TomG's Photos

Discussion in 'Hardscaping' started by TomG, Feb 7, 2011.

  1. 2low4NH

    2low4NH LawnSite Bronze Member
    from NH
    Posts: 1,891

    Ookay uni-axil grid and bi-axil grid have nothing to do with vertical load. you are digging your self a hole here and it has no fabric at the bottom. As you stated soil locks the grid in place and holds it "to the block" the grid is also locked in at each little square by the soil so that means its a soil stabilizer.
  2. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    You're not understanding. Correct is has nothing to do with a vertical load.
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  3. 2low4NH

    2low4NH LawnSite Bronze Member
    from NH
    Posts: 1,891

    No I do understand. I have done ICPI and NCMA I paid attention I have studied and read and learned. Bi-axil grid only means its good in 2 directions so you can roll it out in either direction. uni-axil grid loses 60% of its strength when rolled in the wrong direction. most bi-axil grid comes in 3-4 foot rolls.
  4. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    You may need to read my statement a few times to understand what im saying. Text has no tone or expression so sometimes things are not interpreted correctly.

    I was using grid direction as an example that grid is designed to be * tugged* on. like a rope. Without the seems, the grid will tear.

    You have a hill and you have an old truck with no parking brake.

    Being a creative person. You take a rope and you tie the rope around an old oak tree.

    You then tie the other end of the rope to your truck. This way the truck won't roll / slide down the hill.

    Grid acts in the same capacity. Thus making the grid depicted in toms photo absolutely useless because nothing will be tugging on it. As that's what it's designed for, which is why there are different grades of grid strength.

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    Last edited: Apr 7, 2011
  5. TomG

    TomG LawnSite Senior Member
    Posts: 675

    DVS, wow, just wow is about all I can say, have YOU taken an NCMA class and passed? I don’t like to call people out but I will this time, nether you or your company is listed in on the NCMA website as certified installers. (I looked under Outdoor Creations in Maryland and searched all of Maryland for Andrew with no luck). I actually really respect your opinions on things because you seem very knowledgeable but I am second guessing myself now. For you to say and I quote “Tom, buddy you are WAY off. Grid IS NOT used to " reinforce soil". It is used to stabilize the block, to keep the block from rotating forward “ Is really, really surprising and quite frankly YOU are way off.

    One of the first things they teach you in an NCMA class is that there are two types of SRW’s, “gravity” and “reinforced soil” and that geo-grid does not hold up the wall it stabilizes the soil behind the wall. Here is part of a recent NCMA newsletter: “Reinforced Soil Reinforced soil walls should be specified when the maximum height for conventional gravity walls is exceeded or when lower structures are surcharged by sloping backfills, live loads, and/or have poor foundations. A reinforced soil SRW is designed and constructed with multiple layers of soil reinforcement placed between the SRW courses and extending back into the soil behind the wall at designated heights and lengths as shown in Figure 1b. The geosynthetic reinforcement and the soil in the reinforced zone act as a composite material, effectively increasing the size and weight of the wall system.” How about this video from everyone’s favorite techo-employee: Or this one: Why does he keep calling it a reinforced soil wall if... as you say... the grid doesn't reinforce the soil???

    Now about saying that geo-grid is basically a “tieback” for the SRW units. (that’s what I got from reading your last post) Please read this article from Allan Block. And look at this ICPI tech spec Why would a geo-grid be spec’ed into a wall on a raised patio where the maximum height is 4 feet if it is just a “tieback.” A raised patio is not considered load bearing.

    Lastly you saying “Grid acts in the same capacity. Thus making the grid depicted in toms photo absolutely useless because nothing will be tugging on it. As that's what it's designed for, which is why there are different grades of grid strength.” And “The grid you folks used under the granite is doing absolutely nothing. It is not stabilizing and soil. Grid has it's strength in one direction as that is where pressure is apPlied when the block pulls on it.” I have said before that I don’t like giving out all of our secrets but I’ll share this one. Under the granite steps we put grid in and we don’t run it all in the same direction. We lay the first layer parallel with the foundation and the second perpendicular, and continue that as needed. It actually increases the strength of the soil a lot. Have a look at this video. Also take a look at the two pictures below, they are from a one day class I took on Geo-synthetics from the College of Engineering at the University of Wisconsin-Madison.


  6. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    Thanks for the reply Tom, I never said nor implied grid holds a wall (even though it does). A SRW is a *system*. there is more to a SRW than stacking block and rolling out grid. In terms of a sRW If the correct soil type is used and properly compacted - then soil stabilazion should not be needed, as that's why using structural fill and compacting and testing is necessary. Can grid have more than one use? Well, a dime can be used for things other than paying someone, so the answer is yes. But at the end of the day when you turn your alarm
    Clock on to wake you in the Morning, what is the main purpose of grid?

    Staying on subject, the pic you displayed does not appear to need stabilization of soil. There is no slope. The property is old, so the bulk of settlement is over. Settlement occurs from the bottom up. So what are you stabilizing in the picture?

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    Last edited: Apr 8, 2011
  7. Ground Effects NH

    Ground Effects NH LawnSite Senior Member
    Posts: 601

  8. TomG

    TomG LawnSite Senior Member
    Posts: 675

    I'm still waiting for answers to my questions. But I will suggest that you go out and get NCMA certified, the class will teach you about the importance of geo-grid in walls and that "just using correct soil type and compaction" is not enough for taller walls. While your at it get ICPI certified also.
  9. JoeyDipetro

    JoeyDipetro LawnSite Member
    from CA
    Posts: 117

    I\\\'m new to hardscapes and trying to learn as much as I can. I understand that you are saying that grid is not used to \\\"reinforce soil\\\", but by \\\"keep the block in place\\\" are you saying that it is used to hold the block in place?
  10. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    Tom, lets stay on subject, shall we?

    As I stated - geo-grid is intended for retaining walls, it's intended for VERTICAL structures. Keyword "VERTICAL". Vertical. Vertical. Vertical.

    Staying on subject in reference to your picture of the granite, that is NOT a vertical structure, as I stated.

    Here is something I copied and pasted for you from, again, notice the use of the word "vertical":

    Imagine a small pile of sand on a card it?

    Okay - besides being a mess, you can picture that the sand will

    just run onto the floor, no matter how much sand you try to pile up!

    It will run off the table because sand won't stand vertically.

    Now - envision putting beach towels down on the table that are

    the exact same size and shape of the table. Imagine these beach

    towels between 1-inch thick layers of sand! By repeating layers

    of towels and sand over-and-over again you can make a really

    high, vertical column of sand! You just did what GEOGRIDS

    do for walls that are 40 to 50 feet tall!

    So, GEOGRIDS reinforce the soil or sand to make the sand

    stand up nearly vertically! Geogrids such as Stratagrid are

    manufactured with high quality in a variety of strengths.

    Now, the other day I editted a post, but it was after the 10 minute period allowed for post editting, and being the super important man that I am - I was on a jobsite. Grid can also be used for soil stabilization, (staying on subject and in response to your statement) but in YOUR photo you show it being used as geo-textile fabric.

    We do alotta concrete demolition, so I see what benefits of wire and rebar do in a prospective that many folks do not see.

    In relation to the GRID in YOUR photo:

    GEOGRID is to similar to soil what reinforcing steel is to concrete
    Much higher loads can be carried by the soil structure.

    Again, back to your PHOTO - in order for that statement to be true with your job, your grid would have to be DEEPER in the ground. Which is why I mentioned that "soil settles from the bottom up". As what your picture shows the grid is close to the surface.

    On my old computer I have a video showing what happens without grid. I know I posted the video on a hardscape forum, it may have been 3 yrs ago, but I'm not sure if it was this forum or another.

    Last edited: Apr 8, 2011

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