Underpinning - use of a mechanical vibrator

[liam546]

I am getting a hand with a small section of underpinning in my celler this weekend from a family friend who does this type if work

He tells me a mechanical vibrator isn't necassary but I've read they should be used.

Can anyone advise! [/list]

 

[noseall]

Have you been reading a spec sheet from an over-zealous architect?

They love to specify ridiculously over the top building processes. It makes them feel superior to builders.

I remember one telling me the percentage of plasterboard that must be in contact with the adhesive whilst dabbing and how long the minimum length of tile batten was allowed to be in relation to rafters covered.


A vibrator can be useful as can a nice sloppy mix.

 

[liam546]

Ok thanks, judging by your comments a vibrator isn't an essential tool for this type of work then.

A mix which has a bit of air in will still be strong enough. We are going with a 4:1 mix of ballast and cement

 

[tony1851]

A vibrator can be useful

depends what you're using it for.

 

[tony1851]

Vibrators are only really necessary when you're after a particularly strong mix, such as with reinforced concrete elements.
Foundations just need cheap, mass concrete and a slightly sloppy mix will flow better into irregularities; high-strength concrete isn't necessary here.

 

[liam546]

Thank you very much....guess I should have trusted what my family friend said all along then.

Thanks for help

 

[liam546]

If we are digging a hole about 2 foot deep by about 2 foot wide how many bags of cement and ballast do you think I should buy?

 

[noseall]

If we are digging a hole about 2 foot deep by about 2 foot wide how many bags of cement and ballast do you think I should buy?

Erm....for volume we need another dimension i.e. length?

But assuming you were doing say 1m sections then each section at 600mm x 600mm x 1000mm would require 3/4 tonne of ballast and 5 x 25kg bags of cement. There would be some material left over but this is a ball park estimate.

 

[liam546]

Thank you very much