04ctd

driveway has expansion joints all the way across it, about 12 feet apart.

from my understanding:
expansion joints: between sections, filled with something soft. let sections swell in summer
contraction joints: cuts, allow the section to shrink in winter.

it is starting to have hairline cracks thru it though, enough to where the cracks intersect a little divot is coming out. mostly straight up the middle of the sections.

just wondering, should I cut X's in it to stop the cracks, or leave it alone?

-how deep would you cut?
-cut in a X pattern, or what?
-how many blades will it take & how $$ per blade?

I have access to a saw, so cost is not really an issue, unless i use up the blade.

just wondering if it's worth the effort, the concrete has lasted this long.

i asked on a local forum, and no one really knew, figured everyone on here would know

theres not as much info about it, as you would expect on line:
How, When, and Where to Use Saw Cuts in Concrete

Justwannabeme

Hey Sailor!!!!! long time no see. you guys are awesome.


yes, you can control cracking by reduction cuts. they would be segregating the stress on the floating concrete (4 inch or more?) by applying the cuts
from the top of the driveway near your fence down to the street. we use one inch cut depth then apply a silicone concrete sealer. if your existing cracks are deeper than one inch, then that section (6 x6 ft) matches the depth of the cut. our experience (frost heaves) has been that drop cuts (cuts that separate each concrete panel -4 inch depth type- tend to cause more troubles than stop a problem)

another repair is called a "chaser" in which you cut the crack and fill with mortar patch. this is maintenance and can also be used due to natural breakdown of the surface aggregate (too much floating of the pad makes only the lime coating the surface).

hope that helps, can't blow up the pics on my phone.....

you still poke around in the navy junkyard?

SIXSLUG

I wouldn't bother, control cuts will now just make your pieces smaller and more likely to work out.

Decorative cuts may help hide the cracking a bit, but if no rebar is present, you will likely work pieces looser by driving over it.

We get calls all the time to hide cracks, but we suggest removal and replacement (properly). We don't like fixing other contractors mistakes...

We try to "square up" our control and early entry cuts whenever possible. A good concrete job is 90% subgrade prep. You can visit our website at customconcrete.biz if you want.

04ctd

miss you guys, when are you going to make another whirlwind tour of the Lower 48?

Okay, that's what I thought...I have a few cracks now, but they have traveled to the expansion joints & stopped pretty much.

I do NOT want to make the pieces rise & fall.

no, the Air Force took over, and shut the junkyard down, because it was generating too much income for MWR.

only the AF thinks like that

thanks, i see what you mean, if i make them separate, and then drive over them, they will see saw & lift & fall.

appreciate the insight!

Scotty

When I poured the garage pad we went 6" MP50 lots of rebar. No cuts.
Where I live concrete cracks all the time from the gumbo soil expanding and contracting with the seasons.
I decided to use high quality road gravel base, at least 8" compacted.
Folks kept asking where my cuts were and why didn't I do any.
I have what I expected after 5 yrs...four hairlines from each corner to the small center pit. Those showed up within 90 days.

Neighbor thought it'd be a good idea to cut his cracks. Full of heaves now.

pind

Best avoidance, dig down at least 3 feet below the bottom of your crush base. Put in two feet of riprap, then geo cloth, then 1 foot of good pit run, capped with about 4 to 6 inches of compacted crush. Water til shiny, then pack the crap out of it.

Then lay your mud down after its dried for several days. NNot much movement there. The riprap gives the groundwater a place to go, without causing heaves.

nothing like the voicee ofof bad experience.

bigfoot

A wise man once told me , there are two kinds of concrete .
There is concrete that has cracked and concrete that is going to crack .
If you did not do your home work before placing the drive by adding rebar and putting down base then it is to late and ether way don't worry about it .

railroaderone

An old man that had worked concete forever told me once how to keep it from cracking.

LEAVE IT ON THE TRUCK

bigfoot

problem is if you leave it on the truck you have to chip it out in order to get the next load on

SIXSLUG

There's a bunch of good advice here.

I agree with Scotty on the subgrade and prep being the most crucial, next to not adding too much water during the pour...