How strong should a sand/cement finish be?

[MattWebb]

I've just put up a wall in the back garden, and had a professional builder finish it off with a sand/cement render, as I would never be able to get the finish right.

Only it seems very soft. If I rub my finger along a squared off edge, the edge rubs off leaving a rounded one, and you can easily pick the edge off with your finger nail without any effort. Already (6 weeks after it was done) there are a number of nicks along the edge caused by careless passers by and spoiling the finish. I've also noted that if you rub your hand over the surface of the wall, it feels very sandy and grainy.

Is this normal, or has the builder got the mix wrong with too much sand or something?

Thanks for any advice.

Matt.

 

[jeds]

Approximately the same as your bricks/blocks. Not an easy one to judge but the basic idea is softer mortar with softer bricks - harder with harder. Golden rule is do not use hard mortar with soft facing bricks.

In your case it might be a lime based mortar - which will take longer to cure. Or the brickie might just have over sanded the mix, which is easy to do. Only way to tell is have a sample tested. There are products that will harden the surface of the mortar and make it more durable. Similar to concrete anti dust treatments.

 

[Richard C]

Or the brickie might just have over sanded the mix, which is easy to do.

After 6 weeks that would be my bet.

 

[MattWebb]

Thanks for the responses. I'll have a word with the chap about it, just hope he is reasonable about it.