CementJigsawFairness has always been one of the aspirations of an ideal society. From the school playground to the International Court of Justice, fairness forms the basis of peaceful coexistence. Equality before law, one person one vote, empowerment of women, affirmative action, and the welfare state are attempts at realizing the principle of fairness and building a more equitable society. Environment protection is no exception. The ‘polluter pays’ principle forms the backbone of most multilateral environment agreements, most notably the United Nations Framework Convention on Climate Change (UNFCCC). Under this convention, developed countries responsible for the bulk of greenhouse gas emissions from 200 years of industrialization have to commit to reducing their emissions drastically. Developing countries can industrialize without binding restrictions for the moment. But for how long? Until they reach a sufficient level of economic development? Until the CO2 in the atmosphere reaches 400ppm? Until the consequences of climate change outweigh the benefits of fossil fuel based industrialization?

Developing countries are prepared in theory to accept binding commitments but with a tricky caveat – the commitments should be based on the principle of social justice and not put a massive handbrake on their economic development. Sure, green energy and the carbon market were designed to achieve these goals but it will take several decades and a total overhaul of the standard development pathway for them to have any effect. Developing countries like China and India that are riding on the crest of a quick & dirty economic boom cannot afford to wait for the promised shipment of green tech to arrive. This is at the very heart of the reluctance of developing countries to accept binding greenhouse gas emission reduction commitments. Is there a way to successfully juggle climate change mitigation, rapid economic development and climate justice?

One solution is concrete. Not as glamorous as gleaming wind turbines or shiny electric cars, this ubiquitous construction material has a lot to offer for little investment. For starters it is the most widely used material on the planet. Currently cement production is responsible for 5-8% of all global man-made emissions. Hence even though the cement industry is notorious for greenhouse gas emissions, there is a lot of potential due to the sheer scale of the stuff we use. To put this in perspective, even a modest 10% reduction in emissions in producing a cubic metre of concrete would result in savings equivalent to the total CO2 emissions produced by the entire steel industry. Demand for concrete is expected to double or even treble by 2050. And guess where concrete demand is coming from?

Emission reductions in concrete manufacture can be achieved in two ways – 1) increasing the energy efficiency of cement plants or 2) partially substituting cement with less energy-intensive materials. The first option has pretty much been optimised with the energy efficiency in the best cement plants touching 80%. The second option has more potential. Fly ash, a waste product from burning coal can replace up to 30% of the cement in concrete production. However, there is nowhere near enough fly ash in developing countries to match the demand for cement. Thus the answer lies in finding a locally abundant cement substitute. This will also go some way in addressing the emissions resulting from transporting raw material, cement and clinker around the world.

A potential candidate is clay. Clay is definitely an abundant raw material and studies have shown that calcined clay (clay that undergoes a thermal treatment process) can replace between 30-60% of cement in concrete without compromising its durability. However, more research is needed to accurately predict the behaviour & interactions of calcined clays in concrete and their long-term performance over the lifespan of a concrete building. That is small price to pay for a key piece in the greenhouse gas emissions reduction puzzle.


Technology Roadmap: Low-Carbon Technology for the Indian Cement Industry

The Laboratory of Construction Materials, EPFL

Nanocem: The Industrial-Academic Research Network on Cement and Concrete