What went wrong with my mortar?
Question:I was going to build a small wall today with breeze blocks.
I had everything I needed here, and I downloaded instructions on how to mix the mortar.
3 parts sand
1 part cement
water and a squirt of washing up liquid.
But when I tried to use the mortar, it was like wet sand.
It wouldn't stick to the blocks, and it wouldn't hold them together. Even when it had dried.
In fact, even now when I lift one of the blocks off, I can crumble the remains of the mortar off it quite easily with my thumb.
What did I do wrong?
Too much sand and not enough cement?
I did notice that when I applied the mortar to the block, it seemes to suck all the moisture out of it, leaving me with a crumbly sandy mixture.
Should I have wet the blocks with water before building with them to prevent them from soaking up the water from the mortar?
Answers:
From the sound of it, you didn't use cement, you likely used a mortar mix or sand mix. In the states cement is sold in 94 pound bags and mortar mix is usually sold in 40, 60, or 80 pound bags.
Cement should have been a fine powder like talc. If it wasn't you did use mortar. You still can you the mix, just don't add sand to it and you should be OK.
Don't add to much water. If it is at all runny you have way too much water. If done right the weight of the block should compress the mortar bed to say 1/2" and you then tap it into it final place.
Do water your block but don't have water dripping off them when you go to lay them. Something like 2 or 3 hours beforehand.
Remember:
Concrete mix is cement+sand+large aggregate+water [for paving]
Mortar mix is cement+sand+water [for bricklaying]
Cement is the fine talc-like powder
sounds like no cement added at all
Paddy , you are supposed to open the bag of cement before you mix it, the brown paper you threw away had the cement in.
maybe a touch more cement and leave out the washing up liquid.
ha ha, (sorry) you didn't wet the bricks first! dowse them with water from a hose and soak them! (also never heard of adding washing up liquid)
the bricks are dry so when you put the cement mix on there they suck the water from it and make it all crumbly!
It is better to go with a little more type S mix than not enough. Go with 3 parts sand and 1 1/2 parts type S (or type N if it is above grade. Did you premix the dry stuff before adding the water? When you added water and mixed the mortar was the outcome like a really stiff pudding? or was it more sloppy? The mix needs to be fairly stiff. You can also add a bit of portland cement to the mix to make a strong batch of mortar.
For laying a block wall, instead of using washing up liquid, use Febmix. Febmix is a plasticiser and keeps the mortar flexible and workable. Too much washing up liquid can cause the mortar to crumble. For the mix my husband told me he uses 4 sand to 1 cement, mix with water to a creamy consistency (not too wet). Are you using Holmes sand (sharp sand) or pit sand (fine sand). Fine sand is better for laying a block wall.
What kind of sand are you using? you should be using yellow building sand.The cement could of gone off, if its old cement and been damp it may of been through part of it`s chemical reaction. If it is old bin it and buy new.If you think the blocks are too dry you could use a spray bottle to damp them (not too much you don`t want them too wet) so it is not taking too much moisture from your mortar. You must allow time for it to go off this can take upto 24 hours. You can use washing up liquid in the summer it stops the cement from drying to quick.Your mix is right don`t be tempted to put more cement in this is as bad as not putting enough in. The joints between your bricks will look grey and not brown like it should.
WHY THE THUMBS DOWN? My partner is a bricklayer and has been for years so is my brother and my partners friends. Who were all here at the time of my answer.Honestly Swampy try it i bet i`m right we have just done this in our garden and it works!
It also could be a old bag of mortar.
If you built this wall today you would not expect the mortar to achieved much strength yet and the blocks will be easy to pull off. Likewise the mortar will be "crumbly".
As suggested above I would use 1 part cement 4 parts 50/50 fine sand and a proper plasticizer (not washing up liquid). Here in the UK we mostly use concrete blocks and do not wet them.. The mortar should be creamy and may look a (little) too wet but the blocks soak the water very fast giving just enough time to set the block in position before it becomes stiff enough to support the weight. The real strength comes after a day or two when the cement cures.
reanson they wont stick is you have the wrong mix when laying bricks the mix is 5 parts soft sand to 1 part cement your mix was to strong
I think I asked previously why you didn't choose PRE mix? Any special reason why not?
WAY too much sand to mortar to begin with.
Steven Wolf
1 80 lbs bag of type S mortar to 15 shovel fulls of mortar sand and water is what u should do..u dont need to use an additive or wet the block.we have laid over 100,000 block in the past years and never had a problem...also this is how my block/brick guy does it.
lic. gen. contractor
i am a pro builder and i hope a lot of people read this and spread the word ..NEVER NEVER NEVER ever use fairy liquid ..it the worst thing you can ever do ..it kills the cement ..repeat it KILLS the cement .i have come across this many many times ..by all means go and buy febmix ...fairy is used by crap builders and should be avoided at all times as for the sand you used ..it must be building sand ...the mortar must be mixed by weight not volume ..3 to 1 is too strong for an internal wall..at least 5 to 1 ..weigh the sand and then add the appropriate weight of cement ...say 100 pounds of sand ..20 pounds of cement ..if external the mix can be 3 to 1
What kind of cement did you use? You need Masonry cement which is a Portland cement and lime mixture. The lime is what makes it sticky or creamy. A proper mix will stick to your trowel when turned upside down.
Listen to big dogg.We usually use twenty shovels for block.If you want to strengthen the mortar dont use that liquid put a couple shovels of portland cement. You can buy it the same place you bought the other. Good luck
Leave it alone for a couple more days. Mortar does not gain its strength by drying, it goes through a curing process which does not occur by the end of the first day.
I'm not go in to detail because its been pretty beat to death already but I will say this
1. DON'T WET the blocks
2. DO pre mix your dry ingredients
3. DO NOT ADD a plasticizer (wast of money)
4. DO NOT ADD soap (soap acts as a release agent)
5. DO NOT MIX A FULL BATCH at a time multiply below X 2
6.Try this 1 part cement, 1/2 part lime, and 4 parts sand.
7. MAKE SURE your shovels are EQUAL
8. YOU MUST USE LIME..to make the mixture you describe "sticky"
9. lime penetrates masonry to lock mortar units together.
10. lime allows for an extended board life. (like a plasticizer)
I have been laying brick, block and real stone for over 10 years.
I learned under my father who learned under his father.
For laying block your mortar should be on the stiff side so they will not sink. Mix it as above and after doing so let it REST for a min while doing something else. go back to it and re mix it a bit and check if you need to add water, how do you know how much water you add? just add a little bit at a time and mix it in and then try it on a block if it sticks your close. It should be moist enough to stick but stiff enough to hold the weight of the block. This WILL ONLY be accomplished by trial and error, it is NOT something that can be written..
be patient and get the mixture right so you can worry about the other 15 things you need to know when laying the block.
ok i suspect the cement was not added to the mix properly,
if you added the cement first it may have beome stuck to the edge of the mixer.
you should add the water first then the cement then sand,
if it was a true 3 to 1 mix thats the only explantation, either that or it was not mixed for long enough,
oh by the way it was my fiance who answered your question yesterday
you need some clay in the mix.
for a small project though just buy the bag of mortar
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