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How deep will a 2-stroke jumping-jack rammer compact roadbase?

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  1. #1
    One day ... Gunnaduit's Avatar
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    Default How deep will a 2-stroke jumping-jack rammer compact roadbase?

    I'm working on my roadbase foundation for a 1200 high Versawall retaining wall. How deep will a standard 2-stroke rammer compact the roadbase? As in, how deep of a layer of roadbase can I compact with the rammer? Roadbase is wetted.

    The rammer will be just the usual type you hire from Kennards or elsewhere, just a normal handheld 2-stroke jumping-jack type used for trench compaction. (Different from a plate compactor).

    TIA.

  2. #2
    One day ... Gunnaduit's Avatar
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    Oh well, since nobody has an answer, I googled more. The technical phrase to google turns out to be "lift thickness", i.e. the layer depth to be compacted. Lots of factors involved of course, but moisture content seems to be the most important -- not too wet, not too dry. Lift thickness around 150mm, for roadbase using a rammer, seems to be about the safest to assume without engineering tests, etc. Number of passes also is difficult to say, but 3 passes is in the right ballpark.

    The problem to look out for, if the lift is too deep, is bridging: the top of the lift and the bottom of the lift are compacted, but the middle of the lift is not.

    The best info I found is here:
    How to determine the number of Passes and Lift Thickness for Soil Compaction -- The Constructor.
    https://theconstructor.org/geotechni...paction/45782/

  3. #3
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    Quote Originally Posted by Gunnaduit View Post
    150mm, for roadbase using a rammer,
    correct. if too thick for each layer, you wont achieve a good compaction.

  4. #4
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    Layers of 150 used to be the maximum for bedding sand which has 99% compaction (supposedly)
    I would not go any more than 100 with road base
    I have always found the best compaction is saturation
    Mechanical compaction is good as long as the underlying earth is solid and stable

    but I would question the use of road base as foundation for a 1200 high wall.

    Any retaining wall above 900 for memory must be engineered,
    and the presenter in one of the videos makes a quick mention of engineering for above 800 if I remember correctly.

  5. #5
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    Quote Originally Posted by cyclic View Post
    I would question the use of road base as foundation for a 1200 high wall.

    Any retaining wall above 900 for memory must be engineered
    Possibly depends both on the walling system and the jurisdiction. In Canberra, you can build a retaining wall to 1200 high without a building permit, if it "is constructed in a proper and skilful way", with a few other conditions.

    Versawall is an interesting product, you can build to 1400 high using no fines concrete, without requiring further qualified engineering advice, as long as you stick to their technical design note, "Technical note Versawall® Retaining Wall System", https://www.adbrimasonry.com.au/wp-c...techNote-5.pdf

    This technical note specifies use of compacted roadbase beneath and behind the concrete footing. Following these technical design specs to the letter will go most of the way in satisfying the requirement in ACT to build "in a proper and skilful way", thus compliant. Then everyone is happy.

  6. #6
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    Built a retaining wall (my first wall) 17 years ago out of simular solid blocks.
    Most of the ~30m long wall was 1m high with some parts extending to 1.2 high well over (from memory) the 800mm limit here in "regulation" Vic before engineering is required.

    Made sure site had good drainage, was down hill from the next door, my underlying base was clay which I'd excavated 400mm deep and ~ 800 wide. Compacted it in 150mm layers with a vibrating plate compactor. Wall set back 150mm from the front of the compacted base and first block 50% buried on final ground height for lawn. Wall never moved.

    Also installed great drainage behind the wall (90mm slotted pipe, scoria 500 deep with geotextile over the top to keep the soil from filtering through. Put in 3 x 90mm vertical capped inspection pipes to the top of the wall via Tee's in the 90mm slotted to see if over time any issue's such as water, dirt buildup and it remaind squeaky clean the whole time.

    May have been beginners luck or over kill in some parts, just make sure you build to cope with your site conditions...what ever they are. And as DIY, youve got the luxury to overkill due to lack of knowledge the 2 key areas (foundations and drainage) and still be 5 times cheaper for a large wall than paying for a professional crew.

  7. #7
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    Quote Originally Posted by Bart1080 View Post
    as DIY, youve got the luxury to overkill due to lack of knowledge the 2 key areas (foundations and drainage) and still be 5 times cheaper for a large wall than paying for a professional crew.
    Isn't that the truth -- far cheaper, no corners cut, and no F ups by morons.

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