Wooden driveway expansion joints advise needed

[spurgersalty]

Expansion joints are just that...for expansion as well as contraction. If done right, you would use a material that could be compressed by the 2 now separated slabs(yes separate, run the joint all the way through). Within that joint on 12" or 18" centers would be slick dowels (size dependent on thickness of slab) greased on one side and bare on the other to allow for the concretes expansion and contraction due to temperature changes. The bars sole purpose is to maintain the connection and elevation of the 2 (now separate) slabs.
Control joints (dummy joints) sole purpose is for aesthetic reasons. Either sawed or tooled, their sole purpose is to give the concrete somewhere to crack that can be "beautified" so to speak. The crack is hidden within the joint so it remains unseen to the untrained eye.
Most longer paving areas are separated with expansion joints with control/dummy joints mixed equally (again, aesthetics) within them.

[monark]

I had kids running around barefoot, playing basketball, etc. & I was worried about splinters from the old wood joints. It was a bit tedious, I had to remove the old wood, run a side grinder with a wire wheel to clean the edges, prime with their primer, & then pour the joints. I bought in bulk instead of caulk tubes cause I had quite a bit to repair. I bought cheap flower pot water buckets, cut the snout off & wahla, new joints. This stuff sticks good.

http://www.cmcconstructionservices.c.../#jointsealant

[Jolly Roger]

Well, guess I have been in the business for a long time as well. But a much larger scale then most.

You do not want water to have a direct path under your driveway or sidewalk. It will degrade the subgrade. No amount of natural seepage will come anywhere close to the amount of water intrusion compared to a direct path. Same can be said for dry air, if you have a direct path for air to contact your subgrade you are going to get a lot of movement unless the subgrade has a PI close to 0.

Clean,backer rod and seal the joints.

[spurgersalty]

Originally Posted by monark

I had kids running around barefoot, playing basketball, etc. & I was worried about splinters from the old wood joints. It was a bit tedious, I had to remove the old wood, run a side grinder with a wire wheel to clean the edges, prime with their primer, & then pour the joints. I bought in bulk instead of caulk tubes cause I had quite a bit to repair. I bought cheap flower pot water buckets, cut the snout off & wahla, new joints. This stuff sticks good.

http://www.cmcconstructionservices.c.../#jointsealant

I prefer SL1 and will occasionally use an Adeka product.
Explanation to those that don't know.
Most expansion joint material if done right will come with a removable top (from the top of concrete approximately a 1/2" down by 1/2" wide.).
After pouring (usually the next day) you would come and remove the "cap", sawcut for control joints, and then place a backer rod (only purpose is to create a barrier and use less sealant later) and then seal the joint with any of the above mentioned sealants.
The sealants purpose is to seal the top of the joint to prevent any dirt or other debris from filling the expansion void. If the void becomes filled, you could wind up with a nice triangular concrete section.
Seen it my self in Silsbee a few years back. Almost 2' high where the 2 adjoining slabs apexed. lol....would you want to be the guy that hit that at 35mph

[knuttdeep]

Originally Posted by rangerjohn

Trust me this is one of the silliest answers I have heard of. I have been in the residential concrete business for nearly 20 years.
Basically what you're saying is that the rotted wood is now going to allow water to flow under the flatwork as if it has never been under there before. As if water doesn't leach under the flatwork from the perimeter when it rains or you water? The only time you need to worry about water causing expansion is when the general area has been dry for an extended period. Once the area become moist again the clay will expand (because it has shrunk some) and can cause heaving.

Those joints are there not to control expansion but as a control joint to give the concrete relief to minimize cracking. This is also done with saw cuts and tooled joints. At some point no mater what you do concrete WILL crack!

X100!
For cosmetic reasons you could pour a mixture of sand and Bermuda seed in there; looks pretty cool.
You will have to weed eat every now and then.

[poppadawg]

Man who knew expansion joints were such a divisive issue. I don't really like the way the missing expansion joints look. But the chauking sounds real tedious. That slab gasket looks much easier. Anybody used slabgasket? Was it easy? Was it cheap? I'm a big fan of cheap and easy.