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bbaker6212
03-23-2004, 04:33 PM
According to Quikrete their "precision" non-shrink grout can be used for concrete contertops. Anyone have experience with using this stuff for counters?

http://www.quikrete.com/images/prod_1585_00.gif
http://www.quikrete.com/catalog/Non-ShrinkPrecisionGrout.html

DO-IT-YOURSELF
CONCRETE COUNTERTOPS

http://www.quikrete.com/inside/release_111903countertop.htm

Sponsored Links


bbaker6212
03-23-2004, 04:35 PM
FYI, I started a collection of links and info on CC countertops.
I'll clean up the list and make if easier to read/use later.

http://concrete-counters.blogspot.com/

If you know of other good sources of info, point me to them, and I'll include them in the page.

bbaker6212
03-23-2004, 04:45 PM
btw, what is "water reducer" ? I mean the description is obvious, but what is a good brand and where are guidlines for it's use?
ie, when you should use it and in what quantity?

kemguru
03-24-2004, 08:03 AM
Hi Baker :)

Some non-shrink grouts are an excellent choice for counters. You can play with some reducers, but non-shrink products typically are ready to go without any tweaking. ;)

If you want to mix from scratch, check outů

http://www.fritzpak.com

Reducers/plasticizers are different. Follow the manufacturers directions until you get the hang of it. Then you can play. :D

ejdisbrow
03-24-2004, 09:15 AM
We used the Quikrete non shrink precision grout for our concrete countertops and followed their directions. We have now torn them out and are replacing them with granite.

We had problems with the nonshrink grout. It formed bubbles within as it dried and the bubbled then shattered and left big voids in our countertop. Quikrete would not acknowledge at first that the mix could have been bad but came out and looked at it and refunded out money for the grout. We lived with them that way for two years and now are replacing them.

My husband has made two other countertops out of regular concrete that turned out fine.

FYI

bbaker6212
03-24-2004, 12:18 PM
ejdisbrow, what concrete did your husband use?

I talked to Fritzpack (Gabriel the president actually) about their CounterFlo "Countertop Admixture" specifically made for countertops.

http://www.fritzpak.com/news/ct_press.html

His recommendation:

1. Supplement 10 lbs of Portland cement for each 80 lbs bag of premixed concrete (he mentioned no brands/types).

2. Use 1 scoop (2 oz.) of CounterFlo per bag of concrete, or for every 20 lbs of cement.

So given recipe above it would be 1.5 scoops (3 oz.) of CounterFlo per batch of above.

CounterFlo is $45 per per 8 lb container. This is 192 ounces, enough for 63 batches of above recipe!

bbaker6212
03-24-2004, 12:28 PM
I have an ongoing (but messy) blog to keep track of my countertop research...

http://concrete-countertops.blogspot.com/

If you know of other "kernels" of wisdom, let me know and I'll add them to the blog.

bbaker6212
03-24-2004, 03:49 PM
I spoke with a Quikrete sales rep about the "bubbles" problem.
He said this can happen if you use an electric mixer (paddle) at too high a speed it will put air pockets/bubbles into the mix which can rise and/or coalesce at or near the surface. The solution is to mix slowly and tap edges of bucket to release air.

He knew of several people who had success with their grout. OK, so he's not completely unbiased ;-)

rbatten
03-24-2004, 04:57 PM
I know the subject is CC countertops, but a much better solution is to use exopy resins. They form a solid surface that is not pourous and wont stain or discolor. I will serch for the links and post them.

It took a while to find but here is a start.

http://www.epoxysystems.com/terrazzo.htm

bbaker6212
03-24-2004, 05:48 PM
I could be mistaken but I think it would be too expensive - unless you mean to just put a top coat of epoxy on the concrete which I think is fairly common practice.

Also, the site says it's for 1/4" to 3/8" thickness which is a different look from the 1.5" of concrete.

rbatten
03-24-2004, 06:18 PM
Yes, you put it on top of a base, be it concrete or mdf, plywood, or hardybacker. whatever you want to use. The benefit is that it wont stain or grow bacteria.

kevreh
03-24-2004, 07:04 PM
Originally posted by bbaker6212
I have an ongoing (but messy) blog to keep track of my countertop research...

http://concrete-countertops.blogspot.com/

If you know of other "kernels" of wisdom, let me know and I'll add them to the blog.

Seems like a link to Cheng Design (or a link to his book on amazon) would be a good idea. His book has been the concrete countertop bible for me.

Other than that, good page, lots of helpful info... Some picts might help visualize the ideas. :cool:

cx
03-24-2004, 07:19 PM
Bbaker6212, give us a name, will ya? I can't keep spellin' bbaker6212 alla time, I'm too old. :)

Water reducing admixtures are used with Portland cement mixes for a number of reasons, primary of which are reducing water/cement ratios to increase strength and to increase slump without adding water to facilitate placement.

The "mid-range" reducers will usually allow you to decrease water content maybe 10 or 12 percent. The "high-range" admixtures (frequently called plasticizers) can result in even more dramatic reductions, advertised as up to 30 percent. A fella can make some really strong concrete that way and still be able to place it in normal form structures.

All that being said, there's a hellofa lot to know about using those admixtures, and there are some drawbacks, chief among them (to my thinking) is the working time. Some of the "Super-Plasticizers" will stop working within about 30 minutes and you begin to get a dramatic decrease in slump. Probably not much problem in making a counter top, but you'll wanna be paying attention anyway.

What's in'em? I ain't got nary clue, thought maybe Kemguru was afixin' to give us a hint. :)

I would not add any such chemicals to a product that's advertised as being a "non shrinking" Portland mix. There's already gonna be some magic chemicals in there that we don't know about and no tellin' what a water reducer would do with it. A fella could certainly do some test batches and report back, though. :shades:

As to the lady who had too many bubbles in her concrete mix, the mixing speed is the first thing that sprang to my feeble mind, too. You're a lot better off using a barrel mixer for that kind of work, and if you're gonna make a truly serious effort to make all your batches match perfectly, measure everything (especially the water) very carefully and either time the mixing or count the revolutions for the first mix and make successive batches the same.

I'm secretly hoping to do some of those top in the near future, but I've been saying that for more than a year, now. :D I'll store that blog you've started for more reference material.

My opinion; worth price charged.

And I agree you aughta have a look at Cheng's book if you haven't already.

bbaker6212
03-24-2004, 07:27 PM
Brad (Baker) :D

bbaker6212
03-24-2004, 07:40 PM
Quikrete sales rep (Dave Ford) said same thing - don't add anything to their non-shrink grout - no telling what will happen. Anyway, he said you don't need it. He said it has the following strengths (when dry) as per consistencies:

Plastic 14K psi
Flow 11K psi
Fluid 8K psi

He boldly claimed you can just pour the stuff in "fluid" form without working it and without any wire/bar reinforcements and it will be sufficient.

Hard to believe, but great if true.
He also said he met Cheng at a show adn said he uses Quikrete 5000 (perhaps with his own additives?). He couldn't understand why Cheng used it instead of their grout and Cheng said that's just what he has been using for years, so used to it I guess.

You can bet I'm gonna prototype the fluid grout thing - check my blog later to see if it worked :)

cx
03-24-2004, 08:03 PM
Them's some mighty big claims for sure.

I may hafta do a little experimenting with that stuff myownself. Can't say as I've ever heard of it before, sure I've never seen it. How expensive is it, Brad?

bbaker6212
03-24-2004, 08:06 PM
I bought a bag last night. I think I remember in the range of $12-15 per 50-60 lbs bag. I bought a bunch of other stuff with it so I caint member xactly :)

bbaker6212
03-26-2004, 12:55 AM
Mixed up a batch of the non-shrink grout tonight
and poured it into some test molds - plastic plant "drain trays"
like you put under plant pots. One is about 3/4-1" deep by
6" in diameter, One is 1.5-2" deep by 14" in diameter,
another is retangular 4x18" by 4"deep to just get
rid of the extra and also see how it dries REAL thick (ya
never know, maybe it has application for fireplaces, etc.)

I used 2 gals (1/2 bag) of mix and 3/4 gal of water
as per direction on bag for a "fluid" mix... very
wet like syrup. (bag says 1 gallon and 3 pints per
50lb bag which is slightly under 4 gallons)
At this consitency it pretty much levels itself, so
no troweling done.

Yes lots of bubbles come to the surface even though
I mixed it by hand with a small rake moving slowly. .
Seems like the thinner (depth not consistency) the pour
the less the bubbles. I'm wondering if
it's mixed dryer if it will keep the bubbles from
floating to the top - maybe next batch.
It's still quite wet 1 hour after starting pouring it.

I mixed into the water 1/2 bottle of orange-ish
Quikrete cement dye/color into the water prior
to adding the grout mix. After pouring into
the molds I could see "veins" of the color so
I guess I didn't mix it long/good enough.
But the effect kinda looks cool and organic/natural
like stone. We'll see what it looks like after it
dries. Right now it looks brownish, nothing like the color
of the orange dye probably because of the dark
grey grout.

2 hours after pour...

...they have set up quite a bit.
I took a plastic putty knife and went over the top
of thickest mold - as it had quite a few bubbles
and bumps. This wet up the surface and smoothed
it out quite a bit. I imagine if you had some
really big "pits" you could wait a bit longer for
it to fully set up and then use another "peanut butter"
batch and a rubber grout float to fill in the voids.

kevreh
03-26-2004, 07:31 AM
Brad-


I've found that the wetter the cement is the easier to release trapped bubbles. Also, wetter cement will conform better to shapes and molds. That's why I don't like too dry of a mixture, but I understand that the dryer it is the stronger it is.

If its as wet as syrup that seems to be quite a bit wetter than what I've heard elsewhere (thicker like oatmeal). Keep in mind that the bag's instructions don't know that you're using this for only 1/5-2" deep molds. I'm sure the manufacturer assumes normal use where the cement would be a good 6" deep.

Also, you didn't mention this, but don't forget to 'agitate' the top of the cement with a trowel and apply a sander (without sandpaper) to the edges to release more air bubbles. The other thing is to screed (spelling?) the top so you don't have to mess around with it later.

I've done a couple countertops so far and am planning another one for my master bath remodel. The ideas' crossed my mind on doing a cement cast sink with the counter. Haven't found any good info on mold making though.


later.... :D
kevin

bbaker6212
03-26-2004, 07:57 AM
The "fluid" (syrup) consistency was based on a recommendation from a Quikrete sales rep I talked to. He said even at that it has a streghth of 8000 psi which is sufficient for a countertop (and higher than the Quikrete 5000 product that others have used for countertops). We'll see how it "pans out" :)

ejdisbrow
03-26-2004, 02:38 PM
We mixed the Quikrete nonshrink precision grout, Quikrete liquid color, and water to the fluid consistency. We did not use rebar or reinforcement except around the sink. We had very minimal cracking except for the bubbles.

We also used first a penetrating sealer then an epoxy coating on it and it stained terribly anyway.

We measured the water and coloring with a measuring pitcher so I know it was accurate and we also measured the temperature of the water. We mixed all of our countertop concrete at once except for the test piece which came out fine. We also rented a gas powered (huge) mixer to mix it all. We seriously wanted this to work.

We also vibrated the heck out of the form to eliminate air bubbled. Didn't work.

I really don't know what else we could have done except mix it slower as mentioned here. The countertops held up beautifully except for the bubbles. They are now sidewalks to my garage.

The bad thing about the non shrink grout is the price. I think we paid about $13 a bag for it and needed about 15 bags. A lot more expensive than average concrete. BTW- The fluid consistency did pretty much self level itself in the form.

Good luck.

kevreh
03-26-2004, 03:09 PM
Originally posted by ejdisbrow
We mixed the Quikrete nonshrink precision grout, Quikrete liquid color, and water to the fluid consistency. We did not use rebar or reinforcement except around the sink. We had very minimal cracking except for the bubbles.

We also used first a penetrating sealer then an epoxy coating on it and it stained terribly anyway.

We measured the water and coloring with a measuring pitcher so I know it was accurate and we also measured the temperature of the water. We mixed all of our countertop concrete at once except for the test piece which came out fine. We also rented a gas powered (huge) mixer to mix it all. We seriously wanted this to work.

We also vibrated the heck out of the form to eliminate air bubbled. Didn't work.

I really don't know what else we could have done except mix it slower as mentioned here. The countertops held up beautifully except for the bubbles. They are now sidewalks to my garage.

The bad thing about the non shrink grout is the price. I think we paid about $13 a bag for it and needed about 15 bags. A lot more expensive than average concrete. BTW- The fluid consistency did pretty much self level itself in the form.

Good luck.

Was the water clean, and not too hot or cold?

How long did you let it cure before handeling/moving? Not that this would create bubble but moving when green could compromise integrity.

What was the environment where it cured? Not too warm/cold?

Did you add the correct ratios of sand and gravel?


This has me thinking I'll stick to the plain old cement.

kevin

bbaker6212
03-26-2004, 03:17 PM
Kevin,
You don't add anything to the non-shrink grout. And you shouldn't have to at that price.

I poured min inside the house at about 68 degrees temp.
The water was probably about 55-60.
The more I tapped on the side of the form the more the bubbles showed up on the top. I think the best thing to do is to wait 90-120 minutes for it to setup and then go over it with a trowel
to kill-n-fill the bubbles. Or you could wait longer and apply another thin layer with a rubber grout float to fill them in.

I will try it again probably tonight with about half the water and see how that goes.

If you try cement here is some info you might find useful:
I put all this in my disorganized research blog...
http://concrete-countertops.blogspot.com

I talked to Fritzpack (Gabriel the president actually) about their CounterFlo "Countertop Admixture" specifically made for countertops.

http://www.fritzpak.com/news/ct_press.html

His recommendation:

1. Supplement 10 lbs of Portland cement for each 80 lbs bag of premixed concrete (he mentioned no brands/types).

2. Use 1 scoop (2 oz.) of CounterFlo per bag of concrete, or for every 20 lbs of cement.

So given recipe above it would be 1.5 scoops (3 oz.) of CounterFlo per batch of above.

CounterFlo is $45 per per 8 lb container. This is 192 ounces, enough for 63 batches of above recipe!

=======================

COUNTER-FLO
Concrete Countertop Admixture
NEW PRODUCT INFORMATION

Counter-Flo, Fritz-Pak's Concrete Countertop Admixture is a mixture of water reducers and mineral admixtures specifically designed for use in the production of concrete countertops and concrete statuary. It makes concrete more flowable for easy placement without adding additional water, allowing you to reduce the water:cement ratio in your mix. By lowering water content you achieve higher compressive and structural strength, thus allowing faster demolding and a faster cure. Lower water content will also provide a denser and less permeable concrete, making the concrete less prone to staining. Use of Counter-Flo allows you to place a relatively wetter concrete, reducing the amount of air bubbles, so concrete will yield a better pattern definition.

Packaging:
Counter-Flo comes in an 8-lb re-closable plastic container. Enclosed is a plastic 2-oz (volumetric) scoop for easy dosage. The container yields about 66 scoops of material: enough to treat 1320 lbs of cementitious materials. MSRP is $45.00 per container.

Directions:
Preferably, Counter-Flo should be added to the dry concrete or mix materials before adding water. Blend thoroughly within the dry materials and proceed mixing the concrete normally, but using about 20% less water. If added to wet concrete, sprinkle over all the concrete to avoid areas of high concentration, then mix well for 5 minutes to allow the active ingredient to hydrate and disperse within the concrete.
For pre-bagged concrete: Use 1 level scoop (2-oz volume) per 80 lb bag of concrete. For higher water reduction you may increase the dosage rate, but do not exceed 3 scoops per bag of concrete.

For site made concrete: Determine the total amount of cement in your mix and add 1 level scoop (2-oz volume) for each 20 lbs (9 kg) of cement.
For modified pre-bagged concrete: Add enough Counter-Flo for the pre-bagged concrete and then add Counter-Flo for the additional cementitious material added. Add one level scoop for each bag of pre-bagged concrete and 1 additional level scoop for every 20 lbs of cementitious materials. Cementitious materials include fly-ash, silica fume, slag or calcined clay; include them as part of the cement weight in order to determine the number of scoops to use.

rbatten
03-26-2004, 03:30 PM
This might be a stupid question, but I will ask anyway.

If you are using forms anyway, why don't you use the bottom of the mold as the top of your counter.

In theory the bubbles would rise to the "Bottom".

bbaker6212
03-26-2004, 03:33 PM
Yes, you could do it that way (and I may), but it's more work.
I'm just testing this method out.

kevreh
03-27-2004, 06:51 AM
Originally posted by rbatten
This might be a stupid question, but I will ask anyway.

If you are using forms anyway, why don't you use the bottom of the mold as the top of your counter.

In theory the bubbles would rise to the "Bottom".

rbatten-

thats one common way of making counters off-site. The advantage is that the top of the counter is very smooth since the bottom of the mold is melamin (the white board).

The other technique is cast in place, which means you build the mold around existing cabinets. In this case you would have to finish the top. This is the method Brad is using.

kevin

bbaker6212
03-27-2004, 12:53 PM
I did another set of 3 test pours same as before; 1 inch thick, 2 inch thick, and 3 inches. Same consistency, 3/4 gal of water with 2 gals (1/2 bag) of Quikrete non-shrink grout mix. I used black colorant this time. I used tan-ish last time. Bubbles rising to the surface are MUCH less of a problem if you don't vibrate the mold/forms. I had read that with non-shrink grout, if you vibrate it, the aggrigate will segragate from the mix. This is what I think is causing all the bubbles. Just pour, screed, and leave it alone. Even so, some small bubbles may still appear. If you're doing pour in place the trick is to wait about 1.5 hours for "thumb print" dry then go over it with a trowel. This wets it up and gets rid of any bubbles on the surface. Of course you will still have allot of sanding to do to get it smooth.

I popped yesterdays pours out of the plastic molds. The bottom surface is amazingly smooth. You could see every detail of the mold - even the tiny numbers I hadn't noticed that were molded into the plastic trays. So far, 36 hours later, there are no visible cracks.

Given this, I think pre-casting countertops upside-down is the thing to do. However, the bottom is so smooth it almost takes on a plastic corian-like appearance. Not as good looking IMO as pictures I have seen of tops made with a modified "standard" concrete mix like Quikrete 5000. But these tops were obviously ground down smooth which requires allot of grinding with diamond wheels, etc.

I may do another test adding pea gravel to the mix, to see if it
gives a better, more natural, look.

I was just looking at Cheng's Neo-mix Pro product. It's about the same cost as using the non-shrink grout. Hmmm...

https://www.concreteexchange.com/shop_cat.jsp?catsecid=9

cx
03-27-2004, 03:20 PM
Makes sense, Brad. With a mix with no course aggregate in it, vibrating shouldn't be necesary with the amount of water you're using anyway. Did you have any bubble-like voids against the forms anywhere?

I'll be curious to know how that black slab looks when it's cured a few weeks. I know that's the color the customer wants on the first one I'm likely to do, and I've read that real black is a difficult color to achieve.

rbatten
03-27-2004, 04:44 PM
Brad, could you snap a picture of your castings? I would like to see them.

I am doing a remodel for a friend and "tile" counter tops are next. Wife would luv concrete, so if its a viable option for me to give it a shot, I will.

WilliamL
03-27-2004, 05:19 PM
It is alot easier to pre-cast the concrete.Just remember,everthing is upside down and backwards.Melemine is the first chouce for building the molds,you can see the little dimples in the concrete from the melemine.This can either be ground out with a 600 diamond pad or lighlty sand the melemine before you pour to minimize the dimples.As for pinhole and voids-make a slurry with mix afterwards to fill them in.Vibtating is a good thing to keep the bubbles,just not to long or the aggregate will settle to the bottom of the mold,this would be the top of the counter.As for black-yes,it turns more charcol than anything but a color enhancer helps and buffing it with lambswool and beeswax will bring out the shine.I work at a granite fab shop and we also do concrete tops as well-I'm just not sure how much info I could give out without getting fired.

bbaker6212
03-27-2004, 07:35 PM
I popped out the black ones. There is definitely more "pinholes" in the black than the first brown ones. So it seems some vibrating is advisable. I'm surpised even the 3-4" casts show no signs of cracking after 48 hours of drying. This stuff seems tough as nails too.

Anyone have any pointers on how to create molds for roundover/bull-nose countertop corners?

Coincidentally, and amazingly, I bumped into a guy at Lowes just this afternoon who had taken Cheng's class and was planning on making countertops. Small world! I also picked up a copy of Cheng's book at Lowes, just to see if there are any good pointers on mold making,etc. The pictures are great inspiration.

rbatten
03-28-2004, 04:57 AM
One way is to make or buy molding that has the reverse of the shape you are after. They make router bits in all shapes and sizes, I'm sure you could find one with the right profile. Just route that profile onto a piece of 1x? or 2x? to give you the edge you are looking for. Then miter and mount that in you mold. If you are looking for a full bullnose profile you will need to make two sets of the molding. The second set would need to be mounted at the top of your mold (bottom of countertop) at the right heigth to give you your proper thickness.

Or you could just grind it!

The also have stone router bits at granite city tools, here is the link.

http://www.granitecitytool.com/stone-tool-cat.cfm?catnum=212

They aren't cheap though!

rbatten
03-28-2004, 05:10 AM
Here is another option, although expensive!


http://www.concretecountertopdesign.com/showitem.cfm?itemnum=2167&catnum=0

kevreh
03-28-2004, 06:06 AM
You could make the bullnose mold using router/shaping bits. Problem is that you'll need a fairly beefy router or shaper to do this since the bit would be relativly large.

The ideal thing would be to find something that already exisists. Can't think of any moulding type that would give you a reverse bullnose profile but worth checking out at the local lumber yard since the big orange box doesn't have it all. I guess you could make your own mould using plaster of paris too.

Looks like the molds on that link are made with forms (foam or wood??) and resin (like fiberglass resin).

kevin

WilliamL
03-28-2004, 06:38 AM
Or you could get a piece of pvc pipe and rip it down in half,you would have to router the melemine to reccess the edge of the pipe.This way the finished product would be smooth and you wouldnt have to worry about a release agent.If you use wood,I would put a huge amount of polyeurethane on it so the result would be as smooth as possible.Using a stone router would work but it would expose the aggregate,although some people like the look.

rbatten
03-28-2004, 03:38 PM
That is a great idea! I think even with the lip on the edge it would look like an "Ogee" bullnose.

kevreh
03-28-2004, 06:57 PM
Anyone have any ideas on what to use for a release agent? I know your supposed to use something so the concrete doesn't stick to the melamine but haven't heard of anything yet.

thanks.....
kevin

Artie61
03-28-2004, 07:15 PM
Or u can shape styrofoam and cover with plastic sheathing

Inexpensive

rbatten
03-28-2004, 07:37 PM
You can use a release agent and it might be a good idea, but its not a must. Concrete won't stick to melimine. That is what concrete companies use to build buildings and parking garages. In fact concrete doesnt stick to regular wood.

I just think you will get a cleaner finished product with a release agent, less imperfections.

Do a search for "mold release" and see what comes up. I'm sure there are lots to choose from.

cx
03-28-2004, 08:25 PM
Quoth rbatten (we need a first name for you, please):In fact concrete doesnt stick to regular wood. You might wanna re-think that one, 'specially if you're gonna use plywood. May not stick well enough for mounting tile, but it'll tear off some wood splinters lotsa times. All our plywood forms get oiled and sometimes the dimension wood, too. :shades:

rbatten
03-28-2004, 09:00 PM
first name Bob.

Will it still splinter with quality plywood? No knots or large gaps in grain.

cx
03-28-2004, 09:36 PM
Yes, it will, Bob, especially if you wait several days to wreck the forms. They'll come off pretty clean a lot of times, but don't count on the forms being in good condition if they weren't oiled before the pour. And if you wreck the forms real early, you can have the opposite problem with the plywood pulling chunks of concrete off the slab.

For something like counter tops or other decorative work, I'd sure recommend some sort of form release, especially on new wood forms. But you can get a nice look on the finished concrete with clean, well built plywood forms if you vibrate them well during the pour.

My opinion; worth price charged.

WilliamL
03-29-2004, 04:02 AM
If you use melemine you DO NOT need a release agent,thats one of the reasons you should use melemine..I wouldnt use plyood unless you're looking for a "grainy look".You should be doing test pieces anyway-please make test pieces!If you are hell bent on a release agent,you can buy a release agent from a concrete store.

kevreh
03-29-2004, 07:31 AM
I asked about a release agent because I had some problems with edges flaking off when taking the slab out of the mold. But the more I think about it I wonder if the problem wasn't the melamine but the corners where I put silicone. Maybe I'll have to be more gently when removing the mold (I use the off site, upside down method).

kevin

johnrgrace
03-29-2004, 10:09 AM
Buddy rhodes has some edge molding predone for cast in place.

http://www.buddyrhodes.com/ezcart/list.cfm?action=list&Criteria=100&StartRow=1&adv=1&page=list.cfm&searchfield=Category


I'm sure you could use it for precast. Also you could call a local millwork shop, they could likely make a negative mold for anythign you could think of.

WilliamL
03-29-2004, 03:34 PM
Try grinding the bottom of the mold before demolding.Go slow when demolding.

bbaker6212
03-29-2004, 05:07 PM
Buddy's edge molding looks great. I think I'll give it a try.

Btw, The prototypes I made with the non-shrink grout doesn't look so great. The black one looks OK, but it the color is too consistent - it looks more like plastic than stone. Some may like that, I don't. I may have to experiment with mixing in some pea gravel and grinding the top to expose the aggrigate.

I took some pics of the sample I made. Will post them soon.

kevreh
03-30-2004, 07:28 AM
Originally posted by WilliamL
Try grinding the bottom of the mold before demolding.Go slow when demolding.


Not sure what you mean by this William. When you say bottom of mold, you mean the underside of the counter since its upside down? What does this do, loosen things up a bit?


kevin

WilliamL
03-30-2004, 03:23 PM
Sorry,top of the mold-bottom of the counter.This way if any mud has found its way over the edges it ill help loosen the sides when you grind.

disciplerip
02-15-2008, 12:30 AM
does anyone know how to get a glossy surface with only my own decoritive aggregates visible. I bought some portland cement to place first over my aggregate (3/4" deep) then lathe (to keep aggregates from second 3/4 " layer of quikrete 5000 from falling to bottom surface when i vibrate). is it ok to use pure cement without sand or aggregate ? . also I am worried about the weight of the cc tops on my cheap home depot cabinets that are shimed off the floor

zynmaster
12-15-2008, 05:20 PM
i'm new to the forum but am looking through a bunch of the concrete countertop threads. i have 4 kitchens to do for a builder and was looking for as much info as i can find before i dive in.

a couple of things relating to this thread (i know its old but info is info). cutting pvc is a great way to get a bull nose. you can sand the edge almost paper thin to get it flush and then work the rest out when polishing/grinding the top. also, i haven't seen this mentioned anywhere online but i know people that worked at a local concrete ct place and they've all broken out on their own. they all use plastilina. its a modeling clay you can find in your local art supply stores. its oil based and never dries and comes in various grades (softer-harder) they use it to make rounded corners and also in an extruder that forms little triangular pieces that fit inside of the bottom corners of the mold to give a beveled edge or after you can use another clay tool (i forget the name but the wood handles with various shaped metal wires). once you've lined the corners plastilina you then scrape the clay tool across evenly for whatever shape you're looking for.

mginwyo
07-20-2013, 08:55 PM
I have read a lot online about CC and finally poured my first small section 30" wide (1 bag) then went for the larger counter (7 bags) a week or so later. Did 100% alone so I was busy mixing and pouring and cleaning so no progress pictures.

This is a cast in place job and I used 5000PSI quickrete and an electric 2 bag mixer mixing 1 bag at a time. Included using 1/2 bottle oliquid, - water as per directions on bag.

Once cured, I used a non acid stain (3 colors) to create a pattern on the top.
turned out pretty good all in all. not smooth as glass but not like a sidewalk either. edges were square formed and used a 5/8" roundover trowel to form and shape.

What would I do different? Buy a cheap pencil type vibrator. his is the right tool to keep bubbles out and make finish work easier. Place a ledger on the back wall. Easier to keep the top level while working. I would not use mesh for reinforcement- 1/4 inch wire maybe but mesh just createdspots for bubbles to form and those created a lot of work and weak spots (spalling) when using diluted concrete to fill them in as they popped.

Basically the super plasticiser also needs to be added AFTER the batch is mixed. Doing it with the liquids did not seem to provide the extra slump anticipated. It did not add to the work time but provided faster strength.

I broke the forms off about 16 hours after pour was done and used wet dry paper 220- 320 to smooth the rough spots. don't do this too much or you will wash off the cream and create coarse spots.

If you wait longer than 2 days, you should then wait 10 days and use a grinder.

pencil vibrator is my next purchase I can really see how it will help a lot in the process and would not do this without it next time. Absolutely would add slump with super plasticizers or counterflo from fritzpack.