Displaying items by tag: recycled concrete paste

One unusual thing about coverage of cement in the media is the way that discussions often centre precisely on its absence – that is, on alternatives to cement. These alternatives boast unique chemistries and performance characteristics, but are all produced without Portland cement clinker. They are generally called ‘alternative cements,’ perhaps because ‘cement-free cement’ does not have such a commercially viable ring to it. This contradictory tendency reached a new high in the past week, with developments in alternative cement across Asia, Europe, the Middle East and North America. Together, they hint at a more diverse future for the ‘cement’ industry than the one we know today.

Asia

In Indonesia, Suvo Strategic Minerals has concluded tests with Makassar State University of a novel nickel-slag-based cement. Huadi Nickel-Alloy Indonesia supplied raw materials, and tests showed a seven-day compressive strength of 37.5MPa. Suvo Strategic Minerals says that a partnership with Huadi Nickel-Alloy Indonesia for commercial production is a likely next step.

Europe

Cement producer Mannok and minerals company Boliden partnered with the South Eastern Applied Materials (SEAM) research centre in Ireland to launch a project to develop supplementary cementitious materials (SCMs) from shale on 7 October 2024. The project will additionally investigate CO₂-curing of cement paste backfill for use in mines. Irish state-owned global commerce agency Enterprise Ireland has contributed €700,000 in funding.

UK-based SCM developer Karbonite expects to launch trial production of its olivine-based SCM with a concrete company in 2025. The start-up launched Karbonite Group Holding BV, with offices in the Netherlands, to facilitate this new phase. Karbonite’s SCM is activated at 750 – 850°C and sequesters CO₂ in the activation process, resulting in over 56% lower CO₂ emissions than ordinary Portland cement (OPC). Managing director Rajeev Sood told Global Cement that talks are already underway for subsequent expansions into the UAE and India.

Back in the UK, contractor John Sisk & Son has received €597,000 from national innovation agency Innovate UK. John Sisk & Son is testing fellow Ireland-based company Ecocem’s <25% clinker cement technology in concrete for use in its on-going construction of the Wembley Park mixed development in London.

At the same time, Innovate UK granted a further €3.23m to other companies for concrete decarbonisation. Recipients included a calcined clay being developed by Cemcor, an SCM being developed from electric arc furnace byproducts by Cocoon, a geopolymer cement technology being developed by EFC Green Concrete Technology UK and an initiative to develop alternative cement from recycled concrete fines at the Materials Processing Institute in Middlesbrough. Also included was the Skanska Costain Strabag joint venture, which is working on the London stretch of the upcoming HS2 railway. The joint venture, along with partners including cement producer Tarmac and construction chemicals company Sika UK, will test low-kaolinite London clay as a raw material with which to produce calcined clay as a cement substitute in concrete structures in HS2’s rail tunnels.

Middle East

Talks are underway between UK-based calcined clay producer Next Generation SCM and City Cement subsidiary Nizak Mining Company over the possible launch of a joint venture in Riyadh, Saudi Arabia. The joint venture would build a 350,000t/yr reduced-CO₂ concrete plant, which would use alternative cement based on Next Generation SCM’s calcined clay.

North America

Texas-based SCM developer Solidia Technologies recently patented its carbonatable calcium silicate-based alternative cement, which sequesters CO₂ as it cures.

Meanwhile, C-Crete Technologies made its first commercial pour of its granite-based cement-free concrete in New York, US. C-Crete Technologies says that the product offers cost and performance parity with conventional cement, with net zero CO₂ emissions. Its raw material is globally more abundant than the limestone used as a raw material for clinker. Other abundantly available feedstocks successfully deployed within C-Crete Technologies’ repertoire include basalt and zeolite.

Across New York State, in Binghamton, KLAW Industries has succeeded in replacing 20% of concrete’s cement content with its powdered glass-based SCM, Pantheon. KLAW Industries has delivered samples to local municipalities and the New York State Department of Transportation. Its success expands the discussion of possible circular cement ingredients from the industrial sphere into post-consumer resources.

In Calgary, Canada, a novel SCM has drawn attention from one of the major cement incumbents: Germany-based Heidelberg Materials. It invested in local construction and demolition materials (CDM)-based SCM developer EnviCore on 9 October 2024. The companies plan to build a pilot plant at an existing Heidelberg Materials CDM recycling centre.

Conclusion

Alternative cement developers are still finding the words to talk about their products. They may be more than ‘supplementary’ up to the point of entirely supplanting 100% of clinker. Product webpages offer ‘hydraulic binder,’ ‘pozzolan’ and even ‘cement.’ As alternative ‘cements’ are developed, they build on the work of pioneers like Joseph Aspdin and Louis Vicat. Start-ups and their backers are now reaching commercial offerings, on a similar-but-different footing to cement itself. None of these novel materials positions itself as the sole, last-minute ‘super sub’ in the construction sector’s confrontation with climate change. Rather, they are a package of solutions which can combine into a net zero-emissions heavy building materials offering, hopefully before 2050.

Related to this is the need for ‘technology neutral’ standards, as championed this week by the Alliance for Low-Carbon Cement and Concrete (ALCCC), along with 23 other European industry associations, civil society organisations and think tanks. The term may sound new, but the concept is critical to the eventual uptake of alternative cements: standards, the ALCCC says, should be purely performance-based. They ought not attempt to define what technology, for example cement clinker, makes a suitable building material. According to the ALCCC, Europe’s building materials standards are not technology neutral, but instead ‘gatekeep’ market access, to the benefit of conventional cement and the exclusion of ‘proven and scalable low-carbon products.’

At the same time, cement itself is changing. Market research from USD Analytics showed an anticipated 5% composite annual growth rate in blended cement sales between 2024 and 2032, more than doubling throughout the period from US$253bn to US$369bn. If you can’t beat it, blend with it!

For a further discussion of alternative cement and binders in Europe, see Global Cement’s interview with ALCCC co-ordinator Joren Verschaeve in the forthcoming November issue of Global Cement Magazine on 17 October 2024.

Heidelberg Materials inaugurated a plant near Katowice in Poland this week for separating and sorting demolition concrete. This gives us the chance to catch up with the state of construction and demolition waste (CDW) for the cement and concrete sectors and consider the differences between the strategies of the multinational heavy building materials companies in Europe and the US.

The new CDW recycling unit has a capacity of up to 100t/hr. Heidelberg Materials says that it is the “first company in the industry to introduce high-quality, selective concrete separation at this scale.” The company is using its proprietary ReConcrete process to sort out fractions from the CDW including sand, gravel and, finest of all, recycled concrete paste (RCP). That last one is particularly valuable because it can either be used as an alternative raw material for clinker production by replacing limestone or as a secondary cementitious material. Heidelberg Materials is also promoting the potential use of RCP as a carbon sink over the lifetime of a concrete structure via ‘enforced carbonation.’ The RCP is exposed to raw exhaust gases from cement production allowing it to both mineralise CO₂ and act as a clinker substitute. To further explore this option Heidelberg Materials is building an industrial pilot at its Górażdże plant to test the concept with construction expected by the end of 2024.

Both Holcim and Heidelberg Materials have been visibly busy buying up more aggregate recycling companies over the last nine months since Global Cement Weekly last reported on CDW. Holcim acquired Germany-based Mendiger Basalt in January 2024, Switzerland-based Cand-Landi Group and UK-based Land Recovery in June 2024, and Belgium-based Mark Desmedt in July 2024. It also said at the start of the year that it aimed to conclude 15 - 20 new acquisitions in 2024 with a focus on CDW companies in Belgium, France, Germany and the UK. Heidelberg Materials bought UK-based B&A Group in May 2024 and US-based Highway Materials and Aaron Materials in July 2024. Holcim has set itself a target of recycling 12Mt/yr of CDW by 2030 by using its ECOCycle technology. It reported 8.4Mt/yr in 2023 and hopes to reach 10Mt/yr in 2024.

Some of the recycling companies mentioned above are based in the US but the pace of CDW acquisitions have generally been faster in Europe. In the US, meanwhile, the heavy building materials producers have tended to buy more general aggregates companies. Heidelberg Materials announced on 30 July 2024 that it was buying Albany-based Carver Sand & Gravel. This followed the companies mentioned above and Texas-based Victory Rock, also in July 2024. Holcim said in its first half-year results for 2024 that it had ‘executed’ a bolt-on acquisition in the US that would strengthen its aggregate and ready-mixed concrete business. Cemex also revealed a joint-venture agreement with sand and gravel supplier Couch Aggregates and marine bulk product distributor Premier Holdings in July 2024. It said that the move was part of its “ongoing strategy to accelerate growth in the US and expand its aggregates business.” A big recent deal in the sector was the merger of the US-based operations of Summit Materials and Cementos Argos that completed in January 2024. Although at the time we concentrated on the cement-side of the transaction, it also gave the organisation just under 5Bnt of aggregate reserves.

It may be a stretch to call what’s going on here a trend. Yet the large heavy building materials companies do appear to be acting differently in the US and Europe with regards to aggregate companies and CDW recyclers. The main drivers here are the strength of the US market and the stricter environmental legislation in Europe. Higher population density in Europe compared to the US may also be playing a part in the differences in speed of adoption between the two markets. The ongoing Holcim spinoff demonstrates the differences between the two market regions in bold terms. In short, the company has decided to split itself in two in order to meet the different needs of each market. As for CDW, the trickle of acquisitions keep coming and momentum is steadily building.

Netherlands: EMC Cement and HES International plan to build a 1.2Mt/yr plant in Amsterdam to produce an alternative cement that contains 70% volcanic ash. The cement will also include recycled concrete fines. Production will be carbon neutral and consume 90% less energy than traditional ordinary Portland cement production. The Amsterdam plant is scheduled for commissioning by early 2026.

EMC Cement CEO Atle Lygren said "Our EMC Technology, by replacing 70% of Portland cement clinker, enables significant climate action without the need for costly carbon capture and storage, aligning with the demands of the United Nations Framework Convention on Climate Change and the Intergovernmental Panel on Climate Change."

Switzerland: Carbon capture and storage (CCS) equipment developer and supplier Neustark says it plans to more than double the number of its CO₂ storage sites in Austria, France, Germany, Switzerland and the UK to 34 from 14. Neustark’s process turns mineralised captured CO₂ and existing mineral waste streams into useful limestone. Building materials producers lease Neustark’s storage sites to produce reduced-CO₂ alternatives such as recycled concrete. The sites currently have a total storage capacity of 5000t. Existing customers include Holcim.

Neustark CEO Johannes Tiefenthaler said “Neustark is scaling up rapidly, and we’re well on track to achieve our aim of permanently removing 1Mt of CO₂ by 2030. Our global goal is a series of reliable, region-specific CCS facilities that can be replicated anywhere, offering immediate sustainability benefits to local supply chains.”

Switzerland: McKinsey & Company and the World Economic Forum have recognised Holcim’s ECOCycle recycling technology for construction-demolition material (CDM) as a "Circularity Lighthouse in the Built Environment." ECOCycle technology can process 100% of CDM input into new building materials with 75% lower CO₂ emissions than traditional alternatives.

Chief sustainability officer Nollaig Forrest said “Circularity is a game changer to decarbonise buildings at scale. At Holcim we are operating over 100 ECOCycle recycling centres globally to drive circular construction. With our advanced recycling of CDM, we can already reduce the CO₂ footprint of cement by up to 40%. This is just the beginning; as we innovate and partner across the value chain to evolve building norms, we aim to accelerate the shift to circular construction in all metropolitan areas where we operate.”

Germany: Switzerland-based CO₂ mineralisation technology developer Neustark says that it sees major potential for recycling concrete from construction and demolition waste (CDW) to produce carbon-negative products using its process in Germany. Neustark inaugurated its first German plant, and 12th overall, at Marzahn in Berlin in late 2023. Capital Online News has reported that the start-up estimates that Germany generates 60Mt/yr of CDW concrete, but only recycles 600,000t/yr (1%). This contrasts with international CDW concrete recycling rates as high as 15% in Switzerland and the US.

The start-up, founded at the Federal Institute of Technology Zurich in 2019, currently absorbs 10kg/t of CO₂ in its recycled materials, but aims to reach 60kg/t. Its investors include Holcim.

France: Holcim France has commissioned its new Saint-Laurent-de-Mûre alternative raw materials plant in Rhône Department. The unit produces cementitious paste from construction and demolition waste using Holcim’s ECOCycle upcycling process. It will source construction and demolition waste from the Lyon Metropolitan Area.

Holcim’s global head of circular construction Vincent Teissier said “Advancing such circular technologies is one of the main pillars of our sustainability strategy. This new advanced crushing unit in Saint-Laurent-de-Mûre is a major step toward using construction and demolition materials to their full value.”

France: Heidelberg Materials has announced plans for its CIRCO₂BETON concrete recycling project. It intends to build an industrial-scale selective separation unit at its Achères quarry near Paris. Here it will recycle demolished concrete by crushing it and separating it into its components: sand, aggregates, and recycled concrete paste (RCP). The recycled sand and aggregates will be reincorporated into new concrete.

The RCP will be transported to the Ranville cement plant in the Normandy region. There, a reactor for enforced carbonation will be installed to carbonate the RCP by exposing it to CO₂-containing exhaust gases from the kiln. The carbonated RCP acts as a carbon sink and will replace clinker in new low-carbon cement types. The project has the potential to reduce the CO₂ emissions of the Ranville cement plant by 20%.

CIRCO₂BETON is supported by the ‘Investment for the Future’ Program coordinated by the Ecological Transition Agency (ADEME). In addition, the Île-de-France region supports the selective separation plant at Achères through its zero-waste and circular economy plan. Subject to the funding, construction of both industrial pilots is scheduled to start in 2024 with production of RCP starting in 2025. The carbonation reactor is planned to be operational by 2026.

Nicola Kimm, the chief sustainability officer at Heidelberg Materials, said ”We are investing in a pioneering large-scale project based on innovative process technologies. Selective separation and CO₂ mineralisation are important levers to reduce the carbon footprint of our products. By closing the materials loop, we prove that concrete has the potential to be the most sustainable building product over its entire life cycle from production to recycling.”

Read more about RCP in the Decemeber 2022 issue of Global Cement Magazine

Holcim launched its formal take on construction and demolition waste (CDW) this week with the unveiling of its ECOCycle technology platform at the BAU architecture fair in Munich. This amounts to managing the distribution, processing, grinding and recycling of CDW back into new building material products. It claims that its concrete, cement and aggregate products can contain 10 - 100% of CDW with no drop in performance.

It is hard to gauge whether this is marketing for existing operations or the start of something new. Yet, in its 2022 Sustainability Report, Holcim said that it recycled 6.8Mt of CDW back into building products and that it is on track to meet its target of 10Mt by 2025. This target was neatly put into words as wanting “to build more new buildings from old ones.” Ahead of the announcement of the launch of ECOCycle, it added that it was going to roll out its Susteno product around Europe. This product, made from 20% CDW, was originally released in Switzerland in the late 2010s. Notably, recent acquisitions by Holcim that connect to its growing focus on CDW include Poland-based Ol-Trans in July 2022, UK-based Wiltshire Heavy Building Materials in October 2022 and UK-based Sivyer Logistics in April 2023.

As covered by Global Cement Weekly in February 2023, Holcim is not the only heavy building materials company pivoting to CDW. The European Union (EU) set a 70% recovery target for it in 2020 and various cement company sustainability reports have described the region as being receptive to moves into this sector. Cemex set up a global waste management subsidiary called Regenera at the end of January 2023. This division covers both alternative fuels, CDW and industrial by-products, so it is more general than Holcim’s current effort, but it shows intent in the same direction. Cemex previously set a target of recycling 14Mt/yr CDW by 2030.

Heidelberg Materials has been working on developing recycled concrete paste and its ReConcrete-360° concrete recycling process. As of its last sustainability report, this process had been tested at the pilot scale and is now being developed and scaled for industrial application. In addition to acquiring UK-based Mick George Group in December 2022 Heidelberg Materials has also purchased Germany-based RWG Holding in January 2023 and Germany-based SER Group in February 2023. All three companies operate in the CDW sector.

The other notable contribution that Heidelberg Materials has been making is as a partner of the ‘Circular City - Building Material Registry for the City of Heidelberg’ project. When Heidelberg Materials announced its involvement in the initiative in mid-2022 it said it was the first city in Europe to apply the principles of urban mining. The goal of the project is to take an inventory of the city’s buildings and then compile it in a digital material registry. The basis for the registry is the Urban Mining Screener developed by EPEA (Environmental Protection Encouragement Agency). This programme can estimate the composition of buildings based on building data such as location, year of construction, building volume or building type. Circular economy supply chains can then act accordingly when a building is retrofitted, demolished or deconstructed. So, for example, at the start of the project it worked out that a former US Army housing estate conversion site was calculated to contain approximately 466,000t of material, with about half in the form of concrete, a fifth in the form of bricks and 5% as metal.

That last example compares to a European Commission estimate that, as a whole, Europe generates around 450 - 500Mt/yr of CDW. A third of this is concrete. As with alternative fuels and slag previously, this may be money going into the ground. Recycling building materials is not new but any significant increase in reusing CDW that can reduce the clinker factor of cement (and the cement factor of concrete) offers a potentially cheaper route to building materials decarbonisation than carbon capture and utilisation/storage at current costs. Hence the continued interest.

UK: Legal & General Capital, an alternative investment arm of financial services company Legal & General, has invested around US$15.5m in Cambridge Electric Cement (CEC) and other companies as part of its strategy to decarbonise the residential sector. It is also investing in Hometree and SunRoof, as well as increasing its existing investment in Sero Technologies.

CEC is developing process to create net zero-CO₂ cement product using recycled concrete paste. It launched a two-year industrial trial of its Cement 2 Zero project in February 2023.