Novel Cements
IN BRIEF
- Several types of novel clinkers and cements using new production processes are being developed.
- The possibilities offered are exciting, but in the short to medium term, novel cements will probably mainly be used for niche applications.
- The obstacles of market acceptance, standards, volume and availability of raw materials will have to be overcome.
The European cement industry is highly innovative with large scale research centres in several countries and hundreds of patents filed each year. A number of low-carbon or very-low-carbon cements are currently being developed. While some daunting hurdles and validation of product properties remain, there is ultimately the exciting prospect of entirely new types of cement. However, these new cement types have neither been shown to be economically viable, nor tested on a large scale for long-term suitability and durability. Nor have these products been accepted by the construction industry, where strong materials and strict building standards reign supreme. When the first of these plants go to full scale production, initial applications are likely to be limited and focused on niche markets, pending widespread availability and customer acceptance.
Several parallel novel cement types are being developed including:
- Magnesium silicates rather than limestone (calcium carbonate).
- Calcium sulfo-aluminate belite binders.
- A mixture of calcium and magnesium carbonates and calcium and magnesium hydroxides.
- New production techniques, using an autoclave instead of a kiln and a special activation grinding that requires far less heat and reduces process emissions.
- Dolomite rock rapidly calcined in superheated steam, using a separate CO2-scrubbing system to capture emissions.
- Geopolymers using by-products from the power industry (fly ash, bottom ash), steel industry (blastfurnace slag), and concrete to make alkali-activated cements. Geopolymer cements have been commercialised in small-scale facilities, but have not yet been used for large-scale applications.
Some of these novel cements are showing early potential, but it is important to remember that they have yet to be produced in the kinds of volumes the global construction industry needs. To produce cement in the billions of tonnes that is required by the construction industry takes huge investment and rigorous testing. Establishing fitness for purpose of any cement is neither a simple nor a linear undertaking, and the more unfamiliar the cement type, the more research will be needed.
CHALLENGES
Availability of raw materials
The main raw material for ordinary Portland cement, limestone, is abundantly available across the globe. However, some of the materials needed for novel cements might not be available in sufficient quantities or in the right places, meaning raw materials would have to be shipped over long distances or could require considerable treatment before use.
Proven performance
Cements have been around since Roman times, but while the technology has changed substantially, the process still relies on the same basic raw materials and volcanic heat (around 1,450°C) to bring about the fundamental chemical reaction that turns cement into a binder. Current cement types, including those that use by-products, are tried and tested. It goes without saying that any material that plays such a crucial role in our lives needs to be safe, but it also needs to be long-lasting, without requiring excessive maintenance.
Volume
It takes time to gain market acceptance and develop the necessary production capacity to have a meaningful impact on the industry’s overall emissions.
POTENTIAL SAVINGS
There is a future for new or novel cement types, but given the early stage of their development, it will take quite some time before large-scale production becomes a reality. Furthermore, they are likely to be used in non-structural niche applications for the foreseeable future. Nevertheless, a 5% share of total cement production for novel cements has been included, namely 11 million tonnes. Novel cements will still require energy for their production and will not be zero carbon products. The exact potential carbon reduction is not known at this time but for many of the more promising technologies, it is estimated to be around 50%, which has been applied in the modelling for the expected 5% of total cement production.