After much research I have decided I would like to build my own concrete
countertops. I like the whole modern look so I am going for a simple 1.5
inch cement gray counter. Rather than
casting and trowleing them in place I plan on casting 2 x 4 pieces upside
down in a melamine mold and then piecing them together on my cabinets. My
understanding is that makes for much easier process and smoother
top since the bottom of the melamine is nice and smooth to begin with. The
few grout lines I have are not a big deal. After doing a lot of research on
the web I still have a few questions I need some help on:

1) Quikrete has a product called Non Shrink Precision Grout. Their website
recommends this for counters since it will dry
to 3000PSI in 2 days and 8000PSI in 28 days. A few questions:
1) They recommend to blend this to a syrupy consistency - this makes
it easy to pour and reduces makes a smoother finish - any experience with
this?
2) They say to use this without rebar or reinforcement except for
around the sink, is that correct?
3) I have seen a few negative comments on this particular product.
Any experience out there in using this product for counters?

2) If I use the grout mentioned above (or other concrete mix) and want to
use reinforcement, can I use simple chicken wire I can buy at Lowes for
this? Or do
I have to use the real rebar stuff?

3) I want to use the non shrink grout because it sounds like it makes a
smooth finish, especially since I am casting them upside down in a mold. If
I do need to sand
can I just use regular sandpaper and an orbital sander while the concrete is
still 24 -30 hours fresh? I am not looking for a glass finish, just smooth
enough

4) Any recommendations for a sealer.


thanks
John

john wrote:
After much research I have decided I would like to build my own concrete
countertops. I like the whole modern look so I am going for a simple 1.5
inch cement gray counter. Rather than
casting and trowleing them in place I plan on casting 2 x 4 pieces upside
down in a melamine mold and then piecing them together on my cabinets. My
understanding is that makes for much easier process and smoother
top since the bottom of the melamine is nice and smooth to begin with. The
few grout lines I have are not a big deal. After doing a lot of research on
the web I still have a few questions I need some help on:

1) Quikrete has a product called Non Shrink Precision Grout. Their website
recommends this for counters since it will dry
to 3000PSI in 2 days and 8000PSI in 28 days. A few questions:
1) They recommend to blend this to a syrupy consistency - this makes
it easy to pour and reduces makes a smoother finish - any experience with
this?
2) They say to use this without rebar or reinforcement except for
around the sink, is that correct?
3) I have seen a few negative comments on this particular product.
Any experience out there in using this product for counters?

2) If I use the grout mentioned above (or other concrete mix) and want to
use reinforcement, can I use simple chicken wire I can buy at Lowes for
this? Or do
I have to use the real rebar stuff?

3) I want to use the non shrink grout because it sounds like it makes a
smooth finish, especially since I am casting them upside down in a mold. If
I do need to sand
can I just use regular sandpaper and an orbital sander while the concrete is
still 24 -30 hours fresh? I am not looking for a glass finish, just smooth
enough

4) Any recommendations for a sealer.


thanks
John

Ther curse of any casting process is bubbles..bubbles...bubbles.
That's why concrete is treated with vibrators after dumping nto a
foundation form, for example. If you could fasten your orbital sander
to the bottom of the mold it could eliminate the bubble problem in
just a few minutes.
Your other problem will be getting a good release from your mold. Do
some experiments with different release agents, like waxes, Pam,
silicone sprays, whatever. You might even visit a place that casts
concrete garden statuary and ask for some tips or advice. For advice
on finishing a flawed surface, a terrazo expert would be the person to
ask.
Sounds like a challenging project...let us know how it turns out.

Joe

On Feb 14, 5:13 am, "Joe" wrote:
john wrote:
I would like to build my own concrete countertops
Rather than casting and towelling them in place I plan on casting 2 x 4 pieces upside
down in a melamine mold and then piecing them together on my cabinets. My
understanding is that makes for much easier process and smoother
top since the bottom of the melamine is nice and smooth to begin with.

2) If I want to use reinforcement, can I use simple chicken wire or do
I have to use the real rebar stuff?

Rebar is there to give it strength against flexing. Concrete is only
strong in compression. However there is very little flex on a worktop
except over regions where there are massive holes for the plumbing.

Do you really think that chicken wire is going to be of any use there?

The curse of any casting process is bubbles.
That's why concrete is treated with vibrators after dumping into a
foundation form, for example.

If you could fasten your orbital sander to the bottom of the mold it could
eliminate the bubble problem in just a few minutes.

Drumming the mould after the pour will also do that job. Be careful
not to vibrate the pour too much as it can adversely affect the mix,
vibration is responsible for the stratification of layers in the
planet, see how it will affect a sample mix of assorted sizes of
particles in a concrete mix.

Your other problem will be getting a good release from your mold. Do
some experiments with different release agents, like waxes, Pam,
silicone sprays, whatever. You might even visit a place that casts
concrete garden statuary and ask for some tips or advice. For advice
on finishing a flawed surface, a terrazo expert would be the person to
ask.

The main problem is flaking at the corners. Smear or bead internal
angles with oil based moulding clays, wax and spray with a PVE/meths
mixture.

Do not over vibrate. Major problems with commercial production, is
turnover, weather and quality control vss expenses. A DIYer can afford
to take his time, use a large variety of releases agent together,
watch the weather and use a stronger mix than required.

Fine Homebuilding had a step by step article in its May 2002 issue on
this

buy a "FireSlate" top
http://www.fireslate.com/pages/counter.cfm
or maybe get some helpful tips from them


"john" wrote in message
...
| After much research I have decided I would like to build my own
concrete
| countertops. I like the whole modern look so I am going for a simple
1.5
| inch cement gray counter. Rather than
| casting and trowleing them in place I plan on casting 2 x 4 pieces
upside
| down in a melamine mold and then piecing them together on my cabinets.
My
| understanding is that makes for much easier process and smoother
| top since the bottom of the melamine is nice and smooth to begin with.
The
| few grout lines I have are not a big deal. After doing a lot of
research on
| the web I still have a few questions I need some help on:
|
| 1) Quikrete has a product called Non Shrink Precision Grout. Their
website
| recommends this for counters since it will dry
| to 3000PSI in 2 days and 8000PSI in 28 days. A few questions:
| 1) They recommend to blend this to a syrupy consistency - this
makes
| it easy to pour and reduces makes a smoother finish - any experience
with
| this?
| 2) They say to use this without rebar or reinforcement except
for
| around the sink, is that correct?
| 3) I have seen a few negative comments on this particular
product.
| Any experience out there in using this product for counters?
|
| 2) If I use the grout mentioned above (or other concrete mix) and want
to
| use reinforcement, can I use simple chicken wire I can buy at Lowes
for
| this? Or do
| I have to use the real rebar stuff?
|
| 3) I want to use the non shrink grout because it sounds like it makes
a
| smooth finish, especially since I am casting them upside down in a
mold. If
| I do need to sand
| can I just use regular sandpaper and an orbital sander while the
concrete is
| still 24 -30 hours fresh? I am not looking for a glass finish, just
smooth
| enough
|
| 4) Any recommendations for a sealer.
|
|
| thanks
| John
|
|