Environmentally friendly cement for countries experiencing a construction boom

Project completed
An Indian worker builds a wall with LC3 blocks.
Cement blocks made from LC3 are being used in construction on a trial basis, here for the new SDC offices at the Swiss embassy in India. © SDC © SDC

The SDC is promoting the development of an environmentally friendly type of cement. It is supporting a team of people from Switzerland, India and Cuba who are researching the characteristics of the cement, known as LC3, and producing it on a trial basis. LC3 is made to a different recipe than conventional cement, as a result of which CO2 emissions in production are up to 30% lower.

Country/region Topic Period Budget
India
Climate change and environment
Biosphere protection
01.01.2013 - 31.05.2017
CHF 4'092'000

Cement production is responsible for roughly 5-8% of the greenhouse gas emissions attributable to human activity. The enormous need for infrastructure, particularly in emerging countries such as India, China and Brazil, will cause global demand for cement to double by 2050. This means a massive increase in greenhouse gas emissions. 

The SDC Global Programme Climate Change is supporting a number of initiatives, including the development of a new type of cement called LC3 (limestone calcined clay cement, see box). The amount of CO2 emitted in LC3 production is up to 30% lower than for ordinary Portland cement. The Global Programme Climate Change thus aims to reduce the negative impacts of climate change.

LC3 has been developed under an SDC-funded research partnership between the Federal Institute of Technology in Lausanne (EPFL) and the Universidad de las Villas in Cuba. Since 2012, Indian scientists from the Indian Institutes of Technology (IITs) in Delhi, Bombay and Madras and staff of the NGO Development Alternatives have also been involved in scientific and practical research for the project. The project is led by EPFL.

Meeting international standards

The long-term plan is to establish LC3 in cement markets with high demand. With this in mind, the SDC and the project team are working closely with representatives of the international cement industry. One key step is having the new cement type approved by the relevant bodies. It must therefore meet high standards, for example in terms of safety and durability. The international project team is working to produce the scientific data needed for this purpose on the basis of theoretical research and trial production in cooperation with cement firms in India, Cuba, Thailand, China and Brazil. For example, LC3 blocks are being exposed to extreme conditions and salt water on the Cuban coast in order to measure their durability. 

The team is also investigating whether an LC-65 standard, i.e. with 65% clinker content, is viable in the aforementioned trial countries. LC-65 is already approved in Europe. The project team has additionally investigated an LC3-50 standard with just 50% clinker in Cuba and India. Cement standards are currently being revised in Cuba on behalf of the Cuban government with a view to accelerating the standardisation of LC3.

What is LC3?

LC3 stands for limestone calcined clay cement. This environmentally friendly form of cement contains a reduced proportion of clinker (also called Portland cement) with up to 50% calcined clay (white clay or kaolinite), ground limestone and gypsum. The lower the clinker content, the bigger the reduction in CO2 emissions. Put simply, one bag of clinker can be used to make two bags of LC3 cement. Adding calcined clay saves energy because it burns at a lower temperature (750°C versus 1,450°C). The main advantage over clinker, however, is that no CO2 is emitted by the conversion of calcium carbonate (CaCO3) into calcium oxide (CaO).

Another advantage is that clay and limestone are available in abundance and at low cost in emerging economies. In many cases, waste clay that is unsuitable for porcelain production can be used. Despite all this, LC3 is by no means inferior in terms of quality. Extensive studies have shown it to be highly robust in construction and possess outstanding properties.