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Greening cement is the core challenge of sustainability

By Eamonn Ryan

Commenting on some of the trends identified in the cement and concrete industry, Bryan Perrie, CEO of Cement & Concrete SA (CCSA) says the most significant driver for new technology trends is the quest for sustainability. To address that, cement manufacturers and concrete producers emphasise higher extender contents and lower clinker contents to minimise the potential negative impact on the environment.

Bryan Perrie, CEO of CCSA Where possible, recycling and refurbishment are being considered over the use of virgin materials,” he says.

The current focus on reducing the carbon footprint of cement – an objective which everyone in the industry is working towards – is gaining traction as ever more products come out with more extender and less clinker in – but still retaining concrete performance.

“Not long ago there were only a couple of extended cements on top of the traditional Portland cement, but now if you look at the European standard (which South Africa has adopted) there are 35 to 40 different types. Late last year a new standard was adopted in Europe which South Africa is in the process of adopting, and which approves the use of calcined clay and limestone in cement to reduce the carbon footprint,” says Perrie. While individual companies are guarding their own R&D, being on a competitive basis, organisations such as the Global Cement & Concrete Association (GCCA) are trying to coordinate activities by broadly disseminating information. “Obviously, it is in the nature of competition that cement companies will in the future market their products based on its CO2 emissions. ”Architects, engineers and contractors are all being pushed by their clients for ‘green’ constructions – so this is a competitive issue. Furthermore, the extent to which the extender materials are available locally dictates which product is used. The big extenders are slag (from iron making), fly ash (from coal-fired power stations), limestone (which is quarried to make cement) and now calcined clay of which we have sources in South Africa. One problem is that coal-fired power stations are increasingly being phased out around the world thus reducing fly ash sources.”

Perrie adds that research is also taking place on carbon sequestration whereby the carbon is captured – but notes it is an expensive option. This research is being driven by global carbon taxes, as is the case in South Africa, meaning that the more you can reduce carbon emissions the less tax you pay. n