Researchers in France have developed cement made mostly from clay and limestone, replacing Portland cement with common materials that can be used in concrete mixtures without compromising the final product's performance.

Karen Scrivener, head of the Construction Materials Laboratory at Switzerland's Ecole Polytechnique Federale de Lausanne (EPFL) and project leader, said the cement is a mixture of calcined clay and ground limestone. When the materials are combined, the aluminates from the calcined clay interact with the calcium carbonates from the limestone, producing a cement paste that is less porous and significantly stronger.

Calcined clay and ground limestone have previously been used as adulterating materials for cement in fractional amounts; the researchers discovered, however, that the materials could comprise up half of the cement mixture without having an adverse impact on the final product's properties.

Scrivener told Sourceable that her team believes Limestone Calcined Clay Cement (LC3) could become a benchmark for low-carbon concretes. Unlike the materials currently used to adulterate concrete, clay and limestone are abundant around the planet, making supply a non-issue. Should the material be adopted on a global scale, it could result in a significant reduction in CO2 emissions.

The material was integrated into pre-existing cement production lines during two industrial scale pilot projects, one in India and one in Cuba, which demonstrated the robustness of LC3. The Swiss Agency for Development and Cooperation (SDC) has lent its support to the project, providing funding for further development and testing.