Session: 12-16-03: Drucker Medal Symposium

Paper Number: 99598

99598 - Architected Cementitious Materials 

Abstract.  In the face of climate change, the world’s growing population, and decaying infrastructure, there is a need to develop stronger, tougher, and more resilient civil infrastructure materials. Nature offers abundant insight for developing resilient engineering materials. For example, biological materials commonly present an unparalleled combination of two mutually exclusive material properties, strength and toughness. On the other hand, construction materials typically suffer from a brittle response and low fracture toughness or strength. Two primary challenges are engineering the mechanics of strong and tough design motifs found in biological materials and implementing them via advancing relevant manufacturing processes.  Here, we propose engineering several toughening mechanisms informed by nature, into the architected construction materials (such as cementitious materials).

One of the classical examples of tough natural materials is nacre with a brick-and-mortar architecture of mineral tablets held together by organic protein interfaces that gives rise to several toughening mechanisms. This brick-and-mortar architecture leads to ductile and tough characteristics, owing to the microscopic tablet sliding followed by the crack deflection and branching mechanisms. In particular, strain hardening at the interface, pull-out of platelets from the interface, chain unfolding, and cross-link breakage are among the primary mechanisms likely to contribute to energy dissipation and enhanced toughness of nacre.

This work focuses on designing and fabricating three-dimensional nacre-like cement paste-elastomer composite assemblies through multi-stage depositing of silicone material in-between hexagonal cement paste tablets. The materials’ architecture and the effect on mechanical response and mechanical properties, fracture toughness and ductility were investigated. We hypothesize that introducing the highly deformable and compliant silicone elastomer material adhered strongly to hard cement paste tablets with a high aspect ratio and structural arrangement mimicking that of the natural counterparts, can lead to large-scale tablet sliding mechanism, crack deflection, and ultimately enhanced fracture and damage tolerance. The resulting multi-layered cement paste composite is a tough and deformable composite material while maintaining a high stiffness and flexural strength, compared to the monolith brittle cement paste material. Designs of nacre-like cementitious composites are enabled by a variety of manufacturing techniques, including casting, laser processes, and additive processes. This presentation makes the case that advanced manufacturing offers the opportunity to harness the role of architecture, in favor of materials’ mechanical properties. Development of non-conventional automated technologies such as direct-ink-writing and robotic additive manufacturing processes across multiple scales may be potential practical pathways offering the necessary tools to enable these resilient infrastructure materials at large scales.

Presenting Author: Reza Moini Princeton University, Department of Civil and Environmental Engineering

Presenting Author Biography: Reza Moini joined the Civil and Environmental Engineering Department at Princeton University as an assistant professor in January 2021. He is directing the Architected Materials and Additive Manufacturing Lab at Princeton and is an associated faculty with the Institute of Materials as well as the Andlinger Center of Energy and Environment. Moini completed his Ph.D. in the Lyles School of Civil Engineering at Purdue University in 2020. His current research focuses on the design, mechanics, and manufacturing of resilient architected civil engineering materials. His work is motivated by the intellectual challenge of understanding the mechanics of intrinsically brittle materials and developing tough and flaw-tolerant materials without changing the materials' composition.

Authors:

Reza Moini Princeton University, Department of Civil and Environmental Engineering
Hadi Shagerdi Esmaeeli Princeton University
Shashank Gupta Princeton University
Arjun Prihar Princeton University