Limestone Calcined Clay Cement

Limestone Calcined Clay Cement (LC3) is a low-carbon cement developed by the École Polytechnique Fédérale de Lausanne (EPFL), Technology and Action for Rural Advancement (TARA), Indian Institute of Technology (IIT) Delhi, IIT-Bombay, IIT-Madras, and the Central University of Las Villas (Cuba). The cement can reduce carbon dioxide emissions related to manufacturing by 30% as compared to ordinary Portland cement. In 2014, the LC3 project received 4 million CHF in Research and Development funding from the Swiss Agency for Development and Cooperation (SDC).

History
Limestone Calcined Clay Cement (LC3) stems from research by the EPFL. It is the result of an ongoing cooperation between EPFL and partners in India and Cuba on developing low carbon and resource efficient raw materials for cement manufacturing. In 2014, the Swiss Agency for Development and Cooperation provided 4 million CHF in funding for the research and development of LC3. Testing and standardisation was carried out by the EPFL, IIT-Delhi, IIT-Bombay, IIT-Madras, and the Central University of Las Villas (Cuba). Part of the research focused on specific thematic areas of cement research including hydrate assemblages, pore structure, rheology, reactivity (chemistry), durability and mechanical properties, production, environmental sustainability, and cost effectiveness.

Composition
The main components of LC3 cements are clinker, calcined clay, limestone, and gypsum. The fresh concrete production involves synergetic hydration. Adding large amounts of calcined clay (metakaolin) and ground limestone to the dry cement powder, when adding water to the mix for making concrete, cement and additives start to hydrate and the soluble aluminates released in water from the calcined clay react with the calcium carbonate from the finely crushed limestone. The reactive alumina present in metakaolin reacts with the ground limestone, leading to a less porous structure than in other concretes and providing equal strength as with higher levels of clinker substitution.

Environmental impact
Limestone Calcined Clay Cement is a low-carbon alternative to the standard Portland cement. LC3 can reduce emissions related to cement manufacturing by reducing the amount of clinker, replacing it with finely ground limestone and calcined clays. Low-grade kaolin clays can be used for the production of LC3 and are abundantly available in many parts of the world.