DOES CEMENT HAVE A GREEN FUTURE?

Ever since the Romans were building bathhouses and putting up Pantheons, cement has been in the very DNA of civilization. The world’s most common and popular building materials, cement (and concrete) made possible the stadium, the skyscraper, and indeed, any building over a few storeys high. Cement is the spine of our cities; you might say it is urbanization itself. But perhaps we never thought there would be quite so much of it. In this era of unprecedented expansion and third-world industrialization, the scale of production and consumption has exploded. Global use of concrete has doubled over the last two decades, with cement production skyrocketing in developing countries. China now produces 50% of the world’s cement (over 1.3 gigatons per year) to drive its unprecedented infrastructural development, and its emergence as a global economic giant.

China also makes its cement in older, less modern plants, powering them with coal rather than oil, putting the country’s booming industry in conflict with the emerging “green consciousness.” Given the primacy of cement in global industrialization, its elemental importance in urban and economic growth for both developed and especially developing nations, can it be turned nature-positive, or at least nature-neutral?

First, let’s acknowledge the very good reasons for the enduring – and burgeoning – popularity of the world’s most common construction material. The qualities of cement and concrete read like an engineer’s dream: remarkably strong and durable; resists cold, heat, oxidation, water, snow, hurricanes, and even termites; offers optimum insulation in both winter and summer; and doesn’t burn. And cement is cheap, generally costing about a dime per pound. Making cement, though, requires tremendous heat, about 1,500º C. Every pound of cement manufactured releases roughly an equal amount of CO2 into the atmosphere, with estimates that the cement industry accounts for somewhere around 5-10% of global CO2 production, the culprit behind global warming. And unfortunately, concrete is only concrete when it’s in the form of a wall or road – it can’t be broken down and recycled.

All of which has environmentalists concerned… but some visionaries in the industry have already leapt out of the box. What if, rather than causing pollution, cement… consumed it? What if cement could be carbon-neutral?

Two companies say an environmentally sustainable cement is not only possible, it’s already here.

According to the Guardian newspaper in London http://www.guardian.co.uk/environment/2008/dec/31/cement-carbon-emissions, UK-based Novacem (www.Novacem.com) has developed a cement based on magnesium silicates which:

…not only requires much less heating, it also absorbs large amounts of CO2 as it hardens, making it carbon negative. Set up by (Nikolaos Vlasopoulos, chief scientist) and his colleagues at Imperial College London, Novacem © already attracted the attention of major construction companies such as Rio Tinto Minerals, WSP Group and Laing O'Rourke, and investors including the Carbon Trust.

Novacem's cement, which has a patent pending on it, uses magnesium silicates which emit no CO2 when heated. Its production process also runs at much lower temperatures - around 650C. This leads to total CO2 emissions of up to 0.5 tons of CO2 per ton of cement produced. But the Novacem cement formula absorbs far more CO2 as it hardens - about 1.1 tons. So the overall carbon footprint is negative - ie the cement removes 0.6 tons of CO2 per ton used.

Meanwhile, in Tasmania, John Harrison of TecEco developed a similar method using magnesium oxide. Their Eco-Cement “mimic’s nature,” with carbon sequestration occurring as it hardens, making it a “carbon sink” or remover of CO2.

Other companies such as Holcim (US) http://www.holcim.us/ are making progress in their own right, voluntarily reducing the CO2 intensity of their production 20% by 2010. The Portland Cement Association reports that varied initiatives have lead to a 33% decrease in carbon dioxide output from cement plants since 1975 http://www.cement.org/homes/brief12.asp. And others estimate that new greener cements could eventually absorb trillions of tons of CO2.

Can cement be green? Given its ubiquity, isn’t the real question: mustn’t it? Monmet has a 20-year history with the cement industry – since first delivering small spare parts to cement OEMs to our current level, supplying our partners with over 100 riding rings a year in dozens of international projects. We’re devoted to remaining ahead of the curve and helping our clients and website guests do the same.

Some other useful and informative links: