Anoop Krishnan

UCLA, Civil and Environmental Engineering

“A bottom-up approach on predicting material responses at multiple scales”

Abstract

Construction is a billion-dollar industry, which primarily banks on the availability of cheap and reliable construction materials. With the advent of globalization and urbanization, demands on amenities, and infrastructures have increased multi-fold, which puts additional burden on the construction industry. This situation is further worsened when ubiquitous construction materials, such as cement, are carbon-taxed for its contribution to atmospheric pollution. For example, concrete, the most-widely used material in the world, contributes to five percent of annual anthropogenic CO₂ production primarily due to the sheer amount of use. While there have been significant improvements in the construction practices in the last few decades, very few research has been conducted on understanding and improving construction materials by manipulating its building blocks, i.e., atomic arrangements. To address this issue, we can borrow concepts from physics, materials science, glass science and chemistry to analyze material responses at multiple length and time scales.

In this talk, focus will be given on understanding and manipulating the atomic topology to control macroscopic properties such as creep, and thermal expansion. The role of the atomic network topology on material properties can be analyzed using rigidity or topological constraint theory (TCT), which has been successfully used in the design of gorilla glasses. TCT draws a direct analogy for atomic systems with the truss network in civil engineering, where atoms and bonds correspond to nodes and bars in a truss system, respectively. Using Maxwell’s stability criteria, an atomic network is called isostatic (statically determinate), stressed-rigid (statically indeterminate), and flexible (statically underdetermined) based on the number of constraints of the network. Combining TCT with realistic molecular dynamics simulations on C-S-H, the binder phase of cement, the existence of a direct relationship between material properties and the atomic topology will be established. Further, it will be shown that the methodology can be used to predict optimal compositions for macroscopic properties, such as fracture toughness and creep-resistance, by analyzing the atomic topology only. Improving the durability and service life of materials using such a bottom-up approach can go a long way in developing economically viable and environmentally responsible construction materials.

Bio

Anoop Krishnan is currently a lecturer and a postdoctoral researcher in the Department of Civil and Environmental Engineering at the University of California Los Angeles. Prior to this, he completed his undergraduate education in Civil Engineering from the National Institute of Technology Calicut (India), and Ph.D. in Structural Engineering from the Indian Institute of Science Bangalore (India). The work during his Ph.D. focused on developing multi-scale models for predicting mechanical properties of nanocomposites for engineering applications. His postdoctoral work focusses on predicting properties for the tailored design of a broader range of materials such as glassy, and cementitious systems with particular focus to applications such as radiation- and creep-resistant materials.