Advancing Carbon Emission Reduction Targets in Cement Manufacturing
To halve the clinker factor in cement products, manufacturers have reduced energy consumption and CO2 emissions associated with clinker production in rotary kilns. Typically, producing 1 tonne of cement emits more than 800 kg of CO2. In addition, the environmental impact of industrial by-products such as fly ash, slag and silica fume needs to be minimised.
The strategy for achieving these goals is to partially replace the clinker used in cement production with industrial by-products without compromising performance.
A new sustainable cement technology produces a cement that reacts with CO2 rather than with water; it is produced without hydraulic systems, with lower energy and fewer chemical emissions. This cement is more sustainable than conventional cement.
The new environmentally friendly cement can be produced in existing cement kilns using different proportions from ordinary cement. It uses less limestone and is fired at lower temperatures. Another factor that reduces CO2 emissions in cement production is the reduction of clinker content from an average of 816 kg/tonne to 570 kg/tonne.
To make sustainable concrete products, water, aggregate and the new cement are mixed, formed into the desired shape and then reacted with CO2 to create a durable material structure. The curing process consumes up to 300 kg of CO2 per tonne of cement. The CO2 is stored permanently and safely as solid carbonate in the concrete blocks. This difference is equivalent to a further 37% reduction in clinker.
As a result, overall CO2 emissions from cement production and use can be reduced by up to 70%. The benefits of this new technology include savings in raw materials and water, shorter curing times and improved product durability.
