Thank you all for your enthusiastic responses! I have opened this discussion by request to openly answer questions about artificial rock construction. As a bonus I will also answer any questions about swimming pools, spas and waterfalls where I can.
Hi Steve, I have a question that's been on my mind for a while. Does this mix perform under water, ie, in a salt-water pool? Or does it need additives in the mix? I'm thinking of building some rock that extends under the salt water, around the edge of my pool, by drilling holes about 4" into the bond beam, and inserting 10mm ( 3/8th") rebar into the hole after putting some epoxy into the hole or onto the rebar rod, building a 'cage' as a form onto this rod, and making the rock over the cage. - Also, it seems that the mix is fairly susceptible to curing problems, is this because of the silica fume or fly ash content, with attendant problems with cracking etc, if not kept moist during the cure? Thanks Steve for this forum for general questions! Stone
The concrete is absolutely fine to use in a swimming pool with a salt water generator. I would put some more thought into your rebar dowels before starting the project. I would recommend drilling them an absolute minimum of 12" and you can use a two part epoxy to solidify them in place, or another option which I recommend is fixing them in the holes with non shrinking grout. NOTE- it must be NON shrinking grout to work.
As for the curing of the cement, I have not yet encountered any curing problems. You only really need to be concerned about cracking during the curing stage if the concrete is sitting in the blazing sun and heat all day - this would compromise the smooth curing of any type of concrete. The additives in the concrete mix outlined in this E-book are specifically designed to reduce the frequency of hairline cracking.
If you would like to expand upon any problems you have experienced with the curing of the concrete I would be happy to try to determine why this is happening for you.
Steve, thanks for the reply to questions. Haven't had problems with the mix curing, as I haven't been able to try the mix yet, still waiting on supply of Fly Ash! It's a different situation here in Australia. Not as easy to get some materials here. I've used Silica Fume, with no problems, but in the recent wet weather here, the SF has started to clump together a bit, probably from the atmospheric humidity. Does this compromise the SF, as absorbed moisture would with cement? Regards, Stone
Hi Steve, sorry, I forgot one question. Is it alright to use hessian (burlap) as the backing instead of diamond lath, if it's not available? The lath is very difficult to obtain here, in OZ. Thanks Stone
You can use the burlap in place if need be but you will need to factor this into the structural equation. The concrete when applied via shotcrete process is forced through the small openings in the diamond lathe, where the burlap simply holds the concrete in place. The advantage being that the concrete envelops the diamond lathe which adds to the structural strength as well as ability to climb vertical surfaces. Since you are applying by using an on-site mixer you should probably not have too much trouble with climbing vertical surfaces as opposed to if you had a line up of trucks spinning cement in a gunite process where you empty the trucks as fast as possible to avoid additional charges. =)
The silica fume should be kept as dry as possible. I have started storing all the powders in sealed buckets. The climate here in Vancouver BC is famously moist so this is also an issue here.
If you were building a bridge or high-rise then the silica fume would be considered comromised. Otherwise, I would use it anyway so long as it still will reduce to powder properly in the mixer. The strength of this concrete mix is so incredibly overkill that you will not experience any appreciable loss in preformance.
The fly ash is available already and I have a n entire shipping container full and ready to go out...that being said shipping this to OZ will be pricey as the fly ash is dense and heavy (at least you don't need much). Send me an email and we can talk about the details of how to get it there.
Cheers.
Steve Goodale ArtificialRock.ca 1-888-267-0802 info@ArtificialRock.ca
Is the ebook mentioned above available or are you referring to the Article link on the site?
In the article you mention adding glue to the slurry mix, what type is it?
Apart from possible local authority requirements (ie. rebar), is styrofoam only feasible for smaller rocks or can it (large solid blocks) be used instead of rebar for larger formations? These formations, eg. waterfall (2mx1.5mx1.5m) or larger rock formations (eg.rock wall), would only be supporting the concrete shell and water ,in the case of the waterfall. No animals or people would be climbing these structures.
How soon after creating the rocks/waterfall,etc does one have to apply the coloring? Can you complete the entire rock feature and then say a month or 2 later apply the coloring or does it have to be done before the concrete has fully cured?
Shotcrete was mentioned in the Structural forum I think, is it necessary to use shotcrete or can one just use concrete? I'm sure most DIYers that will be doing home projetcs cannot afford the expense of shotcrete.
The article is the same as the E-book. Call it what you will ultimately it equates to a free online resource dedicated to growing the knowledge of DIY's in the field of artificial rock construction.
The glue mentioned in the slurry mix can be one of two kinds. You can purchase a concrete specific product sold under many names such as "weld-bond". One look (and smell) of the product clearly shows that it is regular white wood glue - or at least a very close relation to regular wood glue. For DIY's I recommend using any regular wood glue in place of the concrete specific version. I have done multiple real life tests using both products and the results are neglidgable. Save yourself some money and raid your childrens "arts and crafts" materials for wood glue. =)
In regards to the shotcrete....a typical shotcrete order of concrete is fiber reinforced small aggregate (sand and birds-eye) concrete which is typically around 35 Mpa. You will usually find fly ash in this mix as well. The important feature of the shotcrete process is not the concrete itself - it is the method in which the concrete is applied to the form structure.
Imagine building a swimming pool. In the "olden" days concrete workers applied the concrete to the vertical walls with a shovel and a flick of an extremely stong wrist. If you are able to muster enough labor to apply your concrete in the same fashion then you don't need the shotcrete process. Be warned though that the shotcrete may be expensive, dangerous and incredibly tiring work, but applying with shovels will dramatically slow down your construction and reduce your overall effeciency in building up any vertical surfaces. If you are building a small to medium sized project in your own back yard and have a few strong friends willing to help - go for the old school shovel approach. If you are building a larger project, working with a timeline or are building these projects as part of your buisness - definitly set your crew up with a small shotcrete operation. An investment in materials and training will pay off in the long haul if you plan to build a lot of artificial rock.
In regards to painting - You can paint the artificial rock at any stage you want. In fact it is slightly to your advantage to wait a minimum of 30 days after sculpting the concrete. If you try to paint too early, the concrete is still pulling in moisture and this will definitely affect the application of water based paints. It will be harder to get a specled look to the finished product as the concrete will cause the paints to all blend together.
I wait 30 days as the minimum, and there really is no disadvantage of waiting even longer to paint - PROVIDED that you make sure the rock is 100% clean and ready to be painted. In a situation where you wish to paint something that is really old or previously weather protected you should give the entire piece a diluted muriatic acid bath. 10-20 parts water to every one part muriatic acid...and don't even THINK about working with muriatic acid without wearing approved chemical resistant gloves up to your armpits, an approved charcoal ventilation mask and nice clear protective goggles. Muriatic acid is no toy and generally not available to DIY's. That being said most DIY's have a way of finding these products that they should not technically be allowed to purchase without proper paperwork and registration.
In regards to your question about the styrofoam being used for your waterfall form, sure you can do this if you want. The disadvantage being that you will certainly lose longevity in your piece. An artificial rock with a structural form will outlast a styrofoam based rock and you also accept the liability of underbuilding the structure assuming that people / animals will not be climbin on it.
It is a judgement call that you will need to make - but to be honest I imagine that building something with the dimensions that you specified out of styrofoam would likely be MORE expensive than building it correctly with a concrete "footer" and a grid of 10 mm rebar as the form skeleton.
Please feel free to expand on your project and I would be happy to help if I can.
I'm still in the planning stages of how we want our garden to look, been for the past month, and I'm not sure how much longer it'll take as I have 2 branches of my current business to run with a possible 3rd opening soon and like most DIY's I have lots of other cakes in the oven.
Oh, and of course I'm waiting for your DVD before I start anything serious.
How exciting! I would love to have a fresh palate with a backyard for myself again. I would definitely go with a 3/4 grotto encircling a hot tob as the main feature. You can extend the sides of the grotto to create a retaining wall to change elevations in the backyard. This would make it easy to have a waterfall - and of course a stream...some stepping stones that look like tips of huge granite boulders just protruding from the surface of the ground leading around the garden...ahhhh.
Why stop there...beach entry 3 sided negative edge pool with an L shaped area to one side equipped with 5 HP swim jets. Floating island in the middle equiped with bar and stainless steel BBQ and underwater stools surrounding the bar on the deep side.
What else...a waterpark for the kids...random action floor jets, big splash waterfall onto the deck which drains into an isolated closed water loop. I also am a huge fan of big, obnoxious art. A giant moai head - 6 feet tall, or a giant fish sculpture or a huge tribute to stone henge something...
SO many things to build and so little time =). Keep me informed as to how the project develops. I would be happy to help in any way I can.
This is a hobby that fascinates me. I have worked with real stone including building a drystack farmer's wall. I find myself studying wall construction everywhere I go, comparing it to mine. I guess you'd say I have the bug. Now that I've become more aware of hypertufa, I'm anxious to discover its possibilities. My first project will be a weathered granite hitching post. I'm torn between using a mold (coffin style with lid) or a styofoam form wrapeed around a 4"X4" post. I have seen several suggestions for a granite type tufa mix (all different of course) so I would really appreciate some advice on this project from you veterans. Thanks in advance! ~ Bob
Hello Group, My name is Paul and I just joined. It has been such a pain trying to sign on and the problem is now solved, I hope. ;-) So this post is to say "Howdy" and to run a test to see if I can post. ::crossing my fingers::
I'm just reading thru to get caught up and thought I would make a couple comments.
A guy I took a class from on rock making is having one this weekend and asked if I would bring my variac, hot wire and some styrofoam over to demonstrate cutting and shaping the styrofoam. I figure why not as I can sit thru that class and one on painting with acids for free as an exchange. ;-) Any questions I have there I will also ask here.
Shotcrete: This person having the class showed me a tool that looks like a poormans shotcrete set up but I will ask more questions for clarification.
As a unit the handle is attached to an air line with an off/on valve. The handle is about 3' long. At the end is a rectangular box of stainless steel that has a rectangular base about 8"x 1'. The sides come up about 1' and slightly angle out. The handle enters the holding chamber at the bottom center of one long side and there are five 1 1/2 dia holes equally spaced along the bottom of the other long side. I will double check on these dimensions as I saw this a year ago. You fill with the cement, a rather thin mixture it appeared and turning on the air, the cement was blown thru the holes onto the rock shape.
I didn't think the volume held was large enough, it blew thru so fast, but it did a great job. The compressor was average pull around size.
I will take another look and ask questions in case someone might be interested.
Hi Steve, been looking at the forum, and the e-book, and noticed something. The magnet to this site, the article, and the forum, was initially the pics of the fantastic work you posted in various places. I haven't been able to get those old links to work again, and I assume others have experienced the same. I'm wondering if you could post pics of other work you've done, as well as some of the original pics you posted, here on the site. It's the pictures of completed work, and stages of construction that really fuels the imagination, and the desire to try the same thing. Thanks again Steve, Stone
Steve, just got back from a big job, and got a chance to quote a job for a couple of waterfalls on another job. The question re. this job is, if I am bridging the artificial rockwork across from a large chunk of 'bedrock' and onto a 1yrd3 boulder, and another one beside it, sitting on the ground, do I lay a piece of reinforcement mesh down the face of the bedrock and onto and across the boulders, in case there is any movement with the boulders settling in the future? Also, do you have other moulds in the works, as the artificial rock face is in total, about 8ft by 20ft? I thought it would be better to have another mould to vary the texture/pattern, so as to avoid repetition to the observer. The job isn't for another 4mths or so, but my quote ( bid) is due in two weeks. I thought to have the base coat shot-creted, but it's in an inaccessible spot on the waterfront. Thanks Steve, Stone
Do you have any pictures - I do ot fully understand your question. As for "inaccessable" for the shot-crete....pish posh...there is always room for shotcrete. You would not believe some of the INSANE shotcrete's I have done. One notable one hanging from a harness 100' down a cliff face shooting along the shoreline during low-tide. Not really recommended but we got it done.
As for texture mats I can provide basically anything you need. If you know what you are looking for just let me know. Otherwise I recommend using the texture mats in combination with sea sponge and hand sculpting. If you are careful you will not be able to see any repeating pattern especiallly if you are handy with the hand sculpting.
Cheers.
Steve Goodale www.Artificialrock.ca 1-888-267-0802
Hi Steve, I'm trying to work out how to post a picture of the job-site so you can get an idea of what I'm talking about, but I don't know how to post the pic. I'll try and find another email address on the site to post the picture to. Thanks, Stone
Attaching Metal Lath to Concrete Wall. HI Steve, wondering about attaching metal lath to concrete wall at heights of about 10 to 12ft. Would you fire a pin ( nail) into a clip or bracket, for adequate strength to hold the lath and the weight of the concrete mix, and a rebar cage drilled and epoxied into the concrete? This configuration for about a 4" thick rock wall up the concrete, making a water wall. Is there any additive suggested for the mix to make it stick better to the vertical face? Thanks in advance for any information, Stone
I was spraying (shot-crete) a 30' tall waterfall that had much the same construction as you have described. A rebar skeleton epoxied into a vertical concrete wall. We used stucco lathe as the backing for the form and tied extensively to the rebar grid.
We also used 2" reinforcement mesh on the face of the rebar skeleton to give the concrete a lot to hold on to while climbing vertical surfaces. The climbing was not a problem at all. We did not have a single area of concrete fall down during the process - best case scenario.
The problem became apparent as we neared the top of the structure. We had installed rebar dowels in the concrete wall to hold the entire structure in place and tied these in with the main rebar skeleton. The enormous weight of the wet concrete was enough to begin pulling out the rebar dowels. We stopped the process immediately. This was a particular safety concern as we were standing on the structure as well to be able to shot rcete the top portion. We were basically done anyway, but what a scare seeing those dowels start to move.
My recommendation is to go HEAVY on the dowels and be sure to sink them a long way into the concrete. I would also recommend to angle them upwards to have gravity assist with holding the structure in place. Remember that you will likely end u pwith more weight that you anticipate when climbing vertical surfaces.
I would also like to point out some other important information:
We used shotcrete for the entire waterfall structure. We did this to provide uniform strength for the entire piece - but most specifically the waterway. You can not afford to have any cold joints or thin areas where the waterway will be - or even a few feet on either side of the waterway as the water will often leech through the concrete.
What this left us with was a rough coat. (very minimal wood floating after spraying to get it into the basic shape we were building)
The sculpting process involved a different mix of concrete (as opposed to the shotcrete mix) which was done 100% in a concrete mixer on site and hand applied over the rough coat and sculpted.
In addition to this we also plastered the waterway area using a dense concrete / powderized crystal mix and used a swimming pool waterproofing technique called a "hard trowel" to ensure the entire waterway would not leak.
As opposed to the hard trowel, you could also use polymer or torch-on waterproofing agents (messy) or a liner / membrane on the waterway (cumbersome)
FYI- the hard trowel technique is not something I recommend unless you have this specific experience. Basically you towel the cement while misting with water after it is almost completely set up. You draw a steel float on edge with a fair amount of pressure and the concrete will raise the water to the surface and finish to a polished smooth texture.
Its much harder than it sounds. If the concrete is left too rough in any areas the water will penetrate too easily and become a problem.
If I was not able to do a hard trwel for the waterway, I would probably recommend adding a membrane over the waterway area after the initial concrete application, but before the sculpting coat is applied.
If you have any questions or need some clarification please let me know.
Cheers.
Steve Goodale Green Pools www.ArtificialRock.ca www.GreenPools.ca 1-888-818-POOL
sorry i posted a new discussion, then realized it should have been here
i am a novice, i have just made my second rock, i used the brown stucco mix, quikrete, i am sure that this is fine for nonstructural rocks for accent pieces. i have found that the workability is ok. once i start getting better, i will try a small structural waterfall. so for the question, if i build the skeleton as you say with the rebar, lathe and chicken wire will the stucco mix be ok. the only reason i ask is due to the inability to find some of the materials for your cement mixture. if not stucco what other premade mixes will be suitable. the brown coat stucco is conveinent, just add water and it is already brown in color. thanks for your comments and suggestions,
what kind of liner/membrane to use, a simple pond type liner?
how would the sculpting coat adhere to the liner/membrane.
is it advisable to incorporate natural rock into the artificial rock, the only problems i could think of is weak joint b/w rock and concrete where water could leak through. would a water sealer fill this void adequately. if so could you suggest a brand to use. thankyou, your information is greatly appreciated.
are there any weight concerns to adding a waterfall to an existing pool slab?
Just wanted to jump in with a response here and let everyone know the artificial rock tutorial, website and this forum are still active. I just dont have the time like I used to for updates but you can reach me via my current business contact information:
Steve Goodale www.GreenPools.ca 1-888-818-POOL greenpoolscanadaATgmail.com