Flowabl fill

Discussion in 'Hardscaping' started by Henry, Feb 21, 2006.

  1. Henry

    Henry LawnSite Senior Member
    Posts: 549

    OK, I know everybody is tired of ep henry pushing flowable fill, but does anyone here actually use it? When I did my icpi class the instructors also recommended it and it sounds like a good idea to me. I will be building a raised patio at my own house soon and thought it would be a good place to try it out. Anyone had a bad experience with it?
     
  2. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    I had always been interested to see what it would do and how it would work. We had a concrete sub do a pour with flowable around a pool for us late last fall on a project we just got back to today. Think it was 60-70 yards or so, areas of it are ~3' deep.

    When you hear "flowable" and "self-leveling", you think that's exactly what it is. WRONG.:D

    It's mostly sand and water, with VERY little portland mixed in. In fact, it's pretty easy to dig in, even once it's "set". "Self-leveling"? Forget it for fine leveling. It will flow, but it's essentially a really, really, really wet sand. If you need to screed it out, I think it would be harder than screeding out regular concrete, due to the fact that after it's off the truck and on the ground, all the water drains out/down. Especially when you have 2-3' of filling to do.

    What we did was fill with the flowable to grade minus a foot for the most part. There were areas that were lower due to running out of fill, but that was OK with us. After it set for several days (or a couple of weeks, don't remember; this was in late November/early Dec), we then put down fabric and compacted gravel over the fill. I'm sure we will still have another lift to pack in before we screed sand and lay pavers, but the 4" or so thats on it now seem to be holding up just fine. I didn't notice any areas that looked like they had heaved at all, but then again, we haven't exactly had a lot of frost in the ground since before Christmas either...

    I don't have any pictures at all of the site, let alone any of the fill going in. Sorry.:)

    HTH.


    Dan
     
  3. bigviclbi

    bigviclbi LawnSite Senior Member
    from nj
    Posts: 894

    Took the class but my instructors didn't go over it. Can someone give me an overview of what it is?
     
  4. Dreams To Designs

    Dreams To Designs LawnSite Bronze Member
    Posts: 1,406

    Vic, check out this site for a decent explanation.

    http://www.prmconcrete.com/flowablefill.htm

    It works great for backfilling against foundations and is recommended for the new Monumental wall blocks Techo has come out with. A couple of the contractors I work with have used it with great success.

    Kirk
     
  5. bigviclbi

    bigviclbi LawnSite Senior Member
    from nj
    Posts: 894

    So you would build your walls then fill in with that. I guess you would still need the crushed to level it to exactly where you want it before you put the sand down? I usually use excavated dirt then the base material to fill my patios, I've never worked with wet products before so do you need to "Float" it like concrete?
     
  6. Dreams To Designs

    Dreams To Designs LawnSite Bronze Member
    Posts: 1,406

    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. Many new homes, and lots of older homes are built with a foundation that should not be backfilled against with crushed stone and compacted to the proper density with plate or foot type compactors. I have not seen it, but have been told by SRW manufacturer reps that foundation damage has occurred due to compacting against foundations. The flowable fill acts as a monolithic material spreading out the forces that would normally be transferred to a foundation wall. If the correct level is attained with the fill, sand is screeded to 1" and pavers, slabs or wall stone can be built right on it. For the Techo Monumental block, it is used for the sole foundation material. These block are 1100 pounds each, and I'm not sticking my hands anywhere near them to screed sand or dust so they sit level. The flowable fill may have to poured into a form depending on the soil condition, but being a liquid product it will find it's own level across the entire distance of the pour or foundation. I have seen the surface smoothed with a trowel, but other than that the fill is ready when it dries.

    Kirk
     
  7. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    You must be using a different mix than what we used. What we used did not find it's own level, especially a fine level. It did "flow" to some extent, but definately not like you'd think when someone says it's "self-leveling".

    Put it this way though, 80 yards of flowable went in with 2 guys (after some forming) inside of 5 hours. To fill and compact that same amount with crushed limestone would have taken 3 guys at least 2-3 days. Gravel as a material would have been cheaper, for sure, but it was done MUCH faster.

    I guess what I'm trying say is if you have a large area (and deep) that needs to be filled, use flowable. If you think you will use it to set a base for a wall, and it will level itself and you won't have to touch it, think again. From my limited experience with it, it is NOT truely "self-leveling".


    Dan
     
  8. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    Neither is concrete, but floating off a footing is super fast and easy.

    I am ex-concrete guy, and flowable fill sounds like a great idea to me, as long as you don't expect it to be perfect.
     
  9. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    Floating off a footing of concrete would be MUCH easier, IMHO, than trying to screed and "float" off a footing of flowable. The water just doesn't hang in the flowable like it does mud, due to there being a very, very, very small amount of portland in the mix.

    Remember, essentially all flowable is, is really, really, really wet sand. Basically what you find at waters edge at the beach. Take that out of the truck (a contained unit where the water HAS to stay mixed with the sand), and put it on the ground, and boom, the water drains out. Wet sand doesn't move very easily.

    Not trying to discurage anyone from using flowable, just trying to make sure everyone knows what they are getting.


    Dan
     
  10. Henry

    Henry LawnSite Senior Member
    Posts: 549

    If I can find a supplier in my area I'll use it for my patio, but will leave room for 4" of qp (3/4-) and 1" of sand. This is the way I was told to do it since it can't be pitched due to the self leveling properties.

    Bigvic, have you ever had a settling issue using the excavated dirt to fill a raised patio?
     

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