LC³ or Limestone Calcined Clay Cement is a family of composite cements containing Portland clinker, calcined clay and limestone. The LC³ technology promises a sustainable growth of economies around the world by reducing upto 40% CO2 emissions compared to Ordinary Portland cement at lower investment and production costs. LC³ uses raw materials and technologies that are already used by the cement industry. The production process is similar to the way of producing normal cements. Thus they provide a practically viable solution to improve sustainability in the cement industry.

Due to lower clinker content, LC3 technology has several advantages over ordinary Portland cement (OPC) and Portland pozzolana cement (PPC). The main advantages are:

• Lower production cost than OPC and PPC in many scenarios
• Opportunity to utilize waste limestone (siliceous or dolomitic)
• Use of non-ceramic grade clay
• Lower energy consumption during calcination compared to clinker
• Low CO2 emissions
• Similar strengths compared to OPC and PPC
• Improved durability compared to OPC due to refined pore structure
• Resistivity of LC3 concretes are significantly higher than OPC and PPC
• Very low chloride migration coefficients
• Reduced sorptivity in the LC3 system

LC3 works on the synergy between clinker, calcined clay and limestone phases. Calcined clay reacts with hydration products of clinker and limestone reacts with calcined clay, giving phases that make the microstructure denser. Calcined clays have been long used as pozzolanic materials in cements and limestone is an established semi-reactive filler in cements. The added synergy from the reaction of calcined clays with limestone producing carboaluminate phases improves the strength and durability of the cement.