Filling in a hole with concrete

[sotal]

I posted a bit of this in the end of my post about removing concrete.

I have now removed the concrete and would like to know what the best way to fill the hole back in is. I've attached pics below. The hole is all lower than the surrounding floor. It currently has some of the loose pebbles raked over it to keep it flat for walking over. So some parts can go lower.

What is the best way to level it up. (the existing floor slopes a bit, so I don't think I could use any self levelling product)

 

[gregers]

looks a bit deceiving but that doesnt look deep enough for concrete?

 

[noseall]

It needs blinding with sand and a layer or 1200g polythene laying on it. That blue layer of polythene will be useless with all that stony stuff puncturing it. What thickness of concrete are you laying to get you back to floor level?

 

[sotal]

Thanks for the replies.

What thickness do I need to do? It varies at the moment between 3 and 5 inches deep (although there is the pebbles on top at the moment). Am I best to remove the pebbles altogether? Should I go further? I stopped when I got to the reinforcing metal. Would I be best to get get down to flat to where the metal is and remove it and then reuse it? Should I save the pebbles to mix in with the new mix?

What do I need to get to make up the new mix and what ratios?

Thanks for the help.

 

[sotal]

Right I've fetched out all the pebbles from the hole. I am now left with the blue polythene which continues under part of the concrete floor. As predicted above this is punctured from the stones. I also have the grid type reinforcing bar which also continues under part of the garage. I had to bend this up whilst removing the stones. I have bent it back down now. Underneath the polythene it is already blinded with sand.

The depth of the hole is 110mm at it's deepest and 90mm at the shallowest. So let's say an average of 100mm depth. The hole is approx 1400mm x 1400mm.

I will get some 1200g polythene - is it OK to just put that over the top of the old polythene?

What kind of mix do I then need to do to fill the hole in and bring me back to level again with the floor? Can I reuse some of the stones that I removed? I kept all the loose ones in rubble sacks.

Thanks for the help.

 

[sotal]

I found an online calculator at:

http://source4me.co.uk/calculate_concrete_mix.php

It works out that I need 0.196m3 of concrete. This breaks down to:

Cement: 63Kg (3 x 25Kg bags)
Sharp Sand:: 118Kg (5 x 25Kg Bags)
Aggregate: 235Kg (10 x 25Kg Bags)
Water : 35L

Hopefully that gives a little room for error as it will give:

75Kg Cement
125Kg Sharp Sand
250Kg of Aggregate



Does that sound the right sort of mix?
I take it I do the whole lot in one go?
Can I reuse the stones that I have bagged up as the Aggregate?
Anything else I should consider?

 

[sotal]

Looking at the prices and the multibuy discounts at Wickes it seems the best value is to buy:

10 bags (25Kg) of sharp sand (£12.90) (I have a use for the rest)
4 bags (25Kg) of Mastercrete Cement (£18.88)

If I can then use the Aggregate that I have then that will give me everything I need for about £30 with hopefully plenty to spare.