MOT Type 1 question

[GJUK]

Hi all,
I've a large self build garage project going on which will be 13.5mx8m.
I'll need about 70 tonne of MOT for the base (heavy clay soil) so my engineer has advised.

The local quarry do MOT TYPE 1 (to council specification) for £21.70 per tonne. + VAT
Or the non council quality, which I was told all the local builders use at £11.40 per tonne + VAT.

Quite a saving to be had due to the quantity I need - what are the pros and cons guys?

Thanks,

Jon

 

[noseall]

With MOT type 1 you are guaranteed sulphate free hard core and an even granular consistency.

 

[GJUK]

Sulphate is bad for concrete I take it?

What do most builders on here do and use?

Thanks,

 

[noseall]

Sulphate is bad for concrete I take it?

The worst, especially where there is moisture present.

What do most builders on here do and use?

MOT type 1 internally. Where deep, bulk up with crushed cheap stuff externally, finish off and shape with MOT.

 

[r896neo]

Yes sulphate is bad for concrete but you will be using a dpm under the concrete so shouldn't be so much of an issue i'd of thought.

70 ton of hardcore sounds like a daft amount, are you working on heavy machinery or HGV's etc??

If he's spec'ed a foot of hardcore I shudder to think what the concrete spec will be...

Also you will need decent compaction equipment for that depth. A vibrating roller as a minimum.

 

[GJUK]

Hi, thanks guys.
I will be using DPM so perhaps I can get away with it.

The MOT is spec'd at 750 mm deep (yeah I know). And then 200mm concrete.
Due to the soil and the hedge nearby.

 

[noseall]

We used 90 tonnes of fill on this patio.....

Slabs

• noseall
• 15 Oct 2015

Porchpatio2

• noseall
• 15 Sep 2015

Patio7

• noseall
• 17 Oct 2015

 

[GJUK]

The cheaper stuff - is it called 'fill' the those in the know?
That looks really smart, nice job.

 

[John D v2.0]

Is the hedge made of alternate oak and Willow trees? At least you know it's never going to move again!
I was going to say you might wan't to compact it in layers to avoid needing too heavy rollers

 

[tomfe]

The local quarry do MOT TYPE 1 (to council specification) for £21.70 per tonne. + VAT
Or the non council quality, which I was told all the local builders use at £11.40 per tonne + VAT.

Even if it's exactly the same stuff you'll pay more for the certification.
Normally the none-certified stuff can be prone to frost but I doubt it would have any effect.

750mm of hard core seems a bit extreme, officially infill over 600mm has to be 'designed'.

I just hope you've got somewhere free to put all that (~120+ m3) of soil!

 

[r896neo]

750mm of hardcore is totally ridiculous. It will be almost impossible to compact a fill that deep without settlement in the medium term.

You should be looking at an enhanced subbase with geotextiles if its that big an issue.

Also are you sure your maths aren't a bit off? 70t of hardcore over your building size will only be around 300mm deep