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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions.

Compacting my hardcore!



 
 
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  #1  
Old March 31st 05, 03:03 PM
Lobster
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Default Compacting my hardcore!

I'm about to start laying a new small section of solid floor (approx 1m
x 1.7m) - first time I've ever done this. Think I've extracted from the
uk.d-i-y archives all I need to know, but could someone explain about
requirement for compacting hardcore prior to laying the concrete? I
have excavated about to about 15" below the final surface (it's earth
now), and was going to chuck in 6" hardcore now. Am I supposed to sort
of jump up and down on the hardcore a bit before I blind it with sand?!

Thanks
David
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  #2  
Old March 31st 05, 03:12 PM
Grunff
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Lobster wrote:
I'm about to start laying a new small section of solid floor (approx 1m
x 1.7m) - first time I've ever done this. Think I've extracted from the
uk.d-i-y archives all I need to know, but could someone explain about
requirement for compacting hardcore prior to laying the concrete? I
have excavated about to about 15" below the final surface (it's earth
now), and was going to chuck in 6" hardcore now. Am I supposed to sort
of jump up and down on the hardcore a bit before I blind it with sand?!



Ideally you need a wacker to compact it. They are quite good fun to use.
Having said that, this is a very small section of floor, and I suspect a
good bit of jumping up and down might be enough.

The reason for doing this is that if you don't compact it sufficiently,
there's a chance of future settlement, which could cause your 1x1.7m
slab to move relative to its surroundings.


--
Grunff
  #3  
Old March 31st 05, 03:32 PM
doozer
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Posts: n/a
Default

Lobster wrote:
I'm about to start laying a new small section of solid floor (approx 1m
x 1.7m) - first time I've ever done this. Think I've extracted from the
uk.d-i-y archives all I need to know, but could someone explain about
requirement for compacting hardcore prior to laying the concrete? I
have excavated about to about 15" below the final surface (it's earth
now), and was going to chuck in 6" hardcore now. Am I supposed to sort
of jump up and down on the hardcore a bit before I blind it with sand?!

Thanks
David


You need a wacker plate. They are heavy (two person lift unless you are
superman) but quite good fun to use. They come in various sizes and you
can get ones that are like a mechanical pogo-stick (probably the most
suitable considering your floor area).

I'm not a builder but considering how much the hardcore compacts when I
have used a wacker plate I wouldn't have thought you could lay a floor
without compacting it first.

If you are feeling poor you can use a post with a bar attached at right
angles to compact small areas but it's really hard, hernia inducing,
work. Jumping up and down on it is practically a waste of time and just
hurts your knees.
  #4  
Old March 31st 05, 03:40 PM
[email protected]
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Default

Cant you just use WinZip?

  #5  
Old March 31st 05, 03:41 PM
bugbear
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Lobster wrote:

I think divX gives good results ;-)
http://www.divx.com/

BugBear
  #7  
Old March 31st 05, 04:02 PM
Tony Bryer
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Default

In article , Lobster
wrote:
Am I supposed to sort of jump up and down on the
hardcore a bit before I blind it with sand?!


As the others have pointed out you need to do a bit more than
jumping on it. You should have nothing bigger than a half brick -
if you have, breaking it up in situ with a sledge hammer will
achieve this and compact it at the same time.

If you're putting a polythene dpm over the blinding it will need
to be free of any roughness. If not putting some light polythene
will stop the grout in the concrete draining through and make
levelling it a lot easier.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm


  #8  
Old March 31st 05, 05:18 PM
Rick
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Default

On Thu, 31 Mar 2005 14:03:54 GMT, Lobster
wrote:

I'm about to start laying a new small section of solid floor (approx 1m
x 1.7m) - first time I've ever done this. Think I've extracted from the
uk.d-i-y archives all I need to know, but could someone explain about
requirement for compacting hardcore prior to laying the concrete? I
have excavated about to about 15" below the final surface (it's earth
now), and was going to chuck in 6" hardcore now. Am I supposed to sort
of jump up and down on the hardcore a bit before I blind it with sand?!

Thanks
David


Others have said how to compact it, the better quality hardcore
(limestone scalpings) will be easier then the cheep stuff (crusher
run). I guess you only need a tonne bag, 25 quid for some good stuff.

9 inches of concerete sounds like quite a bit for a floor, unless you
are building on it.

Leveling the concrete is not so easy, and it can burn if you have too
much skin contact, take care.

Rick

  #9  
Old March 31st 05, 06:06 PM
Dave
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Default

Grunff wrote:
Lobster wrote:

I'm about to start laying a new small section of solid floor (approx
1m x 1.7m) - first time I've ever done this. Think I've extracted
from the uk.d-i-y archives all I need to know, but could someone
explain about requirement for compacting hardcore prior to laying the
concrete? I have excavated about to about 15" below the final surface
(it's earth now), and was going to chuck in 6" hardcore now. Am I
supposed to sort of jump up and down on the hardcore a bit before I
blind it with sand?!




Ideally you need a wacker to compact it. They are quite good fun to use.
Having said that, this is a very small section of floor, and I suspect a
good bit of jumping up and down might be enough.

The reason for doing this is that if you don't compact it sufficiently,
there's a chance of future settlement, which could cause your 1x1.7m
slab to move relative to its surroundings.


I have a similar question to the OP

I want to put an 8 by 12 foot shed on an old greenhouse base. I intend
throwing all the various bricks and rubble in the middle and topping it
off with hard core.

Without tamping it down, will I have any serious settlement problems?

Dave
  #10  
Old March 31st 05, 06:31 PM
doozer
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Posts: n/a
Default

Dave wrote:
Grunff wrote:

Lobster wrote:

I'm about to start laying a new small section of solid floor (approx
1m x 1.7m) - first time I've ever done this. Think I've extracted
from the uk.d-i-y archives all I need to know, but could someone
explain about requirement for compacting hardcore prior to laying the
concrete? I have excavated about to about 15" below the final
surface (it's earth now), and was going to chuck in 6" hardcore now.
Am I supposed to sort of jump up and down on the hardcore a bit
before I blind it with sand?!





Ideally you need a wacker to compact it. They are quite good fun to
use. Having said that, this is a very small section of floor, and I
suspect a good bit of jumping up and down might be enough.

The reason for doing this is that if you don't compact it
sufficiently, there's a chance of future settlement, which could cause
your 1x1.7m slab to move relative to its surroundings.



I have a similar question to the OP

I want to put an 8 by 12 foot shed on an old greenhouse base. I intend
throwing all the various bricks and rubble in the middle and topping it
off with hard core.

Without tamping it down, will I have any serious settlement problems?

Dave


Hmmmm. Hard to tell. I have seen a pile (about two tons) of hard core
just left out (suffering nothing more than minimal foot traffic and the
odd wheel barrow) in a layer about 6 to 8 inches thick. It did settle
but not by any where near as much as if it had been tamped down and it
still set hard (as hard core does when it has been tamped). I suspect
that it would have compressed more if it had been put under heavy load
such as having a car drive over it but it was fine for foot traffic and
wheel barrows.
 




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