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"fill" me in...haha

Discussion in 'Hardscaping' started by Captains Landscape, Mar 25, 2007.

  1. Captains Landscape

    Captains Landscape LawnSite Senior Member
    Posts: 333

    Tell me if I'm wrong. I was looking at the posts on flowable fill and playing in my mind on how we would put it to use. Currently, we set up our base and drive the wall units into the base via dead blow hammer. There is a lip on the back of the block that gets driven into the base (Pavestone) until level. Maybe its just perspective, but wont driving the block and block lip into the base further stabilize the wall? I'm assuming that the flowable fill "sets up" similar to concrete, and wouldn’t allow the block to be driven in. Won't this just create a surface that would allow the base course to "slide" off? It just seems like there wouldn’t be anything to anchor the base unless you always buried 2-3 courses and relied on the backfill (around the base) to stabilize the base course. Even when you pour a slab to veneer stone, you either imbed the stone into the slab or apply a layer of mortar to adhere the stone to the slab...see my point?:confused:
  2. Duekster

    Duekster LawnSite Fanatic
    from DFW, TX
    Posts: 7,961

    I look forward to this tread.
  3. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    Flowable fill is not meant to be your final grade. It is primarily used to bring up raised patios or footers to a rough grade then you add modified stone to get to your final grade. Although flowable fill is workable once dry it is very difficult and the fact that they claim it to be self leveling is far from reality. If you have a raised patio that sits 2.5' above existing grade, you would bring in 2' of flowable fill and bring your final 6" up w/ modified. With regards to wall footers, I don't think flowable fill is necessary. NCMA only requires a 6" base.

  4. Captains Landscape

    Captains Landscape LawnSite Senior Member
    Posts: 333

    For example, if you have a wall that is very long say 500 feet, I heard that laying forms over the compacted sub base, using flowable fill and screeding. Let the base set up for a day and you are good to go. The question above was where I got stuck. I don’t think its cost effective for a small residential wall, but in the event you are building a lengthy wall it may be. This is unless the fill is not proper spec for base, now I'm even more confused because I thought it was.:dizzy:
  5. Captains Landscape

    Captains Landscape LawnSite Senior Member
    Posts: 333

    "Vic, actually you can use this in place of your crushed base. I don't know about filling hollow core blocks with flowable fill, that is an interesting idea. The big advantage is it is self leveling if specified to the right mix. In theory, it will find it's own level and should create a level base to build walls on, similar to a concrete footing, but no where near the strength of a concrete footing. You can use it to fill a raised patio area that can not, or should not be compacted."
    -Dreams to Designs
    quote from "flowable fill" thread
  6. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    I've only seen flowable fill used once, and even very wet (10-15 gallons was added to each truck at delivery) it still didn't "self-level". The "self-leveling" label is BS, IMHO.

    If you want to use flowable as a base for a wall, go for it. I personally don't see a problem with using it for that purpose. Just keep in mind that you *will* need to set forms and screed it off so that it is level in the end. It can be dug out by hand if needed; it's probably not any harder than some of our clay soils around here when they are dry...

    If you are worried about the back lip not beating into the fill, it's a simple matter to break it off. Versa Loc (and probably others) spec packed road base in front of *and* behind the first course of block- that is what 'key's the base course in on the base, so "sliding off" won't ever be an issue.

    As Chris said, flowable fill really should only be used as fill, and road base used to bring your base up to final grade.

    Remember flowable fill comes out of the chute essentially as a REALLY WET sand, and the only reason it has any semblance of strength is because of the portland mixed in. Also, if you do use it, keep in mind that since it is really WET the water has to go somewhere....
  7. Captains Landscape

    Captains Landscape LawnSite Senior Member
    Posts: 333

    Thanks Chris and Felix. I don’t intend on using it as base, I was just thinking about in the event of a longer wall. After all this is the best place to test ideas, not at the client’s property.:p
  8. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    I always thought everyone just chiseled off the lip on the first course?
  9. Captains Landscape

    Captains Landscape LawnSite Senior Member
    Posts: 333

    I think most guys do, but why not "key" it into the base? I've never seen it present a problem. It takes a little longer to get level, but chiseling off the lip takes time too. I don't compact my base improperly, but it takes a few good hits from the tamp to get the block down.
  10. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    It takes a LOT less time to break off the lip than it does to leave it on and fight it. If you spend 15 seconds breaking the lip off, I bet you spend an extra minute or two leveling one with it left on. Which is a significant time savings at the end of the base course. I would also bet that the lip would be a non-factor in the 'keying' if there was packed base in front and behind the block. IOW, it's not worth leaving it on.

    But, hey, if you want to, there's nothing that says you can't. Your other option would be to flip the block over and leave the lip on and towards the front if the block was solid enough... :waving:

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