What is LC3?

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 up to 40% CO2 emission compared to Ordinary Portland Cement (OPC) at lower investment and production costs.  LC3 uses raw materials and technologies that are already used by the cement industries.  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.


LC3 has been seen to develop ultimate strenghts comparable to OPC’s produced using the same clinker.  Strenght development in LC3 has generally been observed to be faster than OPC and Portland Pozzolana Cement (PPC).  LC3 is expected to satisfy all the other requirements of physical characteristics laid down in most of the country standards.  Additionally, calcined clay and limstone improves cohesion of fresh concrete which prevents segregation and bleeding.


The main raw material in LC3 is kaolinitic clay.  Clays containing 40% to 60% kaolinite are ideal for the production of LC3.  Reddish clay with high iron content are suitable.  Such clays are abundantly available as waste in mines where higher grade white clays are used for high value applications.  The clays are calcined between 700°C to 800°C to make them reactive. Calcination requires almost half the energy required for clinker production.  In LC3 limestone with as little as 75% calcium carbonate content can be used.  These low grade limestone, as well as dolomitic limestone are often rejected in cement plant quarries. Limestone with impurities such as quartz can also be used in LC3 production.  No calcination of the limestone is required.  Apart from calcined clay and limestone, Ordinary Portland clinker is used in the production of LC3.


Under most severe conditions, the performance of LC3 is better than or at par with OPC and PPC. LC3 has a high chloride penetration resistance and produces a dense microstructure with high resistivity, making it ideal for harsh conditions like in marine or desert environment. LC3 concrete blocks placed 2013 at an exposure site offshore in the northern coast of Cuba show no sign of corrosion according to studies carried out.  LC3 is also highly suitable for use with reactive aggregates that are normally rejected for concrete production.


Due to the lower calcination energy requirements, and the lower clinker content, LC3 is more economical to produce than OPC for similar performance. Especially at locations with shortage of high quality fly ash, low limestone quality or excess reserves of waste limestone, LC3 is more economical to produce than PPC. LC3 is also suitable for production where clinker is being imported or the production costs are not competitive. Due to its lower clinker content and lower capital investment required for calcination of clays, LC3 allows higher returns on capital investments. Also, clay and limestone which are otherwise discarded by cement plants can be utilized in LC3 which leads to low raw material cost.


The production of LC3 emits as much as 40% less CO2 than OPC and 11% less CO2 than PPC. The production of LC3 implies less energy consumed in comparison with OPC and even PPC in many scenarios. LC3 also offers an interesting solution for the utilization of low grade mine rejects widely available with the cement and ceramic industry. Thus, while it reduces GHG emissions from the cement industry, it also helps in utilization of waste materials, thereby promoting resource efficiency of materials. The production of LC3 implies less energy consumed in comparison with OPC and even PPC in many scenarios.


LC3 can reduce CO2 emissions per tonne of cement by up to 40%.


LC3 requires less energy and can be made using fairly low grade and low cost clays.


LC3 does not require substantial capital investments and can be produced in existing plants.