I am about to start a project where I plan to cast a number of large
concrete pavers in a mold for a patio and a walkway. The pavers will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan to use
some synthethic fibers mixed into the concrete as well to prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot. My
issue is to whether to use the regular or the high early concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster might
be weaker and more susceptible to cracking. My biggest concern is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum longevity?

Thanks,

Naveen

wrote:
The pavers will
be 2" thick and vary from 2'x4' to 2x8'. .. My biggest concern is that
cosmetically the pavers look good for as long as possible.


I would suggest that a 2'x8' paver only 2" thick is not likely to last
long without cracking unless you have an outstanding foundation and very
light traffic.

--
Joseph Meehan

Dia 's Muire duit

On May 18, 7:09 pm, wrote:
I am about to start a project where I plan to cast a number of large
concrete pavers in a mold for a patio and a walkway. The pavers will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan to use
some synthethic fibers mixed into the concrete as well to prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot. My
issue is to whether to use the regular or the high early concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster might
be weaker and more susceptible to cracking. My biggest concern is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum longevity?

Thanks,

Naveen

Greetings,

If I was going to make something 2'x8' and only 2" thick that I wanted
cured quickly I would look at making it like ferro cement and NOT like
poured concrete. Ferro cement is commonly used to make boats and
water tanks which have strong thin walls. The process basically
involves tacking rebar together and then coating it with as many
layers (5 or more on each side offset from each other) of chicken wire
(attached to the rebar with hog rings) as you can manage to squeeze
high cement mortor through (1 part cement 2 parts fine sharp sand).
You can then steam cure the slab for 24 hours and it should be ready
to put into immediate service.

Hope this helps,
William

"Joseph Meehan" wrote in
:

wrote:
The pavers will
be 2" thick and vary from 2'x4' to 2x8'. .. My biggest concern is
that cosmetically the pavers look good for as long as possible.


I would suggest that a 2'x8' paver only 2" thick is not likely to
last
long without cracking unless you have an outstanding foundation and
very light traffic.


I would not refer to a 2'x4' or larger concrete slab as a "paver".
He might as well just cast his walkway in place.
Just moving such a piece of concrete,rebar or none,is liable to crack it.

--
Jim Yanik
jyanik
at
kua.net

2'x8'x2" will weigh about 400 pounds and will require about 2.66
cubic feet of concrete which will require 5 80 pound sacks of
premixed concrete (make sure you are not pricing or considering
the 40# or 60# bags).

Anything made of concrete that is long and thin will probably
crack.

Rebar should have 1 1/2" of cover. You will have less than 3/4".

Regular sacked concrete is about 2500 # concrete, the minimum
allowed by code for foundations. Prestress concrete runs up
towards 6000#. Most commercial concrete is 3500 with air
entrainment.

There are special processes to create what you are after, but they
require exotic concrete blends, special procedures, and technical
curing. You can probably produce them if you do a bit more
research on what will be required.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




wrote in message
oups.com...
I am about to start a project where I plan to cast a number of
large
concrete pavers in a mold for a patio and a walkway. The pavers
will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan
to use
some synthethic fibers mixed into the concrete as well to
prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot.
My
issue is to whether to use the regular or the high early
concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster
might
be weaker and more susceptible to cracking. My biggest concern
is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum
longevity?

Thanks,

Naveen

On May 18, 5:36 pm, "DanG" wrote:
2'x8'x2" will weigh about 400 pounds and will require about 2.66
cubic feet of concrete which will require 5 80 pound sacks of
premixed concrete (make sure you are not pricing or considering
the 40# or 60# bags).

Anything made of concrete that is long and thin will probably
crack.

Rebar should have 1 1/2" of cover. You will have less than 3/4".

Regular sacked concrete is about 2500 # concrete, the minimum
allowed by code for foundations. Prestress concrete runs up
towards 6000#. Most commercial concrete is 3500 with air
entrainment.

There are special processes to create what you are after, but they
require exotic concrete blends, special procedures, and technical
curing. You can probably produce them if you do a bit more
research on what will be required.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)


wrote in message

oups.com...



I am about to start a project where I plan to cast a number of
large
concrete pavers in a mold for a patio and a walkway. The pavers
will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan
to use
some synthethic fibers mixed into the concrete as well to
prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot.
My
issue is to whether to use the regular or the high early
concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster
might
be weaker and more susceptible to cracking. My biggest concern
is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum
longevity?

Thanks,

Naveen- Hide quoted text -

- Show quoted text -

Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate custom concrete forms and then have them
installed. The only reason I am attempting something like this is
that is looks fantastic when the paver/slabs are in place and some
sort of ornamental grass such as dymondia is alowed to grow in between
the spaces.

Basically the site on which I will be installing these paver/slabs is
very hard clay with little give. I expect there to be normal to light
foot traffic. The idea with the 2" thickness was to limit the weight
so that I could physically install the slab. Additionally, with the
paver/slabs that I have seen, they all appeared to be roughly 2" in
thickness. I actually cast one that was 2' x4' and was able, without
too much trouble to pick it up and move it into place.

I was hoping to solve the potential cracking issue by either adding a
little thickness to the paver/slab, using a littl more rebar, fiber or
simply curing the concrete wet for 30 days.

Naveen

On May 18, 9:14 pm, wrote:
On May 18, 5:36 pm, "DanG" wrote:



2'x8'x2" will weigh about 400 pounds and will require about 2.66
cubic feet of concrete which will require 5 80 pound sacks of
premixed concrete (make sure you are not pricing or considering
the 40# or 60# bags).

Anything made of concrete that is long and thin will probably
crack.

Rebar should have 1 1/2" of cover. You will have less than 3/4".

Regular sacked concrete is about 2500 # concrete, the minimum
allowed by code for foundations. Prestress concrete runs up
towards 6000#. Most commercial concrete is 3500 with air
entrainment.

There are special processes to create what you are after, but they
require exotic concrete blends, special procedures, and technical
curing. You can probably produce them if you do a bit more
research on what will be required.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)


wrote in message

roups.com...

I am about to start a project where I plan to cast a number of
large
concrete pavers in a mold for a patio and a walkway. The pavers
will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan
to use
some synthethic fibers mixed into the concrete as well to
prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot.
My
issue is to whether to use the regular or the high early
concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster
might
be weaker and more susceptible to cracking. My biggest concern
is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum
longevity?

Thanks,

Naveen- Hide quoted text -

- Show quoted text -

Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate custom concrete forms and then have them
installed. The only reason I am attempting something like this is
that is looks fantastic when the paver/slabs are in place and some
sort of ornamental grass such as dymondia is alowed to grow in between
the spaces.

Basically the site on which I will be installing these paver/slabs is
very hard clay with little give. I expect there to be normal to light
foot traffic. The idea with the 2" thickness was to limit the weight
so that I could physically install the slab. Additionally, with the
paver/slabs that I have seen, they all appeared to be roughly 2" in
thickness. I actually cast one that was 2' x4' and was able, without
too much trouble to pick it up and move it into place.

I was hoping to solve the potential cracking issue by either adding a
little thickness to the paver/slab, using a littl more rebar, fiber or
simply curing the concrete wet for 30 days.

Naveen

Greetings,

Have you considered pouring a flat concrete slab to go under your
ornate concrete? This might sound crazy but when it cracks you might
wish you had.

Hope this helps,
William

" wrote in message
oups.com...
On May 18, 9:14 pm, wrote:
On May 18, 5:36 pm, "DanG" wrote:



2'x8'x2" will weigh about 400 pounds and will require about 2.66
cubic feet of concrete which will require 5 80 pound sacks of
premixed concrete (make sure you are not pricing or considering
the 40# or 60# bags).

Anything made of concrete that is long and thin will probably
crack.

Rebar should have 1 1/2" of cover. You will have less than 3/4".

Regular sacked concrete is about 2500 # concrete, the minimum
allowed by code for foundations. Prestress concrete runs up
towards 6000#. Most commercial concrete is 3500 with air
entrainment.

There are special processes to create what you are after, but they
require exotic concrete blends, special procedures, and technical
curing. You can probably produce them if you do a bit more
research on what will be required.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)


wrote in message

roups.com...

I am about to start a project where I plan to cast a number of
large
concrete pavers in a mold for a patio and a walkway. The pavers
will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan
to use
some synthethic fibers mixed into the concrete as well to
prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot.
My
issue is to whether to use the regular or the high early
concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster
might
be weaker and more susceptible to cracking. My biggest concern
is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum
longevity?

Thanks,

Naveen- Hide quoted text -

- Show quoted text -

Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate custom concrete forms and then have them
installed. The only reason I am attempting something like this is
that is looks fantastic when the paver/slabs are in place and some
sort of ornamental grass such as dymondia is alowed to grow in between
the spaces.

Basically the site on which I will be installing these paver/slabs is
very hard clay with little give. I expect there to be normal to light
foot traffic. The idea with the 2" thickness was to limit the weight
so that I could physically install the slab. Additionally, with the
paver/slabs that I have seen, they all appeared to be roughly 2" in
thickness. I actually cast one that was 2' x4' and was able, without
too much trouble to pick it up and move it into place.

I was hoping to solve the potential cracking issue by either adding a
little thickness to the paver/slab, using a littl more rebar, fiber or
simply curing the concrete wet for 30 days.

Naveen

Greetings,

Have you considered pouring a flat concrete slab to go under your
ornate concrete? This might sound crazy but when it cracks you might
wish you had.

Hope this helps,
William

I don't think 2" is nearly thick enough for pavers/slabs that large. I would
make a good foundation and pour 4" sections in forms where I wanted them.
Neither rebar, fiber, or long curing will prevent cracking of a section like
you propose, even if you do not move it. Be aware that fiber will probably
prevent a smooth surface and rebar would be very difficult to keep within
such a thin section over 4 or 8 feet. The rebar would also be likely to rust
and cause the concrete to split because of inadequate concrete coverage.

Overall, my personal opinion is that this is not a good idea at all.

Don Young

wrote in message
oups.com...
I am about to start a project where I plan to cast a number of large
concrete pavers in a mold for a patio and a walkway. The pavers will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan to use
some synthethic fibers mixed into the concrete as well to prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot. My
issue is to whether to use the regular or the high early concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster might
be weaker and more susceptible to cracking. My biggest concern is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum longevity?

Thanks,

Naveen


Actually I've seen a concrete slab something like 2'x6'x2" supported at both
ends by cinder blocks with three guys jumping on it in the middle. It
actually bend about 4" in the middle and spring back to original shape when
those guys got off - no cracks and seems to be indestructible. Flexible
concrete! Don't remember the composition but I believe it had lots of fiber
mixed with the concrete.

Like someone said your small one is about 200 lbs (2.7 x 60 lb bags plus
rebars plus water) and the large one about 400 lbs (5.3 x 60 lb bags plus
rebars plus water) and will crack without some very special treatment. Also
unlikely you could lift these slabs by yourself like pavers all day long
without screwing your back.

I'm doing pavers myself but its more like 1' x 2' x 3". I'm using a
concrete vibrator, no rebars.

"Joseph Meehan" wrote in message
...
wrote:
The pavers will
be 2" thick and vary from 2'x4' to 2x8'. .. My biggest concern is that
cosmetically the pavers look good for as long as possible.


I would suggest that a 2'x8' paver only 2" thick is not likely to last
long without cracking unless you have an outstanding foundation and very
light traffic.

Agreed!

Ivan Vegvary

wrote in message
ups.com...
On May 18, 5:36 pm, "DanG" wrote:
2'x8'x2" will weigh about 400 pounds and will require about 2.66
cubic feet of concrete which will require 5 80 pound sacks of
premixed concrete (make sure you are not pricing or considering
the 40# or 60# bags).

Anything made of concrete that is long and thin will probably
crack.

Rebar should have 1 1/2" of cover. You will have less than 3/4".

Regular sacked concrete is about 2500 # concrete, the minimum
allowed by code for foundations. Prestress concrete runs up
towards 6000#. Most commercial concrete is 3500 with air
entrainment.

There are special processes to create what you are after, but they
require exotic concrete blends, special procedures, and technical
curing. You can probably produce them if you do a bit more
research on what will be required.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)


wrote in message

oups.com...



I am about to start a project where I plan to cast a number of
large
concrete pavers in a mold for a patio and a walkway. The pavers
will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan
to use
some synthethic fibers mixed into the concrete as well to
prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot.
My
issue is to whether to use the regular or the high early
concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster
might
be weaker and more susceptible to cracking. My biggest concern
is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum
longevity?

Thanks,

Naveen- Hide quoted text -

- Show quoted text -

Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate custom concrete forms and then have them
installed. The only reason I am attempting something like this is
that is looks fantastic when the paver/slabs are in place and some
sort of ornamental grass such as dymondia is alowed to grow in between
the spaces.

Basically the site on which I will be installing these paver/slabs is


"very hard clay with little give"

Clay is one of the worst sub-bases available. Very expansive when wet.
Gauranteed to heave and crack your pavers.

Ivan Vegvary

wrote:
I am about to start a project where I plan to cast a number of large
concrete pavers in a mold for a patio and a walkway. The pavers will
be 2" thick and vary from 2'x4' to 2x8'. Each paver will have
embedded 3/8" rebar and remesh for reinforcement. I also plan to use
some synthethic fibers mixed into the concrete as well to prevent
cracking. I am debating if water reducer would be needed.

I am using the bagged Quikrete you can get at the Home Depot. My
issue is to whether to use the regular or the high early concrete.
Faster cure time would help me get the project completed faster.
However, I am worried that the high early, since it cures faster might
be weaker and more susceptible to cracking. My biggest concern is that
cosmetically the pavers look good for as long as possible.

Does anyone have any experience with this process, or have any
suggestions that would help produce a casting with maximum longevity?

Thanks,

Naveen

I know next to nothing about concrete, other than a few tips learned
when speaking with contractors when my hubby was building manager for
our condo. If I was pondering a project such as yours, I would use
smaller pavers and no rebar. I'm thinking that the thickness of the
concrete over the rebar will be only about 7/8" on either side. Seems
likely you would end up with a lot of burst concrete from the rebar
rusting and no surface strength along the rebar. I like pavers with
grass as you describe, but I would be inclined to use smaller pavers and
forget the rebar.

On May 19, 8:32 am, Norminn wrote:

I know next to nothing about concrete, other than a few tips learned
when speaking with contractors when my hubby was building manager for
our condo. If I was pondering a project such as yours, I would use
smaller pavers and no rebar. I'm thinking that the thickness of the
concrete over the rebar will be only about 7/8" on either side. Seems
likely you would end up with a lot of burst concrete from the rebar
rusting and no surface strength along the rebar. I like pavers with
grass as you describe, but I would be inclined to use smaller pavers and
forget the rebar.

Sorry to burst your bubble, but with a response like that you
obviously know far more about concrete than you give yourself credit
for.

R

On May 19, 6:57 am, RicodJour wrote:
On May 19, 8:32 am, Norminn wrote:



I know next to nothing aboutconcrete, other than a few tips learned
when speaking with contractors when my hubby was building manager for
our condo. If I was pondering a project such as yours, I would use
smallerpaversand no rebar. I'm thinking that the thickness of the
concreteover the rebar will be only about 7/8" on either side. Seems
likely you would end up with a lot of burstconcretefrom the rebar
rusting and no surface strength along the rebar. I likepaverswith
grass as you describe, but I would be inclined to use smallerpaversand
forget the rebar.

Sorry to burst your bubble, but with a response like that you
obviously know far more aboutconcretethan you give yourself credit
for.

R

Pouring a concrete foundation is out, since my site conditions won't
really allow for it. I can lay a subbase of sand or pea gravel if
that would hopeflly preventing the clay from heaving.

Given the responses I am willing to pour thicker paver slabs in place,
given that most who have responded think that this would prevent
cracking. What is the mimimum thickness - 3", 4"? If I pour to this
thickness, can I avoid intalling a subbase, since that would entail a
great deal more work?

With regard to the thickness of the concrete being 2" liable to break
from the movement and rusting of the rebar, how is this problem
avoided with concrete countertops, given that these are generally cast
pretty thin and poured in long sections with rebar and remesh from
what I have seen? Obviously countertops are subject to less tensile
pressure than something being stepped on, but are subject to
moisture.

One of the other options I ran across was a company here in CA called
Rapid Set (www.rapidset.com/ConcreteMix_data.asp). They make high
performance concrete which is great deal more expensive than the
bagged Quickrete. It costs about $12 a 60lb bag. I weirdly enough
ran into a rep yesterday in the Home Depot who said that if used
properly, the stuff is guaranteed not to crack since it is primarly
used for roads and other high performance situations. It sets in 15
minutes, but apparently this time can be extended with a set control
substance you can by from them. I am going to call them on Monday
and see how this could be used, and what adjustments would have be
made for my specific situation. Just curious, does anyone have
experience with a product such as this?

Naveen

Concrete does not like to be long and thin no matter how thick it
is. As a general rule the length should never exceed 1.5 of the
width. You will notice joints tooled or cut into exterior
concrete roads, sidewalks, driveways, etc. If the concrete is
cracked, try to visualize why. You are bucking an uphill battle
other than this next bit.

I was quite surprised by an article in one of my magazines.
Here is quite an interesting article from the March issue of
Concrete Construction magazine:
http://www.concreteconstructiononline.com/industry-news.asp?sectionID=691&articleID=456524
If I had read it elsewhere I would have been a doubting Thomas.
It may well give you some of the information you seek.

Concrete countertops are interior and sealed, hopefully the
reinforcement won't start to rust. It is the expansion of the
rust that destroys the concrete.


There are many different acrylic modifiers to add to the concrete
to increase flexural strength. If you have little or no
experience with concrete I would be concerned with your ability to
keep up with the Rapid Set product.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




wrote in message
ups.com...
On May 19, 6:57 am, RicodJour wrote:
On May 19, 8:32 am, Norminn wrote:



I know next to nothing aboutconcrete, other than a few tips
learned
when speaking with contractors when my hubby was building
manager for
our condo. If I was pondering a project such as yours, I
would use
smallerpaversand no rebar. I'm thinking that the thickness
of the
concreteover the rebar will be only about 7/8" on either side.
Seems
likely you would end up with a lot of burstconcretefrom the
rebar
rusting and no surface strength along the rebar. I
likepaverswith
grass as you describe, but I would be inclined to use
smallerpaversand
forget the rebar.

Sorry to burst your bubble, but with a response like that you
obviously know far more aboutconcretethan you give yourself
credit
for.

R

Pouring a concrete foundation is out, since my site conditions
won't
really allow for it. I can lay a subbase of sand or pea gravel
if
that would hopeflly preventing the clay from heaving.

Given the responses I am willing to pour thicker paver slabs in
place,
given that most who have responded think that this would prevent
cracking. What is the mimimum thickness - 3", 4"? If I pour to
this
thickness, can I avoid intalling a subbase, since that would
entail a
great deal more work?

With regard to the thickness of the concrete being 2" liable to
break
from the movement and rusting of the rebar, how is this problem
avoided with concrete countertops, given that these are
generally cast
pretty thin and poured in long sections with rebar and remesh
from
what I have seen? Obviously countertops are subject to less
tensile
pressure than something being stepped on, but are subject to
moisture.

One of the other options I ran across was a company here in CA
called
Rapid Set (www.rapidset.com/ConcreteMix_data.asp). They make
high
performance concrete which is great deal more expensive than the
bagged Quickrete. It costs about $12 a 60lb bag. I weirdly
enough
ran into a rep yesterday in the Home Depot who said that if used
properly, the stuff is guaranteed not to crack since it is
primarly
used for roads and other high performance situations. It sets in
15
minutes, but apparently this time can be extended with a set
control
substance you can by from them. I am going to call them on
Monday
and see how this could be used, and what adjustments would have
be
made for my specific situation. Just curious, does anyone have
experience with a product such as this?

Naveen

On May 19, 8:38 am, "DanG" wrote:
Concretedoes not like to be long and thin no matter how thick it
is. As a general rule the length should never exceed 1.5 of the
width. You will notice joints tooled or cut into exteriorconcreteroads, sidewalks, driveways, etc. If theconcreteis
cracked, try to visualize why. You are bucking an uphill battle
other than this next bit.

I was quite surprised by an article in one of my magazines.
Here is quite an interesting article from the March issue ofConcreteConstruction magazine:
http://www.concreteconstructiononline.com/industry-news.asp?sectionID...
If I had read it elsewhere I would have been a doubting Thomas.
It may well give you some of the information you seek.

Concretecountertops are interior and sealed, hopefully the
reinforcement won't start to rust. It is the expansion of the
rust that destroys theconcrete.

There are many different acrylic modifiers to add to theconcrete
to increase flexural strength. If you have little or no
experience withconcreteI would be concerned with your ability to
keep up with the Rapid Set product.

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On May 19, 6:57 am, RicodJour wrote:
On May 19, 8:32 am, Norminn wrote:

I know next to nothing aboutconcrete, other than a few tips
learned
when speaking with contractors when my hubby was building
manager for
our condo. If I was pondering a project such as yours, I
would use
smallerpaversand no rebar. I'm thinking that the thickness
of the
concreteover the rebar will be only about 7/8" on either side.
Seems
likely you would end up with a lot of burstconcretefrom the
rebar
rusting and no surface strength along the rebar. I
likepaverswith
grass as you describe, but I would be inclined to use
smallerpaversand
forget the rebar.

Sorry to burst your bubble, but with a response like that you
obviously know far more aboutconcretethan you give yourself
credit
for.

R

Pouring aconcretefoundation is out, since my site conditions
won't
really allow for it. I can lay a subbase of sand or pea gravel
if
that would hopeflly preventing the clay from heaving.

Given the responses I am willing to pour thicker paver slabs in
place,
given that most who have responded think that this would prevent
cracking. What is the mimimum thickness - 3", 4"? If I pour to
this
thickness, can I avoid intalling a subbase, since that would
entail a
great deal more work?

With regard to the thickness of theconcretebeing 2" liable to
break
from the movement and rusting of the rebar, how is this problem
avoided withconcretecountertops, given that these are
generally cast
pretty thin and poured in long sections with rebar and remesh
from
what I have seen? Obviously countertops are subject to less
tensile
pressure than something being stepped on, but are subject to
moisture.

One of the other options I ran across was a company here in CA
called
Rapid Set (www.rapidset.com/ConcreteMix_data.asp). They make
high
performanceconcretewhich is great deal more expensive than the
bagged Quickrete. It costs about $12 a 60lb bag. I weirdly
enough
ran into a rep yesterday in the Home Depot who said that if used
properly, the stuff is guaranteed not to crack since it is
primarly
used for roads and other high performance situations. It sets in
15
minutes, but apparently this time can be extended with a set
control
substance you can by from them. I am going to call them on
Monday
and see how this could be used, and what adjustments would have
be
made for my specific situation. Just curious, does anyone have
experience with a product such as this?

Naveen- Hide quoted text -

- Show quoted text -

That article is a very interesting read. Not only for they were able
to achieve, but in understanding the underlying forces that cause
concrete to crack. I was not aware of the curling aspect.

Just to show that I am not crazy, you can see some pictures of the
paver/slabs I am talking about at the this link http://picasaweb.google.com/naveenreddyla

Any thoughts on how they are making this work? Or is this just wasted
money. Mind you I have seen this done on a number of homes.

Naveen

clipped

With regard to the thickness of the concrete being 2" liable to break
from the movement and rusting of the rebar, how is this problem
avoided with concrete countertops, given that these are generally cast
pretty thin and poured in long sections with rebar and remesh from
what I have seen? Obviously countertops are subject to less tensile
pressure than something being stepped on, but are subject to
moisture.

Countertops would never be exposed to the amount of water that outdoor
applications are. Rusting rebar is a fairly common concern in Florida,
with all the balconies on condos....We have had a number of spots on our
condo where rebar had rusted and cracked concrete. This occurred on
balconies and second-floor deck in open atrium. Salt is an added issue
here, but concrete/stucco has to be painted and maintained to slow or
stop the problem. Condo across the street had 13 stories of balconies
jack-hammered, repaired and painted a couple of years ago.

I would also be concerned with the 8' length pavers cracking from
expansion and contraction. We have sidewalks with extremely long
sections and all the sections have cracked, roughly in the center.

With your clay soil and the possibility it can heave or shrink from
changes in water content, it seems that consistency would be the major
issue. If it rains, it will be evenly wet and expand fairly evenly, I
would think. Another reason smaller pavers would make a
difference...easier to pull up and re-level if the soil moves.

On 19 May 2007 00:16:11 GMT, Jim Yanik wrote:
I would not refer to a 2'x4' or larger concrete slab as a "paver".
He might as well just cast his walkway in place.
Just moving such a piece of concrete,rebar or none,is liable to crack it.

I've moved 2'x4' several times, and even thinner pieces than the 2" the
O.P. is planning to cast.

That said, the 2'x8' will be considerably more interesting... But I
think doable.

However, 2" thick is adequate for a walkway on a good base, but I'm
skeptical of its use for heavier loads.

sdb

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On 18 May 2007 18:14:37 -0700, wrote:
Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate custom concrete forms and then have them

It sounds like you are in way over your head. You need a LOT more study.

Basically the site on which I will be installing these paver/slabs is
very hard clay with little give.

Very poor base. Proper base will be done by excavating and putting in a
few inches of compacted 3/4" road base, perhaps topped by compacted and
leveled sand. Finally layer an inch or so of moist sand screeded to
height. Then lay and bed the pavers in that base.

I expect there to be normal to light
foot traffic.

Can you guarantee that? Or is this adjoining or near a driveway where a
vehicle might drive onto it? If really only foot traffic then a base of
2" compacted 3/4" road base will probably be enough. (Still need the
inch or so of moist sand screeded, into which to bed the pavers.)

The idea with the 2" thickness was to limit the weight
so that I could physically install the slab. Additionally, with the
paver/slabs that I have seen, they all appeared to be roughly 2" in
thickness. I actually cast one that was 2' x4' and was able, without
too much trouble to pick it up and move it into place.

Buy pavers. They use lightweight aggregate, air entrainment, etc. to
reduce the weight and cost and increase the strength.

I was hoping to solve the potential cracking issue by either adding a
little thickness to the paver/slab, using a littl more rebar, fiber or

Fiber or ferrocement would probably work, maybe remesh (10ga or so) but
even 3/8" rebar in a 2" slab is iffy.

Don't forget some retaining method at the edge. Steel is nice, set down
about grade (ground level) to about 1/2" above grade.

sdb
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On May 21, 4:59 pm, sylvan butler
wrote:
On 18 May 2007 18:14:37 -0700, wrote:

Thanks for the responses so far. I would not have thought of idea
that I am proposing, other than I have seen this type of work done in
a number of homes here in Los Angeles - albeit expensive ones I have
seen on architectural tours. I could not afford the cost of having
some one else fabricate customconcreteforms and then have them

It sounds like you are in way over your head. You need a LOT more study.

Basically the site on which I will be installing these paver/slabs is
very hard clay with little give.

Very poor base. Proper base will be done by excavating and putting in a
few inches of compacted 3/4" road base, perhaps topped by compacted and
leveled sand. Finally layer an inch or so of moist sand screeded to
height. Then lay and bed thepaversin that base.

I expect there to be normal to light
foot traffic.

Can you guarantee that? Or is this adjoining or near a driveway where a
vehicle might drive onto it? If really only foot traffic then a base of
2" compacted 3/4" road base will probably be enough. (Still need the
inch or so of moist sand screeded, into which to bed thepavers.)

The idea with the 2" thickness was to limit the weight
so that I could physically install the slab. Additionally, with the
paver/slabs that I have seen, they all appeared to be roughly 2" in
thickness. I actually cast one that was 2' x4' and was able, without
too much trouble to pick it up and move it into place.

Buypavers. They use lightweight aggregate, air entrainment, etc. to
reduce the weight and cost and increase the strength.

I was hoping to solve the potential cracking issue by either adding a
little thickness to the paver/slab, using a littl more rebar, fiber or

Fiber or ferrocement would probably work, maybe remesh (10ga or so) but
even 3/8" rebar in a 2" slab is iffy.

Don't forget some retaining method at the edge. Steel is nice, set down
about grade (ground level) to about 1/2" above grade.

sdb
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The time of being in over my head is long since past. Two retaining
walls, french drains, and 80 cu yard of excavation and removal of dirt
and rubbish and I am still going.

I can guarantee that there will be light foot traffic, since this is
not a car accessible location. The only other weight would be normal
patio items.

As far as the compacted gravel sub base with sand. This was the
original plan, until we decided to plant the dymondia or some other
ornamental grass between the paver slabs. I figured having a dirt
base underneath would be easier to plant with. I was also hoping that
the strength of the concrete would be able to overcome any shifting of
the earth. I suppose I can some scoop the some of the sand out from
the perimeter of each paver/slab once they are put in place, and
replace with soil.

Does anyone have a recommended minimum thickness that the paver/slab
should be. If I increase to 3.5"-4" thickness will this work with the
3/8" rebar, mesh and fiber? I know this will be quite heavy, but I
can reduce the size of the paver/slab to be roughly 2' x 4', or maybe
slightly smaller so that I can get them in place.

I am looking to price out how much casting these paver/slabs would
be. Though the the rapid set strong concrete sounds like an
interesting option, the cost becomes prohibitve quite quickly, and
making the effort not worth the time. My initial hunch is that
pprecast pave/slabs will be expensive, which is why I decided to
undertake this project in the first place.

On 22 May 2007 10:27:39 -0700, wrote:
The time of being in over my head is long since past. Two retaining

It doesn't sound like it...

walls, french drains, and 80 cu yard of excavation and removal of dirt
and rubbish and I am still going.

Good. But you evidently don't know pavers.

As far as the compacted gravel sub base with sand. This was the
original plan, until we decided to plant the dymondia or some other
ornamental grass between the paver slabs. I figured having a dirt
base underneath would be easier to plant with. I was also hoping that

With 2" thick pavers, the base doesn't much affect the grass growing
between the pavers.

the strength of the concrete would be able to overcome any shifting of

Best to treat concrete as a wear surface. The base is critical. If you
don't have a base, think "bridge" and imagine the large concrete and
steel beams necessary for even a foot bridge.

the earth. I suppose I can some scoop the some of the sand out from
the perimeter of each paver/slab once they are put in place, and
replace with soil.

With 1" of loose, screeded sand as I described, there will not be
significant sand between the pavers to "scoop out".

Does anyone have a recommended minimum thickness that the paver/slab
should be. If I increase to 3.5"-4" thickness will this work with the
3/8" rebar, mesh and fiber? I know this will be quite heavy, but I

3" would be fine. Generally if the rebar has over 1" of concrete on all
sides it will be OK in a mild, earth-bound climate.

can reduce the size of the paver/slab to be roughly 2' x 4', or maybe
slightly smaller so that I can get them in place.

You can move a 400lb concrete slab? Impressive.

I am looking to price out how much casting these paver/slabs would

Check out the price of buying pavers.

sdb
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On May 23, 3:02 pm, sylvan butler
wrote:
On 22 May 2007 10:27:39 -0700, wrote:

The time of being in over my head is long since past. Two retaining

It doesn't sound like it...

walls, french drains, and 80 cu yard of excavation and removal of dirt
and rubbish and I am still going.

Good. But you evidently don't know pavers.

As far as the compacted gravel sub base with sand. This was the
original plan, until we decided to plant the dymondia or some other
ornamental grass between the paver slabs. I figured having a dirt
base underneath would be easier to plant with. I was also hoping that

With 2" thick pavers, the base doesn't much affect the grass growing
between the pavers.

the strength of theconcretewould be able to overcome any shifting of

Best to treatconcreteas a wear surface. The base is critical. If you
don't have a base, think "bridge" and imagine the largeconcreteand
steel beams necessary for even a foot bridge.

the earth. I suppose I can some scoop the some of the sand out from
the perimeter of each paver/slab once they are put in place, and
replace with soil.

With 1" of loose, screeded sand as I described, there will not be
significant sand between the pavers to "scoop out".

Does anyone have a recommendedminimumthicknessthat the paver/slab
should be. If I increase to 3.5"-4"thicknesswill this work with the
3/8"rebar, mesh and fiber? I know this will be quite heavy, but I

3" would be fine. Generally if therebarhas over 1" ofconcreteon all
sides it will be OK in a mild, earth-bound climate.

can reduce the size of the paver/slab to be roughly 2' x 4', or maybe
slightly smaller so that I can get them in place.

You can move a 400lbconcreteslab? Impressive.

I am looking to price out how much casting these paver/slabs would

Check out the price of buying pavers.

sdb
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I meant I have been in over my head ever since the project
started...........

So I will plan on putting in at least a 2" compacted gravel sub base
with the 1" layer of sand on top. I will cast the paver/slabs at a
minimum 3" thickness with 3/8" rebar and remesh. This is SoCal, so
the weather is temperate and generally dry, and would have lesser
impact on the concrete/rebar than in other areas.

Does anyone know the shape the rebar should be in for an application
such as this - bent so that it runs offset a few inches along the
interior perimeter of the paver/slab or should there be a bar running
down the middle as well? Any thoughts on using galvanized, or any
other coated rebar?

I was not against reducing the size of the pavers/slabs, down from my
initial plan. I just wanted to explore the pitfalls of my design
before I started. It looks I will have to reduce the the size ( the
2'x 8' are absolutely out) of the paver/slabs because of longevity and
weight considerations of concrete. Based on my measurements and the
gaps between the the paver/slabs for the planned area, the reduced
size of each paver/slab would be about 21" x 44".

The reason I am intent on these large style paver/slabs, is in
essence, to match the style of the house. This a 60's modern house,
and there is not a whole lot on the market in tems of pavers that the
match the clean look that I am going for. Many of the precast products
are very traditional/tuscan/country looking and frankly would be a
mismatch. The really basic plain pavers tend to look pretty generic
and institutionalized. If anyone can point to a source for something
like I am trying to achieve, I will gladly buy it.

The other option is to have a contractor come in and do a custom job,
which will probably cost an arm and a leg. Given the that patio area
is roughly 275 square feet, I think this doable.

I bought this house with what was essentially a junk pile for a
backyard, which had never been used. I am trying not to spend an
inordinate sum of money on this work, becuase I feel it would add
little market value (but a ton of personal utility) to the house.

Naveen

On 23 May 2007 17:54:06 -0700, wrote:
So I will plan on putting in at least a 2" compacted gravel sub base

I prefer what is called "3/4 road base" around here. It is a mix of
crushed (not round) gravel from 3/4-inch down to dust. It compacts.
Round gravel and even sharp gravel without fines does not compact well.

with the 1" layer of sand on top. I will cast the paver/slabs at a
minimum 3" thickness with 3/8" rebar and remesh. This is SoCal, so

If it were me, I'd go back to 2", forget the rebar, use fiber mix 'crete
and 10ga remesh cut to size of the paver minus about 1-1/2-inch from all
the edges.

I'd prefer to take the time and do a test cast of a 1-inch and a
1-1/2-inch paver works over that solid base. With just foot traffic, I
think it has a good chance to be OK.

You might be able to cast the pavers in-place over the base, and just
remove the forms from between and fill in the gaps with dirt. No moving
big heavy slabs. (I'd form up with 2x4's in a nice grid pattern,
then fill in all the "paver" spots with concrete. Remove the 2x4's the
next day. You could even have the concrete delivered, since you'd be
placing the entire batch at once.)

sdb
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replying to deans, william bardsley wrote:
Probably a good idea to cast in place. On that 2x8 if its doable, cut a
control joint even a thin one and hope that is where it cracks. Fiber is great
and a little thicker is good to if you cast in place. Let the concrete cure
for 3-4 days before moving. 6 6 10 wire good if u can keep it centered in the
2" of concrete. Use the standard 3500 pre mix and throw a shove or two of
portland cement in with the blend when mixing. MIX GOOD!!!! That is very
important!!! See U can do it cheaply like u wanted but must make the work to
do it!! Good luck.

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