Cement, Energy and Environment

1.0 INTRODUCTION A er the ini a on of the Portland cement in India during the advent of twen eth century, 1953 saw the formula on of na onal standard on Portland Slag Cement (PSC) and a decade later in 1962, the na onal standard on Portland Pozzolona Cement (PPC) saw the light of the day. But since then no major developments in the cement industry sector happened except new amendments or revisions. For example the PPC standard has been revised four mes ll 2015 and the Bureau of Indian Standards (BIS) has formulated a new standard for composite cement IS 16415, permi ng simultaneous use of both flyash and slag. A very important development in the domain of na onal standard specifica ons of PSC and PPC which has taken place in 2018, is the introduc on of grading of these cements based on their 28-day mortar strength results, at par with OPC.With compressive strength remaining the primary dis nguishing parameter for cement quality, the compe ve retail marke ng strategy of bagged cement in India mostly relied on high 1-day non- standardized mortar strength property and rapid strength gain in the early age, both of which are handicapped in the case of blended cements. Also there are apprehensions that in the 2020s there could be adverse impacts on resource conserva on and CO 2 emissions reduc on strategies. It is widely known that the World Business Council for Sustainable Development (WBCSD) has laid out a roadmap for low-carbon transi on of the Indian Cement Industry with the involvement of Cement Sustainability Ini a ve (CSI), which includes several major Indian cement companies, in 2013, using 2010 as the base or reference year. This roadmap was reviewed in 2018 and the review reported that only 5% reduc on of CO was achieved between 2 2010 to 2017.The next target is set up for the year 2050, to reach a direct CO emission intensity of 2 about 45% lower than that of 2010 levels. While the task remains herculean, there are many measures contemplated like reduc on of clinker factor or taking the help of innova ve binary, ternary or even quaternary cement blends. It is therefore necessary to develop alterna ve binders which are cost effec ve and more environment friendly and introduce a new technology to cement manufacturing methods that are consistent with the principles of durability and sustainability. As we don't have 30-40 years' me, as taken by the PPC/PSC blends, we should use a more scien fic approach i.e. using nanotechnology for producing nano cement, which may be considered as a poten al future in this regard as shown in Figure 1 . Hence, manufacture of nano- sized cement par cles and the development of nanobinders [1, 2] is another poten al approach area where limited number of inves ga ons has been carried out. Currently cement par cle size ranges from a few nano- meters to a maximum of 100 micro meters while the nanocement par cle sizes are less than 500nm (Figure 2) and it has the ability to decrease the size of the cement par cle to the Nano scale to increase the cement chemical ac vity. Nano cement can be defined as the cement that has been chemically treated and re-grinded to the nanometer scale. So, Nano cement is a modified Portland cement and it makes Prof.Mainak Ghosal Governing Body Member & Ex-Jt.Secretary, Coal Ash Ins tute of India NANO CEMENT PRODUCTION FOR CONCRETE STRUCTURES 67