Sandbag Castle in Eindhoven showcases low-carbon concrete alternatives in floating art installation

Yvonne Mak's Sandbag Castle is a floating installation in the Dommel river in Eindhoven, built from hundreds of concrete sandbag-shaped modules. The work is designed around low-carbon concrete alternatives and includes over ten experimental formulations, such as calcined clay, geopolymer concrete, recycled aggregates, and self-healing mixes. The installation sits beside the Van Abbemuseum Cafe and uses red warning flags to point at the tension between protective infrastructure and its environmental cost. Developed with main partner TBI, the project turns a familiar material into a public demonstration of lower-emission concrete options for construction. For anyone tracking low-carbon building materials, the value here is the visible proof that these mixes can be cast, stacked, and displayed in a real-world setting. The next step will be whether the formulation and embodied carbon data are made public for specifiers and engineers.