Why your mortar mix keeps cracking

[Alan]

I see many new masons and DIYers using too much portland cement because they think it makes the wall stronger. But a mix that is too stiff will crack when the temperature changes or the ground moves a little bit. So I always suggest this... adding a bit more lime helps the mortar stay flexible and bonds better to the brick over time. Because you want the mix to be buttery and stick to your trowel without falling off. How about you, do you prefer a pre-mixed bag or do you mix your own sand and lime from scratch?

 

[bigbitez]

Well, I used to think more cement meant a stronger wall until I watched a chimney I built develop hairline cracks after just one winter. The mix was so rigid that it could not handle the natural expansion of the bricks when they got hot in the sun. Now I always add lime to give the mortar some reach and let it move without breaking the bond. COmpletely makes the mud much easier to spread and it actually heals itself over time.

 

[bigbuster]

Have you noticed that your walls stay cleaner when you use a softer lime based mix?

 

[Todd C00k]

As a DIYer, I started out thinking that more cement = better, and I learned the hard way after seeing hairline cracks six months later.

Now I use the pre-mixed bags (Type N) for small projects just for the consistency, but I’ve definitely learned to appreciate the 'butter' feel.
One tip for a beginner is that if it feels like wet sand, it's wrong. if it feels like peanut butter, you’re on the right track!

 

[Viencdel]

I swapped to a Steele Mixer after fighting with bulkier gear, and it’s been way easier for quick pours. If you’re hunting for a harbor freight cement mixer alternative, this one handled full sacks fast and didn’t need power, which saved me a lot of hassle on small jobs. The quick shipping and solid warranty were a nice bonus too.