Lime and cement in Tanzania

I have been looking at your blog and was wondering if you would have any insight into using, up to a hydrated lime and cement mixes for plastering on concrete blocks.

We are currently building a small hotel in Tanzania at the coast and are blending modern and traditional construction techniques. We would like a more traditional finish that can just be periodically limewashed for maintenance. We are thinking of keeping the plain lime wash for the exterior, but putting a pigment into the interior plaster.

My question is what type of ratio (lime, cement, sand) would be good for our project given the background material (concrete blocks with cement mortar), the weather, hot and humid with rainy periods, and availability of materials (so far I have only found hydrated lime not putty and basic cement not Portland). We will likely be plastering during a fairly hot and (relatively) dry period though.

Any other advice you might have would also be appreciated (such as how long to leave the hydrated lime in water before use – drying time between coats, etc)

Thanks so much for passing on your expertise,

Our formula is One bag portland (94 lb.s) 1/4 50 lb. bag lime 20 shovels (4 - 5 gallon buckets) sand.

On block you can put in a lot more sand, reduce shrinkage cracks if you want, up to 30 shovels, without reducing strength.

However, I like to keep my formula the same, 20 shovels all the time.

It is strange you don't have portland. The cement you have is probably portland strength. Type S masonry cement is next best, which is for structural masonry like basements.

Hydrated lime doesn't need to be soaked for cement. We put dry lime in our dry mix and mix it all together. The idea is to mix mortar dry first, then add water.

Thanks so much for visiting my site, from so far away.