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From Nano to Macro: The Multi- scale Approach
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Ms. Aleena Alex*
Email: aleenalex@gmail.com
In high school, I’ve learnt a poem called ‘For Want of a Nail’. It goes something like this ‘for want of a nail, a shoe was lost; for want of
a shoe, a horse was lost ...’ and so on .... The loss of the horse leads to the loss of a rider, then the message, the battle and finally the kingdom. The message of the poem is that it is the little things that contribute in their own minute way towards forming the bigger picture. This is also the foundation of an exciting new field of research called multi-scale materials modelling. Just as the simple nail decided the fate of the mighty kingdom, the nanoscale material properties and interactions determine the final mechanical strength, durability and performance of a structure.
Therefore, how important it is to investigate a structure from a multi-scale perspective?
Before we answer this question, we need to understand the concept of hierarchy in a material system. Take a very familiar structure such as a building. The building is composed of beams and columns that impart structural strength to the structure. These structural elements are in turn made of concrete, which consists of cement, sand, aggregate and water. Cement is a complex mixture of minerals that acts as a binder or glue holding together the various components of concrete. But of course, you would have observed cement as a powder. Then, how does it get this binding property? That occurs as a result of its reaction with water, forming a gel-like product called calcium silicate hydrate or, as we civil engineers like to call it, C-S-H. Now, this C-S-H is a fascinating compound. It’s a chameleon
* Ms. Aleena Alex, PhD Scholar from Indian Institute of Technology, Madras, is pursuing her research on “Development of a 3D Multiscale Materials Model for Hydrating Cement”. Her popular science story entitled “From Nano to Macro: The Multi-Scale Approach” has been selected for AWSAR Award.