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
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?
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:
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 . . . .
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
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.
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.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.