Sustainable Consumption of Cement in India
Despite being the second largest producer in the world, the per capita consumption of cement in India is significantly lower than many other developing countries like Brazil, Egypt and Vietnam. Cement production is one of the key indicators of economic growth and it is expected that within the next 2 decades, the per capita consumption in India will more than double. Government programmes like ‘Housing for All’ and ‘Dedicated Freight Corridor’ are likely to fuel this growth.
Due to the high growth rates witnessed in the last 2 decades, a majority of cement plants in India are quite modern and efficient. Fly ash and slag based blended cements hold over 70% of the market and even the ordinary Portland cement, is often mixed with fly ash at the construction sites and ready mix concrete plants. Still, the usage of cement in the country is far from efficient and it is doubtful that current construction practices will be able to support the aspiration of sustainable growth in the country.
One of the important reasons for this is the lack of awareness with the individual home builders, who make the largest users of cement in the country. Cement is one of the most advertised commodities in India with the advertisements creating a perception that cements with higher compressive strength make stronger and more durable homes. Although it is generally true that stronger concretes can be made using stronger cements, neither does higher strength always mean better performance, nor is higher strength required for all applications. For example, it is estimated that more than half of the cement in housing is used in masonry applications for binding and plastering bricks. Since plasters do not bear load and the bricks being bound have typical strengths lower than 10 N/mm2, cements being marketed with strengths of 53 N/mm2 or even higher in many cases, are not only unnecessary, but also inefficient for use in such applications. Even in structural concrete applications, higher strength cements can be less durable than normal cements under various aggressive environments. For example, it is known that cements which have higher fineness, which also generally have higher strengths, tend to crack more than other cements.
Additionally, higher strength cements generally have higher lime content, requiring higher consumption of higher purity limestone. Since it is projected that India would not have sufficient limestone to put up new cement plants after 2050, it is crucial to conserve this limited resource and to optimise its consumption in the cement industry. The demand for higher strength cements also discourages the blending of fly ash and blast furnace slag in cements since these additives tend to reduce strength especially at the early age.
Engineers generally agree that most of the issues in construction occur due to poor workmanship rather than poor quality materials. Increasing the strength or quantity of cement is no substitute for good quality workmanship. In order to allow India to develop, it is important to raise awareness with the users and to encourage cement companies to market products that would be the most suitable and efficient for the Indian market. Since this would lead to the sale of several types of cements, all of which may not be suitable for all applications, branding and awareness will have an important role to play.
In order to cater for the reinforced concrete sector, where relatively higher cement strengths are required, it is necessary to develop cements that have a lower environmental impact without having lower strengths. Limestone Calcined Clay Cement, or LC3, is one such cement, which is being developed in an international collaboration where DA and IIT Delhi are playing leading roles. This cement promises to provide India a high strength alternative at a more reasonable environmental cost.
The society, the industry and the government all share the responsibility of ensuring that the growth of India is sustainable. It will take efforts from all these stakeholders to make changes that would allow the construction industry to adopt these long-awaited changes. ■
Shashank Bishnoi and