Displaying items by tag: Slag

US: CRH subsidiary Ash Grove Cement says that it is undertaking an upgrade of its Port Manatee, Florida deep water cement terminal to install a high capacity FLSmidth Kovako unloader and modernise existing material transfer and electrical systems, as well as establishing self-loading capabilities. The aim of the upgrade is “to improve Ash Grove’s capacity to import cement clinker, slag and fly ash to meet the existing and future needs of customers in the Florida and South Georgia markets.

Regional president Monica Manolas said, “The underlying fundamentals in the Florida market are positive with good population and employment growth. The upgrade of the Port Manatee import terminal will expand our capabilities and strengthen our ability to meet growing demand in the region.”

The company says that construction will begin in early 2021 and the upgraded terminal will open in late 2021.

Bangladesh: Cement producers imported US$760,000-worth of raw materials in the 2020 financial year which ended on 30 June 2020, down by 13% year-on-year from US$874,000 in the 2019 financial year. Clinker, calcareous stone, granulated blast furnace slag (GBFS) and gypsum imports totalled 18.6Mt, down by 11% from 21.0Mt, compared to annual growth of 15 - 20% since 2010.

The Daily Star newspaper has reported that this was due to decreased cement demand, with sales falling to 65,000t in April 2020 from 125,000t in March 2020 on account of the start of the nationwide coronavirus lockdown. Premier Cement managing director Amirul Islam said, “We are not getting the benefits we expected from the government. The sector’s capital is gradually running out, so all kinds of discretionary tax cuts are needed to save this industry.”

Bangladeshi cement producers import raw materials from Thailand, Vietnam and China.

Singapore: Jurong Port has ordered three Siwertell ship unloaders from Bruks Siwertell to handle cement imports. The port’s cement terminal already has three Siwertell ship unloaders that have been used for over 20 years. Two of these will be replaced as part of the upgrade project.

The three new ST 490-M screw-type rail-travelling unloaders will each discharge cement, fly ash and cement slag from vessels up to 50,000dwt at a continuous rated capacity of 800t/hr. Two of the new unloaders are scheduled for delivery in May 2022 and the third by the end of 2022. All will be fully assembled prior to delivery and transported by heavy-lift ship. Final commissioning and performance tests will be carried out in Jurong Port.

Japan: Taiheiyo Cement has partnered with JFE Steel and the Global Institute for Environmental Technology to develop a carbon capture and storage system. The system will use wet alkaline earth metals extracted from steel slag to produce carbonates from exhaust gases at cement and steel plants. The partners are investigating the possibility of using these carbonates, specifically calcium carbonate and magnesium carbonate, as additives in cement production at Taiheiyo Cement’s plants. Taiheiyo Cement president Masafumi Shigehara said, “With the effects of climate change becoming apparent both in Japan and overseas, the importance of global warming counter-measures is increasing.”

Australia: A paper published in the journal Resources, Conservation and Recycling has reported that concrete made with treated slag is 8% stronger than standard slag concrete and 17% stronger than concrete made with conventional aggregates. A Royal Melbourne Institute of Technology (RMIT) team produced treated slag concrete using slag that had absorbed phosphate, magnesium, iron, calcium, silica and aluminium during use in wastewater treatment. Researcher Biplob Pramanik said, “The things that we want to remove from water are actually beneficial to concrete.” Pramanik said that the findings have promising implications for the water and concrete sectors within the circular economy.

Cement and concrete products with sustainability credentials have increased in recent years as societies start to demand decarbonisation. In spite of the recent drop in the European Union (EU) Emissions Trading Scheme (ETS) price, there has been a trend in recent years in the construction industry towards offerings with better environmental credentials. Indeed, this week’s position paper from Cembureau on a carbon border mechanism concerns directly the growth of these kinds of products within Europe. Typically, the higher profile projects have been slag cement or concrete implementations such as Hanson’s use of its Regen cement substitute in a London sewer project or David Ball Group’s Cemfree concrete in a road project also in the UK. In this short review we’ll take a selective look at a few of the so-called low carbon cement and concrete products currently available.

Table 1: Some examples of methods to reduce embodied CO₂ in cement and concrete. Note - the product examples are selective. In some cases many other products are available.

Looking at cement first, the easiest way for many producers to bring a lower carbon product to market has been to promote cements made using secondary cementitious materials (SCM) such as granulated blast furnace slag or fly ash. These types of cements have a long history, typically in specialist applications and/or in relation to ease of supply. For example, cement producers in eastern India often manufacture slag cements owing to the number of local steel plants. However, cement producers have more recently started to publicise their environmental credentials as they reduce the clinker factor of the final product. Alongside this though, in Europe especially, a number of so-called low carbon cement producers have appeared on the scene such as EcoCem and Hoffman Green Technologies. These newer producers tend to offer SCM cement products or other low carbon ones built around a grinding model. It is likely that their businesses have benefitted from tightening EU environmental legislation. How far cement producers can pivot to SCM cement products is contentious given that slag and fly ash are finite byproducts of other industries that are also under pressure to decarbonise. Although it should be noted that other SCMs such as pozzolans exist.

As will be seen below a few of the methods to reduce embodied CO₂ in cement and concrete can be used in both materials. SCMs are no exception and hold a long history in concrete usage. As mentioned above David Ball Group sells Cemfree a concrete product that contains no cement. Harsco Environmental, a minerals management company, invested US$3m into Carbicrete, a technology start-up working on a cement-free concrete, in late 2019.

Limestone calcined clay cements are the next set of products that are starting to make an appearance through the work of the Swiss-government backed LC3 project, more commercial offerings like FutureCem from Cementir and H-EVA from Hoffman Green Technologies and today’s announcement about ThyssenKrupp’s plans to fit the Kribi cement plant in Cameroon with its Polysius activated clay system. They too, like SCM cements, reduce the clinker factor of the cement. The downside is that, as in the name, the clay element needs to be calcined requiring capital investment, although LC3 make a strong case in their literature about how fast these costs can be recouped in a variety of scenarios.

Calcium silicate cements offer reduced process emissions by decreasing the lime content of the clinker lowering the amount of CO₂ released and bringing down the temperature required in the kiln to make the clinker. Solidia offers its calcium silicate cement as part of a two-part system with a CO₂ cured concrete. In the US LafargeHolcim used Solidia’s product in a commercial project in mid-2019 at a New Jersey paver and block plant. Solidia’s second core technology is using CO₂ to cure concrete and reducing water usage. They are not alone here as Canada’s CarbonCure Technologies uses CO₂ in a similar way with their technology. In their case they focus more on CO₂ mineralisation. In Germany, Schwenk Zement backed the Celitement project, which developed a hydraulic calcium hydro silicate based product that does not use CO₂ curing. Celitement has since become part of Schwenk Zement.

Solidia isn’t the only company looking at two complementary technologies along the cement-concrete production chain. A number of companies are looking at recycling concrete and demolition waste. Generally this splits into coarse waste that is used as an aggregate substitute in concrete and fine waste that is used to make cement. LafargeHolcim has Evopact for the coarse waste and Susteno for the fine. HeidelbergCement has EcoCrete for the coarse and is researching the use of fines. Closing the loop for heavy building material producers definitely seems like the way to go at the moment and this view is reinforced by the involvement of the two largest multinational producers.

Of the rest of the other low carbon cement methods detailed in table 1 these cover other non-Ordinary Portland Cement (OPC) such as geopolymer and calcium sulphoaluminate cements. The former are a type of alkali activated binder and generally lack common standards. The latter are similar to slag cements in that they are established specialist products with lower CO₂ emissions than OPC.

With concrete when trying to make a low carbon product the first choice is whether to choose a low-carbon cement as the binder or even not to use cement at all in the case of Regen or Cemfree. From here the next step is to simply use less cement in a concrete mixture. There are a number of ways to do this from optimising aggregate gradation, following performance specifications more closely, using strength tests like maturity methods and generally adhering to quality control protocols better to deliver more consistency. Read the Mineral Production Association (MPA) publication Specifying Sustainable Concrete for more detail on this. Using concrete admixtures can also help make concrete more sustainable by improving quality and performance at construction sites through the use of plasticisers and accelerators, by decreasing embodied carbon through the use of water reducers and by improving the whole life performance of concretes. The use of locally-sourced aggregates is also worth noting here since it can reduce associated transport CO₂ emissions.

More novel methods of reducing embodied CO₂ emissions in concrete include the use of geopolymer concrete in the case of Zeobond Group’s E-Crete or adding graphene as Concrene does. Like geopolymer cements, geopolymer concretes are relatively new and lack common standards. Products like Concrene, meanwhile, remain currently at the startup level. Finally, if all else fails, offsetting the CO₂ released by a cement or concrete product is always an option. This is what Cemex has done with its Vertua Ultra Zero product. The first 70% reduction in embodied CO₂ is gained through the use of geopolymer cement. Then the remaining 30% reduction is achieved through a carbon offsetting scheme via a carbon neutral certification verified by the Carbon Trust.

As can be seen, a variety of methods exist for cement and concrete producers to reduce the embodied CO₂ of their products and call them ‘low-carbon.’ For the moment most remain in the ‘novelty section’ but as legislators promote and specifiers look for sustainable construction they continue to become more mainstream. What has been interesting to note from this short study is that some companies are looking at multiple solutions along the production and supply chain whilst others are concentrating on single ones. The companies looking at multiple methods range from the biggest building material producers like LafargeHolcim and HeidelbergCement to smaller newer ones like Solidia and Hoffman Green Technologies. Also of note is that many of these products have existed already in various forms for a long time like SCM cements and concretes or the many ways concretes can be made more sustainable through much simpler ways such as changing aggregate sourcing or working more efficiently. In many cases once markets receive sufficient stimulus it seems likely that low carbon cement and concrete products will proliferate.

Global Cement is researching a market report on low carbon cement and concrete. If readers have any comments to make please contact us at This email address is being protected from spambots. You need JavaScript enabled to view it.

Brazil: Itaci Cement has purchased 100 hectares of land in Tabuleiro do Norte in the north-eastern Brazilian state of Ceará. Diario do Nordeste has reported that the company has invested US$66m in a development, though whether this will take the form of a clinker grinding or integrated cement plant has not been disclosed. Companhia Siderúrgica do Pecém (CSP) will reportedly supply granulated blast furnace slag to the facility when operational for use as a feedstock.

Sweden: Construction and engineering conglomerate Peab’s subsidiary Swecem has engaged German-based Gebr. Pfeiffer for the supply of one MVR 2500 C-4 grinding mill at its granulated blast furnace slag (GBFS) grinding plant in Oxelösund in Södermanland. The mill has four grinding rollers and a table diameter of 2.5m, giving it a 25t/hr slag grinding capacity.

Swecem operates a concrete plant in Kungsängen. It currently uses ground granulated blast furnace slag (GGBFS) supplied by Irish-based Ecocem’s 0.7Mt/yr Dunkirk grinding plant in France.

India: Dalmia Bharat has blamed the general election for its slow cement sales volumes growth in its first quarter. Its sales volumes of cement increased slightly to 4.55Mt. Its revenue grew by 7% year-on-year to US$365m in the first fiscal quarter to 30 June 2019 from US$340m in the same period in 2018. Its earnings before interest, taxation, deprecation and amortisation (EBITDA) rose by 27% to US$95.7m from US$75.2m.

The cement producer also said that its power and fuel costs per tonne had been negatively affected by its Kalyanpur plant operating at low capacity utilisation levels, partly due to a lack of coal. However, it noted that its raw material costs had been ‘moderated’ due to falling slag prices.

France: Hoffmann Green Cement Technologies and Bouygues Construction have signed a 30-month initial technical and commercial collaboration agreement to develop and test concrete formulations using new cement made from Hoffmann’s H-EVA technology. Hoffmann Green Cement inaugurated its pilot plant at Bournezeau, Vendée in late 2018. The unit will manufacture cement products using flash-calcined metakaolin and blast-furnace slag. Bouygues Construction is a global construction company with a presence in over 60 countries.