Anyone test soil hardness themselves??

Discussion in 'Hardscaping' started by mrusk, Apr 8, 2006.

  1. mrusk

    mrusk LawnSite Gold Member
    Messages: 3,260

    Since i've been getting a few calls for engineered reinforced retainingwalls i started to talk with the towns i work in, inspectors. It sounds like they do not do soil hardness test as the wall goes up.

    So i figure if i get these jobs i am estimated i better buy a tester and do it myself. It could be a good selling point also. I found a couple sites that sell the gauge that you stick into the ground for around 1600? Are these good enough?

  2. neversatisfiedj

    neversatisfiedj LawnSite Bronze Member
    Messages: 1,028

    I wonder the same thing. Like what scale job should I worry about compaction rates ? I jus do residential walkways and walls and such . But I still want to do the best work I can . Should I be worried about testing soils ? ICPI site says to test , but they also show a roadway going on , not exactly what I would be doing.
  3. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    Thats a good point i have been building walls since 97 and havent had a problem yet. I make my footers 2' wide and 2' deep and fill 1.5" agg. and compact. I feel this is sufficient since in my mountain area we have a lot of rocks in the clay areas and solid shale else where. If i hit what i feel is a soft spot i place a layer of geo-grid in my footer between the lifts and compact. Please keep me posted on what you find out. I just remembered we did a job 2 years a go for a guy who was building a garage and the company was bringing in pre cast concrete walls and sitting them on a gravel footer and the stone was what we call pea gravel. Now if this garage 2 story at that can sit there i think my 3-5' allen block walls will stay for a while.

  4. kris

    kris LawnSite Bronze Member
    from nowhere
    Messages: 1,578

    Are you talking about a Dynamic Cone Penetrometer? I don't know If I would bother....yes better than nothing.

    Should you be worried about testing? It is not reality to test on every normal residential job but I would hire someone at least once that does NUCLEAR DENSITY testing. That way you can get a good "feel" that you are doing things OK with the equipment you have. Also get sieve analysis on your gravel and sand from your supplier.
  5. Squizzy246B

    Squizzy246B LawnSite Senior Member
    Messages: 837

    We test EVERY wall we build to 24" below the footing and to 18" in front and behind. We use a manual slide penetrometer which gives good results in sands & loams provided it is operated correctly and a good grid is shot.

    We get good work on referrals from GEO engineers to repair walls which have failed and this about 45% due to lack of or uneven compaction.

    However, the requirements provided for our walls are, in my opinion, lacking. If the engineering requirement is to acheive say a minimum 6 blows at the first 12" and 9 at the second 12" thats well and good but it doesn't say anything about exceeding that requirement and acheiving consistent compaction. If part of the wall footing hits 6 blows and the another part hits 10 then this is a recipe for failure although it meets the engineers requirements.

    I've spoken to many engineers about this, and they totally agree...I'm just yet to see a proper spec on a wall drawing, for a structural retaining wall that is not a spec borrowed from a building standard.:realmad: Ok ...Ok..I'm going to take my pills now!

    In short, yes, test your compaction and have confidence in your work...Its like levelling a house pad in a machine without having a laser/level to work off...your shifting dirt but are you doing anything productive??

    I'm always at my guys to test compaction before we start so they can test again as they go and see if it coming up. If its not then you need to excavate more instead of wasting another hour walking a compactor up and down acheiving nothing.

    Ok..Ok I'm going
  6. mrusk

    mrusk LawnSite Gold Member
    Messages: 3,260

    I'm waiting for Bill to comment on this. I just don't feel safe building 7 ft tall walls with driveway surcharges, without soil hardness test. I do not care what the inspector thinks looks visually ok. If the wall fails some day, even though i built it just how the engineer designed it, i know i will get draged into the mess also and get sued. I want to advoid that at all cost.

    I'm acctually trying to move my business towards just retaining walls. It seems like most landscapers really do not understand much about walls and sur charges. They always try to find ways to get around engineering, making it seem like a engineer is someone to be afraid off.

    I just enjoy building walls more than any other form of hardscaping!
  7. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    I have done quite a few like that however im in and dont know your soils. I have eng. sometime and most the same. Just over kill everything and you wont have a problem. 2.5 deep footer some crusher run if necc. compact layer of geo grid. Reg. clean stone , bury 1.5 block. I would dig 100% of height of wall so i could grid 100% thats the key. 2-3' of gravel behind wall then backfill the balance with shale or crusher run. This will provide a strong wall and handle the surcharge. Check my web site
    One of my pics there is a wall 6 years old with a car parked on it.

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