Sand for bricklaying, repointing, parging


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Old 12-27-20, 07:31 PM
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Sand for bricklaying, repointing, parging

I'm restoring an old brick building (former county jail) from about 1876. I'm currently replacing or repairing failed joints and bad bricks and in certain areas I will plaster over the repaired areas. I've seen a lot of vague and even contradictory information about what kind of sand to use for these processes: fine sand for bricklaying and pointing, course for parging; course for parging, etc. Does it matter? How fine is too fine?
 
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Old 12-28-20, 05:03 AM
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Yes, different kinds of sand are used for different jobs. If you just want to get one sand I would get ordinary mason's sand. The larger grain size when doing stucco and parging is partially there for texture. If your mortar work will be exposed and want to match the old it's a good idea to try and match your sand to what was used originally.
 
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Old 12-28-20, 08:08 AM
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Thanks for the response. I have two types of sand available to me locally: coarse and fine. Like this:

Coarse


And fine:


I've been warned elsewhere about using sand that is too fine. Is this too fine?
 
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Old 12-28-20, 09:56 AM
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I judge my sand by a window screen. Almost all of the mason sand will pas through a normal window screen with some staying on the screen. That is good for masonry and works OKAY for stucco. Less fines and more coarse stuff would make better stucco but you want nearly all to pass through a 1/8" screen and all to pass through a 1/4" screen.
Now if you live where a lot of stucco is done you can ask for plaster sand. If you live where a lot of masonry is the predominant exterior the mason sand will be just fine. Or buy bagged play sand. That is a good mixture. You don't want dust but you want a mix of sizes. Avoid closely graded sand, that is sand that is all the same size. And the sharper the sand the better. Round sand makes for a weaker mix.
 
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Old 12-28-20, 12:10 PM
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Congratulations for restoring a historic building.
Sand is primarily "packing material" or "void filler" used to reduce the amount of expensive binder needed (cement, lime, or asphalt) With rough stone or field stone, the mortar has an added job of leveling out the weight of stones in the higher courses.
With brick masonry, especially historic brick, you need to take care that the mortar is softer than the brick.
A mix of course and fine sand makes a MUCH denser mortar, uses less cement, BUT is "stiffer" and less forgiving with poorly or unevenly fired bricks. Straight coarse sand or straight fine sand are about even in strength, with coarse sand having more mortar by weight and more "sticky" and pliant.
 
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Old 01-02-21, 06:59 PM
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My building is from 1876 and used local "sand" bricks which are mostly soft and unevenly fired with some turning glassy. To make sure the mortar is softer than the bricks, the Texas Historical Commission recommended a formula of 3 parts sand, 1 part lime, and 1/16 portland. I throw in a bit of pigment to match the color of the old mortar. I find the finer sand much easier to work with, but I do worry about problems down the road.
 
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Old 01-03-21, 09:14 AM
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Lime mortar has the interesting property of self healing. Some lime leaches out of the matrix and filling minute cracks. There are probably explanations of how this works online. finer sand allows tighter jjoints. Historical preservation commissions know what they are talking about. Also look for Presevation Briefs online somwhere and look for anything about masonry.
Is the ratio of lime : sand by weight or volume? compared to sand lime is quite light in dry form
or is it lime putty : sand?
 
 

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