Bio-inspired composite cement: a new material to increase durability using natural principles

Princeton’s university engineers developed a new composite cement inspired by oyster and abalone shells. The new material is more resistant and stretchable than the conventional cement. Particularly, the new cement is 17 times more crack resistant and 19 times more stretchable. This innovation could improve the durability of brittle ceramic materials like concrete and porcelain.

The researchers drew their initial inspiration from nacre (mother of pearl), a natural material found in certain shells. Specifically, nacre's structure is characterized by hexagonal aragonite tablets bonded by a soft biopolymer, which provides both strength and flexibility. This mechanism, involving tablet sliding and energy dissipation, allows nacre to withstand significant stress without fracturing.

The team of the study, with Assistant Professor Moini as principal investigator, replicated this structure using Portland cement paste and polyvinyl siloxane polymer. Using this mixture, they created multilayered beams with alternating cement paste and polymer layers and then they conducted bending tests. The beams with separated hexagonal cement tablets connected by polymer exhibited the highest ductility and fracture toughness, akin to nacre's properties.

In addition, the study approached the engineering materials by understanding natural mechanisms rather than merely mimicking structures. The researchers noted that further work is needed to apply these techniques in real-world scenarios and explore their effectiveness in other ceramic materials.

A graduate student who participated in the project emphasized the potential of this composite in making concrete safer and more durable. By alternately layering cement paste and a thin polymer, significant improvements in crack resistance and ductility can be achieved. In all, the leader of the study and Assistant Professor, Moini, stated that the research in these materials is in its initial stage. However, the study aims to serve as a stimulus to explore design possibilities and intends to engineer the interplay between hard and soft material properties, interfaces, and geometries in construction materials.