Sustainability & Blended Cements

Sustainable development could be stated as, Economic and Social developments without detriment to the environment and natural resources. Sustainable development thus is a way of ensuring a better quality of life for  all in the present &  for generation next . A typical definition of sustainable development that was reaffirmed at the Earth Summit in 1992 in Rio de Janeiro as “Sustainable Development” as economic activity that is in harmony with the earth’s ecosystem.

With the Rapidly growing industrialization one of most urgent sustainability issue is – Global Warming, The term refers to a steady increase in the earth’s surface temperature since 1950s. The devastating effects of climate change are being experienced worldwide. Researchers & scientists have found a linear relationship between the earth’s surface temperature and atmospheric concentration of CO2 which makes up to 85% of the gases responsible for the green-house effect. Before the industrial revolution, the Earth’s atmospheric CO2concentration remained at 280 ppm. During 1950 -2000, it rose to 390 ppm , presently  it is 400 ppm, and rising at the rate of 2-3 ppm every year. About 450 ppm is said to be the critical threshold that must not be crossed to prevent irreversible climate change. The window of opportunity is thus limited to 20 years.

Over 90% of carbon emissions from the Concrete are attributable to Portland Clinker Production in Cement kilns approx 0.8 to 1 T CO2 per  Ton of clinker. In 1990, direct CO2 emissions from cement were about 940 million T/y as compared to 1740 million in 2005. During 15 years, the carbon footprint of the cement industry has almost doubled. It will triple the cement industry’s carbon footprint by 2030 which is not acceptable.

There are three options available with the cement , concrete and construction Industries for  reducing the carbon footprint (i) To consume less Concrete in new Structures (ii) Consume less Cement in concrete  (iii) Consume less Clinker in Cements (Blended cements) 

The concept of using ‘blending’ natural reactive  siliceous materials in lime mortar and construction materials is age-old, and can be traced to the ancient history. Romans and Greeks utilized this concept through use of volcanic ashes, to construct monumental durable structures. Even after two millennia, a number of ancient structures, including the Pantheon and the Coliseum, stand testimony to this ancient wisdom of the Romans and the Greeks. As far as the Indian subcontinent is concerned, it is believed that the use of such materials goes back to the age of Mohenjo-Daro and Harappa.

The Portland cement concrete cult began in India in the early part of the twentieth century and the local materials had to be adapted to the local market conditions. In India ,large mass-concreting project sites like  Bhakra Dam, Rana Pratap Sagar Dam, Koyna Dam are some of the projects completed in the fifties and sixties which used pozzolanic materials  as mineral admixture in mass concreting.

ACC Ltd has had prominent existence for 78 yrs as one of the first  Cement Manufacturers of Blended Cements in the Country (PPC&PSC), Portland slag cement (PSC) was introduced in the country in the sixties. The credit for the establishment of the first slag granulation plant in the premises of Tata Iron and Steel Company Ltd. and production of slag cement (PSC) totally based on in-house development goes to the ACC Ltd. The introduction of Portland Pozzolana Cement (PPC) which followed shortly was prompted by the market push created by the gap in demand and supply. It is interesting to note that the introduction of PPC, then, was done with the use of calcined clay pozzolana in the absence of suitable industrial wastes like fly ash. With the increasing generation of fly ash from the coal-fired thermal power stations, the interest slowly shifted from use of calcined clay pozzolana to fly ash as a cement substitute material in the manufacture of PPC. ACC Ltd. even then had Blended Cements (PPC & PSC) as a prominent share of its Product Portfolio.

After the Cement de-control in Eighties, the newer Cement Manufacturers popularized the OPC Brands and the ratios in the total Cement manufactured in the country gradually tilted in favour of high strength OPC, while ACC Ltd continued with the PPC & PSC brands. However in the last decade there has  been a gradual shift in market towards PPC and PSC (in certain Markets of the country ) , which could be due  to the observations of extensive deteriorations in the constructions of the high OPC strength era.  

The paper discusses some of the avenues in the present Cement Market of the country to establish sustainable Blended cement products exemplified by   the initiatives from ACC Ltd.,  on how through its in house R & D efforts the company continued to have a Blended Cement (PPC/PSC) dominated  product portfolio with optimized   PPC and PSC  with lower Clinker factor (Lower Carbon Label), with  improved concrete performance  and increased resistance to environmental deteriorations when used in Concrete . The Paper further discusses the requirements of the cement Market in India and the appeal of the customers  for Blended cements with specialized properties ,referring to some of the ACC’s initiatives in developing special Premium brands tailor made  to customer needs  as well as to climatic conditions of the cement Markets in India  like F2R (Foundation to Roof Cement), Concrete+ (to compete and perform vs OPC 53), Coastal+ (for coastal climatic conditions for coastal line Markets of India), ACC Plus+ ( Cement with improved  concrete performance) and ACC Gold ( water repellant  Cement  to prevent water permeation through the concrete construction. All these special products being fly ash or slag based with low carbon credits. The pursuit of the company being to lead the customers to create durable sustainable constructions in the country with Cements of lower clinker factor. This has initiated all the major Cement Brands in the country to evolve special Cement Brands with improved performance in Concrete at site. The Paper was presented and publishes on Jan 2017 NCB Hyderabad Symposium on Blended Cements for sustainabile Development 2017

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