For every 20 tonnes of man-made CO2 that enter the atmosphere, one comes from the kilns of cement factories. Emissions in cement production are threefold:
From the production of the electrical energy used to grind the raw materials and clinker;
From the fuel burned to heat the raw materials in a kiln to 1450°C to form clinker, which is later crushed and blended with gypsum to make cement;
Proce
ss emissions: as the limestone is heated, it changes into lime and CO2. These emissions represent 60 to 65% of total emissions linked to cement production. Reducing the amount of clinker in cement, reduces the amount of CO2 in the atmosphere. LC3 allows growth without abstinence due to resources and CO2 efficiency
With current clinker production facilities, production capacity for cement can be increased twofold without increasing total CO2 emissions. Quarry life can then be considerably extended and costly Carbon capture and storage technologies for emission abatement can be avoided. Emissions of LC3 are estimated to be 20-30% lower than Portland cement because:
Reduced clinker content leads to less process emissions from the decarbonation of limestone in clinker and less emissions from heating limestone to form clinker
Grinding limestone takes less energy than heating it
Calcination of clay takes place at 800°C and uses roughly 55% of the energy needed for clinkerisation at 1450°C. Existing equipment can be used
LC3 can be produced with existing manufacturing equipment, leading to only marginally increased investments for calcining equipment. Lower cost of production
Reduced clinker content, decreased fuel consumption for calcination compared to clinker plus the fact that limestone does not need to be heated should contribute to lower production costs. Lower production costs are one of the main drivers for technology uptake. A well-known technology
Clinker–Limestone systems and Clinker–Calcined Clay systems are well established. In effect, LC3 is optimises the synergy between two already known chemical systems. This leads to a higher degree of confidence that the materials will be durable since the chemical nature of the hydrates and pore structure are similar to other blended cements which have proven durable. Ressource efficiency
Using low-grade clay and limestone does not require opening new quarries nor deplete agricultural soils. As a result, LC3 is a very attractive and feasible option to satisfy development and environmental objectives.
