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  • Inauguration and award presentation October 2011
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  • Roofing Ceremony Nov 2010
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Portland Cement clinkers and Celitement compared in terms of mass and energy balance

Production of one ton of Portland Cement clinker leads to approx. 870 kg of carbon dioxide. 80% of this emission is due to decarbonation of calcium carbonate.

The following sketch assumes that Portland Cement clinker consists only of the main mineral tricalcium silicate Alit: Burning the raw materials generates three parts of carbon dioxide from calcium carbonate. The intermediate product calcium oxide reacts with silicium dioxide to tricalcium silicate Alit.

Alit reacts with water to form calcium hydroxide portlandite and a calcium-silicate-hydrate CSH. Mechanical strength of the product originates from CSH.

Ordinary Portland Cement made by the conventional process does not allow for a fundamental reduction of carbon dioxide emissions: both the high process temperature of 1.450°C and a minimum amount of calcium are vitally important - failing this leads to unreactive products.

Celitements contain a small amount of calcium, i.e. need less lime. The following sketch presents a Celitement mass balance with a molar ratio of calcium to silicon of one, made from lime. Production of burnt lime CaO generates one part of carbon dioxide. Calcium oxide, silicon dioxide and water were transformed to Celitement.

Mixing with additional water starts the hydration reaction and the only product, calcium-silicate-hydrate, is formed.