On Tuesday, May 25th 2004 the ECO-Serve management organised a workshop on the theme “Blending” in Brussels, Belgium. All members off the ECO-Serve Network were invited to join this workshop. It was a satisfactory and useful workshop with more than 40 participants. At the end of this technical report you can find the programme with links to the different presentations and reports.
Mr. Anders Henrichsen, ECO-SERVE co-ordinator, opened the workshop and welcomed the members (PPT-file). The main focus of the workshop was the use of blending as a technology towards achieving the ECO-Serve goals. These goals can be summarised as:
· Reduce Environmental Impact from Construction
· Secure Growth and Prosperity for Society
· Establish a Model for Assessment of the Optimal Balance between growth, prosperity and environmental impact
The importance of blending was demonstrated by giving an overview of examples of blending technologies which contribute to these goals: selfcompacting concrete, ecopave concrete, cement treated base, high stability aggregate, blending of conventional and alternative fuels in cement clinker production, optimised pavement design and blending cementitious materials in cement.
Mr. Henrichsen also explained how the EcoConcrete LCA Tool (which was presented later during the workshop) can be used to assess the value of a given process, product, technology or design methodology.
Following this introduction, two speakers were invited to give a 30 min. presentation
Mr. Jean-Marie Chandelle of the Joint Project Group gave an interesting presentation on the reduction of CO2 emissions in the EU (PPT-file). He presented the European Emissions Trading Scheme (EU-ETS), explained the linking directive and showed the impact of the CO2 trading on the power prices in Europe.
Several studies who looked at the indirect impact of the EU Emissions Trading Scheme on power prices estimated an unjustifiable price increase in power prices from 15 to 50 %. This is not based on the real costs from the CO2 trading and leads to windfall profits for utilities.
It is a fact the EU ETS will increase the marginal cost of electricity production in fossil-fuelled plants. Coal-fired generation will be more seriously affected than gas-fired generation. Renewable, hydropower, nuclear and biomass generation, however, should not be affected as their core emissions are either zero or CO2 neutral.
Power producers may pass on the additional cost linked to the allowances to their customers via the existing pricing mechanism. The problem is that, in the absence of real-competition in the power market, power companies will charge the extra cost linked to EU ETS regardless of whether the power purchased is from a source with CO2 emissions or not. This pricing mechanism will lead to exorbitant windfall profits for power companies in certain Member States at the expenses of energy intensive industries, with no economic or environmental justification.
For an average European calculation this would lead to a cost increase of € 7/MWh although the true CO2 costs are only € 0,25/MWh.
Therefore power intensive industries (including the cement industry) call for an unbundling of electricity prices to ensure that the cost of emissions is charged only in a matter proportionate to the production of electricity from sources with CO2 emissions.
The second speaker, Björn Lagerblad of CBI (Swedish Cement and Concrete Research Institute), presented the results of the research CBI has done on the use of inert ultra fine particles as cement replacement in concrete (PPT-file).
Typical substances that can replace cement are: fly ash, silica fume, natural pozzolanas, metakaoline, rice hush and ground blast furnace slag. These materials react pozzolanic or are like GFBS latent. Pozzolanas react with the cement paste especially with the portlandite and forms more paste that saves cement. There is, however, also the effect of the amount and grain size of the filler and some fine materials give a stronger concrete.
The investigation tested different fine materials in order to find the effect of mineralogy and fineness on the concrete properties (hydration, strength, microstructure) and the possibility of reducing the amount of cement.
The research showed that the incorporation of fine fillers in concretes can speed up cement hydration, increases concrete strength, improves the microstructure, improves the effectivity of silica fume and reduces the cement content of concrete without loosing strength.
It also showed that wetgrinding of quartz gives fillers that are comparable or even better than normal products, easy to handle and safe for workers and environment (silicosis).
After these presentations four parallel sessions were held to discuss blending as a viable solution to achieve ECO-Serve goals. Below you can find a short summary of these parallel sessions with links to the full report. Each session discussed a different topic:
- Session 1: Environmental impact (Report)
The first session dealt with the environmental impact of blending. After a short note from the session chairman, Mr. Carswell, on the effect of carbon dioxide emission and their potential reductions (PPT-file), the open discussion among the members addressed the workshop topic on three different levels:
Technical aspects of materials and structures for environmental protection: the charcaterisation of a material or a process with regard to its environmental behaviour should be discussed on the basis of LCA and not simply on the basis of particular constituents (e.g. carbon dioxide emission).
Scientific research work and political framework: distinction between risk assessment and quantification of environmental impacts which must be created and compiled in research work and target values set forth to protect the environment which are subject to political consideration
Scope of ECO-Serve network: ECO-Serve network cannot establish target values or environmental protection schemes or perform research work, so the network should mainly focus on the compilation of knowledge and information that exists also outside of the network and identify future research needs.
- Session 2: Blending strategies in coming 10 years (Report)
Based upon the presentation of Emmanuel Chaniotakis, the second session discussed the blending strategies in the coming 10 years (PPT-file).
Today the situation is such that the industry must use cem I, II, III etc. and combine it with different content of additives such as limestone filler, fly-ash etc. at the production site (concrete factory or at the cement factory). The importance of good technical knowledge on these sites was stressed.
The future needs that were discussed during the session:
- adopt different materials used at different locations in Europe to local use and different exposures
- harmonize definitions between areas as there seem to be different interpretations
- need for guidelines on blending cement to reduce mistakes
- need for guidelines on alkali-silica testing and for testing how admixtures comply with the various blended cements.
- Use of performance tests instead of only single materials testing
- need for adopting or inventing technology for chemical admixture procedures as well as need for early strength improvements.
It was also concluded that ECO-SERVE should combine and spread knowledge about best practices to be used locally in different parts of Europe because the difference in use of pozzolanas in Europe is great and it is not possible to use one method or statement for all the locations.
- Session 3: Legislation/ standardization (Report)
During session 3 the legislation and standardization in Europe and the different member states were discussed.
The session showed the necessity for further legislation and standardization on the use of wastes and by products as well as recycled aggregates. Apparently this can be achieved if standards move from prescriptive approach to performance approach. There is a real need for dissemination of national standards available in some EU countries in this area. This will encourage the use of such materials even in countries where such norms do not exist. As the body of information and experience increases the standardization will follow.
- Session 4: Performance requirements (Report)
The focus during session 4 (performance requirements) was on three issues: early age properties, strength (long time) and durability.
One difficulty is that many test methods are suitable only for cement type CEM I and not for blended cement types. Furthermore, only a few cement types are allowed in the XF4 exposure class in EN 204 due to durability reasons.
Other topics discussed were for instance the insufficient correlation between laboratory test methods and real conditions, the standardization who doesn’t keep up with the development of new materials and the use of stainless steel.
After lunch Mr. Alejandro Josa of the Catalan Cement Association gave a presentation on environmental thinking in the construction industry. (PPT-file)
During his presentation Mr. Josa explained that the need to assess and minimise the environmental impact of any activity is evident, particularly by the construction activity.
LCA is a method, that quantitatively assesses the impact of processes or products on the environment and is, in general, accepted as a reference method by Governments, NGO’s, industry, etc. but it is not completely standardised (yet) and different methodologies and assumptions, leading to different results or type of results (sometimes very different), can be used, which means that its results are not always completely definitive.
LCA enables environmental improvement of processes and products through the comparison of alternatives fulfilling the same function.
Following his presentation on environmental thinking, Mr. Josa also presented the ECO-Contrete LCA Tool developed by EcoConcrete (former Joint Project Group) (PPT-file). After a description of the tool and its use, the group was split up into the four clusters, to show some examples of application of the ECO-Conrete tool. Based up this, the clusters could decide whether they want to use the tool within the ECO-Serve network.
The results of these discussions within the clusters can be found here.
The workshop ended with a panel discussion with the cluster leaders which was moderated by Mr. Oliver Kornadt of the University of Weimar.
