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  1. #1
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    Compacting Earth

    Before builing a house why do we have to compact earth over a period of 1 or 2 years? Can anyone explain this? Why not cement it? Why do it all?


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    Maybe Thailand is short of steamrollers?

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    Quote Originally Posted by ChalkyDee View Post
    Before builing a house why do we have to compact earth over a period of 1 or 2 years?
    You don't have to, but the alternative is to pile deep enough to avoid resting the building on the soil beneath, and this is rather expensive.

    New soil will consolidate - as any gardener can tell you.

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    Because if you dont , the chances are within a short time after completion and the soil has compacted . You will have some pretty horrendous cracks in your walls ( not the sort polyfilla would cure . )

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    Anytime that soil is disturbed it must be compacted, Best way is to do it in layers with damp soil and then compact with a vibration roller of an acceptable weight, or with a "Sheep Foot Roller", those can be seen at land fills where the wheels are steel and have the sheep foot attachments on them.

    If you just have a roller with a smooth drum then it has to be done in layers of less than a foot at a time.
    The surface is always the loosest and down deeper where it has had the weight of the upper soil will be the best compacted, therefore if you have new fill and have no way to compact to 100% compaction then pilings driven to old and compacted soil is the best way.
    You will notice that the first hits of the pile hammer will sink the pile a goodly amount, then as it gets deeper into a tighter soil it will go only a little ways each hit, when it moves so little that you have to hit it 3 times to get 1/8 of an inch you have reached acceptable compacted soil and have desired penetration,, drive your series of piles and then pour your foundation on these pilings, your house will stand crack free for years to come, or you can do as the Thai and build a house that will start to crack soon after being built and get worse as years go by and then at 20 years, tear it down and build a new one.
    Just like the hyways they build here on lightly compacted soil, they start to fall apart soon after the road is opened and they dig it up in sections and repair it..

    Ever notice that when they are building a tall or large building in the outside world that they first dig a deep hole where the foundations will be?
    That is to get down to compacted earth as the surface is not suitable to build on, even for a small home the foundations are down in trenches anywhere from a foot to a meter down in undisturbed soil unless it is rocky, here most of the land has no rock structure, so depth counts.

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    I mentioned a pile driver, but I have never seen one crane mounted here.
    They use a derrick thing with an engine and hoist and it is put together on the site, must not be to expensive tho as there was one here in the village driving for a new house over by the klong, only time I have seen one on home construction tho.

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    Quote Originally Posted by blackgang
    I mentioned a pile driver, but I have never seen one crane mounted here.
    I've seen them in Bangers for some of the bigger buildings. Fucking great things that make everything shake for a couple of hundred yards.

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    Like I said, I have only seen the derrick kind here, but never seen any in BKK as I have not spent much time there.
    I have always ran or worked on the crane boom mounted leads and a drop, diesel fired or air/steam driven hammers.

    But piles is the way to go when there is just mineral earth to build on and no rock structure for 1000 meters down.
    I drilled a bore hole for water down to 153 meters and hit nothing but sand and clay..

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    Thailand Expat Boon Mee's Avatar
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    ^
    We're drilling 30k feet below the seabed and run into the same shit. Sometimes a little oil too!

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    ^, but you are not planning on building a house out there are you??

    30k feet is a pretty deep hole, how much water over the sea bed??

    How long is the tool string from the drill deck to the bottom of the hole??

    Drillship or platform??

    Storm Drilling still in business??

    I worked for dearborn marine services myself.

    And Brown Root/ Haliburton.

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    Quote Originally Posted by ChalkyDee View Post
    Before builing a house why do we have to compact earth over a period of 1 or 2 years? Can anyone explain this? Why not cement it? Why do it all?

    Thais do not know how to compact when buiding in general. I worked in construction and the legal recommendation on backfilling was 3 passes every 100mm of backfill with a vibratory compactor, regardless of machine. The reason why Thais allow for 1 to 2 years is because they allow gravity to do the work for them. But that doesn't always work and only a vibration compactor will eradicate air pockets or voids, a regular cause of subsidence. Do not build on land that hasn't been compacted with a vibrating compactor as per the 3 passes for every 100mm of backfill or overlay. It will subside in most cases. Even if you put a concrete raft over uncompacted soil after a few years soil sinkage will cause problems to the raft and even worse to the perimeters of the raft, the weakest part.

  12. #12
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    ^unless you're using a hand whacker 100mm (4") is a bt over-kill 12 - 16 inches with a good heavy sheepsfoot and a smooth roll finish is fine. wet as you roll.

    As to the OP The leaning tower of Pisa comes to mind...

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    I notice they dig the footings for the supporting concrete piers down into the original ground level. That makes sense.

    But the concrete floor is sitting on the fill. And they add another foot or so of lose fill to the under floor area before pouring the floor slab. Which would make compacting the first lot of fill a waste of time.

    I am only making these observations from photos, so if I have got it wrong, can someone enlighten me?

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    Thailand Expat Boon Mee's Avatar
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    Quote Originally Posted by blackgang View Post
    ^, but you are not planning on building a house out there are you??

    30k feet is a pretty deep hole, how much water over the sea bed??

    How long is the tool string from the drill deck to the bottom of the hole??

    Drillship or platform??

    Storm Drilling still in business??

    I worked for dearborn marine services myself.

    And Brown Root/ Haliburton.
    We're currently drilling in a little over 9K feet. The derrick & rig is rated for 10K feet of water but the company I work for is building 3 more drillships in Korea right now that can drill in 12 to 15K feet of water.

    The tool string length depends on where our client decides to stop drilling. Right now it's some 39K feet with a 7" bit on the end. We can stand quadruples in the derrick so that cuts down on trip times.

    This is a drillship - 845 feet long.

    Storm Drilling has been out of business for a long time. Think it was bought out by Zapata back in the 1980's?

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    A well designed slab with beams is sufficient.
    Filling is only required if there is doubt about the density of the land to begin with, not all land has to be filled.
    I never saw a house in Australia (3 bedroon single story) built on a backfilled block or piles used.
    Most were built on concrete filled trenches (not more than 6"), where the stumps were then placed and then the floor beams etc etc.
    Off course the buildings were generally wood framed, and a lot lighter than the concrete monolths built here.
    Most older houses in Issan have been built on stumps sunk into the earth, no concrete! Timber construction, lightweight, and pliable.
    A lot of people could learn a bit if they bothered to study them, except for the high cost of timber, and the need for thermal insulation, a better and easier way to build IME

  16. #16
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    The addition of fill really has nothing to do with construction techniques, it is to raise the house above the high water mark during monsoon so the water does not get into the house.
    Wood construction is usually eaten by bugs,

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    So, would I be correct in assuming that the concrete floor slab is supported by the concrete piers independently of the fill underneath?

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    The piers are connected and part of the main foundation that support the walls and the floor is poured inside of the walls and is mostly supported by the fill.
    At least thats the way they did my house. That is here,Elsewhere most fills and especially under the floor slab are rubble fills and there is very little compaction needed on a rubble fill.

  19. #19
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    Quote Originally Posted by blackgang View Post
    The piers are connected and part of the main foundation that support the walls and the floor is poured inside of the walls and is mostly supported by the fill.
    At least thats the way they did my house. That is here,Elsewhere most fills and especially under the floor slab are rubble fills and there is very little compaction needed on a rubble fill.
    Thanks for that info. Clears things up for me.

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