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Products: Is it acceptable to use Ordinary Portland Cement [OPC]?

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    • CommentAuthorRachel
    • CommentTimeMay 26th 2008
     
    Dear Paul,
    Sorry, I did mean 40% of the worlds C02 emmissions... I can see that their figures CAN be realistic, especially with the amount of cement that China, USA, and now developing countries are pumping out.
  2.  
    That quote from BFF sounds inexplicable- and I would have thought that it would be non-hydraulic limes which reabsorbed more CO2? Surely the more eminently hydraulic a variety of lime is, the closer it will get to OPC in its characteristics, such as how quickly or slowly it reabsorbs co2.
    • CommentAuthorjon
    • CommentTimeMay 26th 2008
     
    The carbon content, be it in concrete, steel or imported timber appears to me to be almost irrelevant by comparison to the impact of annual carbon emissions of any given building process.

    The concentration of the articles cited on initial capital embodied carbon appears to me to be, at best, misguided.
    • CommentAuthorbiffvernon
    • CommentTimeMay 26th 2008
     
    Mike, Singleton Birch get all their lime on site - the works are in the middle of a humungous quarry. I don't have the data but I'm sure they will be happy to provide it.
  5.  
    Your missing my point, it is where the lime is transported to from there that I am talking about.

    How much lime comes from abroad, and how much will this increase if [more local] cement production were to be reduced?
    • CommentAuthorbiffvernon
    • CommentTimeMay 26th 2008
     
    Why would one need to import lime from abroad? There's plenty of the raw material in Britain. We will run out of the fuel for the kilns but will never run out of limestone.
    • CommentAuthorMike George
    • CommentTimeMay 26th 2008 edited
     
    So isn't any imported now?
    • CommentAuthorjon
    • CommentTimeMay 27th 2008
     
    I couldn't see a significant merit in the use of lime when I looked at it.
    • CommentAuthorbiffvernon
    • CommentTimeMay 27th 2008
     
    Of course it's imported now, Mike. We import all sorts of stuff that we could make here. St Astier, from France, is the main supplier of naturally hydraulic lime, for which there is not so much suitable limestone in Britain, though there is some in Lincolnshire which Singleton Birch is developing.

    Jon, you need to look a bit harder!
    • CommentAuthorjon
    • CommentTimeMay 27th 2008
     
    I have looked Biff but could not find an environmental justification for it except under specific (occasional) circumstances:

    I used the ethical arguments published below for the evaluations:

    http://www.istructe.org/thestructuralengineer/HC/Abstract.asp?PID=7682

    I think it is up to the proponents of lime to prove their case. I have not seen this demonstrated but, if it could be demonstrated, I would be very interested.
  11.  
    That's not fair Jon - it's a buy only one
  12.  
    You have partly answered your own question about importing Biff. We would import more because we already import now. I wonder whether this is because of the inflated prices that UK suppliers charge for their products? Lets face it lime is not the cheap option is it? unless you use the bog standard bagged stuff that I do, in which case it is only slightly dearer than OPC.

    Price is often the bottom line for most customers, with green considerations coming second I'm afraid. For that to change lime needs to come down in price, and if there were increased demand, maybe it would - who knows

    Getting back to Embodied Energy, given the information gleaned from the papers listed so far here, it is not clear how much energy is used in the production of lime, only that it 'can be on a par with cement'

    I doubt that Singleton Birch would be forthcoming with that information either, having tried and failed in the past to find out this kind of data for insulation material. If it were good they would surely advertise the fact.

    It also seems that Lime can incur significantly more energy use in transportation to merchant/site than OPC as a lot of it comes from abroad.

    I just wish when statistics are presented they would give the whole picture rather than just the part that suits the presenters own ends. I suppose that is why they were invented
    • CommentAuthorjon
    • CommentTimeMay 27th 2008 edited
     
    Sorry Mike

    The reason that lime proves to be almost irrelevant is that the embodied content of mortar, when carbon discounting is set to zero, is so small: Hence lime only becomes ethically justifiable if it increases the durability of the structure under consideration.

    Edit: I'll try and get Kathy to change it's status if there's enough interest
  14.  
    A couple of weeks ago I heard an earth builder describe the the production process for OPC as "a process for producing CO2 with cement as a by-product". Maybe he was biased?
    • CommentAuthorjon
    • CommentTimeMay 27th 2008 edited
     
    The process certainly produces a lot of CO2 Chris. Earth may be a good way to go providing that it does not cause excessive replacement of the remainder of the house that it supports: As the structure of a house, when annualised over its lifetime, only accounts for perhaps 25% of CO2 emissions, if the demolition rate increases then the remaining 75% of CO2 contributors (appliances, finishes, carpets, electrical etc) increase their effective CO2 emission rate due to the increased replacement rate.

    Compare this to initial capital embodied carbon and you'll find that structure (when including finishes) accounts for well over 80% of CO2 emissions. This is why I think using initial carbon values is misleading.
  16.  
    Posted By: jonSorry Mike

    Edit: I'll try and get Kathy to change it's status if there's enough interest


    Only me so far by the look of it - I guess the truth hurts:bigsmile:
    • CommentAuthorbiffvernon
    • CommentTimeMay 29th 2008 edited
     
    Posted By: Mike GeorgeI doubt that Singleton Birch would be forthcoming with that information either, having tried and failed in the past to find out this kind of data for insulation material. If it were good they would surely advertise the fact.

    It also seems that Lime can incur significantly more energy use in transportation to merchant/site than OPC as a lot of it comes from abroad.


    On the tour of their works that I went on, they showed us exactly what they were doing and how they did it, including how much gas they used to fire the kilns and how they managed their gas use with changing prices adjusting times of maintainance work etc and the possibilities of alternative energy sources for the future. Since energy is a big part of their costs they are acutely aware of the need to manage it carefully and they really didn't seem to have any secrets.

    On transport they were particularly bitter about government rail policy. Much of their limestone production goes to the steelworks at Scunthorpe. There is a railway that actually goes through their site and on to the steelworks but they can't use it as there is no siding and no money for reinstating the siding that was removed many years ago. All the product has to go by lorry.
    • CommentAuthorMike George
    • CommentTimeMay 29th 2008 edited
     
    Posted By: biffvernon
    On the tour of their works that I went on, they showed us exactly what they were doing and how they did it, including how much gas they used to fire the kilns and how they managed their gas use with changing prices adjusting times of maintainance work etc and the possibilities of alternative energy sources for the future.


    Thanks Biff, Did they give you any figures, such as kWh per Tonne of lime produced in the kiln? Its all very well to say how well they manage their energy use - any clued up manufacturer will do that nowadays, and it's obviously very comendable that they are looking to the future.

    What manufacturers don't usually do is put a figure on what they use - As I said, I have tried and failed to obtain such data before. I wait in anticipation for someone in the know to present such hard data.
    • CommentAuthorbiffvernon
    • CommentTimeMay 29th 2008
     
    Posted By: Mike George
    Thanks Biff, Did they give you any figures, such as kWh per Tonne of lime produced in the kiln?
    Yes, like I said, they didn't seem to have secrets. Why don't you just phone them up and ask. If they think you are a potential lime enthusiast they will be all the more obliging. They are a very nice firm with a strong ethical basis to their business - not part of some global multinational. Look up their history.
  20.  
    Posted By: biffvernon
    Posted By: Mike George
    Thanks Biff, Did they give you any figures, such as kWh per Tonne of lime produced in the kiln?
    Yes, like I said, they didn't seem to have secrets. Why don't you just phone them up and ask. If they think you are a potential lime enthusiast they will be all the more obliging. They are a very nice firm with a strong ethical basis to their business - not part of some global multinational. Look up their history.


    Why not just share the figures with us? :confused:
    • CommentAuthorbiffvernon
    • CommentTimeMay 29th 2008
     
    Er, like I know I've got a brain the size of a planet, but I don't use it to remember data presented in a talk given over a year ago. I didn't even take notes, but I did come away with a mug, a ruler and a mouse mat. Sorry, but you'll just have to give them a ring if you want numbers.
  22.  
    Okay Biff, my last go, we're going round in circles here.

    There are many claims made about the credentials of products, systems, processes etc - from multifoil, ASMET, thermal mass, AGW etc

    I agree with Jon and think it is for the proponents of such things to prove their case.

    Lime is no different. If a major argument for using lime is the 1Tonne cement = 1 Tonne CO2, and it seems to me that it is, then the most obvious marketing strategy for those producing lime is to publicise directly comparable figures which show exactly how wonderful their product is. I don't see any such figures.
    • CommentAuthorbiffvernon
    • CommentTimeMay 30th 2008
     
    Presumably the Marketing Department think that builders don't care about such figures. They may well be right.

    Singleton Birch 01652 686000

    Ian Pritchett, managing director of Lime Technology Ltd. Tel: 0118 9696949, email: ian@ijp.co.uk. probably knows a thing or two about lime.

    As do the good folk at Building Limes Forum, Glasite Meeting House, 33 Barony Street, Edinburgh, EH3 6NX admin@buildinglimesforum.org.uk

    You could work it out for yourself with the help of this article: http://practicalaction.org/practicalanswers/product_info.php?products_id=231
    • CommentAuthorsteveleigh
    • CommentTimeMay 30th 2008
     
    I've been talking to an old builder, who works for me, regarding this discussion.
     
    He reckons for building walls or plastering a mix of OPC and sand (7 to 1) uses far less carbon than the comparable lime because you would use three times as much lime in to get the equivalent. Both are breathable.
     
    Is he right?
     
    Concreting is an another story.

    Cheers Steve
    • CommentAuthorjon
    • CommentTimeMay 30th 2008
     
    Yes Steve, he is right (using standard published values) and providing the two materials have equivalent lives.

    However, it's such a marginal carbon issue that it's irrelevant.
    • CommentAuthorbiffvernon
    • CommentTimeMay 30th 2008
     
    OPC and sand (7 to 1) releases more CO2 than Lime and sand (7 to 1), but I wouldn't employ that old builder before retraining him.
    • CommentAuthorsteveleigh
    • CommentTimeMay 30th 2008
     
    Biff,

    The old builder is a first class tradesman with almost 45 years experience and he says a mix of 7 parts sand to 1 part lime will not work. He says that 2.5 parts sand to 1 part lime is the equivalent to about 7 parts sand to 1 OPC. Therefore, proving that almost three times as much lime is used to achieve a similar mix.

    If you want to save carbon for building and plastering walls use OPC.

    Reference : http://www.jiancai365.cn/new_view.asp?id=8477 and http://www.muralist.org/fresco/plastering.html

    Also most builders use OPC in their Lime mixes!


    Cheers Steve
  28.  
    Hi Steve, I have used 6 sand:1 OPC which I have to say is pretty damn difficult to work with, unless of course you add lots of plasticiser which I don't like doing. I used this mix once only, as the Architect would not budge - never again.

    My favoured mix is a combination of Sand, OPC and Bagged Lime [6:1:1] Incidentally this is the mix recommended in the BS for external rendering in areas of high exposure.

    I have often seen lime mixes quoted as 3:1 If I were to not use Lime at all I would probably go as lean as 5 sand :1 OPC. Your builder must have arms like Popeye to use 7:1.

    You make a very good point about this though, and one which is not usually factored in when assessing relative CO2 emissions
    • CommentAuthorsteveleigh
    • CommentTimeMay 30th 2008
     
    Hi Mike
    My conclusion is that Lime could initially use significantly more carbon than OPC and this is not including the carbon costs of importing Lime.

    They still eat spinach up north Mike!:smile:

    Cheers Steve
  30.  
    Thinking more, the sand where I live is dredged, and therefore very coarse.

    Is the sand oop North the quarried loamy stuff? that would explain why it is usable at 7:1

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