O/T Mortar mix

[tomga]

How do you tell when your mortar mix is not too wet or too dry? I'm trying to replace a few blocks on a barn and can't get the mud to stick to my vertical joints. Thanks for any suggestions.

 

[bejohnson]

you can get a grout bag and push it in

 

[Joe Hynes]

Not that I am a mason but I asked the guys that did my basement about getting the mortar stickier. He said you need to add more mortar to the mix. I think he said they used 16 or so shovels of sand per bag. When you are doing stone or veneer you go down to like 9 shovels.
I did a shooting bench and had issues the same as you.
One trick is to slap some mud against a block and it should stick to it. If not add some more mortar and mix it well.

Joe

 

[fordtractor2000]

lime will make it more sticky too

 

[rhouston]

not a mason either, Are your blocks wet or dry? I found dry blocks pull the moisture from the mortar and it falls off. Wet the blocks a while before you start to use them. Too wet and you have the same issue. I also agree with the other post about less sand.

 

[Stephen Newell]

If you are buying bag mortar mix it is usually pretty weak stuff. I always supplement it with hydrated lime and portland cement to the mix, probably about pound coffee can of each. Some brands might take more. If you were doing a lot of it I would recommend mixing your own. For above grade walls you would use Type N mortar which is 1 part portland cement, 1 part hydrated lime and 6 parts sand. As far as laying cinder blocks I usually mix it to where it will set up on a board without running. If it's too thin the weight of the block will squeeze out the mortar when you set it in place. Then in warm or hot weather I always wet the blocks ahead of time. When you butter the ends you need to use a little pressure when applying the mortar to get it to stick and use a large trowel. It needs to be pressed into the texture of the block. It still will occasionally will fall off but most of the time will stay in place.

 

[Tim in OR]

I deliver masonry products for a living. I do not have any 1st hand experience using those same products however. The masons that I see, never wet the block, and scream if the block is wet when we deliver it. When I see them laying block, they just put the mortar on the layer below and on the end of the block they are laying. It amazes me that they seem to get the correct amount of mortar most every time. Most masons around here use the type "S" pre mix rather than mix their own.
Tim in OR

 

[Billy NY]

Ideally you need a higher slump like was said below, or in other terms a "tighter mix" as I've heard many masons, bricklayers and others call it.

The thing to remember is the water/cement ratio relative to strength. Too much water, will result in a lower slump(mound up trowel full on a board and observe how much it sags or measure how much)and a weaker compressive strength. Same is true with adding cementitious material, like portland, too much and the mix design may not reach the desired strength. Those would be my biggest concerns. In reality, you can take a proven mix design and raise its slump, without sacrifice of strength, as long as that mix design is correct.

For example I can get a pre mixed bag of mortar that will pass 3000 psi test from cubes taken and compressed, using an ASTM formula to determine its actual strength once they fail on the machine. If I reduce the water proportionally, its likely to raise its strength, to a certain point, that's the range of the slump you may want. If you hap hazzardly mix you're own with a shovel without being careful to control or measure each material comprising of the mix your resutls will vary and will not be consistent, so if mixing by hand, use a basic mix design, use care to measure, then adjust your water to create a material that is workable and take notice of the slump and amount of water so each batch is consistent,

I have found there is an optimum moisture content in the existing substrate,(your wall) or masonry materials. Too dry, it will absorb the water in the mortar too rapidly, too wet it may not bond, key word is optimum, you could soak the area then let it dry down until it the mortar will bond, or won't sag out, which is the amount of slump the material has, as per the above.

Also keep in mind, if the area you are trying to repair has been left in disrepair for a long time, there could be extraneous dirt, residue, dust or what have you, preventing the mortar from bonding, it would be wise to clean the area prior to the repair.

 

[northvale]

wrong. Keep blocks dry, bricks can get wet. The skill a mason develops is getting the mortar to stick. I stood next to a guy who made it look simple and of course I couldn't do it at all. Not a trick, just skill.

 

[Rich_WI]

Skill is the biggest factor, you either got it or you dont. After that, its the mix. Go with a premixed bag and you can eliminate 90% of the mix problems. Just remember, the stronger the mix, the harder it is to work with (less sticky). The primary reason for that is the lime in it, more lime means a weaker mix but easier to work with. From the strongest to the weakest, it goes: Type M, S, N, O, K. Type N should be fine.

As for how wet or dry, here is the easiest way I can explain it via the internet. Mix your mortar in a 5 gallon bucket and pour it onto your mud board. It should come out of the bucket but just not quite hold the shape of the bucket but not so wet that it "pours". If it holds the shape of the bucket but flattens out on the mud board (like a hershey's kiss), its close but probably a little too dry. If you mix it like described, you will be real close. If you use a grout bag like mentioned above, mix it a wetter yet.

FYI, there are no blanket statements in masonry like blocks cant be wetted down and only bricks can. It all depends on the specific material but in general, NOTHING is allowed to be wetted down. Its usually stated in the material specs.