Concrete mix advice

[Notch7]

If the total depth is 75mm, what should the depth of the hardcore? and the cement? be...

The 75mm is the concrete depth -although as I said maybe you could go down to 50mm, but the thinner you go the more risk of it cracking due to ground movement.

you need really to dig out the soft top soil and replace with hardcore.

Its a bit tricky to give advice on depths as its all dependant on ground conditions. If there are lots of trees around then roots might cause a lot of movement, especially in clay soil. In stable ground bearing soil like sand, mudstone etc theres less risk of movement.

Do you actually need concrete? -could you just put down type 1 hardcore use a whacker plate, then blind off with sharp sand and lightly whacker that.

 

[ash1212002]

The 75mm is the concrete depth -although as I said maybe you could go down to 50mm, but the thinner you go the more risk of it cracking due to ground movement.

you need really to dig out the soft top soil and replace with hardcore.

Its a bit tricky to give advice on depths as its all dependant on ground conditions. If there are lots of trees around then roots might cause a lot of movement, especially in clay soil. In stable ground bearing soil like sand, mudstone etc theres less risk of movement.

Do you actually need concrete? -could you just put down type 1 hardcore use a whacker plate, then blind off with sharp sand and lightly whacker that.

The soil is easy to work with, the ballast and cement has arrived

I've dug down to approx 75mm added a weed membrane and now applying some hardcore which will then be followed by the cement

 

[tomfe]

So ideally you want at least 100mm of hardcore and then then 75mm on concrete.
If I was laying artificial turf I'd do it on hardcore so there would be less chance of standing water and would not need any drainage.

 

[ash1212002]

So ideally you want at least 100mm of hardcore and then then 75mm on concrete.
If I was laying artificial turf I'd do it on hardcore so there would be less chance of standing water and would not need any drainage.

I've dug down to 75mm added a weed membrane and pea gravel on top to cover the membrane and then will pour the concrete

Is that totally wrong?

 

[ash1212002]

Also as as this is the first time im using a mixer

What would be the volume of water required for a 6:1 mix?

Do i add water first followed by the ballast and finally the cement?

 

[ash1212002]

Bump

 

[tomfe]

It's not the best way. Your pea gravel will move when you lay the concrete, it'll also be hard to wheel barrow over.
I would be worried about cracking and movement but as it's not exposed and is a small area this may not be a problem.

6 to 1 is fine, you could go a little stronger at 5 to 1.
Put a bucket of ballast then the cement then the rest but one then the water let it mix then add the final bucket. Really you can do it what ever you like but this way you don't normally need to scrape the bottom.

Make sure your cement mixer can take 7 of what ever sized bucket you are using.

 

[Notch7]

Also as as this is the first time im using a mixer

What would be the volume of water required for a 6:1 mix?

Do i add water first followed by the ballast and finally the cement?

In a belle mixer, I do 3 full builders buckets of ballast, 2/3 bucket of cement. Then around 4 to 8 litres of water.

Water amount depends on how moist you ballast is. When you pour the concrete into the wheelbarrow, it wants to be stiff enough to stay a peak, but soft enough that when you bounce the whellbarrow it slumps down to a gentle mound.

 

[ash1212002]

I've completed the job a few hours ago, digged further down to 150mm

Applied weed membrane followed by pea gravel and a layer of dry ballast upon which i then applied the cement

To get to the right level, ended up using twice the amount, i think i must have used 600kg of ballast and 4-5 bags of cement!.. in hindsight i should have put down more dry ballast down, nevertheless I'll have a thicker concrete base which should be a good thing!

Happy with the overall result!

Cheers all for your input