Building with Concrete Block

[WVBill]

I'm building a low (32" tall - 4 courses) concrete block wall. I have poured a concrete footer and am starting to lay the block.

I can't get the mortar to stick when I try to "butter" the end of the block. I spread it on but then as soon as I turn the block so the head face is vertical the mortar just falls off.

I've mixed the mortar per the quikrete directions (2.5 parts mason's sand to 1 part masonry cement) with water to the consistency of mayonnaise.

But it just won't stick...

What am I doing wrong?

WVBill

 

[Willl]

Butter the block that is already in place.

 

[Willl]

If it won't stick to your 'block already in place', play with your "consistency of mayonnaise".
Might be a smudge to thin.

 

[EddieWalker]

It's too dry to stick. Add more water to your mix and it will hold allot better. Of course, just add a little water at a time to get it right. Too much water will ruin the strength of mortor, or turn it into soupl.

Eddie

 

[Egon]

Add a little Portland and some lime. Experiment with the mixture.

Application method is also important. The mortar sorta has to be pressed onto the block in one quick motion.

It takes a little practice.

 

[WVBill]

Thanks, guys.

I played with the consistency of the mortar today - added a little bit of water and tried pressing it onto the block.

Managed to get a bit to stick but not the full 3/8 in. thickness the joint is supposed to be.

I've been forcing it into the joint from the sides and top - not the way to do it, I know....

I'll get a bag of portland this week and try adding some of that to the mix.

352 blocks to go. By the time I get to the top course I should have it figured out.

WVBill

 

[Egon]

Don't rush ahead till you get that mortar to stick!

The Portland cement will add strength to the mix. Lime adds stickiness. Try using more mortar cement. Make real small batches till you get one to work. You can use a drill and little paint mixer and a milk carton or even smaller to practice with. Also let the mortar sit for about 10 minutes and then mix again to allow for better water distribution. Just make sure you keep track of the ratios and if in doubt go heavier on the mortar cement.

When applying the mortar it has to be a quick type slap shear motion.

Now please note: I am far from knowledgeable on this topic and do not intend to get more knowledge on using concrete blocks!!

 

[wroughtn_harv]

"fluffy"

I once had a mason's mason tell me the mortar needed to be "fluffy". The mayo thing sounds way too wet from what I've learned. I'd think more like frosting.

Another thing is we wet down the blocks prior to using, hope this helps.

 

[Cliff_Johns]

I don't know about concrete blocks, but when I've done stone masonary in the past, I learned to "throw" the mortar onto the stone to make it stick. You don't smear or press it on. You take the slice of mortar on the edge of the trowel, turn the trowl perpendicular to the block and flick your wrist to "throw" it against the rock (or in this case concrete). It should slide off the trowel and onto the block. Sorry I can't describe it better, but I think you'll find that most mortar mixtures, even a little wet or dry, will stick with this method. It takes a few tries to get your aim down.

And, yes, wetting the concrete a little will help, and will imporve the bond and curing of the mortar. It makes it dry more evenly instead of giving up all it's moisture to the block near the juncture of block and mortar.

Cliff

 

[Egon]

A site with some information. There are dozens of them out there.

mortar mixes

http://cnci.org.za/inf/publications_pdf/mortar.pdf

 

[mjarrels]

Use brickloc type "S" cement.

mark

 

[Kendall69]

Also,wet the block. Sometimes the block is too hot from the sun and the mortor instantly dry's out when it hits the block. The block sucks all the moisture out of the block. By wetting the block it should stick better.

 

[EddieWalker]

Bill,

I usually just buy the ready to use Type N mortor. Just add water and mix. If it doesn't stick, I have it too dry and will add a little water until it's right. I'm sure everyones advice on changing the mix is accurate, but why not just by the sacks ready to use?

Eddie

 

[schmism]

my experience with block mortor has been its to wet if it wont hold a 3/8" amount so it kinda slimes off.....

usually a more dry mix has worked for me in the past.... but as others have mentioned, your results may varry based on mixture type and applicationn.

 

[Egon]

Different building materials require different mortar for best results. The premix will be the minum specs allowable and just changing water content may not meet the construction demands.

 

[WVBill]

Success!!

I did a small test batch this evening. The "recipe" on the bag of Masonry Cement calls for 2.25 to 3 parts sand to one part Masonry Cement for Type S Mortar (called for by code for a building foundation wall). That's what I was mixing it at.

So tonight I doubled it to 2.5 parts sand to 2 parts Masonry Cement and it stuck on the vertical joints real nice.

Now, at that ratio it's probably not technically "Type S" any more - but I doubt the inspector has a way of telling anyway - any the part of the wall I'm doing now will be buried over 2 feet deep the next time he inspects....

Anyway, the next time I mix a batch, I'll back it down to 2.5 parts sand to 1.5 parts Masonry Cement and see if it still sticks...

Thanks for the help, guys.

WVBill

 

[_RaT_]

Tpye S for sure. I like to add in a little fire clay, it makes it stick very well.

 

[Egon]

Sounds good.

 

[forgeblast]

what type of mortar would you use if you were building a bbq. I will be building one this summer, and i dont want the joints to crack with the heat.
thanks,
Forgeblast

 

[smitesmash]

also, check that your morterboard is wet when you mix the mortar on it. If it starts out dry, it can suck the moisture out of the mortar before you apply it to the blocks.