RS Kabra, Executive Vice President – Commercial, Wonder Cement, talks about the impact on profitability of the cement business and quality of the end product.

Tell us about the supplementary cementitious materials used by your organisation in manufacturing of cement.
The major cementitious materials used in India are fly ash and blast furnace slag. Fly ash is generated in huge volumes mainly in coal based thermal power plants and is a major hazard to the environment across the country. Slag is generated in the blast furnace of steel manufacturing plants.
We utilise fly ash as supplementary cementitious material in the manufacturing of Portland Pozzolana Cement (PPC) at all of our cement plants, as the plants are situated nearby thermal plants. With the use of fly ash as a SCM, besides contributing to environmentally friendly disposal of fly ash, we are also contributing in reduction of CO2 emission by reducing the use of thermal heat and electricity. This also leads to conserving natural mineral resources of limestone.
Blast furnace slag, another important supplementary cementitious material, is a by-product of the steel making process. The use of slag as a supplementary cementitious material is also well established in manufacturing of cement, specially in cement
plants which are located near steel plants. Our cement plants are not located near any steel plant; thus, at present we do not use slag as a supplementary cementitious material.

What are the key benefits of using supplementary cementitious materials?
The most important benefits of using SCMs in manufacturing of cement is environmentally
friendly disposal of these hazardous materials and a significant reduction in CO2 emission by savings in thermal heat, electricity, and conserving natural resources (limestone).
Substituting a cementitious material in the raw mix for cement manufacturing helps us in conserving natural minerals (limestone), thermal heat (coal), and electricity.

How does the use of supplementary materials increase the profitability of the cement manufacturing for your organisation?
Use of supplementary cementitious materials has a direct impact on the profitability of cement manufacturing companies as replacing natural limestone by SCMs results in reduced requirement of thermal heat, electricity etc.

What is the proportion of supplementary cementitious materials in the production of cement by your organisation?
The Bureau of Indian Standards guidelines permits the use of supplementary cementitious materials up to 35 per cent in PPC cement, accordingly at Wonder Cement we use up to 35 per cent fly ash in the manufacturing of Portland Pozzolana Cement.

Tell us about the quality standards and checks implemented for the final product made using supplementary materials.
In terms of quality, the end product, PPC manufactured by Wonder Cement is always substantially higher than the quality standard prescribed by the Bureau of Indian Standards (BIS) and also higher than most of the other brands of cement available in the market.
This high standard of quality of PPC manufactured by us is possible because of the adoption of the best available technology in the world, including automatic sampling, automatic testing and based on test results, automatic corrective actions, etc. There is absolutely no scope for manual errors or manual dependency in the process of cement manufacturing at WCL.
Tell us about the role of technology in deciding the proportions of SCMs.
Technology plays a very important role in producing quality cement as well as optimum use of SCMs. The processes of automatic sampling, automatic testing and automatic corrective actions play a major role in maintaining the quality of cement as well as optimum use of SCMs.

What are the major challenges you face while using supplementary materials for cement manufacturing?
There is availability of the latest technology, advanced equipment, and continuous use of technology rather than human dependency. Therefore, we do not see any challenge in using supplementary cementitious materials.

How does the use of cement made of supplementary materials impact its carbon footprint?
Fly ash is a supplementary cementitious material and is being used as part replacement of clinker in the raw mix for the production of PPC. Reduction in the use of clinker directly results in the reduction of the use of thermal heat and electricity, required in the manufacturing of clinker. The reduced use of clinker also results in conserving the natural mineral limestone as well as the energy consumed in mining the limestone.

• –Kanika Mathur