21 January 2016 13:51:14 IST

A concrete solution to cement

University of Texas, which has a Leadership in Energy and Environmental Design (LEED) Platinum status

With green buildings gaining ground, geocements are coming up as a green alternative for normal cement

You must have heard of ‘green buildings’ — those that let in more sunlight and air so that people living in them would need a lot less electricity, can recycle water, and inculcate other ‘green’ habits. There are about 800 of them in India, and they stand on an area of 3.25 billion square feet. About 3,500 more are waiting to be labelled as ‘green’.

Greenness ratings

These buildings are rated for their ‘greenness’, the highest rating being ‘platinum’. Globally, a green building movement is underway, for it gives a nice feeling to be living or working in one.

Dr Ajay Mathur, Director-General of Bureau of Energy Efficiency, says that 70 per cent of the buildings that will stand on this planet by 2030 are yet to be built. Therefore, there is room for enough number of them to be green.

Now, the thing about green buildings is, it is not quite enough if they have larger, East or West facing windows and light-letting-but-heat-reflecting glass panes. No.

The material they should be made of, should have consumed less energy when they were being made. The ‘energy content’ of the building materials is also a key factor in their ‘greenness rating’.

Energy rating

Green building experts, such as architects trained in the area, have long been grappling with the problem of finding the right material to build the structures. Steel is great, but making steel is one helluva energy-consuming process.

Wood is nice, but would you want to cut trees to build a ‘green building’?

You are left with concrete, which isn’t great either. When you produce a tonne of cement, the biggest constituent of concrete, you let out 800 kg of carbon dioxide into the atmosphere, apart from three kilograms of Nitrogen Oxides and particulate matter. As you know, CO 2 heats up the earth, creating a phalanx of disastrous effects; other pollutants are bad for our lungs.

But we cannot, not produce cement, can we? Every year, Portland cement companies produce three billion tonnes of cement, which means about 24 billion tonnes of CO 2 are let off into the atmosphere. While we are building concrete buildings, roads, and bridges, we are also smoking ourselves extinct.

Not all bad

However, there is some good news on the horizon. For a number of years, scientists have been looking at alternative ways of making cement (and hence, concrete). If you use more of fly ash, which is a residue from thermal power plants, and slag from steel plants in the making of cement that is some progress. But could we not use only fly ash and slag for making cement?

To put it very simply — and at the risk of oversimplifying it — fly ash and slag will not bind. You need a good ‘binder’, so that the stuff you produce can bind itself into a rock, and stand for hundreds of years. The problem, therefore, was reduced to one of discovering a good ‘binder’.

Scientific progress

Here is where good news comes in. Scientific progress made in this area has come up with a new material called ‘geopolymers’, the result of which is ‘geocement’. Well, this is not entirely new. A French scientist called Joseph Davidovits was (probably) the first to mention geopolymers in his papers, back in 1978. But geopolymers are slowly gaining ground (literally, for there is an airport in Australia whose runway is made entirely of this material) in the recent years.

This material could well become the building material of the future. An Indian company called Kiran Global Chems Ltd, which just introduced Geocement in the market, says that this material takes 80 per cent less energy in making, emits less than 200 kg of CO 2 per tonne, about a fourth of Portland cement’s emissions, sets very fast and is a lot stronger.

This company has been in the business of producing a chemical called Sodium Silicate, and lo and behold! That is a key material used for producing the binder.

For Kiran, the sodium silicate market has rather been listless in the last few years, so it branched off into Geocement, so that it could use its own sodium silicate. Incidentally, it purchased technology from Joseph Davidovits himself.

Pretty soon, other companies will follow, perhaps forced by regulations. So, have we finally found a solution to the vexing problem of getting a truly green material to build green buildings? We will know in some years — keep a sharp eye on the developments.