Hydrophobic and durable mortar

Advanced materials for construction and restoration must prove to be both sustainable and durable. The durability of cement-based materials such as mortar and concrete typically suffers from water penetration, resulting in corrosion of steel structures embedded inside the material and therefore to damage and weakness of the building structure. Several techniques and approaches have been developed to minimize the ingress of water in an attempt to increase the lifetime ans thus lower the environmantal impact of cementious structures. Researchers from Technical University of Munich (TUM) have developed a biofilm-enriched mortar with hydrophobic properties. This hybrid material can be supplemented with cement substitutes (SCMs) and also proves to be highly resistant to chemical attack and thermal stress - especially to the freeze-thaw cycles that regularly occur in Central Europe and are a major cause of damage. The biofilm enriched mortar exhibits strong hydrophobic properties by imitating the lotus effect. It shows an increased durability, is not harmful to the environment and can even be painted and is therefore also ideally suited for restorations.

Here a mortar hybrid material is presented where a bacterial biofilm is supplemented, increasing the hydrophobic properties. Bacterial biofilms are ubiquitous communities of bacteria encased in a matrix of self-produced biopolymers. In such a biofilm matrix, the bacteria are able to resist various environmental challenges, e.g., chemicals, desiccation, or removal from surfaces. By adding defined dosages of cement substitutes (SCMs), the mechanical strength of the mortar material can be significantly improved without losing the hydrophobic effect of the biofilm. Furthermore the formulation is highly resistant to sulphate attack.

• Biofilm creates an hydrophobic effect
• Mechanical strength can be improved by adding cement substitutes
• Highly resistant to sulphate attack
• Ideally suited for construction and restoration

• Biofim-enriched hybrid mortar has been tested and analyzed on laboratory scale
• Lyophilized powder of the bacterial biofilm available as dry admixture
• Mechanical properties with different amounts of biofilm contents have been measured