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  1. #1
    The Voice of Reason
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    making rocks with concrete

    we have no rocks. i thought about getting some bags of concrete and making a rock garden. just place the bags and wet them down. have any of you tried that? is there a better way?
    I'm never gonna be a Rock Star

  2. #2
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    faux rock.

    i was going to make this feature with it but we had enough real material left.

    the process is to use huge chunks of styrofoam, carve them to the shape you want, then texture in a layer of concrete. i'm fairly certain you have to add some kind of support in the form of wire mesh to prevent cracking, and there is a process of texturing the outside of it to make it look like a real rock using rubber mats and non stick powder.

    Never got into the process deep enough to help you out more, but that's the basic jist.
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  3. #3
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    . . .knock down your neighbor's chimney and use the busted stone/bricks. . . okay, okay, maybe something a little less crass (sheesh, I could've suggested the head-stones at the cemetery. . .) It seems logical that if there are any buildings coming down in the 'hood, that there'd be some chunks of the old foundation in there too. . . um, just watch out for the re-bar. . .

  4. #4
    ^ That's what I do
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    Go down to a local quarry and ask them for rocks. They'll be happy to get rid of a pickup truck full. My dad did this when he landscaped our yard. He gave the owner a 6-pack of beer to say thanks.
    '08 Specialized Rockhopper 29er (modified)

  5. #5
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    How about taking a section of rough ground and dig some small holes, leave the dirt loose on top but real irregular, pour a section in a manageable size, and flip it over and place it where you want it, do another similar but different section and place it next to the first and so on. The loose dirt will embed itself into the concrete and look somewhat natural. Embed smaller natural rocks to keep it local looking. We've had to do this with some steep fall line sections of older trails to keep them somewhat sustainable. It eventually looks like concrete and you can just wet bags of concrete and strip off the bags and put a little texture as they go into final set or put a stucco like texture on them when the concrete is very freshly set. We have even dry mixed concrete into sandy soil and tamped the trails and waited for rain to kick the concrete mix later. It helps some, but the mix has to be deep and thick or a thin crust will easily break up and disintegrate.
    You can hand form concrete into rocks if you mix it stiff and build it that way. Use gloves and eye protection as the cement (lyme) in the concrete mix is caustic to skin and eyes (and lungs,too). Be artistic....landscapers do it all the time. You don't want to build sidewalks though.
    IF YOU CAN READ THIS, YOU'RE NOT RIDING (or building)!

  6. #6
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    Why do you want to make a rock garden?

    Most mountain bikers avoid rocks and roots and make the trail wider in the process!

    JK! NOT!

    Do a fundraiser and buy a truck load of rocks. Concrete may not be an approved building material in some forested areas because it can change the ph of the surrounding soil.

    However, check out the cool faux boulders they build at your local zoo. They use ferro cement sprayed over metal grid forms.
    Michael Vitti
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  7. #7
    The Voice of Reason
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    i've got one of those bags of concrete that has been sitting in my back yard for several years and looks like it would be great for a small rock garden. however the thought of dragging 80lb bags of concrete into the woods (or a truckload of boulders for that matter) has nixed the idea. that pH thing is something to consider. i'll just stick with log crossings.
    I'm never gonna be a Rock Star

  8. #8
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    Rock work is a pain in the ass, but there is no other natural surface that holds up better.

    Many many times you can harvest rock from somewhere around the trail.

    Any rock work you do on a trail takes hard work and time, but the payoff, is it basically lasts forever.
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  9. #9
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    Sidewalk!

    We're gonna buggie in chunks of sidewalk and flagstone with it -- upside down/rough -- on Saturday. I'll post some pics...

  10. #10
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    Quote Originally Posted by Skookum
    faux rock.

    i was going to make this feature with it but we had enough real material left.

    the process is to use huge chunks of styrofoam, carve them to the shape you want, then texture in a layer of concrete. i'm fairly certain you have to add some kind of support in the form of wire mesh to prevent cracking, and there is a process of texturing the outside of it to make it look like a real rock using rubber mats and non stick powder.

    Never got into the process deep enough to help you out more, but that's the basic jist.
    Thing is, it's still styrofoam underneath. It'll be soft. I've used a similar technique to build backgrounds for fish tanks and vivariums in the past.

  11. #11
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    photos, as promised



    One of four armored sections; click through for many more shots...

    Note that the limestone resting on the high ground is not the material we embedded; the 'flagstone' was ~8" thick concrete slab, broken with a sledge and buried to grade.

  12. #12
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    Quote Originally Posted by fully
    One of four armored sections; click through for many more shots...

    Note that the limestone resting on the high ground is not the material we embedded; the 'flagstone' was ~8" thick concrete slab, broken with a sledge and buried to grade.
    Ok i wasn't sure of the application. Again if you look at the link i provided above. At the base of the feature are what are called Turfstone Pavers. For the park we purchased a pallet and the cost was cheaper than if we built a form and bought concrete to make our own.

    If a club were to have a bunch of these at their disposal, it makes for quick work on that kind of trail application.

    The link again....

    http://farm4.static.flickr.com/3110/...28e5d3.jpg?v=0
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    ~....|....\
    ...~.|.....\
    ....~|____\
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    .\....FAILBOAT..../

  13. #13
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    We've been using some Z-brick in sandy stuff and where we run into our black muck, pure organic tire stealin' stuff we have here in the lowlands and almost always in the Malelueca tree groves we have here. Other parks are allowed to use wood to get up and over that stuff, but we currently are not allowed to build with wood at this time.
    IF YOU CAN READ THIS, YOU'RE NOT RIDING (or building)!

  14. #14
    The Voice of Reason
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    Quote Originally Posted by Skookum
    Ok i wasn't sure of the application. Again if you look at the link i provided above. At the base of the feature are what are called Turfstone Pavers. For the park we purchased a pallet and the cost was cheaper than if we built a form and bought concrete to make our own.

    If a club were to have a bunch of these at their disposal, it makes for quick work on that kind of trail application.

    The link again....

    http://farm4.static.flickr.com/3110/...28e5d3.jpg?v=0
    turfstone is wicked if you fall on it. i like the cobbles though.
    I'm never gonna be a Rock Star

  15. #15
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    Go to your local Home Depot or Lowes and ask for retaining wall scraps...many times the prefab concrete rock they have will have pieces broken off and therefore they can not sell. If you tell them what it is being used for I'm sure you could get a donation.
    MTOBikes.com

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  16. #16
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    We were lucky on the job fully posted and had a lot of the materials donated. The concrete came from the city in large slabs. No rebar in it or anything. A few hits with a sledge and it was broken into usable chunks.

  17. #17
    Dream Design Dig Repeat
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    Quote Originally Posted by Megashnauzer
    turfstone is wicked if you fall on it. i like the cobbles though.
    Uh, yeah. I found that out at Colonnade on Sunday. Actually was only my second time back there after we finished construction and the place was mobbed with people. It should stay very busy now that the rains have hit (and hit hard).

    I hope we only use Turfstone for takeoffs on jumps in the future. Nasty on landings, but was the only affordable option at Colonnade where every inch of trail had to be armored.

    We did a few rocks using the method Skookum mentioned, and will probably do more biggish slabs at our next project, Duthie Hill. Expanded metal lath makes a good reinforcement - but whichever creative method you use, definitely make sure it's metal reinforced otherwise it'll fall apart over time (unless of course you use mega thick concrete).

  18. #18
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    Quote Originally Posted by sfuller
    We were lucky on the job fully posted and had a lot of the materials donated. The concrete came from the city in large slabs. No rebar in it or anything. A few hits with a sledge and it was broken into usable chunks.
    It was probably an old sidewalk. That was going to be my suggestion. Works pretty well, doesn't it!
    Texas based trail builders: www.sstrails.com

  19. #19
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    Quote Originally Posted by Megashnauzer
    we have no rocks. i thought about getting some bags of concrete and making a rock garden. just place the bags and wet them down. have any of you tried that? is there a better way?
    You have no rocks? There's millions of them on this earth...and you can't find any?

  20. #20
    The Voice of Reason
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    we actually have rocks they are just veeeery tiny.
    I'm never gonna be a Rock Star

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