Indo-Swiss project in low-carbon cement to get boost in India
A low-carbon cement LC3 jointly developed by Indian and Swiss researchers, is set to grow in India where the demand for cement will increase hugely as the country embarks on a $1 trillion infrastructure development plan.
"We are in touch with several agencies including the National Council for Building Material in India. They have all shown keen interest in the material," said Karen Scrivener, Full Professor, Construction Material Laboratory at Ecole Polytechique Federale De Lausanne (EPFL), a leading technology institute in Switzerland. After having tested its efficacy in pilot programmes, the objective is to make LC3 a standard general-use material and a feasible and viable product for sustainable development in global cement market, she said.
The Limestone Calcinated Clay Cement (LC3) can help reduce CO2 emissions by about 30 per cent and is made using limestone and low-grade clays. It is also cost-effective and does not require intensive modifications to existing plants to adapt to production of the new type of cement, Scrivener said.
"We hear that concrete is responsible for 5-10 per cent of man-made CO2 emissions. But this is remarkably low considering that it makes up about 50 per cent of everything we produce. It is the only material which can satisfy the growing demand for construction," she said.
The demand for cement is increasing hugely in the fast- growing Indian economy and it is imperative that the growth is synergised with ecologically sustainable material and technology, she noted.
The government has said there is immediate potential for investments totalling $1 trillion to build infrastructure. It also has plans for 100 smart cities to give a fillip to urbanisation.
The research partners in the project funded by Swiss Agency for Development and Cooperation, include IIT Delhi, IIT Madras, IIT Bombay and Delhi-based Technology and Action for Rural Development.
New technology will make cement manufacturing carbon-neutral, UCLA Each year, manufacturers produce around 5 billion tons of portland cement ù the gray powder that mixes with water to form the material that holds stone chips together. That´s nearly three-quarters of a ton for every person on Earth. For every ton of cement produced, the process creates approximately a ton of carbon dioxide, all of which accounts for roughly 7 percent of the world´s carbon dioxide emissions. The demand increasing every year ù especially in the developing world, which uses much more portland cement.
One of those scientists is Gaurav Sant of the California Nano Systems Institute at UCLA, who recently completed research that could eventually lead to methods of cement production that give off no carbon dioxide. Gaurav Sant, an associate professor of civil and environmental engineering and UCLA´s Edward K. and Linda L. Rice professor of materials science, found that carbon dioxide released during cement manufacture could be captured and reused. The study is published in the journal Industrial and Engineering Chemistry Research.
During cement manufacturing, there are two steps responsible for carbon emissions. One is calcination, when limestone, the raw material used to produce cement, is heated to about 750 degrees Celsius. That process separates limestone into a corrosive, unstable solid ù calcium oxide, or lime ù and carbon dioxide gas. When lime is combined with water, a process called slaking, it forms a more stable compound called calcium hydroxide. The major compound in portland cement is tricalcium silicate, which hardens like stone when it is combined with water. Tricalcium silicate is produced by combining lime with siliceous sand and heating the mixture to 1,500 degrees Celsius.
But Sant and his team showed that the carbon dioxide given off during calcination can be captured and recombined with calcium hydroxide to recreate limestone ù creating a cycle in which no carbon dioxide is released into the air. In addition, about 50 percent less heat is needed throughout the production cycle, since no additional heat is required to ensure the formation of tricalcium silicate.
Sant said the method is analogous to how limestone cementation occurs in nature, where limestone forms the tough exoskeletons of coral, mollusks and seashells, and when microbes form limestone that cements grains of sand together.
If cement manufacturers continue to operate as they currently do, and if proposed carbon taxes in the U.S. and other nations are eventually enacted, cement production would be much more expensive than it is now. Were that to happen, a new method for producing cement with little or no environmental impact would be of even greater interest, Sant said.
The research was supported by the National Science Foundation and was conducted in the Laboratory for the Chemistry of Construction Materials in the UCLA Henry Samueli School of Engineering and Applied Science, the Electron Imaging Center for Nanomachines at the California NanoSystems Institute, and the Molecular Instrumentation Center in UCLA´s department of chemistry and biochemistry.