Flowable fill

Discussion in 'Hardscaping' started by neversatisfiedj, Jul 28, 2007.

  1. neversatisfiedj

    neversatisfiedj LawnSite Bronze Member
    Posts: 1,028

    Anyone ever use it for a landing ? Kind of pricey at 145/yd. But you ,make up for it with compaction assurance and speed of installing it.
  2. ChampionLS

    ChampionLS LawnSite Bronze Member
    Posts: 1,066

    Make your own!. Get a cement mixer (rental) and make a slop mixture of Portland/concrete sand. I've used a ratio of 1:10. It will solidify enough to avoid any settling, and if you had to cut or chip through it, you can easily do it with hand tools. Give it a shot.

    Heres some info on Flowable Fill:

    Coal fly ash can be used as a component in the production of flowable fill (also called controlled low strength material, or CLSM), which is used as self-leveling, self-compacting backfill material in lieu of compacted earth or granular fill. Flowable fill includes mixtures of Portland cement and filler material and can contain mineral admixtures, such as fly ash. Filler material usually consists of fine aggregate (in most cases, sand), but some flowable fill mixes may contain approximately equal portions of coarse and fine aggregates.(1) Fly ash has also been used as filler material.
    The desired range of compressive strength in flowable fill mixtures depends largely on whether or not the hardened material may have to be excavated and removed at some future time. If removability is necessary, the ultimate strength of flowable fill should not exceed 1,035 kPa (150 lb/in2) or jack hammers may be required for removal.(1) For flowable fill mixes used for higher bearing capacity applications, such as structural fill or temporary support of traffic loads, a greater range of compressive strength mixtures can be designed.

    Flowable fill is considered a controlled low strength material by ACI as long as its compressive strength is less than 8270 kPa (1,200 lb/in2).(2) In higher strength applications, the strength of flowable fill mixes can range from 1380 to 8270 kPa (200 to 1,200 lb/in2), depending on the design requirements of the project in question.

    There are two basic types of flowable fill mixes that contain fly ash: high fly ash content mixes and low fly ash content mixes. The high fly ash content mixes typically contain nearly all fly ash, with a small percentage of Portland cement and enough water to make the mix flowable. Low fly ash content mixes typically contain a high percentage of fine aggregate or filler material (usually sand), a low percentage of fly ash and Portland cement, and enough water to also make the mix flowable.(3)

    There are no specific requirements for the types of fly ash that may be used in flowable fill mixtures. "Low lime" or Class F fly ash is well suited for use in high fly ash content mixes, but can also be used in low fly ash content mixes. "High lime" or Class C fly ash, because it is usually self-cementing, is almost always used only in low fly ash content flowable fill mixes.(4) There is also a flowable fill product in which both Class F and Class C fly ash are used in varying mix proportions.(4)
  3. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    I think flowable fill would be great for a large, raised patio.

    But the drawback is - you need to be able to get the truck right to the area where you're working. It's more money - but will save on labor.

    ICPI has a feature in their latest magazine featuring flowable fill.

    One drawback is - it's suggested to pour the fill in lifts and let it set up. That kinda defeats the purpose!
  4. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    Then there is no benifit. I have not built any large raised patios yet, but when i do i will just rent a trench compactor and do 12 inch lifts.
  5. neversatisfiedj

    neversatisfiedj LawnSite Bronze Member
    Posts: 1,028

    This is not a large project at all. It is a landing with 3 steps. The landing is only 18 inches off the ground. The landing only measured 7' x 7'. I will just fill with road base and compact with a jumping jack. I'm just afraid the jumping jack will not my block out of whack when tamping.
  6. ChampionLS

    ChampionLS LawnSite Bronze Member
    Posts: 1,066

    If you can't get the truck to the patio, but you have a skid steer or loader, just fill up the bucket and make the trip. Two guys with wheelbarrow's will work too on a smaller job. I doubt any job is really that out of the question for accessibility.
  7. ChampionLS

    ChampionLS LawnSite Bronze Member
    Posts: 1,066

    I wouldn't use a jumping jack. That's way too much compaction. You can easily blow out the sides or push your steps forwards. I would use a good hand tamper and do it in lifts, or if you must use the jumping jack, GO EASY!
  8. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    Matt - Try using your trench compactor next to any wall block! You will spend more time tearing down and rebuilding than anything. We have priced out FF on many jobs of various sizes, and the only ones it makes sense on are the small ones. The price of aggregate is extremely cheap where we are and it just does not pay to use the FF.

  9. neversatisfiedj

    neversatisfiedj LawnSite Bronze Member
    Posts: 1,028

    FF is 142.00/yd here in MD.

    Will hand tamping really work ? I don't think you can get enough force with it.
  10. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    Use clean aggregate as fill, then put down geo-textile and a small lift of tamped/compacted roadbase.

    Flowable fill here is around $60-70/yard, IIRC. Road base runs about $4-5/ton picked up at the quarry. You don't save money on the material by any means. Where you save it is on the labor and opportunity costs associated with the extra time involved with compacting gravel in lifts.

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