Manhole Benching Mix

[Johnny Jekyll]

Building a manhole. Can't source any Grano Dust locally for the benching. Is it ok to use Sharp Sand instead for the benching? If so what's the ideal mix? Presume adding a bit of Febmix helps (I'm not quick enough to work with SBR)? Thanks guys.

[saveasteading]

Yes that's fine. Don't be tempted to use too much cement. Also keep it fairly dry mix, but pre-wet the surface.   All of that will keep it strong and limit cracking.

 

If you've got time to get it in, some fibre additive would make it even stronger.

[Johnny Jekyll]

Thanks @saveasteading , so what would the ideal mix be when using sharp sand? 3 sharp to 1 cement? Any building sand?

[saveasteading]

Confession time. I don't trust my  memory, and always read what it says on the cement bag.

Just don't add a bit more

 cement for luck.. or water for convenience.

 

You shouldn't need building sand, as the febmix will make it workable..