Fly Ash in Cement - A Win Win Solution

(Aggregate Research 7-29-2010) Gunnar Syversten, General Manager of HeidelbergCement Northern Europe, based in Norway, discusses the use of fly ash.  As presented at the EuroCoalAsh 2010 Conference, held in Copenhagen, Denmark in May 2010.
 
Heidelberg Cement in the world
 
HeidelbergCement is one of the leading cement producers in the world, with a history going back to its origin in Germany in the 1870s. Today the company is the forth largest cement producer with 79 million tons in 2009. The company holds the fourth position also in the production of ready-mixed concrete, where the annual production is 35 million cubic metres. However, HeidelbergCement is the largest aggregates producer in the world. Aggregates is mainly rock and gravel product for use in concrete, asphalt, but also road and railway building material and other entrepreneurial products. Our aggregate output in 2009 was 240 million tons.
 
HeidelbergCement has its strongest positions in Europe and North America, but has also high activities in parts of Asia and Africa.   The region of Northern Europe includes the Scandinavian countries; Denmark, Norway and Sweden, as well as the Baltic countries Estonia, Latvia and Lithuania. In this region we have about 2,700 employees in over 200 locations. Last year we achieved sales of 5.5 million tons of cement and clinker, 11.9 million tons of aggregates, and 1.8 million cubic metre of ready-mixed concrete. We also have a large production of precast concrete products. 
 
Our operations consists of 6 cement plants, one in Estonia, two in Norway and three in Sweden. We have a strong market position and distribute our cement to more than 50 terminals and silo stations scattered along the coast in our region. Due to the geography of our markets, ship transport to our terminals ensures us an efficient logistics. The silos also act as a logistic buffer – in total our silos has a storage capacity of 750,000 tons. 
 
A sustainable cement industry
 
The cement industry needs to move towards an even more sustainable production in the future. In HeidelbergCement Sustainability is one of our five strategic pillars. Within the Sustainable pillar we have set six issues where we have set targets. The use of fly ash is one component to achieve some of these targets.
 
The cement industry is a major emitter of CO2. At the moment here are two main approaches to reduce these emissions; reduce the use of fossil fuels when producing clinker, and add supplementary materials in the cement. In Northern Europe we do both with great success!
 
The next step for us to reduce our CO2 emissions will most likely be through CCS and the use of Oxy fuel technology. 
 
We have achieved up to 30 % use of biomass fuels, such as animal meal, paper and wood. All our plants have plans to increase the use of alternative fuels, and we will see a continuous development in this respective. 
 
When it comes to adding supplementary materials in cement, we have an ambition to have a 30% substitution rate in our cements by 2020. Based on our production in 2009, this means that 1.2 million tons of substitute materials will be needed.
 
We utilize several alternative raw materials in producing cement. Synthetic gypsum and waste gypsum from plaster boards replaces natural gypsum. Waste from steel furnaces and chemical industry replaces natural iron ore. Wastes from secondary aluminium smelters replace bauxite. And, not at least, fly ash is used both to as a raw material resource to replace aluminium-iron-silica and as a clinker replacement. 
 
Why use fly ash in cement?
 
One of the most important aspects of using fly ash in cement when making concrete, is that it lowers the emissions of CO2. An example: A submerged tunnel that opened in April in Oslo, Norway, is constructed with six elements with a total of 70,000 m³ of concrete. To make this, it was used 26,660 tons of cement with a fly ash content of 30 %. Compared to a traditionally cement the use of fly ash saved 8,000 tons of CO2 – similar to 60 million cars passing the tunnel. 
 
We have also other benefits from using fly ash. We can produce cement that has low heat during setting, and low early age concrete cracking potential. We make stable self-compacting concrete, providing easy form filling and reinforcement imbedding. We also get cement qualities that contribute to high density and chloride penetration/corrosion resistance.
 
In Norcem, our Norwegian cement producer, we have used fly ash for almost 30 years. Our yearly consumption has been well over 100,000 tons the last five years. This has given us a high level of experience and expertise in using fly ash in cement. 
 
In our sector, fly ash is either put in the cement by the cement producer or it is mixed in at the concrete plant. HeidelbergCement, with operations both in cement and concrete production, has taken a strategic choice to add the fly ash in the cement. We believe this has several advantages.
 
Adding fly ash to a cement mill leads to a more homogeneous cement binder. The mixing is more thorough and the coarse part of the fly ash will be ground to finer particles. Thus it is possible to use a higher volume of fly ash.
 
The extensive quality control at a cement plant ensures the standard of the product, and the handling and facilities at a cement plant is suitable for large quantities. 
 
On the marketing side, the cement producer plays an active role communicating environmental benefits from using concrete. This is a good way to communicate how the coal fired power industry works together with the cement industry to find sustainable solutions.
 
A good partner
 
HeidelbergCement will be able to utilize large volumes of fly ash in its cements business in the future, next to similar raw materials like lime stone, granulated blast furnace slag and pozzolana. HeidelbergCement group, and the Northern Europe region, has a strong market position in the local cement market, and is one of the leading cement suppliers in Europe. HeidelbergCement can, and will, be a strong partner for anyone involved in the production of fly ash.
 
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