Simple Guidelines for Producing Sustainable, Durable and Economical Concrete

Dr. Narayan V Nayak, Principal Advisor, Gammon Engineers and Contractors Pvt Ltd.

There is a dire need to control environmental pollution across the world. Concrete is a must for infra development. Cement, which is the main binding material for concrete, adds CO2 to the environment. At present 7.4% of CO2 is contributed by cement to greenhouse gases.

Our aim is to produce more concrete, but with less cement and thus less emission of CO2. For this, we have to use waste materials like fly ash and slag. These secondary cementing materials (SCMs) reduce emission of CO2 and make concrete more durable and economical.

Source of SCMs
All the SCMs are industrial waste products except Metakaoline (MK). SCMs include:

Fly Ash (FA): From waste product of thermal power stations
GGBS: Waste product from steel plants

The above two are known as fine SCM

Metakaoline (MK): A natural product heated to 7000 to 8000 C to make it amorphous.
Micro Silica (MS) / Silica Fumes (SF): A waste product from silicon industries.
Rice Husk Ash (RHA): Product from rice husk, which is generally considered as a waste product. We are still in an experimental state in India though it is marketed in USA under Agro Silica.
Ultrafine Slag (UFS): Produced from GGBS and commercially known as Alccofine 1203.
Ultrafine Fly Ash (UFFA): A much finer variety of fly ash, suitably collected from classifiers.