Admixtures to reduce the shrinkage in earthen construction

Earth-based building materials are currently receiving renewed interest due to their low carbon footprint, large availability and unlimited recyclability. However, significant progress needs to be made before these materials become widely accepted and utilized. Shrinkage and cracking during the drying process are one main obstacles, particularly for poured earth, which has higher water content than compacted earth. Shrinkage due to water loss may result in large cracks both due to self-restraint (i.e. shrinkage gradients) and external restraint (e.g., from other structures). Currently, the shrinkage reduction of earth materials is commonly achieved using mineral binders, such as Portland cement or lime. These binders, however, increase the environmental burden and disrupt both the hygroscopic properties and the recyclability of such materials. This subproject thus aims to develop admixtures that are able to control shrinkage, at the same time maintaining the original performance in terms of moisture transport and recyclability. Such admixtures would also allow good integration into sustainable wood-clay structures for sustainable housing. In these hybrid structures, reduced shrinkage is essential for the mechanical interaction of the two materials.

Project Team

Project Leader

Pietro Lura

Members

Ellina Bernard, Yi Du


Partners

ETH, Chair of Sustainable Construction

BASF

Eberhard

Funding Organization

Think Earth - Regenerative Building Innosuisse flagship Initiative - TP2 (a full description of the whole flagship  initiative can be found here)