From seashells to cement, nature inspires a much tougher cement composite

Amazing stuff!

"... reported that creating alternating layers of tabulated cement paste and thin polymer can significantly increase crack resistance and the ability to deform without completely breaking (ductility). ...
the team developed a composite inspired by a natural material called nacre, or mother of pearl, which is found inside certain shells. ...  at the microscopic level, nacre consists of hexagonal tablets of the hard mineral aragonite glued together by a soft biopolymer. ...
This sliding action, combined with the crack deflection and biopolymer deformation, enables nacre to endure substantial mechanical stress while maintaining its structural integrity, making it both strong and resilient. ..."

From the abstract:

"Enhancing fracture toughness and ductility of brittle materials such as concrete remains a challenge. Nature offers numerous mechanisms to enhance fracture toughness using purposeful designs of materials’ architecture. Natural nacre exhibits high fracture toughness by promoting inelastic deformation and hierarchical toughening mechanisms. Here, “nacre-like-separated” and “nacre-like-grooved” cementitious composites inspired by brick-and-mortar arrangement of mollusk shells are proposed. These nacre-like composites are engineered by laser processing cement paste into individual tablets and grooved patterns (as intentional defects) and laminating them with limited amounts of suitable elastomeric (polyvinyl siloxane) interlayers. It is found that interlayer deformation, tortuous crack propagation guided by the defects, and crack bridging are the main toughening mechanisms in these composites that lead to rising resistance curves. The study hypothesizes tablet sliding as an additional toughening mechanism in “nacre-like-separated”, preventing tablet failure and leading to the postponed onset of bulk composite failure. These mechanisms significantly enhance both fracture toughness and ductility by 17.1 and 19 folds, compared to constituent hardened cement paste, respectively. By engineering laser-induced defects into tabulated cementitious-elastomeric material at meso-scale, a class of tough and ductile cementitious composites is introduced, resulting in significantly high fracture toughness values (73.68 MPa.mm1/2), comparable to Ultra-high-performance-concrete without sacrificing the strength."

From seashells to cement, nature inspires tougher building material - Princeton Engineering Inspired by the material that makes up oyster and abalone shells, engineers at Princeton have created a new cement composite that is 17 times more crack-resistant than standard cement and 19 times more able to stretch and deform without breaking. The findings could eventually help increase the crack resistance of a wide range of brittle ceramic materials, from concrete to porcelain.

Tough and Ductile Architected Nacre-Like Cementitious Composites (open access)

Credits: Zementverbundstoff mit Perlmutt-Effekt ist super dehnbar und rissfest US-Forschende haben einen neuartigen Zementverbundstoff entwickelt, der wesentlich rissfester und dehnbarer ist als herkömmlicher Zement.

Fig. 2 Fabrication of nacre-like composites. 

The researchers created beams with alternating layers of hexagonal cement tiles and thin polymer.