This work explores how clay can be used to introduce compression strength into flexible surfaces. By using robotics for controlled deposition, the process becomes parameterised, allowing a traditional material to be developed into a precise and predictable building system.
Continuation of https://blog.iaac.net/robotics-for-ecological-buildings-clay/
Introduction
This project proposes a system, how stitched textiles can be turned into lightweight architectural surfaces through robotic clay spraying, bringing together local materials, textile intelligence, computer vision, and robotic fabrication into one unified system.
Context & Properties
Clay as Local Material
The project begins with a local material: clay. In Catalonia, it can be sourced from regions like Empordà and Bages, both within 100 kilometers of Barcelona, keeping transport distances and carbon emissions low. Raw, unfired clay is prioritised to avoid the energy-intensive firing process, making the material reversible, reusable, and low-carbon. Its malleability and natural compatibility with water-based mixtures make it particularly well suited for robotic spraying.
Source: https://www.sigmapolyproducts.in
Local clay extraction sites in Catalonia
Clay deposits in the Empordà and Bages regions supply construction-grade material within 100km of Barcelona. Zero importation, minimal transport footprint.
Raw vs Fired Clay
Firing clay requires temperatures above 900°C, an energy-intensive, irreversible process. Raw clay eliminates the kiln entirely, remaining reversible, reusable and carbon-minimal.
Workability
Unfired clay is malleable, adhesive and workable during fabrication — properties that make it uniquely compatible with robotic spray deposition onto textile surfaces.
Clay Reinforcement : From Ancient Technique to Controlled Deposition
Before proposing a new system, existing precedents were examined to understand how clay has historically interacted with flexible structures. Techniques such as Wattle and Daub, Quincha, and Tendinoso walls all rely on a similar principle: a lightweight fibrous framework defines the geometry, while clay provides mass, enclosure, and stiffness. Across cultures and centuries, the relationship between flexible substrates and earthen coatings has already proven itself effective.
Wattle and Daub System
A woven lattice of branches coated with clay, sand and straw. The flexible structure provides the form and the clay provides rigidity and mass .
Quincha
Vertical cane stakes define a structural grid, packed and plastered with clay. The geometry of the cane determines where and how the clay is applied in this case the pattern controls deposition.
Tendinoso Wall
A lightweight framework of tensioned fibers and vegetal elements coated with earthen mixtures. The underlying network controls geometry and load transfer, the clay provides enclosure and stiffness.
Function: Structural Wall System
Material: Raw Clay + Woven Branches + Straw
Technique: Manual Daubing over woven lattice
Relevance: Clay rigidifies flexible structure
Function: Load-bearing wall system
Material: Raw Clay + cane or bamboo
Technique: Manual plastering over structural cane grid
Relevance: Flexible structure geometry governs clay deposition
Function: Enclosure and load distribution system
Material: Raw Clay + tensioned vegetal fiber (jute)
Technique: Clay coating over tensioned fiber network
Relevance: Tension-compression composite logic
Spraying and Coating : State of the art
Contemporary examples of clay and robotic fabrication were then examined. Terrapalha demonstrates that clay naturally adheres to textile surfaces, though the application remains manual. ClayKnit introduces robotic clay spraying onto knitted meshes, while ETH’s KnitCrete applies robotic concrete spraying over textile formwork. Together, these projects establish the potential of combining textiles and robotic deposition, yet none explore selective clay accumulation or programmable thickness gradients. This is the gap the research addresses.
Terrapalha — A Cabana (2013)
A summer pavilion built with eucalyptus poles, jute fabric and raw clay. Panels were prefabricated in the studio, jute plastered by hand with clay mixtures and assembled on site. The result demonstrates that raw clay adheres naturally to textile and produces a thermally massive, spatially inhabitable surface
ClayKnit – Gosch et al. (2021)
This research proposes spraying liquid clay with a six-axis robotic arm onto knitted meshes to produce lightweight, double-curved ceramic elements. The mesh acts simultaneously as stay-in-place form-work and permanent structural reinforcement, taking advantage of the complementary relationship between clay—which absorbs compression—and fibers—which absorb tension.
Robotic Knitcrete – ETH Zurich (2023)
CNC-knitted textile formwork with robotic concrete spraying. The knitted mesh acts as both structural support and stay-in-place formwork for thin-shell geometries. Demonstrates that textile geometry can govern structural form at architectural scale through robotic fabrication.
Robotic Function: None
Material: Raw Clay + Jute Textile
Technique: Hand Plastering + Prefabricated Panel Assembly
Gap: No Robotic Control – Deposition is non-uniform and unrepeatable
Robotic Function: Robotic Clay-Spraying
Material: Liquid Clay + Knitted Synthetic Mesh
Technique: Uniform Spray Deposition Over pre-formed mesh
Gap: No Selective Deposition – Uniform Thickness – No Gradient Control
Robotic Function: Robotic Concrete-Spraying
Material: Concrete + CNC Knitted Textile Formwork
Technique: Progressive Spray Deposition Over Knitted Geometry
Gap: Uniform Thickness – No Gradient Control
WIP
