Cement clinker is a key component of concrete, but also a major source of industrial greenhouse gas emissions. This is why substitute agents are already being used today to reduce the clinker content in cement production. Sika supports the process of substitution with its concrete and cement admixtures, while at the same time researching new solutions with a view to reducing the clinker component further.
Tests show that our solutions for LC3 work well
Supplementary Cementitious Materials – or SCMs for short – are substitute products with cement-like characteristics that can replace part of the cement in concrete. These are typically industrial waste products such as slag from the steel industry and fly ash from coal-fired power plants.
The company is already promoting the substitution of clinker in concrete with its concrete and cement admixtures. Here the challenge lies in the development of concrete strength and durability.
"With today’s SCMs, the proportion of cement in concrete could theoretically be reduced by 30%–60%. In practice, however, these substitute products are only available to a limited extent, which is why demand is now significantly outstripping supply and the SCM substitution rate has remained stuck at around the 25% level over the last ten years." Philippe Jost, Head Construction and Member of Group Management
Global research efforts
In order to be able to further lower the proportion of clinker in cement, scientists all around the world are working on new substitute products. One thrust of this research is to make even more quality categories of steel slag and fly ash usable. Philippe Jost stresses the importance of these initiatives: “If these materials could be more broadly used, this would have a huge impact immediately.” As things stand, a proportion of industrial waste products end up in landfill for a variety of reasons. For example, fly ash is not suitable for use as a substitute material in cement production if it contains too many coal particles, as this negatively impacts the quality of the final concrete. “At the moment, a residual coal proportion of 1%–2% is manageable. But if this figure could be increased to 5%–6%, less fly ash would end up in landfill,” explains Philippe Jost. Other research approaches focus on the use of slag that is not yet utilized as an SCM in cement production. This development is all the more significant given that many countries will no longer be able to rely on coal-fired power stations in the future for climate and environmental protection reasons.
Reducing clinker content by 50% with LC3
The LC3 research project of the Swiss Federal Institute of Technology in Lausanne (EPFL), in which Sika is participating, is highly promising. With the use of a new additive, the volume of clinker used in the production of cement should be reduced by up to 50% in the future. This is a huge leap forward. In contrast to today’s substitute products, LC3 is not a waste product but is produced from limestone and clay. “A crucial advantage of LC3 is its availability: Whereas the supply of current substitute agents is limited, the world is home to almost inexhaustible volumes of limestone and clay,” says Philippe Jost. “Another positive aspect is that LC3 is a precisely formulated product.”
Sika solutions for LC3 ready for market
Sika has developed special concrete and cement admixtures with which customers can adapt their materials to the new LC3 characteristics. “We are ready,” stresses Philippe Jost. “The first tests in collaboration with clients that manufacture LC3 show that our products work well.”
Using Sika solutions, there are no changes in terms of water consumption, workability, curing, or durability of the LC3 concrete compared to conventional concrete.
Philippe Jost, Head Construction and Member of Group Management
New technology requires official approval
Cement and concrete manufacturers are currently working on the expansion of LC3 production. But if this new technology is to make the breakthrough on a broader front, country-specific approvals will be required. “Building standards will also have to be adapted,” adds Philippe Jost. This is a process that will take some time. But Philippe Jost remains confident. “The social and political pressure to reduce greenhouse gases will accelerate the process.” For Sika, LC3 offers the opportunity to establish a new technology in the construction industry. Above all, however, Sika is demonstrating “that we live up to our claim of being an enabler for sustainability in the construction industry.”