Trouble with mortar on concrete block...

Discussion in 'Homesteading Questions' started by Wisconsin Ann, Apr 12, 2009.

  1. Wisconsin Ann

    Wisconsin Ann Happy Scrounger

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    I'm trying to figure out what the problem is with our mortaring technique with this block wall. If anyone has any insight, I'll be MORE than happy to hear it :)

    The problem: Mortar won't stay on the block as we butter them and try to place them. It just falls off like crazy. Thought maybe it was too dry, so we mixed it a little wetter on the next batch and then it just oozed down after we placed the blocks.

    It is chilly out. about 40degrees. New block. New mortar mix.

    Any thoughts on what would be the problem? Mortar too cold? MOrtar to dry? too wet? I've done brick and not had problems...but this time around it just doesn't want to stick at ALL.

    eta: I should mention I tried to find troubleshooting guides online and while I could find guides...nothing talked about mortar not sticking. It was mainly about pointing and such.
     
  2. Windy in Kansas

    Windy in Kansas In Remembrance

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    Decades ago I worked as a laborer in order earn funds to put my wife through college. Most all of my time as a laborer I worked for masons or masonry contractors.

    There were times that we sprayed water onto the blocks but that was usually during the hotter times of the year so that the joints wouldn't dry out so fast to promote strength.

    The masons I worked with during winter would begin laying blocks or brick if the temperature was 32º and climbing. On such cold days we heated a barrel of water and used that in the mixer.

    I'm with you, I've never been around such a problem as mortar not sticking if it has the correct amount of cement in the mix.
     

  3. ET1 SS

    ET1 SS zone 5 - riverfrontage Supporter

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    What is your portland to sand mix?

    You need more portland.
     
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  4. Macybaby

    Macybaby I love South Dakota Supporter

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    Other than not having enough cement in the mix, DH says the only time he's seen this is with dirty bricks, even a fine coating of dust will do it. He says normally he sees the masons wet down the bricks to make sure there isn't any dirt/dust on them. We live in an area where the wind blows a lot, so things can get coated with fine dust overnight.

    Cathy
     
  5. mtman

    mtman Well-Known Member

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    sounds like its to dry and you might be taking to long you have to keep it moving or the curing process starts
     
  6. Beeman

    Beeman Well-Known Member

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    Test mortar. Take a trowel of mortar and give it a downward shake forcing the mortar down on the trowel. Then hold the trowel upside down and the mortar should stay on the trowel.
    You should be buttering the ears of the block. Stand it on end and swipe the trowel at an angle spreading the mortar onto the block. Mortar should stay as you lift block unto mortar bed you laid for it to set on.
     
  7. T-Bone 369

    T-Bone 369 Well-Known Member

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    I assume that you are talking about the head joints (that's the vertical joint in the wall) as opposed to the bed joint (that's the horizontal joint). Bed joints are spread on the previous course and the block laid into it. The head joint is buttered while the block is sitting on it's end then pulled into the previous block while it's being laid. If the mortar is too stiff (not enough water) or too lean (too much sand) it's not as sticky - when you pick up the block it can fall off. If your using the pre-mix where all you add is water I guarentee it's pretty lean. Also, I always "bump" the block before I lay it - just lift it an inch or two and bump it back on the ground. That helps set the mortar to the block. Brick is the same - only use the handle end of your trowel to set it. Hope that helps.
     
  8. MJFarms

    MJFarms Well-Known Member

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    Cheap mortar.. Not enough cement in the mix.
     
  9. Wisconsin Ann

    Wisconsin Ann Happy Scrounger

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    Ahhh....okay. this is a premix that we're using, so.....Y'all have given me some ways to go here. We'll try adding more cement to the mix and see what happens :) Artificer had wondered about the mix and if it was going to work well enough. Pretty frustrating to put your mortar on the er, head joint and watch it fall off like dough off a floured board!

    We'll add the "bump" to our routine, too.

    thanks folks :)
     
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  10. ET1 SS

    ET1 SS zone 5 - riverfrontage Supporter

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    Premixes suck.

    Mix your own, it is a skill that you will use for the rest of your life.

    Mortar should stick suspended to an upside down trowel, for a while.
     
  11. TnAndy

    TnAndy Well-Known Member Supporter

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    Don't use the "pre-mix" if it includes sand.....most of it skimps on the cement portion.

    Buy a mortar cement ( either Type N, or Type S for exposure to the elements....has more Portland cement in the mix ) and mix with sand on site. One 70lb bag of mortar to 15 heaping shovels of sand, and enough water to make a workable mix.
     
  12. Rocky Fields

    Rocky Fields Failure is not an option.

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    Hey.

    I am a stone mason.

    Central WI still has nights below freezing. You better wait until the nights are warmer, so the mortar cures properly and doesn't freeze. If the mortar freezes, it won't bond properly and will pull away later. Commercial mortar antifreeze is available, but it is expensive.

    Buttering a block is an acquired skill. Making mortar from scratch is recommended. It takes skill to handle a mason's trowel. Being an amateur, you probably would be better off trying a margin trowel(2") for buttering the ends. Buy a Marshalltown if possible...the Chinese carp is too stiff.

    Buy a masonry basics book on eBay.

    RF
     
  13. texican

    texican Well-Known Member

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    Is it an application that could use surface bonding cements? Dry stack the blocks, and trowel the surface cement on...
     
  14. Wisconsin Ann

    Wisconsin Ann Happy Scrounger

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    Thanks for the advice :)
    Texican, nope...it's a wall that will need to support some inside pressure.

    What was making us crazy is that we've both done other smaller projects using either block or brick and mortar. Not a lot of them, but enough to say "yup, we can do this simple wall". The mortar has always just been easy to use. Mix, grab some with the trowel, smack in on the brick, and put it in place....no worries about it sloughing off or not sticking. Then this mess!

    We'll use the remaining bags of premix as a base mix for my small projects...I can add more cement using the mixer. I'm making some hyper tufa planters and this premix might work well for that.

    We'll go the "mix your own" route for the wall. It's less expensive and we can be sure what's in it.

    Never count a day as lost when you learn something, and we for SURE learned something on THIS job :)
     
  15. artificer

    artificer Well-Known Member

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    It shouldn't have been that hard. I was looking at [ame="http://www.youtube.com/watch?v=8VGjA66RSm0"]this video on Youtube[/ame], and this is how I expected mortar to act. I know I'll never be as good as this guy, but you shouldn't have to keep the block horizontal, and then scrape the mortar on the ends to butter the blocks. I had to trowel it on like I was plastering. Anything less, and it just dropped off.

    Different type of mortar, so it might not have the same adhesion as regular mortar, but if it can do this, it should at least stick to the blocks.
    [​IMG]

    Why I used premix: The trailer was maxed out for weight with blocks. In order to get sand for mortar, I would have had to drive 3 hours, spend $20 in diesel to get the truck. It was just easier to throw the 8 bags of premix in the van, and call it good.

    The premix was Menards All-Star brand, which is supposedly a Quikrete product. No doubt in my mind that it contains the absolute minimum amount of masonry cement. I also think there is some variation between bags, as well.

    Start to finish time for last batch that I threw half of it away was 1/2 hour. It was either abandon the job, or throw the hammer through the wall.

    For moisture, I tried dryish, then kept adding water until the block would sink into the mortar when you set them down, and it still didn't stick. Yep, tried the "fill the trowel, knock down, and flip to see if it sticks" test. It would stick for a while as long as it wasn't too thick. (1/2" - 3/4"?) The dryish mortar would stick to the trowel.

    Next weekend I'll pick up a bag of mortar cement, and dose that into the premix. I'll probably end up getting a 15yard truck of sand for future projects and mix my own. It should last for a while.

    I planned out the block laying to allow at least 48hours of over 32 degree temps. Last weekends slab was poured then insulated so the low 20's nightime temps didn't hurt it. (shot it with the IR gun in the morning... 54 degrees)

    Thanks for everyone's suggestions.

    Michael
     
  16. Farmerwilly2

    Farmerwilly2 Well-Known Member

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    It'll lay better if you have a mixer to entrain some air. If not work it with a mortar hoe to whip it up. Don't know a better way to put it than that. Mix it rich enough, wet enough, mixed enough, on a clean block. Use your dry line and your level. One of the best tips---get somebody else to carry the block if you can talk them in to it.
     
  17. agmantoo

    agmantoo agmantoo Supporter

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    Look on the bags of premix and see that it says type N. I will wager that it does and as a consequence you do not have enough portland cement. You can obtain a bag of portland cement and add some to the type N premix to improve its adherence.
     
  18. ET1 SS

    ET1 SS zone 5 - riverfrontage Supporter

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    Premix is good for sinking a post in the ground. You want something to act as an anchor, but really do not care if it holds.

    For anything else, mix your own.

    I keep a big pile of sand nearby, and a few bags of portland inside. So anytime a project comes up I am ready, and I can mix any portions that I need for the job.
     
  19. Freeholder

    Freeholder Well-Known Member

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    Well, I sure wish I'd thought to talk to you guys before we did the foundation for our garage! It sounds like most of the trouble we had was (other than just plain inexperience) was caused by using pre-mix! I'll remember that next time I have a project to do.

    Kathleen
     
  20. TnAndy

    TnAndy Well-Known Member Supporter

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    I sorta doubt it would even say on a bag of premix. Premix is generally a mix of sand and masonry mortar sold to homeowners. Masons would almost NEVER use the stuff.

    Many of the companies that sell it skimp on the contents of the mortar, and from what I've seen, also use too coarse a grade of sand....they probably buy only one grade and use it for their masonry premix and their bagged concrete mix....concrete sand generally being more coarse sand.

    And that is another factor if you plan to make your own "mud".....buy MASONRY grade sand.

    Masonry Cement ( Brand names "Brixment" "Dixie" etc ) is a combination of Portland Cement, and hydrated lime.

    Type N is 2 parts Portland to 1 part hydrated lime....this is the most common type of masonry cement found. The lime is what gives the cement excellent "workability" that making a mix of pure Portland/sand doesn't have. It's the LIME that makes it sticky on the trowel and the block.

    Type S, the next most common type found, is 4 parts Portland Cement to 1 part hydrated lime. This is used where the masonry will be exposed to weathering, or higher strength is required.....the higher ratio of Portland give it this quality....but it IS harder on your hands, I find. to work with given more Portland in it.

    There are a couple other mixes ( O, M ) but you generally won't find them in a bagged form for sale.

    Sand is added to masonry cement in the ratio of 3 parts sand to 1 part cement. For a 70lb bag ( which seems to be pretty standard ), I've always used 15 heaping shovels of sand to a bag, and mix in a paddle type mortar mixer. You can mix about 1/2 bag in a standard contractor type wheel barrow using a hoe. ( done a lot of that too before I bought a mixer )