casting concrete

[madmick22]

hi all,
I am looking for advice for the strongest mix ratio to cast a concrete bench,
I have cast some small pavers using 1 part cement 2 sharp sand and 3 parts aggregate but have noticed they break quite easily after cured,is there a better recommended mix for pavers
thanks for any help as I am just wasting material trying to get the right strength so any help would be very welcome
regards
michael

 

[rjm2k]

I'm no expert and can't offer advice on the mix, however for a sizable piece of work like a bench it may be worth considering re-bar too.

 

[r896neo]

it needs to be at least 50mm thick and you need to use a variation of grain size. Some 10mm stone some 5mm grit and some plastering sand to give something to rub up.

It should also be pretty strong like 4:1

Most importantly it needs vibrated to remove air bubbles.

As said a sheet of mesh would do wondered for its bending strength.

 

[leeco]

For as good strong mix I use, (with a builders bucket). 2 x buckets of 10mm gravel 1 and 1/2 buckets of river/sharp sand to one bag of cement. This mx is a good strong mix


Vibrating
When filling moulds up with concrete you will have air trapped in the concrete. The best way to remove this air is with a vibrating table, but these can be quite expensive.

I have made one of these benches and i added 8mm rebar

 

[rxbren]

rebar and fibre concrete