Concrete access way for 7.5 tonne delivery lorry - Guidance on depth and materials

[Zanji]

I volunteer as a Gardener for a charity locally.
I have been asked to plan and cost up materials required to construct a concrete hardstanding for a 7.5 tonne wood chip delivery lorry to use when delivering wood chip for a boiler system. It visits every ten days or so, arrives and spends some 15 minutes standing whilst delivering the wood chip.
The area that needs to be concreted is 3.5 meters wide by 9.25 meters long. The assumptions I have made for estimating purposes are:
1. we need 150mm of MOT compacted as a base using a standard whacker plate.
2. we need to use steel mesh to strengthen the concrete
3. we need a 150mm layer of ready-mix concrete strength C20 and a 25mm slump laid on top of the MOT.

It would be great if my assumptions above could be confirmed or corrected as appropriate.

Also should the concrete pad be laid as one mass or should it be a series of 3.5m by 3m slabs?

I have laid domestic drives and slabbed paths before with no issues of collapse or subsidence. However, I have not had to tackle anything of this scale before.

[Tony McC]

At 150mm thickness, the max bay span would be 4.5m, so you could, in theory, have two bays (just the one movement joint) at 3.5 x 4.65 - just 150mm above the recommended max so nowt to worry about, too much.

However, we would usually regard 7.5T as HGV loading so would look to use 200mm depth of concrete, steel mesh top and bottom with min 50mm cover, and that would give a max bay span of 6m, so the 3.5 x 4.65m would be well within tolerances.

I'd also up the concrete strength to C30, mainly for abrasion resistance, and particularly so if there is any turning movements.

As for the sub-base, 150mm should be fine, but make sure you get at least 300mm spread at aany open edges.


I know some will regard this as OTT, but for these smaller jobs, I always think it's best to be safe than sorry, and the actual cost impact isn't that significant.

[Zanji]

That's most useful Tony.
Many thanks

[Zanji]

Final Question for this ....
Do we need to dowel the joint between the two slabs?
I'm inclined not to.

[Brucieboy]

You'll struggle to lay ready mixed concrete for a reinforced slab at 25mm slump - I suggest you order S2 (70mm slump).

[Tony McC]

Well-spotted, Brucieboy - I missed that bit!