Homebrew cracking

[Thomobigands]

Morning all,

First batch of homebrew this morning. Seemed to go fine but as it is drying, it is cracking? Is this normal?

I soaked each brick for 30 seconds although was then around 30 minutes before the mortar was applied.

Any thoughts?

[Thomobigands]

May 6, 2017 10:47:15 GMT Thomobigands said:

Morning all,

First batch of homebrew this morning. Seemed to go fine but as it is drying, it is cracking? Is this normal?

I soaked each brick for 30 seconds although was then around 30 minutes before the mortar was applied.

Any thoughts?

[downunderdave]

May 6, 2017 10:48:50 GMT Thomobigands said:

May 6, 2017 10:47:15 GMT Thomobigands said:

Morning all,

First batch of homebrew this morning. Seemed to go fine but as it is drying, it is cracking? Is this normal?

I soaked each brick for 30 seconds although was then around 30 minutes before the mortar was applied.

Any thoughts?

I think your problem is too much clay. The usual brew is 3:1:1:1 sand, clay, cement, lime which is very high in clay content for a mortar. The clay imparts better workability (stickiness) and also gives the mortar refractory (fireproof) qualities. Unfortunately though, clay has pretty high shrinkage.  Maybe you overdid it with the clay addition. It depends on the type of clay used too because some clays have higher shrinkage rates than others. Another possibility is the sand used which often naturally contains some clay. This can then increase the proportion of clay in the brew. Whatever the cause just reduce the clay amount and your problem should be solved.

[Thomobigands]

Thanks for the reply. That makes sense, I'll ease off on the clay. I cracked on since that post and am up one soldier course and one and a half normal courses. Still some slight cracking but if I reduce the clay from now and also cover with another layer of mortar generally it should be OK?

My ratio is also 4:1:1:1.

[Thomobigands]

Mmmm, still a bit 'cracky' this morning? Couple of bricks came away without too much pulling too. Maybe I didn't leave it long enough? Only been 12 hours and bricks were soaked for 10 minutes.

Help!

I love this project when all goes well but not when it throws a curve ball!

[Thomobigands]

Mmmm, still a bit 'cracky' this morning? Couple of bricks came away without too much pulling too. Maybe I didn't leave it long enough? Only been 12 hours and bricks were soaked for 10 minutes.

Help!

I love this project when all goes well but not when it throws a curve ball!

[oblertone]

Build it, leave it alone, then cover it with (several) layers of left over homebrew. No one will see your cracks and the pizza won't care.

[Thomobigands]

Ha, I like your thinking. It's not the look I mind, it's wondering if it will hold together. I started another thread on the same subject with some photos. I have had to rebuild the front sections already because the bricks just lifted off!

[downunderdave]

aS I mentioned previously different clays have different shrinkage rates. e.g. Bentonite which has very small particles also has a very high shrinkage rate and is therefore best avoided. Don't know what sort of clay you are using, but probably the cheapest and best for the application is bricklayers clay.

[Thomobigands]

Thanks for the reply Dave. I will try and turn down the clay a bit. It is from Kilnlinings, refractory supplies so wouldnt expect it to be anything untoward.

Just been out and checked my rebuilt entrance pillars and they seem pretty solid this time so I will just carry on, perhaps not putting so much on in one go. I also found that I wasn't compressing the sand when measuring so was short changing myself perhaps, meaning a mixture that was too rich.

[Thomobigands]

Thought I would update this post for the benefit of others given that I still find myself reading old posts for tips.

I finally tamed the homebrew by halving my mix to make it more manageable. 1.5 sand, 0.5 cement, 0.5 lime, then just under 0.5 fire clay. More like a quarter of clay.

I don't know if the fire clay I have is extra potent or if there is extra clay in the sand but this ratio seems to work. It means I can only lay 3 or 4 bricks at a time but this means nothing goes off which is what I think it was doing before as I couldn't work that fast.

So more mixes but each one is more thoroughly mixed so I'll stick with this rather than be tempted to double up with a bigger mix again.

I also lightly mist the newly laid bricks with a spray bottle to stop it drying too fast.

Finally, I mainly use a brick trowel but sometimes I find that rubber gloved hands are better for cramming that homebrew into some of the tighter spaces!

I hope all this helps someone out there.