CEE Seminar: Nanotechnology and Sustainability of Concrete Construction

McDonnell Douglas Engineering Auditorium
Surendra P. Shah, Ph.D.

NAE Member, Professor
Civil and Environmental Engineering
Northwestern University

Abstract: Super tall buildings such as 1-kilometer-high Kingdom Tower are constructed with concrete as a structural material. Such tall buildings are made with so-called high-performance concrete, which can have strength five times that of conventional concrete. The development of high-strength concrete is a result of our understanding of particle packing, rheology and microstructure engineering. Concrete is a critical material for infrastructure; the world-wide consumption of concrete is about two tons for every living human being every year. However, its continuing use will require improving its sustainability. Nanotechnology is playing an increasing role in making concrete more sustainable. Some examples are given in this talk.

One approach to making concrete more sustainable is to replace Portland cement (and its significant carbon footprint) with fly ash, a waste material from burning coal. When fly ash replaces Portland cement, the rate of strength development slows down, which is not desirable. Addition of nanoparticles such as nano silica accelerates the chemical reaction by providing nucleation sites. In addition, characterization of the nanostructure of calcium silicate hydrate by nano indentation, AFM, FTIR and NMR shows beneficial nanoscale modification.

Manipulation of concrete rheology has been key to making concrete more constructible. The viscosity should be sufficiently small so that concrete can be pumped a great distance, but the material should be thixotropic to reduce the pressure on form work. The addition of a small amount of nano clay has been shown to accelerate the rate of thixotropy. Rheology of aging colloidal suspension is being studied by computation modeling as well as by measuring the dimensions of flocculated particles by using laser spectrometry.

​Concrete is a brittle material, prone to cracking. Concrete structures are reinforced by see bars at a millimeter scale. However, flaws in cement paste are in nanoscale. To reinforce concrete at the nanoscale, the addition of carbon nanotube is studied. The key challenges include dispersion and rheology. Recent studies have demonstrated that adding a very small amount (0.05%) of well-dispersed CNT has a profound effect on performance: mechanical properties, piezo-resistivity, transport properties as well as corrosion reinforcing steel. Such multifunctionality is probably related to the altered nanostructure of concrete.

Bio: Surendra P. Shah is a Walter P. Murphy Emeritus Professor of Civil Engineering and was the founding director of the pioneering National Science Foundation Science and Technology Center for Advanced Cement Based Materials. His current research interests include: fracture fiber-reinforced composites, nondestructive evaluation, transport properties, processing, rheology, nanotechnology and use of solid waste materials. He has co-authored two books: Fiber Reinforced Cement Based Composites and Fracture Mechanics of Concrete. He has published more than 500 journal articles and edited more than 20 books. He is a past editor of RILEM’s journal, Materials and Structures.

Shah is a member of the U.S. National Academy of Engineering, a foreign member of the Chinese Academy of Engineering and the Indian Academy of Engineering. He has received many awards, including the Swedish Concrete Award, American Concrete Institute’s Anderson Award, RILEM Gold Medal, ASTM Thompson Award, American Society of Civil Engineer’s Charles Pankow Award and the Engineering News Record News Maker Award. He was named one of the 10 most influential people in concrete by Concrete Construction Magazine. He has been awarded an honorary membership in American Concrete Institute and RILEM (based in Paris).

In 2007-2008 he spent time at the Indian Institute of Technology, Mumbai, as an honorary professor under the auspices of a Fulbright grant, and in 2014 he received a Fulbright Senior Lecturer award to spend five months at IIT Madras.

In addition to his position at Northwestern University, Professor Shah is now also a Presidential Distinguished Professor at University of Texas at Arlington. He has also taught at the University of Illinois Chicago, and served as a visiting professor at MIT, University of Sydney, Denmark Technical University, University of Singapore, Darmstadt University, Laboratoire Central des Ponts et Chaussees, Paris, and University of Houston.

Currently, he is a member of the Institute of Advanced Studies at Hong Kong University of Science and Technology and an honorary professor at Hong Kong Polytechnic University, Dalian Maritime University, Nanjing Technical University, South East University, Nanjing, and a Distinguished Professor at Indian Institute of Technology, Madras, India, and Jinan University, China. He is also an honory member of Tongji University.