Additives for Shrinkage Reduction
The strength of earth building materials comes from clay minerals and capillary bridges between particles, but this structure also leads to significant shrinkage and cracking during drying, limiting them to smaller elements like bricks. SP2 teams ETH, Empa, BASF, and Eberhard Bau AG are testing biodegradable additives that reduce shrinkage, aiming to produce crack-free, recyclable materials that lower landfill waste.
The strength of earth materials relies on clay minerals and the numerous capillary bridges between clay particles. However, this structure also leads to significant shrinkage and cracks during drying. Therefore, they are mainly used for smaller elements like bricks, and their application as poured earth is still under development. Solutions to reduce shrinkage are paramount.
In the Think Earth Subproject 2, "Additives against Shrinkage in Earth-based Materials," the Chair of Sustainable Construction at ETH and the Laboratory for Concrete and Asphalt at Empa collaborate with BASF and Eberhard. BASF will provide bio-based and biodegradable additives to reduce shrinkage. Specific additives will be screened after understanding the crucial aspects of drying that lead to shrinkage and cracks. Eberhard will test these additives on a large scale. Additionally, the recyclability and hygrothermal behavior of the developed materials will be tested. The goal is to reduce shrinkage through green chemistry to produce competitive, crack-free earth-based materials and reduce the amount of excavated earth in landfills.