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Housing - Renovation: Limecrete mixing ratio

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  1.  
    • CommentAuthortvrulesme
    • CommentTimeJan 19th 2022
     
    I am in the process of planning to lay a limecrete floor. Getting conflicting information regarding the NHL to Aggregate ratio and what to use for the aggregate. Just wondering if someone could please advise on what they have had success with in the past.

    2:1 or 3:1 by volume?
    Slabbing Aggregate, Coarse sand, LECA as the aggregate?

    Many thanks in advance
    • CommentAuthortony
    • CommentTimeJan 19th 2022
     
    2:1 and better with lime putty

    Will you linseed oil it once dry?
    • CommentAuthortvrulesme
    • CommentTimeJan 19th 2022
     
    <blockquote><cite>Posted By: tony</cite>2:1 and better with lime putty

    Will you linseed oil it once dry?</blockquote>

    Thanks a lot Tony. So following limecrete and allowing to dry out, plan is for UFH pipes followed by lime screed and finally limestone flags.

    I haven't heard about using linseed. Is this to prevent cracks or for something else?
  4.  
    We used Pumice as the aggregate, I guess it helps with the insulation value of the slab (if this is of any use in your application?)
    NHL5 was the binder.
    • CommentAuthortvrulesme
    • CommentTimeJan 19th 2022
     
    <blockquote><cite>Posted By: Dominic Cooney</cite>We used Pumice as the aggregate, I guess it helps with the insulation value of the slab (if this is of any use in your application?)
    NHL5 was the binder.</blockquote>

    Thanks a lot Dominic. Where did you source this from? I can't seem to find any stockists. I've heard LECA does a similar job. Also what ratio did you use to NHL5?
    •  
      CommentAuthordjh
    • CommentTimeJan 19th 2022 edited
     
    I've never made a mix with a lightweight aggregate. We got our concrete from a readymix company. A quick bit of reading seems to indicate that it's not straightforward to calculate the right mix. Pumice, Leca and other materials including something called Lytag seem to be available from e.g. https://www.specialistaggregates.com/light-weight-aggregates-multi-packs-bags-c-164_168.html Lytag seems to be noticeably cheaper; I don't know about its other credentials.
    • CommentAuthortony
    • CommentTimeJan 19th 2022
     
    If slabs aren’t going on top 3:1 will be fine

    Linseed oil seals the surface to turn it into a breathable durable floor - don’t do it if slabs going on top
    • CommentAuthortvrulesme
    • CommentTimeJan 19th 2022
     
    <blockquote><cite>Posted By: tony</cite>If slabs aren’t going on top 3:1 will be fine

    Linseed oil seals the surface to turn it into a breathable durable floor - don’t do it if slabs going on top</blockquote>

    Perfect, thanks a million
    • CommentAuthortvrulesme
    • CommentTimeJan 19th 2022
     
    Here’s what I’m going to go with using limestone chippings as the aggregate.

    1 Part NHL5 : 1 Part sharp sand : 2 Parts 12 – 18 mm aggregate and approximately 5 – 6 litres of water per 50 kg of lime.

    The pumice and expanded clay are crazy expensive and I just can’t justify it
  10.  
    Posted By: tvrulesmeWhere did you source this from?


    I think it all came from Ty-Mawr on a flatbed truck; Pumice aggregate in big bags, pallets of bagged NHL5, crushed recycled glass aggregate for the screed (consistency of sharp sand) in builders bags. I think they also supplied the LECA in big bags that went below the slab (300-400mm deep IIRC)

    there's a pic on here somewhere.
  11.  
    We wanted a breathable floor and an insulated one, we were only going to do it once so we did it right.
    • CommentAuthortvrulesme
    • CommentTimeJan 20th 2022
     
    <blockquote><cite>Posted By: Dominic Cooney</cite>We wanted a breathable floor and an insulated one, we were only going to do it once so we did it right.</blockquote>

    Yeah I agree. Problem is that every supplier I speak to has a different version of what right is....
    •  
      CommentAuthordjh
    • CommentTimeJan 20th 2022
     
    TyMawr and Mike Wye are the two suppliers that spring to mind for this sort of thing.
  14.  
    Posted By: tvrulesmewhat right is....


    the basic premise is straightforward, insulation layer at the bottom, as much as you can afford (you'll only be doing it once) geotextile to separate the layers so that its breathable (if you want breathable, unless you have Radon issues) then a limecrete slab. The pumice as aggregate added a bit to the insulation value which gave us more insulation for the given depth (our dig-out depth was restricted due to bedrock) if you have more depth you could put more insulation underneath and use any aggregate for the limecrete slab.
  15.  
    I think the idea with the crushed recycled glass aggregate for the screed was that it is a good conductor around the UFH pipes, but it basically was the same consistency as sharp sand only using a recycled material rather than newly quarried. I can't see you having any problem with using sharp sand for the screed around the pipes.

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