Concrete is one of the oldest building materials with a history dating back to ancient Egypt. Today, concrete – comprised primarily of water, aggregate and cement – is the most widely used material in the world. Despite being a fairly low-impact material environmentally speaking, creating concrete still takes energy; thus the wide deployment of the material is reflected in its significant carbon footprint. In response, the industry is beginning to pursue more eco-friendly versions that would help curb energy requirements, and they’re using supercomputers to do it.
As part of a recent study, scientists from the the National Institute of Standards and Technology (NIST), the University of Strasbourg and Sika Corporation ran advanced simulations on Department of Energy supercomputers to explore methods for achieving less energy-intensive concrete mixtures.
As explained in this NIST feature, the study is targeting an essential ingredient in concrete: the binding agent that causes cement to harden when it comes in contact with water. The process of manufacturing this binding agent in high-temperature kilns generates a significant amount of carbon dioxide, a greenhouse gas implicated in climate change. The World Business Council for Sustainable Development estimates that worldwide cement manufacturing is responsible for at least 5 percent of man-made carbon dioxide emissions.
The concrete industry is working on manufacturing processes for concrete that are less energy-intensive. One approach is to use replace augment the mixture with alternative materials like fly ash, but this requires supplementation with expensive chemical additives. There is a push to customize these chemical additives to facilitate the use of alternative materials, ultimately producing a quality cement product that maintains desirable flow qualities all while using less energy.
“We’d like to be able to design concrete that performs better on the job and doesn’t demand so much energy to manufacture,” says NIST computer scientist William George. “But what should we make it from? And what can we replace cement with? The answers will affect its properties. So we realized we needed to learn more about how suspensions work.”
Studying how particles and fluid interact and behave is mathematically and compute-intensive, requiring sophisticated simulations and the computing power to run them. This is where the DOE’s leadership-class supercomputers come in. As part of an INCITE Award, the NIST team was granted more than 110 million core hours at the Argonne Leadership Computing Facility. The team ran simulations that revealed how parameters – like the size and number of suspended particles – affect the concrete suspension.
The study yielded important clues about how fresh concrete will behave given the properties of the fluid that is used. This led to the team being able to develop a general theory of suspensions’ properties. Not only could this result in improved concrete with a lower carbon footprint, NIST researchers are applying the lessons learned to guide future alternative materials design.