RESEARCH DATA
Funding: IBOIS
Status: Ongoing (since July 2025)
Research Collaborator: TsungWei Cheng, architect, NTUST
Research Director: Prof. Yves Weinand, architect and engineer, IBOIS
ABSTRACT
Architecture, construction, and engineering industries account for a significant share of global carbon emissions, creating an urgent need for alternative materials and construction strategies. Earth and timber have emerged as promising candidates; however, most existing studies either focus narrowly on material mechanics and structural performance or treat the two materials independently. This research challenges conventional construction logistics by proposing a hybrid, self–load-bearing wall system based on actively bent, interlaced timber grids combined with shot-earth infill.
Shot-earth—an innovative term adapted from shotcrete—refers to the process of spraying earth-based material onto a surface. This research aims to develop a mold-free earth-spray method in which timber lattice grids serve as permanent reinforcement. In the hybrid system, earth primarily resists compressive forces, while the timber grids distribute tensile forces.
Three parameter sets are explored through the prototyping of a self-bearing wall:
- Timber grid density and gap size
- Grid geometry and assembly strategy
- Spray sequence and earth-layer thickness
Timber grid density determines the maximum sprayable gap while preventing material penetration. Unlike earth-printing processes, the spray direction is perpendicular to the wall surface, giving greater freedom for deposition on both sides. For this reason, rebound behavior is systematically evaluated. Grid geometry and layering strategies address deformation within the timber lattice and load distribution through fiber orientation and earthen interlocking, comparing ordered and randomly interlaced configurations.
The final parameter set examines spray sequence and layer thickness in double-layer timber frameworks. Thicker earthen layers increase the risk of cracking and shrinkage during curing, whereas thinner layers may result in excessive rebound and material loss.
In conclusion, this research investigates whether actively bent timber grids can serve simultaneously as permanent reinforcement and as spray-control formwork for mold-free, shot-earth, self-bearing wall construction. A 1 × 1 m prototype is used to test failure thresholds, rebound rates, penetration limits, and assembly sequences across different grid configurations. The project contributes a validated hybrid timber–earth construction logic, supported by prototype-based testing and quantified performance thresholds.
