Given the rise in urbanisation, extraction and use of natural resource materials, further leading to greater generation of waste is bound to create a vicious cycle of production and consumption. However, several economies worldwide are attempting to ‘decouple’ use of natural resources from the growth of the economy. This is referred to as ‘Resource Decoupling’, which means reducing the rate of use of (primary) resources per unit of economic activity. This understanding of ‘dematerialisation’ is based on the concept of using less materials, energy, water and land for the same economic output, and it is connected with an increase in the efficiency with which resources are used (Caleb, et al., 2017).

Waste Materials and Building Product Standardisation

Taking this into consideration, the Bureau of Indian Standards, the National Standards body of the country, has been considering the scarcity of sand and coarse aggregates from natural resources, and has evolved a number of alternatives which are aimed at conservation of natural resources apart from promoting use of various waste materials without compromising on quality. These measures have included permitting the Concrete Code (IS 456) as also in the National Building Code of India i.e. the use of slag - waste from the steel industry, fly ash waste - waste from thermal power plants, crushed over-burnt bricks and tiles - waste from clay brick and the tile industry, in plain cement concrete as an alternative to sand/natural aggregate, subject to fulfilling the requirements of the Code.

Further for the 15 varieties of cements, for which Indian Standards have been developed, more than three-fourth of the cement produced in the country pertains to Portland Pozzolana Cement and Portland Slag Cement, popularly known in the market as blended cements (BIS, 2017). Research continues to take place to increase the use of supplementary cementitious materials to reduce the clinker factor in cements.

Innovation for Climate Change Mitigation: LC³

In this sphere, Limestone Calcined Clay Cement, commonly known as LC³ has made a successful break-through in both innovation in cleaner technology as well as resource efficiency and use of secondary raw materials. LC³ provides the perfect cement blend that has a mix design of 50% clinker, 15% non-cement grate (waste) limestone, 30% waste china clay (overburden) from mines and 5% gypsum. The blend has two major advantages for sustainable production. Firstly, about 45% of raw material in the blend is waste and secondly clinker content is reduced to 50%. Life Cycle Analysis reveals that LC³ production can reduce carbon dioxide emissions up to 30% and save up to 50% limestone as compared to conventional cement. The LC³ cement is also found to have comparable durability and strength as compared to conventional cement. Further, the most suitable clays for production of LC³ are overburdens (waste clay) from china clay mines.

Barriers to Upscaling Production of LC³

In the present Indian Standards, replacement of cement with calcined clay as a pozzolan is limited to 25% (IS 1489) and limestone as performance improver is limited to 5% (IS 269) (Medepalli, Shah, & Bishnoi, 2016). Resistance in the standardisation for the use of LC³ has mainly been in the form of poor technical understanding of the process and the strong lobby of the Indian construction sector.

Various structural applications require various compressive strength and therefore the conventional approach to ‘one-type fits all’ causes a hindrance to innovation and flexibility to exploit local opportunities for raw materials, both for clinker and for supplementary materials like fillers.

Thus, while the Indian cement market continues to wait for the Indian standard on LC³ based building materials, a necessary change in the standardisation process is the need for assessment of various applications and the flexibility that can allow for greater use of supplementary cementious materials (in this case industrial waste) and thereby reducing the use of natural resources. This range in standards for materials will ensure a larger market for building products as well as allow for greater innovation in increasing the use of waste materials, thus reducing dependence on natural resources.

Mapping Awareness at the International Level

At the international level, LC³ has gained a lot of positive response. Several African countries like Ghana, Ivory Coast, Togo, Benin, Mauritania, Uganda etc. have shown interest in identifying the potential of LC³ in their region. At the recent UN Climate Change Conference (COP23) in Bonn, Germany, 6th- 17th November 2017; TARA, the social enterprise wing of the Development Alternatives Group along with its project partners set up a LC³ exhibition to showcase the potential of LC³ in mitigating climate change.

The cement value chain makes up a large propotion of all economies, including a range of stakeholders from large companies to individuals. While the cement industry, especially under the Cement Sustainability Initiative tries hard to increase efficiency and environmental sustainability in the sector, commitment of the government through public procurement policies, stringent policies on use of natural aggregates and incentives for research and development are the need of the hour. ■

References:

• Olivier, J. G., Janssens-Maenhout , G., Muntean, M., and Peters, J. A.H.W (2016). Trends in global CO₂ emissions; 2016 Report. The Hague: PBL Netherlands Environmental Assessment Agency, Ispra: European Commission, Joint Research Centre.

• WBCSD. (2015). Low Carbon Technology Partnerships Initiative-Cement. New York: World Business Council for Sustainable Development.

• BIS. (2017). Indian Standards for alternative materials to natural sand and other natural resources . Retrieved from Bureau of Indian Standards: Press Release : http://www.bis.org.in/other/PR_ NSNR.pdf

• Caleb, P. R., Gokarakonda, S., Jain, R., Niazi, Z., Rathi, V., Shrestha, S.,. Topp, K. (2017). Decoupling energy and resource use from growth in the cnstruction setor: A baseline study. Dt. Ges. für Techn. Zusammenarbeit.

• Medepalli, S., Shah, V., & Bishnoi, S. (2016). Production of Lab Scale Limestone Calcined Clay Cements using Low Grade Limestone. 7th International Conference on Sustainable Built Environment.

• Scrivener, K. L., John, V. M., & Gartner, E. M. (2016). Eco-efficient cements: Potential, economically viable solutions for a low-CO2, cement based materials industry. United Nations Environment Programme.

• UNEP IRP. (2011). Decoupling Natural Resource Use and Environmental Impacts from Economic Growth. A Report of Working Group.

Pratibha Caleb
pcaleb@devalt.org

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