of Prof. Achim Menges (ICD) as chair, Prof. Dr.-Ing. Dr.-Ing. E.h. Dr. h.c. Werner Sobek (ILEK) as supervisor and first examiner, and Prof. Dr. Benjamin Dillenburger (dbt, ETH Zurich) as second examiner.
Congratulations to Daria Kovaleva on her outstanding achievement.
Abstract Doctoral Research
To address the growing urgent need to reduce resource consumption, embodied energy, and waste in construction, this thesis presents a new method for the zero-waste production of lightweight concrete structures using water-soluble sand formwork. The application of lightweight construction principles allows the creation of efficient and expressive structures with minimal material consumption and, consequently, an ecological footprint. Due to its ability to take any conceivable shape, concrete provides architects and engineers with virtually unlimited design freedom and is ideal for putting these principles into practice.
However, despite the wide availability of design solutions known since the middle of the 20th century, lightweight concrete structures are still not widely used due to the lack of adequate sustainable production methods. This often involves formwork manufacturing, which is still labor-intensive and wasteful and accounts for over two-thirds of the production budget. Digital production methods, such as additive and subtractive manufacturing, enable highly precise creation of geometrically complex objects. However, their broader application in formwork production is limited by their narrow specialization in the types of geometry produced, the generation of waste during processing, and the use of toxic and non-recyclable formwork materials. Therefore, the emergence of a flexible and environmentally friendly formwork method suitable for producing geometrically complex structures is necessary for the broader application of lightweight construction with concrete.
Offering a comprehensive approach to the above-described problem, this thesis proposes a novel zero-waste technology to produce lightweight concrete structures using additive manufacturing of a specially developed water-soluble sand and binder mixture. The powder-bed-based 3D printing of granular materials gives the greatest freedom in terms of geometric complexity, while the water-soluble nature of the formwork material mix allows it to be fully recycled after casting and reused in further production cycles.
Following the overall goal of promoting lightweight concrete construction, this technology also has an inverse effect on designing lightweight structures. It makes it possible to realize structural morphologies that would be inefficient or even impossible to produce with conventional formwork methods. The water solubility of the formwork material allows the creation of structures with geometrically complex external shapes and internal configurations. This enables not only improved structural performance but also the integration of other functional elements, such as MEP systems, acoustic and thermal insulation.
The work on the thesis includes the conceptualization of a closed-loop production cycle, the creation of an automated manufacturing process based on 3D printing of sand molds with a specially developed material mix, and the development of necessary accompanying CAD-CAM tools. The proposed technology is validated in the production of formworks for lightweight concrete structures of various scales, from small-scale prototypes to architectural demonstrator.
The dissertation is a monograph:
Kovaleva, Daria (2025): Zero-waste sand formworks for lightweight concrete structures. Doctoral Thesis. University of Stuttgart. Institute for Lightweight Structures and Conceptual Design. https://doi.org/10.18419/opus-16567.
The following publications were produced during the doctoral research:
Kovaleva, Daria; Tomovic, Ivan; Gericke, Oliver; Blandini, Lucio (2024): Structural design and analysis of Marinaressa Coral Tree. In: Proceeding of the IASS 2024 Annual Symposium. Zurich, Switzerland, August, 26-30. ETH Zurich.
Kovaleva, Daria; Nistler, Maximilian; Verl, Alexander; Blandini, Lucio; Sobek, Werner (2022): Zero-waste production of lightweight concrete structures with water-soluble sand formwork. In: 3rd RILEM International Conference on Concrete and Digital Fabrication, vol. 37. Loughborough, UK, June 26-29. Cham: Springer International Publishing (RILEM Bookseries), pp. 3–8. https://doi.org/10.1007/978-3-031-06116-5_1.
Kovaleva, Daria; Nistler, Maximilian; Blandini, Lucio; Sobek, Werner; Verl, Alexander (2022): Rezyklierbare Sandschalungen – Auf dem Weg zur Kreislaufproduktion leichter Betonbauteile. In Beton und Stahlbetonbau 117 (5), pp. 333–342. https://doi.org/10.1002/best.202200009.
Kovaleva, Daria; Nistler, Maximilian; Verl, Alexander; Blandini, Lucio; Sobek, Werner (2021), Abfallfreie Herstellung leichter Betonbauteile mittels wasserlöslicher Sandschalungen. In: Proceedings of 1. Fachkongress Konstruktiver Ingenieurbau. Ostfildern, Germany, September 28- 29. Esslingen Technical Academy (TAE).