According to experts, calcined clay cement can reduce carbon emissions.
As the world converged at the sixth United Nations Environment Assembly to discuss climate change, construction industry stakeholders were also advancing the conversation on decarbonising the industry.
On February 13, last year, the Limestone Calcined Clay Cement (LC3) Group, a consortium of experts in calcined clay cement, held an information day in Nairobi.
The event hosted by Meru University at Panari Hotel brought together key stakeholders in the construction industry — from cement manufacturers to relevant government bodies, policy makers, professionals in the concrete industry and members of the LC3 Consortium from various continents.
The information day was an opportunity for stakeholders to learn about LC3. Calcined clay cement has the potential to lower costs and reduce carbon emissions significantly.
Speakers from countries that are producing LC3 cement on an industrial scale shared their experiences, challenges and lessons.
Cuba’s two decades in LC3 Sector
Prof Fernando Martinera, the Head of LC3 and the Technology Resource Centre (TRC) in Latin America, shared Cuba’s journey in the production of calcined clay cement.
Cuba began producing the cement in 2004 in collaboration with Switzerland. The main goal at this time was to uncover sustainable alternatives that would replace clinker with supplementary cementitious materials.
For close to 10 years, Prof Martinera and partners have been involved in several projects focused on trying to understand calcined clay.
In January 2013, the country entered the first phase of industrial trial production of LC3 which entailed sourcing the right clays, followed by calcination of the clay in March.
In August, that year, the cement grinding process began and between September and December, the cement was used in construction. The following year the concrete made from LC 3 was closely observed and evaluted.
In 2014, Cuba also produced various construction materials such as hollow blocks, prefabricated panels and concrete blocks.
In 2015, Columbia requested support in setting up their first industrial LC3 plant, Planta De ARGOS. In the years that followed, the cement produced was scaled up from generating housing construction materials to building major infrastructure.
One of the biggest projects in which the cement was used was a seven-kilometre tunnel that demonstrated LC3 ’s scalability. In 2019, Cuba was involved in setting up another industrial trial which focused on producing LC2 , an alternative of LC3 .
Important lessons on production
Cuba has been producing calcined clay cement for the past 10 years, and as Prof Martinera explained, this came with important lessons in the product’s sustainability. The professor shared some of technical production lessons learnt during the information day.
This included potential challenges manufacturers could face during production and how to resolve them. In addition, manufacturers in Cuba and other countries have gained experience on how to choose clays — one of the biggest challenges at the beginning of production.
Equipment makers have gained a better understanding of their needs and manufacturers now have different choices of equipment.
Standardisation procedures for the LC3 cement that requires 50 percent clinker have been established — a fact that will encourage more manufacturers to start producing LC3.
Most importantly, 10 years in production has produced evidence of carbon emissions’ reduction as well as sustainability in industrial production.
Meanwhile, players in the industry are now looking into alternative formulations for LC3 cement using different percentages of clinker.
India’s experience on working with LC 3 Concrete
Representing India, the Head of LC3-TRC, Asia and a professor at the Indian Institute of Technology, Prof Shashank Bishnoi, delivered an interesting presentation on the performance of concrete made using LC3.
Prof Bishnoi took the stakeholders briefly through the research work, then the laboratory and field work.
He started by explaining the main differences between LC3 and the other types of cement like Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC). The main difference is the components used.
While all three are made of certain percentages of clinker, OPC has the highest percentages at 95 percent and LC3 has the lowest percentage of clinker at 50 percent.
Clinker is the most crucial component in cement. In Kenya, and many countries around the world, it is imported and this affects the cost of cement significantly.
With the dollar-shilling value fluctuating unpredictably, the cost of cement has also been changing in a similar pattern over the last one year due to the cost of imports.
In diagrams shared by Prof Bishnoi, the lower clinker percentage in LC3 is compensated with locally available clay, limestone and low quantities of gypsum.
Prof Bishnoi also shared the process a country goes through to get to industrial production of a new product like LC3 .
The process begins with encouraging early uptake of LC3 and that involves convincing the industry to consider the product and coming up with production standards.
Once the standards have been created, the industry can study feasibility of the product by mapping where the raw material is located, evaluating the economics of the product and taking note of policy issues.
Industry players can then move into production, while observing compositions in available raw materials.
This is important because clay is made up of a variety of minerals and may vary in different regions.
Impressive benefits
During the production stage, industry players will also look into the cement’s workability as well as production conditions and durability of structures built with the cement. Once all these things have been established, the industry can get into the most important and final stage, which begins with pilot production and construction.
During this phase, various building materials and projects should be tested to ascertain the sustainability and economic appeal of LC3.
Currently, Kenya is at the standardisation stage and has not started producing LC3 cement. India has gone through these stages successfully and done housing projects with the cement.
Prof Bishnoi shared with stakeholders some important findings on how LC3 works. For instance, the field experiments established that LC3 based concrete has a faster curing process, which means developers can cut down their construction time. He also said that LC3 cement requires less water, which makes it suitable for regions with water scarcity. Its compressive strength is relatively higher and performs well, or even better compared to OPC cement.
Decarbonising the industry and climate change were important topics during the information day.
Prof Karen Scrivener, Head of the LC3 Group, a fellow at the Royal Academy of Engineering, UK and one of the first inventors of LC3 delivered a presentation on how LC3 can play a major role in decarbonising the industry.
The concrete industry is one of the biggest producers of CO2 emissions through production and transportation. Prof Scrivener explained that LC3 has an impressive resistance to chloride penetration and alkali silica reaction — a fact that makes it a durable option.
Chloride attacks on concrete structures is a major problem.When chloride penetrates concrete structures, it corrodes the steel reinforcement, thus reducing the building’s strength significantly. It is estimated that 40 per cent of failures in concrete structures is attributed to chloride attacks. LC3 has great promise in reducing these failures, subsequently increasing buildings’ lifespan.
Prof Scrivener also noted that clays are generously available in multiple regions around the world, and this means production is localised and imports are reduced significantly. Calcined clays are also highly reactive, meaning there is promise to substitute clinker further in the future.
In comparison to other methods of reducing carbon emissions in the industry, Prof Scrivener demonstrated that LC3 production and application in the industry will cost much less.
For instance, carbon capture, storage and usage is quite effective but extremely expensive. Carbon capture is a process of trapping CO2 produced through industrial processes and preventing it from polluting the atmosphere. The cost of CO2 capture and storage depends on the technology used, transportation and the storage methods.
In comparison, LC3 offers a cost-effective solution if the concrete industry focuses on greener designs and efficient concrete production.
Prof Scrivener looked at comparisons between LC3 and other potential cement options. The conclusion was that other alternatives such as cement from algae and alkali activated materials are impractical, costly and unscalable.
Climate change, carbon markets and new opportunities
One of the most experienced speakers at the event, with over 40 years’ experience in the cement sector, Laurent Grimmeissen, a senior expert and partner at Cementis (a swiss-based consulting company) shared interesting developments in the growing LC3 sector.
“For the first time, last year at the COP28 in Dubai, cement was recognised as a solution to climate change rather than a problem,” he said, adding that, if the concrete sector was to achieve efficient and climate friendly production, LC3 was the only way.
Mr Grimmeissen further advised stakeholders to engage in more workshops and involve government bodies as policy reforms play a major role.
With the world going greener, Mr Grimmeissen noted that countries and companies with green procurement practices are likely to attract a lot of support.
He also talked about the growing voluntary carbon market where companies with green projects can sell their carbon credits based on how much their projects are mitigating carbon emissions.
In addition to selling carbon credits, companies can also attract funding or grants from governments that are supporting climate action. IKI, an initiative by the German Government, is one of such initiatives.
The government’s stand
Representatives from multiple government agencies such as the Kenya Bureau of Standards (Kebs), State Department of Public Works, Kirdi, Ministry of Investment, Trade and Industry, and others, graced the event.
There is optimism that the government is in support of LC3 production in the country.
“The government is working on mainstreaming new building techniques and innovations,” said Kennedy Matheka, an assistant director from the Ministry of Public Works.
Mr Matheka said that the government is keen on supporting projects that contribute to its sustainability goals and that the green building policy and legal framework is currently being revised.
Stakeholders’ voices and concerns
Stakeholders from the commercial sector of the industry were also present, and while they expressed interest in taking up LC3, they also raised a few concerns which were addressed during a Q&A session.
DN2 Property had a follow-up interview with Dr Joseph Mwiti, Head of LC3 Africa, and a lecturer at Meru University. Dr Mwiti will also be heading the Technology Resource Centre for Africa, which was launched at Meru University February 14.
One of the critical issues raised was the process of identifying and mapping locations that have the right type of clays. Some of the cement companies that are interested in producing LC3 have been researching suitable locations to set up plants.
Mapping clay sources is one of the most tedious processes and several people wondered whether it was possible for the Meru University team working at the resource centre to share the locations with the right clays publicly.
Both Dr Mwiti and Prof Scrivener highly discouraged that, saying it would open a can of worms.
“Sharing information about locations with the right clays will definitely affect the prices of potential mines. Cement companies might struggle to acquire the mines and this trickles down to the cost of setting up,” said Dr Mwiti.
In addition, such locations are likely to attract squatters and other interested parties looking for ways to benefit.
It also emerged that not all clays are suitable for production of LC3 .
“Clays are made up of a variety of minerals. The reactive ingredient we look for is kaolin content. We need to have at least 40 percent of kaolin content in the clay,” explained Dr Mwiti.
The biggest challenge is that interested manufacturers usually want to identify the clays alone, which can cost a lot of money.
Dr Mwiti said that identifying the right clays and obtaining them from the ground requires proper handling.
“You could pick something that is not required or you might have to go to a certain depth to get clays with the right minerals. Cement companies need to involve experts at this stage to avoid wasting resources and making wrong financial decisions,” he said.
More production in Africa
Currently, the newly launched resource centre is supporting three other countries in Africa; Malawi, Senegal and Rwanda.
Dr Mwiti said that these countries are at the initial stages of identifying clays and testing them. This brings the number of African countries with LC3 production activity to six. Tanzania are at phase one, while Cote d’Iviore and Ghana have set up production plants. Angola is setting up its first plant.
The resource centre is open to the public, professionals in the concrete industry, government agencies, other African countries and international bodies.
“We are working with Kebs through a technical committee on concrete and lime on standardising LC3 . We are also working with the National Construction Authority and other government agencies like the State Department for Public Works. At the international level, we are collaborating with UN habitat and diplomatic missions,” Dr Mwiti said.
The cost of calcination
The other issue raised was the high cost of calcination.
Essentially, calcination is the process of heating clay at high temperatures between 600 to 800 degrees to make it reactive. Due to the high cost of energy, there were concerns that calcination costs might affect the cost of producing calcined clay cement.
In response to this, Prof Scrivener said that the cost of calcination is much lower compared to the cost of importing clinker, especially with the dollar gaining significant value over most African currencies.
