I'm installing a constructional hearth and back panel for our log burner installation and am using aerated blocks for convenience and to reduce the weight load some on our suspended timber floor.

It's a strawbale build and we're lime rendering inside and out, so I want to take advantage of the materials already on site and mix a hot lime mortar for the blocks. I've seen a suggested mix ratio of 1:3 quicklime powder to sharp sand. Anyone able to confirm this please? Would a pozzalanic additive be needed (I'm thinking crushed clay plantpots as we have some kicking around), and at what ratio?

We're using quicklime powder in our render, which is why I'd prefer to use the materials already on site.

When you mix the quicklime powder with water does it heat up and seem to boil?

Ty Mawr or Mike Wye would probably be able to advise.

I imagine you could use the same render mix -just make sure the wall is well damped down before rendering.
You could always do a quick trial on a few blocks.

Thanks both. jfb, yes good idea. I have seen online the suggestion that the aerated blocks are more absorbent, which does make rational sense. Tony, any idea if it needs a pozzalanic additive?

No pozz, keep blocks damp, the will suck water like mad, I would set up a drip or use bucket that slowly drips