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Question on pouring concrete into molds

17 years ago

I've lurked here a while, but this is my first post. I'm considering buying a set of molds on ebay and pouring them to create a patio. Can someone tell me how long they have to set before I can remove the mold and pour more? I'd hate to have concrete set up in the wheelbarrow while waiting for it to set up in the mold.

Any pointers would be appreciated.

Comments (11)

  • 17 years ago

    Grandma, we just finished (last night!) a patio made with the quikrete form that looks like stones. It really is as easy as it says on the package. We were at an advantage in that we have a small electric concrete mixer but mixing the 'crete in a wheelbarrow wouldn't be that difficult.

    In truth, as stated on the package, you can fill the cavities in the mold, pat it down, smooth it out and lift the mold. You will get the consistency for the concrete down pat after about 2 pourings. We figured out how much water it took for a bag of concrete, subtracted just a little to compensate for the humidity (YIKES) and then we were a concrete pouring team. We did wind up using the upper end of the recommended water amount. My husband mixed and I filled the mold. I'll try to send you a picture of ours in process. We used a colorant but you don't have to. We also used the high strength concrete so hubby can drive over the patio with the riding mower. Also, the package says you use one 80 pound bag of concrete per mold pouring but we were able to get about 1-1/2 mold pourings from one bag.

    We felt very proud of ourselves and it looks good. We still have to put either sand or concrete between the "stones" but we can't make up our minds what we want to use.

    Good Luck! This is really an easy proces.
    PS - We are also Grandma and Grandpa so don't think only spring chickens can do this!

  • 17 years ago

    Grandma -- If you're talking about those flat molds that are shaped like rocks or bricks put together in a square, I might be able to help. If you're using the quik-crete that is already ready to just add water, you can make a fairly muddy mixture (maybe the consistency of thick cake batter) and pour it into the mold. I like to do a shovel full at a time and work from one corner clockwise. This way you can use your gloved hands to get the bubbles out. Once full and satisfied with the top finish (ie rounded or flat), then you only leave the mold on for about 5 minutes. If you leave it too long, the mold begins to stick to the concrete. When you remove the mold you can kind of smooth off any rough edges with your hands or a wooden stick.

    I also find that a 60 pound bag of quik-crete makes about 1 & 1/3 molds.

    Hope you and I are talking about the same type of mold and this was somewhat helpful.


  • 17 years ago

    Here is the link to my picture of the patio in the early stage.

    You will have to cut and paste. Only once have I been able to post a picture in a post.

  • 17 years ago

    Carol, that looks REALLY nice. Shari, only 5 minutes?
    Here's what I'm considering:

    The idea is that instead of buying expensive flagstone, I could pour my own (using Quickcrete - can you color Quickcrete?) and then lay them out and interplant with something like wooly thyme.

    We do all of our own landscape work, but I've never attempted something like this. You both make it sound VERY doable. Do I need to coat the mold so that the concrete won't stick to it? Or just not leave the mold on for too long?

  • 17 years ago

    For those kinds of molds you will need a Mold Release and let them cure for about 24 hours then carefully unmold them. I have used 10 parts denatured alcohol and 1 part non-detergent oil for a mold release mixed in a plastic spray bottle but I prefer the Universal Mold Release from Smooth on brand products, aerosol spray. I order mine direct from Smooth On since I use alot of it. If you color your mixture I have used the liquid colors available at Lowes, Home Depot, Menards. I mix a certain amount in my water before I mix it in the dry mix to get a more uniform color through out the pour, just remember how much you add each time.
    I also have used the form for a Cobblestone design, poured it , put small pea gravel in it and then lifted it off.
    Tried to put a picture link in but for some reason it wants to reject it.

  • 17 years ago

    Grandma, we did not use any kind of release agent with the Quikrete mold. Quikrete sells liquid colorant in several different colors - terra cotta, red, buff, charcoal gray (I think). The instructions say to use 1/2 bottle of colorant per bag of concrete. This worked well for us. And it is better to dilute the colorant before adding it to the concrete. Be sure to take into account the water used for the colorant as part of the total water added.

    After discussing the project last night, we are going to use sand topping mixed with dry colorant to put between the stones. Because of where this patio is, it needs to be very stable. However, I love your idea of the thyme!

    The molds on eBay look nice but I think you would have to have a release agent and you would have to let the concrete set up before you removed the mold. So the finished product would take a while. I have molds from eBay and they have held up well. I even have one that is a flagstone design! But the concrete has to set up in the mold before I can use the flagstone.

    If you feel artistic, someone mentioned to me that you could probably take dry-cleaning bags and lay them on the surface of the Quikrete "stones" (after removing the form) and sort of get the look of flagstone. I didn't try that. I just patted the tops of mine with my rubber coated garden gloves and got a texture that suited us.


  • 17 years ago

    I've been using a walkmaker mold. Picked it up at Lowe's but HomeDepot and other places sell them too. It gives good directions with it. I don't use any release agent. Just mix up the crete per directions that usually come with it (comes out pretty thick) put in into the mold, smooth it out, wait a minute or two and lift off and do your next one. I'm enlarging my back patio by going around the existing 10 X 16 pad with this. I plan to stain all with brush on concrete stain when I'm finished. I can only do a little at a time as I have a bad back and have to limit myself on this kind of work. But its really very easy and the ending results are very nice.

    Good Luck

  • 13 years ago

    I have just bought a rubber mold for concrete and i want to make a mold do i have to spray it before i pour it and what do I use

  • 3 years ago

    I am using 1 part castor oil to 8 parts denatured alcohol in a spray bottle as my release agent for concrete in molds. It's working very well.

  • last year

    I have a plastic mold & found out from that a concrete mold release agent or a cooking spray like Pam works well. The cooking spray keeps your molds cleaner. You do not need to use a lot, just lightly spray the mold. Do NOT use a petroleum based spray like wd-40 this will eat into the plastic molds. They also advise How long to I let my pieces set in the mold:

    If using a fast setting concrete a couple of hours is good. If temperatures are cool then 3-4 hours is best. If using a regular setting mix, 24 hours is best, or if temperatures are cool below 50 degrees you should let set at least 48 hours.

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