Displaying items by tag: supplementary cementitious materials

Betolar has called today for a global performance-based standard to replace existing prescriptive standards. Riku Kytömäki, the head of Betolar, argued at the London-based Concrete Expo that the lack of a performance-based standard is holding back the use of low-carbon materials from replacing cement in concrete production. He said “the current regulations across the markets are restricting the use of circular materials allowed in concrete buildings.” Betolar produces Geoprime, an additive designed for use in cement-free concrete production with ash and ground granulated blast furnace slag (GGBFS). This gives the company a financial reason to want standards to change, as it will potentially allow it to sell more of its product. However, as the company points out, “there is a huge need for new alternatives.” The world needs around 4Bnt/yr of cement but there is only 300Mt/yr of slag available.

Building materials producers and related companies wanting to change rules and standards in response to new trends is a common refrain. For instance, the increased use of alternative fuels by the cement sector has prompted all sorts of regulatory changes. However, rather than simply asking for amendments to the existing ways of doing things, Betolar is advocating for more wholesale change. It isn’t alone. Also this week the ASTM in the US announced that it is writing a specification to include a wider range of secondary cementitious materials (SCM). In addition, many of the interviews Global Cement Magazine has conducted with companies developing and marketing new types of cement and concrete in recent years have said similar things. Examples include the use of graphene, carbon nanotubes or sequestering CO₂ into industrial by-products to create novel secondary cementitious materials (SCM).

Prescriptive versus performance-based approaches to buildings and building materials tie into wider design philosophies about construction. The prescriptive approach provides detailed descriptions of regulations, methods and components, such as cement and concrete standards. With respect to concrete standards, this might mean setting mandatory SCM and cement proportions, determining allowable water content, certain types of aggregate to be used and so on. The performance approach focuses on the end results, although it can be just as codified and standardised as the prescriptive route. For concrete, for example, this means that performance is measured by standard test methods with defined acceptance criteria stated in the contract documents with no restrictions on the parameters of concrete mixture proportions.

For cement and concrete standards the prescriptive approach dominated in Europe and North America in the 20th century. However, this began to change in the US in 2002 when the National Ready Mixed Concrete Association (NRMCA) started working on its roadmap towards its Prescription to Performance (P2P) initiative. The key aim of the scheme was to shift the emphasis from prescribing (or indeed proscribing) the ingredients and their proportions in a concrete mixture to an emphasis on the performance properties of the combined materials. A decade later in the mid-2010s it found during a progress review that about half of the sample of project specifications studied were classified as ‘prescriptive.’ The biggest prescriptive restriction was on the quantity of SCMs set by specification writers. These were often percentages required in certain circumstances, such as freezing and thawing cycles, but imposed on all usage.

The current bout of interest in performance-based standards appears to be driven by the growing demand for cement and concrete products to lower their clinker factor by using higher amounts of SCMs. A far wider range of SCM-based products are being developed and coming to market and then encountering regulatory burden. These new material manufacturers are meeting up with the sustainability lobby, which also has an interest in decarbonising building materials. In 2022, for example, the Belgium-based Environmental Coalition on Standards (ECOS) started pushing for performance-based standards for cement. In a statement it said that, “it is commonly accepted that prescriptive specifications are convenient, but that this convenience is obtained at the expense of (eco-) innovation and decarbonisation.” It added that the switch to performance-based standards would also strengthen the European internal market for construction products as part of the Construction Products Regulation (CPR). It noted the ASTM standards for hydraulic cements (ASTM C-1157), that were developed in the 1990s in the US, and more recent developments in the field in Latin America.

It is worth pointing out that the prescriptive route does have its advantages. Using a prescriptive system is easier for less-experienced practitioners or generalists as it sets a minimum standard, even if it is over-engineered. Responsibility is shared out among the supply chain under a performance-based system for the quality of concrete. Under a prescriptive system, the supplier or contractor can be held responsible for quality control issues. For the performance approach this has to be specifically defined, although systems are in place to help. Making it harder via ‘red tape’ for new products to enter a market may stifle innovation but it also gives these new products far more time to be tested rigorously.

The whole prescriptive-performance standards issue opens up the wider implications of decarbonising construction materials. Where once there was a relatively small number of different types of cement and concrete now there are potentially hundreds, each looking for market share. Whether this situation will be the same in a decade’s time remains to be seen. A few common SCM-based cement and concrete products and formulations may predominate. For now, the future seems wide open and bigger changes, such as the global performance-based standards Betolar is advocating, may be required to support this. Considering the massive variation between countries and states, even within the US and the European Union, let alone the rest of the world, this seems ambitious. But it is not impossible!

UK: Riku Kytömäki, the chief executive officer of Betolar, has called for a global performance-based standard to replace the current building requirements that restrict the use of new low-carbon materials to replace cement in concrete production. He made the comments at the London Concrete Expo. Kytömäki argued that current standards state that concrete manufacturers must use a certain percentage of cement to strengthen the finished product. Betolar’s product Geoprime is an additive designed for use in cement-free concrete production with ash and ground granulated blast furnace slag (GGBFS). However, “ageing” standards rule out the use of these kinds of products such as this despite their sustainability advantages.

Kytömäki said “It is time for global concrete industry to step up their sustainability efforts. New material innovation is available. It is cost-effective and helps to meet stricter durability requirements. However, the current regulations across the markets are restricting the use of circular materials allowed in concrete buildings.” He added that his company’s product Geoprime, “does not require large investments, but there is regulation to be developed quickly so that new solutions and materials can be used."

Betolar says it has analysed over 200 side-streams other than slag and fly ash, providing flexibility to process locally available side-streams. It added that there are also significant CO₂ savings to be found in logistics when manufacturing processes take place near the source of the industrial side-streams.

Canada: The Cement Association of Canada (CAC), with its members and partners in the concrete sector, has released Concrete Zero, an action plan to help the local cement and concrete sector reach net-zero CO₂ emissions by 2050. The five priority areas it is focusing on include: eliminating the use of coal and petroleum coke as fuel sources for clinker production; reducing the volume of clinker used to produce cement; increasing the use of supplementary cementitious materials; working towards building carbon capture, utilisation and storage capacity; and advocating for performance-based codes, standards and specifications, procurement policies and increased material efficiency in construction. Targets include reaching a 100% fuel mix from non-fossil-based sources by 2050. The latest plant follows the goal of achieving a 40% emissions reduction by 2030 as part of its Roadmap to Net-Zero Carbon Concrete by 2050.

Adam Auer, the president and chief executive officer of CAC, said “Our net-zero action plan is ambitious and cannot be achieved by industry action alone. Working with government, industry, and partners in the design, architecture, and construction industry will be essential for success. Canada’s cement and concrete industry are committed to doing our part to help Canada build a better, cleaner future. Working together, we can deliver Concrete Zero.”

US: ASTM International’s concrete and concrete aggregates committee (C09) is developing a proposed standard specification for a broad range of supplementary cementitious materials (SCM). Larry Sutter, an ASTM International member and the principal engineer at Sutter Engineering, commented that this performance specification (WK70466) will ease the adoption of new materials used for SCMs as established sources become less available.

Sutter said “For a variety of reasons, historic sources of SCMs, like coal fly ash from electric power generation, are in short supply and new materials are emerging.” He added, “These new materials do not fall under existing specifications, leading to the need for new specifications. Rather than writing a new specification for every emerging material, we are writing a performance specification that can be used to cover the full range of them.”

Sutter noted that concrete made with SCMs can be less costly, more durable and more sustainable than ordinary Portland cement. New specifications will allow these new materials into more construction projects. This effort relates to the United Nations Sustainable Development Goal #7 on clean and affordable energy.

Heidelberg Materials announced a US acquisition at the same time as the ongoing IEEE/IAS-PCA Cement Conference in Dallas, Texas this week. It has entered into a purchase agreement to acquire The SEFA Group, a fly ash recycling company based in Lexington, South Carolina. Its operations include five beneficiation plants, five utility partners, 20 locations and over 500 employees. It supplies fly ash to over 800 ready-mixed concrete plants in 13 states. It processes around 1Mt/yr of ash from storage ponds using its proprietary thermal beneficiation process. No value for the acquisition was disclosed.

The proposition for a heavy building materials manufacturer of securing a supply of fly ash is an attractive one. Fly ash can improve the performance of concrete, reduce its cost by lowering the amount of ordinary Portland cement (OPC) required and decrease the associated carbon footprint. It can also be use to make blended cement products. Heidelberg Materials and its US-subsidiary Lehigh Hanson could have various options here including using this new supply of fly ash internally, selling it on to other companies or licensing the beneficiation technology. Heidelberg Materials’ global sustainability report in 2021 reported that just under 9% of its cement-type portfolio comprised pozzolana or fly ash cements.

Graph 1: Coal combustion product production and use, 1991 – 2021. Source: ACAA.

Data from the American Coal Ash Association (ACAA) shows in Graph 1 that coal combustion products (CCP) production have declined in the last decade as the proportion used has steadily risen. In its annual production and use survey, the ACAA revealed that the use of harvested ash continued to grow in 2021 and that it constituted around 10% of the volume of ash recycled from current power plant operation. Thomas H Adams, the executive director of the ACAA, said “The rapidly increasing utilisation of harvested CCP shows that beneficial use markets are adapting to the decline in coal-fuelled electricity generation in the US. New logistics and technology strategies are being deployed to ensure these valuable resources remain available for safe and productive use.” Separately, the ACAA reported that coal-fuelled power stations represented about 50% of the country’s electricity demand in the mid-2010s compared to 20 – 25% in 2021 despite base-load remaining the same. It forecast that fly ash production was likely to remain fairly constant to around 2040 but that harvesting would help to cut the gap between supply and demand in some regional markets. It said that over 2Bnt of coal ash was in disposal. However, no indication of how recoverable this was given although it did note the higher cost of beneficiation. Work on updating specifications was ongoing to suit current circumstances.

As with the slag market, this presents a dilemma for cement and concrete producers that want to become more sustainable. They want to use more by-products from other carbon-intensive heavy industries – such as coal-fired power stations and steel plants – but these industries themselves are also trying to become more sustainable and are producing less secondary cementitious materials. Heidelberg Materials’ interest in a fly ash beneficiation company makes sense because it secures a bigger portion of a dwindling resource from the direct operations and opens up the possibility of selling the beneficiation technology to others. It is also worth mentioning that other fly ash thermal beneficiation processes are available. For example, Charah Solutions installed its MP618 technology at its Sulphur terminal in Louisiana in early 2019.

The general fly ash market in the US looks set to track the level of coal-fired power generation for the foreseeable future. Yet the proportion of CCPs being used continues to rise. In this context focusing on harvesting may be starting to make more financial sense. Charah Solutions’s new unit in 2019 and SEFA Group’s new units in 2020 and 2021 seem to support this view. Heidelberg Materials’ acquisition of SEFA Group may be further confirmation of this.

US: Germany-based Heidelberg Materials has entered into a definitive purchase agreement to acquire The SEFA Group Inc., the largest fly ash recycling company in the US. Based in Lexington, South Carolina, the operations of The SEFA Group include five business units, five utility partners, 20 locations and more than 500 employees. The group currently supplies quality fly ash to more than 800 concrete plants in 13 states.

Heidelberg Materials said that the reuse of fly ash from energy generation in alternative products such as composite cements enhances its circularity efforts within its value chain by reducing the CO₂ emissions of its cement and concrete. The transaction is anticipated to close in June 2023.

“Fostering circularity by increasing the use of by-products and recycled materials from other industrial sectors is an essential part of our strategy,” said Dr Dominik von Achten, Chairman of the Managing Board at Heidelberg Materials. “Our focus is on rapidly and significantly reducing our CO₂ emissions and The SEFA Group will make an outstanding contribution in this regard to our US business.”

UK: The UK government has committed to investments worth Euro22.8bn in early deployments of carbon capture technology. It will announce a shortlist of new projects for deployment later in March 2022.

The government said "This unprecedented level of funding for the sector will unlock private investment and job creation across the UK, particularly on the east coast and in the North West of England and North Wales. It will also kick-start the delivery of subsequent phases of this new sustainable industry in the UK."

Ireland-based Ecocem responded to the budget with a call for funding for more short-term areas besides carbon capture. It said these will be essential in order for the UK cement and concrete industry to reach its 45% decarbonisation target by 2030. The slag-based cement products company called for funding for low-clinker technologies which have already been developed and can be rolled out at scale before 2030, until carbon capture becomes a 'scalable, viable option.'

Canada: Progressive Planet has secured a contract to supply its PozGlass recycled glass-based supplementary cementitious material (SCM) to Lafarge Canada. The cement producer says that it will test the commercial viability of all PozGlass produced at Progressive Planet's Kamloops pilot plant in British Columbia, once the plant commences PozGlass production in 2024.

UK: Cambridge Electric Cement (CEC) has launched the two-year trial of its Cement 2 Zero project, aimed at scaling up production of its net zero-CO₂, demolition waste-based alternative cement. It aims to produce 20t of the material for use in a low-impact construction project. CEC’s method, developed at the University of Cambridge, is based on the conversion of demolition waste into a slag-forming material within a steel furnace.

Developer Julian Allwood said “By combining steel and cement recycling in a single process powered by renewable electricity, we could supplement the global supply of the basic construction materials to support the infrastructure of a zero emissions world and to enable economic development where it is most needed.”

Australia: Germany-based Christian Pfeiffer has received an order for a grinding circuit comprising a 16.3m-long ball mill and a QDK T 250-Z type separator from Hallett Construction Materials. The circuit will have a capacity of 84t/hr, according to the supplier. Hallett Construction Materials plans to use the equipment at its upcoming Port Augusta slag cement grinding plant. The plant is scheduled for commissioning in January 2024.

Hallett Construction Materials chief executive officer Kane Salisbury said, “For us, the sustainability of the plant is the highest priority. That’s why we manufacture cement containing 100% slag.” Salisbury added “The Christian Pfeiffer process experts convinced us that the ball mill, in combination with a high efficiency separator, is the best system to serve our requirements.”