Displaying items by tag: Fly Ash
Ash Grove Cement to upgrade Port Manatee cement terminal
23 September 2020US: 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.
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.
Tokyo Cement supports underwater sculpture park
28 July 2020Sri Lanka: Tokyo Cement has supported its partner the Sri Lanka Navy in completing an underwater statue park. The Sunday Observer newspaper has reported that the 1200m2 park in Trincomalee Bay, Eastern Province, lies at a depth of 18m and unfolds a historical storyline. Tokyo Cement supplied its Tokyo Super blended hydraulic fly ash cement to the project.
Project leader Piyal De Silva said, “Our Coral Conservation Programme (CCP) partner Tokyo Cement will carry out monitoring and maintenance activities and will provide material and technical support to set up a coral nursery for replanting corals within the Underwater Marine Sanctuary (UMS). The marine park will gradually become the home to coral colonies native to the Trincomalee Bay area. With the corals, it will attract young fish, which will ultimately lead to the formation of fish communities.” Tokyo Cement has been involved in coral reef restoration around Sri Lanka since 2010.
Diamer Basha Dam to use concrete containing fly ash
20 July 2020Pakistan: The upcoming Diamer Basha Dam and 21MW Tangir Hydropower Project will use concrete made from Ordinary Portland Cement mixed with fly ash and other additives. The Frontier Works Organisation said, “This reduces thermal loads on the dam and reduces chances of thermal cracking,” according to China Daily News. The Chinese-backed project is scheduled for completion in 2028.
India: JK Cement’s sales rose by 10% year-on-year to US$763m in the financial year to 31 March 2020 from US$691m in the same period in 2019. Its sales volumes of cement decreased slightly to 9.8Mt and its profit after tax nearly doubled to US$63.5m. However, its sales fell slightly in the fourth quarter, sales volumes of cement dropped by 7% year-on-year to 2.9Mt and it reported a significantly reduced standalone net profit.
The cement producer said that its operations had gradually stabilising since coronavirus lockdown measures were relaxed. All of its integrated and cement grinding plants had resumed production and despatch. It noted that due to lower power demands less fly ash was available so it is sourcing this from other locations. Labour shortages are also affecting bag supplies and the availability of drivers. As part of cash conservation measures it has restricted capital expenditure to US$66m in the current financial year.
A short look at low carbon cement and concrete
01 April 2020Cement 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.
Material | Type | Method | Product examples |
Cement | SCM cement | Lower clinker factor | Many products |
Cement | Limestone calcined clay cement | Lower clinker factor | LC3, FutureCem, Polysius activated clay, H-EVA |
Cement | Calcium silicate cement | Reduced process emissions | Solidia, Celitement |
Cement | Recycled concrete fines | Reduced lifecycle emissions | Susteno |
Cement | Geopolymer cement | Reduced process emissions | Vertua |
Cement | Calcium sulphoaluminate cements | Reduced process emissions | Many products |
Concrete | CO2 curing/mineralisation | Uses CO2 and reduces water usage | Solidia, CarbonCure Technologies |
Concrete | Recycled concrete coarse | Reduced lifecycle emissions | Evopact, EcoCrete, FastCarb |
Concrete | SCM concrete | Uses less or no cement | Cemfree, Carbicrete, Regen |
Concrete | Uses less cement in mix | Uses less cement | |
Concrete | Admixtures | Uses less cement | |
Concrete | Locally sourced aggregate / better supply chain logistics | Reduced transport emissions | |
Concrete | Geopolymer concrete | Uses no cement | E-Crete |
Concrete | Graphene concrete | Uses less cement | Concrene |
Concrete | Carbon offsetting | Separate offsetting scheme | Vertua |
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.
Norochcholai Coal Power Plant targets US$5.5m in fly ash sales to cement plants in 2020
10 March 2020Sri Lanka: Norochcholai Coal Power Plant (NCPP) is courting buyers for its fly ash, of which it says it produces US$5.5m-worth annually. In 2019 NCPP sold US$3.3m to Sri Lankan cement producers. Daily News Sri Lanka has reported that the company has undertaken measures to increase the value of the fly ash to cement producers, in order to obtain a higher price. NCPP manager Indrasiri Gallage said, "By selling fly ash to cement producers the plant has also helped to free the country from reliance on clinker imports."
An expansion, including the installation of a new 300MW coal-fired power plant, will eventually bring the NCPP’s capacity to 1200MW. The plant is currently working to increase the value of its bottom ash for paving block production.
Charah extends fly ash contract at power plants in Ohio
11 September 2019US: Charah Solutions has been awarded an extension to its contract to provide byproduct sales and material handling operations for Luminant’s Miami Fort Power Plant and Zimmer Power Plant in Ohio. Charah Solutions will continue to manage and market coal combustion products produced by these two units. It currently sells and markets grade Class F fly ash from the two power plants via its materials network to concrete product manufacturers and ready mix concrete producers in the Midwest, Northeast and South regions of the country.
In addition, Charah Solutions will continue all other coal combustion residuals material handling and disposal operations at both locations, including landfill management and byproduct loadout, as well as the operations and maintenance of the plant flue gas desulphurisation (FGD) system at Miami Fort.
University of Dundee study looks at fly ash moisture
02 September 2019UK: A study by the University of Dundee has dispelled the myths of substantial performance differences between concretes made with cement containing dry or wet-stored fly ash, with comparable reinforcement corrosion between the two.
Vertical News has reported that the research, whose backers included the Department for Environment, Food & Rural Affairs and Heathrow Airport Holdings, was aimed at “quantifying moisture effects, which indicate agglomeration of fly ash and a tendency for this to increase with free lime content, storage period and temperature.”
Researchers tested five moistened fly ashes and samples from two power station stockpiles, and further investigated different material and storage variables, comparing the concretes at 75mm slump and 28 day strength. Air permeability and water absorption of moistened fly ash proved greater with high free lime (up to 0.9%) and lower with low free lime (to under 0.1%). What benefits there were improved with longer storage. The moistening of low-free-lime fly ash generally yielded similar, or slightly higher, carbonation and chlorine diffusion. The moisture caused little change in high-free-lime ash’s carbonation, while increasing chloride diffusion. Furthermore, high storage temperature equated to greater carbonation.
In spite of these intriguing chemical differences, the study concluded, "these didn't seem to have a noticeable effect on concrete resistance.”
Natural pozzolan use in the US
03 July 2019Charah Solutions has been steadily building up its fly ash distribution business in recent years with an eye on the supplementary cementitious materials (SCM) market. This week it opened the third of its new series of SCM grinding plants, at Oxnard in California, US. The unit sticks out because it is focusing on grinding natural pozzolans. The plant will receive natural pozzolan by truck and rail and then use Charah’s patented grinding technology to produce pozzolan marketed under its MultiPozz brand. The previous plants in this series mentioned natural pozzolans but this is the first to promote it explicitly.
The change is potentially telling because global demand for granulated blast furnace slag (GBFS) outstrips supply. Both performance benefits and environmental regulations are pushing this. It’s a similar situation for fly ash, also driven by trends to close coal-fired power stations in some countries. As Charles Zeynel of SCM trading firm ZAG International explained in the March 2019 issue of Global Cement Magazine, “...volcanic pozzolans are a potential SCM of the future. This is gaining traction, but it’s slow progress at the moment. This will be the answer for some users in some locations.”
The problem though is that natural pozzolans are down the list of preferred SCMs for their chemical properties after silica fume, GBFS and fly ash. The first is expensive but the latter two were traditionally cheap and easy to obtain if a cement or concrete producer had access to a source or a distribution network. Natural pozzolans are very much subject to variations in availability.
It’s no surprise then that Charah is promoting natural pozzolans in a Californian plant given that state’s environmental stance. It’s unclear where Charah is sourcing their pozzolan from but they are not the only company thinking about this in the US. Sunrise Resources, for example, is working on the environmental permits for a natural pozzolan mine near Tonopah in Nevada. As it described in its company presentation, California and Nevada are the most affected states in the fly ash supply crisis because they are, “...at the end of the line when it comes to rail deliveries from power stations in central and eastern USA.” It also estimated that California used 0.9Mt of pozzolan in its cement production of which about 90% is fly ash. The state produced 9.6Mt in 2015. Other companies are also mining and distributing natural pozzolans in the US as the website for the National Pozzolan Association (NPA) lists. Although, if this line-up is comprehensive, then the field is still fairly select. Most of these companies are based in the west of the country.
One last thing to consider is that various groups are tackling a potential future lack of SCMs for the cement industry by making their own pozzolanic materials through the use of calcined clay. These groups include the Swiss-government backed LC3 project and Cementir’s Futurecem products. Using clay should bypass the supply issues with natural pozzolans but the cost of calcining it requires at the very least an investment to get started.
As concrete enthusiasts often point out, a variant of pozzolanic concrete was used by the Romans to build many of their iconic structures, some of which survive to the present day. To give the last word to the NPA, “What is old is new again: natural pozzolan is back!” If environmental trends continue and steel and coal plants continue to be shut then it might just be right.