In one of our earlier posts “CRC Application Cases – Sustainability” we comment on how difficult it is to compare the environmental footprint of CRC to other materials – and use this as an excuse for why we have not yet put together an EPD (Environmental Product Declaration) for our products. Truth be told, it was not really something we rushed to do, as we well knew that the high cement content and the steel fibres in CRC would probably not give us the best result – and even though EPD and LCA (Life Cycle Analysis) has been discussed for years, it has rarely been a requirement for projects.
We finally realized, however, that making weak excuses was probably not the way to be World Leaders in UHPC and we now have an EPD for Hi-Con balconies. For those interested in more detail it can be found on our website here
We based the EPD on two representative projects – and chose them to cover our range of balconies as well as possible with regard to how many m2 we get per m3 of CRC, how many moulds are needed, how big the brackets for installation were etc. The two projects are shown below:
Kongens Have – on the left – are flat, grey CRC balconies with isokorbs (76 in total with 46 variations), while Fælledudsigten – on the right – are white CRC box-balconies (122 in total with 31 variations).
The process of compiling the EPD sounded quite simple – to include everything that was used in the two projects – but it turned out to take longer than expected. It was not very difficult – it just required attention to detail, which is not one of my strong points. Every time I thought I had completed the task, Charlotte from FORCE Technology (who helped us put the LCA and EPD together) had a few more details that she had to have sorted out. Fortunately, she was very patient as I have to admit that finding out exactly what cranes were used for mounting the balconies, how many bolts were used for the brackets, how much glue was used for the moulds etc. was usually not too high in my priorities. In the end I am sure that Charlottes diligence paid off, as the verifier had very few questions before our LCA and EPD were accepted.
As it turned out the figures were better than we expected! The carbon footprint until the elements are ready to leave the plant – from cradle to gate – is about 1050 kg of CO2 per m3 of CRC, and if we include transport to the site and installation (A4 and A5 – and the mounting brackets factor quite heavily in the result) the total footprint is about 1320 kg of CO2.
It is still a bit difficult to compare our results to other materials. Data for similar types of elements are not easy to find – and when you do find them it is mentioned repeatedly that the data should not be used for comparisons. We are, however, a bit reckless in that regard so we have tried to compare anyway – and luckily for us we compare favourably to similar types of elements. Our carbon footprint based on m3 is higher than for conventional concrete, but when we look at the effective carbon footprint (based on what is used for 1 m2 of balcony) for the different materials we have less of an impact than conventional concrete as we typically use less than half the amount of material. In addition we have other advantages such as a much longer service life without the need for maintenance (100 years+) (and we were ready to use that argument as well if it became necessary ;-)).
I would have liked to comment on how we compare against other types of UHPC (even though I don’t expect there will be much difference), but I have not been able to find any information on EPD’s on UHPC – just more general comments on sustainability like we used to come up with. If any of you have this type of information, please send me an e-mail or leave a comment.
Next step for us would be to reduce our carbon footprint as much as possible – but the easy solutions for this (reducing cement content and fibre content) are really not an option in this case. As expected cement content and stell fibre content have the biggest impact on carbon footprint for our type of UHPC, but for reasons of performance and documentation we can’t change the mix formulation as much as would be required. Going through this process and just having the figures has, however, made us more aware of how even the smaller things matter, and we have already started to change as much as we can in that regard (our factory manager is instrumental in this). One example is by minimizing our waste (for example by using our excess concrete for casting standard products that can actually be sold and used), another is trying to use more standard moulds, where small alterations can be made.
In the longer run we may also change the mix formulation – for example from i2 to i3 – for some of our balconies, which would reduce the carbon footprint significantly. I3 was used for the Catharina bridge – but as our CE marking for balconies (which should be our Christmas present to ourselves this year) is based on i2, this is not something that is done quickly. In the long run we will not be satisfied by just being a little more environmentally friendly than conventional concrete – but for now we have to settle.
Thank you for reading the post, feel free to leave a comment and questions below.
Bendt Kjær Aarup
R & D Manager
+45 20 70 68 11
One thought on “Sustainability – the results are in!”
Effective – or areal – carbon footprint is the proper measure for UHPC and any structural material. Hence, it is a structural property rather than a material property. Nice presentation by the way, Bendt.