Mini crusher output good enough as MOT1?

[mbga9pgf]

Hi all, very simple question. I am about to start landscaping the surrounds of my house, with a view to lay about 50m2 of patio surrounding the house to help drain water away from the footings, which, due to the age and original use of the property, has no damp proof course. At present, I have a stone chip surround and then soil, which doesnt do wonders for rising damp on the inside of the house.

Now, I have a shedload of spare blockwork, a load of concrete slab a brick porch that needs tearing down. Rather than go out and buy 6 bags of MOT1, could I instead hire a mini breaker and use the breaker run as the subbase for the patio, or is the size and consistency of a crusher run unsuitable for use as sub-base?

When adding up the cost of a skip, plus disposal, I can save myself a fortune, just unsure what the typical size of output on those crushers and whether concrete block/brick/old concrete slab would be suitable as a sub base.

Thanks in advance!

mbga

 

[r896neo]

Personally i don't think so as it has very few fines in it. As far as i understand it doesn;t conform to the BS standards in comparison to MOT type 1 but that's more for large commercial projects.

For residential use under flags laid on mortar i'd say it'll be fine. For use under block paving maybe less so.

Ask on 'the brew cabin' which is the forum on paving expert.com as there are guys on their who use crushers a fair bit including one who hires them.

 

[Markbon]

I you're asking if its ok to use hard core as a sub base under a patio rather than type 1. Then yes all day long. Hardcore should be no bigger than half a brick and well compacted. A whacker plate etc is strongly advised with type 1 or hardcore. Blind it with small bits and sharp sand.

 

[r896neo]

I have a nice equation for you

Rubble hardcore with no fines + sand blinding = sunken patio

 

[Markbon]

If that equation is for me I must point out that I said you need small bits or fines if you want to call them that.
And most crushers these days do 20-70 mm so should be fine. The cost if s/sand blinding has to be remembered though.

 

[r896neo]

fines is dust, type 1 MOT is 20mm to dust and everthing in between so it compacts. Running a vibrating plate over rubble hardcore just rams it into the soil and then bounces. The material itself does not compact and throwing some sand and smaller bits over it is not a miracle cure.

The sooner people stop propagating that myth the better.

Running it through a crusher as the OP suggested is suitable because that crushes it to give a spread of sizes much like MOT

 

[Markbon]

So you're saying you cant use hardcore under a patio?
The OP only wants to lay some slabs not a motorway.

 

[mbga9pgf]

fines is dust, type 1 MOT is 20mm to dust and everthing in between so it compacts. Running a vibrating plate over rubble hardcore just rams it into the soil and then bounces. The material itself does not compact and throwing some sand and smaller bits over it is not a miracle cure.

The sooner people stop propagating that myth the better.

Running it through a crusher as the OP suggested is suitable because that crushes it to give a spread of sizes much like MOT

I am hopefully going to get a mini crusher with adjustable output, 20mm-dust. I know the MOT spec requires certain quantities of each size with a lot being at the dust end, I just need to know if my plan will work bearing in mind the considerable quantity of concrete, blocks, bricks and knackered split paving slabs I have to work with

Thanks again all!

 

[mbga9pgf]

fines is dust, type 1 MOT is 20mm to dust and everthing in between so it compacts. Running a vibrating plate over rubble hardcore just rams it into the soil and then bounces. The material itself does not compact and throwing some sand and smaller bits over it is not a miracle cure.

The sooner people stop propagating that myth the better.

Running it through a crusher as the OP suggested is suitable because that crushes it to give a spread of sizes much like MOT

I am hopefully going to get a mini crusher with adjustable output, 20mm-dust. I know the MOT spec requires certain quantities of each size with a lot being at the dust end, I just need to know if my plan will work bearing in mind the considerable quantity of concrete, blocks, bricks and knackered split paving slabs I have to work with (and dont want to pay to landfill). I will be covering with a 5:1 sharp sand/cement base and large sandstone slabs for paving just for a bit more background. I dont intend to split the bricks with a chisel in half and lay them as sub base!

Thanks again all!

 

[mbga9pgf]

update

right, resurrecting an old thread of mine....

about to start paving works outside. i ended up using a lot of the hardcore around the garden to fill in some pretty whopping holes and to re-route a stream with. also came in useful for the french drains etc.

Second idea. the eejits who lived in the house we bought did a gravel drive, except they laid no subgrade and tried to rely on geotex membrane to prevent weed growth, which is now failing miserably.

instead of using hardcore, i am planning to now use this gravel (10-20mm sharpcaggregate) washed, combined with a little sharp sand and a couple of spades of cement to hydraulically bind it. I am planning to excavate out, build in the edging stones to retain the sub base, and fill to 150mm of a slightly damp mix.

I was thinking that whilst the 10-20mm sharp gravel they have used as chippings wont bind, a little sharp sand and cement will provide the adhesion it needs, saving a fortune in crushed stone, not to mention skipping costs for the existing gravel. plan to tamp down once its in situand grade appropriately.

bad or good idea?

 

[r896neo]

good idea but you need to form a lean mix concrete so will need a decent sand quantity. cement could be down as low as 10:1

So minimum would probably be 7 stone 3 sand and 1 cement

Any less than that and it will not hold together.

 

[mbga9pgf]

good idea but you need to form a lean mix concrete so will need a decent sand quantity. cement could be down as low as 10:1

So minimum would probably be 7 stone 3 sand and 1 cement

Any less than that and it will not hold together.

Awesome. Building sand do or best to use sharp sand? (Planning on using sharp)

 

[Mursal]

If you don't mind me asking what sort of a crusher were you going to hire?

 

[r896neo]

Sharp sand is best for making concrete but in reality any sand will do

 

[ban-all-sheds]

..saving a fortune in crushed stone, not to mention skipping costs for the existing gravel...

I've a similar cost equation to work out when I take down an old concrete garage and put up a wooden building which will need the base of the existing garage extending.

Do I pay to have the old concrete panels taken away, and pay to have crushed stuff brought in, or do I hire a crusher?