DIY concrete countertop mix

[cshaw]

I’m planning on building an outdoor kitchen in the future with concrete block (stucco finish) and concrete countertops.  I’m currently building some concrete benches in my backyard and want to experiment with the same concrete mix I’ll end up using for the concrete countertop.  Both Quikrete and Sakrete make a concrete countertop mix, but they are not available locally (might be able to order them through HD/Lowes).  They are also very expensive.
I’ve been looking online for a DIY mix and have a recipe I may go with.  I’m wondering if anyone here has ever done a DIY concrete mix for a countertop with successful results.  If so I’d be interested in hearing what your DIY mix consisted of. 

Thanks.

[Glenstache]

I have not been through the whole process, but did help a friend for an afternoon... with very poor results. He used 5000 psi quick set mix, added fiber reinforcer, and added color mix. Here's the problem: the color agent also doubled as an curing accelerator resulting in about a half batch of concrete fused in place inside the rented mixer. Mucho bummer. He later mixed with a regular set high strength concrete, fibers and color and they turned out great. I would recommend mixing up a  small half gallon or so of your DIY recipe, do some slump tests on it and work with it so that you get a good idea of the handling characteristics and if your proportions need adjusting before doing a full slab.

[Spork]

My nephew-in-law (is that a real term?) has done this successfully.  I'm not sure what he did, but I can tell you: he spent almost a year experimenting in the back yard with various mixes, various sprinkled chips and building extremely exact forms.  He did not pour it in place.  He made slabs and carefully transported them inside (with lots of friends).

[zolotiyeruki]

My nephew-in-law (is that a real term?) has done this successfully.  I'm not sure what he did, but I can tell you: he spent almost a year experimenting in the back yard with various mixes, various sprinkled chips and building extremely exact forms.  He did not pour it in place.  He made slabs and carefully transported them inside (with lots of friends).

I've never heard of anyone pouring it in place.  I thought the point was that you pour it upside down on a very smooth surface, so that when you right it, it looks pristine.

[Bob W]

There are some great books on this on amazon.

[Spork]

My nephew-in-law (is that a real term?) has done this successfully.  I'm not sure what he did, but I can tell you: he spent almost a year experimenting in the back yard with various mixes, various sprinkled chips and building extremely exact forms.  He did not pour it in place.  He made slabs and carefully transported them inside (with lots of friends).

I've never heard of anyone pouring it in place.  I thought the point was that you pour it upside down on a very smooth surface, so that when you right it, it looks pristine.

Exactly what he did... I think he used melamine for the forms.

[cshaw]

Great information folks; I appreciate it.  I am actually going to pour in place using forms from http://concretecountertopsolutions.com/categories/edge-profiles/. 
The mix certainly needs to be "flowable" to achieve a nice smooth finish.  I fully expect some sanding/buffing will be required to achieve the finish I want.

Thanks.

[nereo]

There are some great books on this on amazon.

Bob W. - is there one in particular you'd recommend?  I'm thinking of making a concrete counter-top as a fun summer project.

otherwise... posting to follow...

[Papa bear]

I built a concrete countertop for a kitchen on a rental with my dad a few years ago.  Quick rundown of that story and my takeaways.

- poured the concrete on site and finished in place
- used 1/2 backer board on top of cabinets for a base
- built edge and sink cutout with melamine board and caulk (what a PITA)
- used quikrete 5000 mix (has fiberglass support) and added a few shovels of cement (quikrete tends to run light on cement and too much aggregate)
- additional support with screws into the backer board and tie wire criss crossed
- mixed in a wheelbarrow with a liquid coloring agent (added to the water and mixed with that first)
- mixed on the dry side (too much water and you'll crack)
- poured in place (more like shoveled), vibrated with a putty knife with small hand sander on handle
- screed and finish with float
- every 30 minutes or so, re trowel with stainless steel blade
- repeat until glass smooth and starting to set.
Total build time for complete noobs - 12 hours, material cost approx $200

Pulled the forms off the next day, color was not even, and edges weren't smooth. Sprayed on coloring agent with water and wiped with microfiber (2-3 times) until color took evenly. Small batch of cement with color and used a putty knife to fill in edges. Let cure another day. Bought finish, applied sealant finish, then apply wax finish.

What I learned when I found the concrete supply house for the finishing agent:

- buy the premade edge forms!!!!
- build your own concrete mix, add fiberglass reinforcement separate (you can mess around and use fancy aggregate to get better colors, textures, etc)
- pour in place, use chicken wire as additional reinforcement (set wire on screws from backer board)
- purchase a "plasticizer" for part of the liquid.  The concrete will cure faster and it does NOT shrink when it dries.  This will make the continually troweling of the counters work a LOT faster
- mix coloring agent more completely (potentially rent a small mixer)

Go find a concrete supply house and ask a lot of questions.  I learned more from them in 15 minutes than I did from hours of online research.

[cshaw]

Great stuff Papa Bear, I appreciate the post and level of detail.  My Z Countertop forms arrived today so I'm excited for my days off to pour my benches.  Your concrete mix sound really similar to what I'm planning on going with.  This will be a fairly small pour but good practice for the outdoor kitchen I hope to start this summer.  I'll be sure to update with my exact mix and results when I get done.  Here is my before shot of where I'll be pouring the benches.

[MrSal]

ive seen those Z Countertops they look nice indeed!

I may go that route on a fuuture date. As of now, Ill only be doing an overlay concrete over a laminate countertop to see how it goes. If it goes wrong i may go the full concrete countertop!

[DaveO]

I used the Z Counterforms to pour my kitchen island and wall countertop a few months ago.  I use the Quikrete Countertop Mix that came in a Blue bag (~$15ea).  I decided to use that over the Z liquid flow because shipping all the additive, mesh, clips, etc. seemed much more expensive than picking up conventional reo.  The countertop still turned out well, but I had a hard time finishing it smooth because of my lack of experience.

I think you'll learn a lot pouring the benches, but I would give a second thought to using the flowable mix additive that they sell.  It would really make a much more uniform color and make the finishing easier on a beginner.

[dave__]

Check out this thread on another forum:

http://www.avsforum.com/forum/15-general-home-theater-media-game-rooms/1151574-making-concrete-bar-tops-7.html