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Understanding the use of mass concrete in period buildings

  • 22-12-2022 4:02pm
    Registered Users Posts: 2,479 ✭✭✭

    Hi all,

    I am working on a terraced town building, at least mid 19th century but potentially 18th century. We can see the gables are very old brick from the attic. I think before sizes were standardised. One of the gables has issues at ground level such as cracks. It has a dense cement surface. So I drilled a small inspection hole to understand the make up, and to check the thickness of the cement, and either the cement is much thicker than I thought or it is mass concrete. I drilled in an about inch. Based on this, do you lads think it is mass concrete? Given that we know there is intact brick wall overhead, was mass concrete used in such cases?


  • Moderators, Regional North West Moderators Posts: 44,823 Mod ✭✭✭✭muffler

    Back in the day when plastering was plastering you could expect to find 20mm and more unlike the wafer thin 2 coats that is common today. I would drill a little further, say another 10mm and see then. You'll know if you hit mass concrete as opposed to render.

  • Registered Users Posts: 1,087 ✭✭✭Roger Mellie Man on the Telly

    Your gables are solid brick with a thick sand cement render. Concrete wasn't used for housing in Ireland in the mid 19th C.

    The only reason there might be concrete is if there were retrospective (e.g. stabilising) works applied.

  • Registered Users Posts: 2,479 ✭✭✭Yellow_Fern

    The place was heavily altered say around 1970s and a chimney was removed. I will inspect more. Thanks a lot. Happy Christmas.

  • Registered Users Posts: 11,550 ✭✭✭✭Calahonda52

    Language important here.

    You are not drilling through cement, you are drilling through a sand cement plaster render.

    You could also have ended up in between two bricks so an inch is not enough.

    Can lend you this, just put in a 6" extractor :)

    “I can’t pay my staff or mortgage with instagram likes”.

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    Language is important.

    1. Cement mixed with sand is Cement Mortar.
    2. The brickwork in the 18th century house above would have been constructed with Lime Mortar. -Lime mixed with Sand.
    3. Cement mixed with Lime and Sand is Gauged Mortar.
    4. Masons construct block walls with Cement Mortar.
    5. Plasterers plaster Internal walls with Cement Mortar.
    6. Plasterers render External walls with Cement Mortar.

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  • Moderators, Regional North West Moderators Posts: 44,823 Mod ✭✭✭✭muffler

    Well done. Give that man a pint for knowing it all.

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    Merry Christmas Muffler.

    Language is very important.

    You are so kind.

  • Registered Users Posts: 2,479 ✭✭✭Yellow_Fern

    I appreciate all the feedback. This party wall is very complex. It was previously badly blistering shiny glass paint. It took a long time to find the source of water. Eventually traced to a leaking vertical soil pipe (indoors), leaking for 40 years or so. I had thought the wall was a big sponge of very old brick and lime encased in a thick portland layer, where the water built was slowing leaving through some large cracks in the portland. it might still be, but maybe it is just a slab of mass concrete. A puzzle. Happy Christmas

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    You said that the house is 18 th century which ended on 31 st Dec 1800.

    Portland Cement was patented in 1824.

    There is proof that Portland Cement was used in Ireland approx 1850.

    I do not understand when you mention that the “very old brick and lime encased in a thick Portland layer”.

    Very puzzling. Merry Christmas Yellow_Fern

  • Registered Users Posts: 984 ✭✭✭Still stihl waters 3

    If its old plaster it could be 1.5 to 2 inches thick in parts, I'd get a small kango and see can I get back to the brick or if its too hard it could very well be concrete, it may be it went under remedial works at some stage in its history

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  • Registered Users Posts: 2,479 ✭✭✭Yellow_Fern

    Fair enough. The house is at minimum mid 19th cen, but it could well be 18th or even 17th. The brickwork which is visible at the attic gables (and in holes on upper floor) is composed of very early brick with creamy mortar and thus I reason not portland. interior finish is a very dense thick grey material. Very firm, not evidence of any flaking which is why I am wondering could it be mass concrete.