Thread: How did you make your expansion joints for concrete?

Will be pouring some concrete in a few days. I'm looking for ideas on how to make the expansion joints. What material did you use, why and how.

Not sure about Thailand but there are bituman based expension joint material. the beest way to go. I'm someone there can point you in the right direction. but there are many types.

We put wooden laths about 1/4 " thick wrapped in polythene bags between the panels when the concrete was poured - eased them out when the concrete was still "green".
We had a drum of tar spare after filling some electrical junction boxes- melted it and poured that in the slots when the concrete was fully cured.
Have no idea if that is the correct way but it was what was available on site and is still as good as the day we did it.
16 years ago !!!

(The re-bar mesh was cut at the joints)

Elwood: There is also a plastic type of material a friend of mine has seen used here in Thailand. The problem is to find out what it's called and where to purchase it. But I'm looking. Should have more luck tomorrow, its Monday. Happyman: If I can't find the commercial type of material for the job, I will more than likely go with your idea. Did you buy the wooden laths as is? Polythene bags are what? Basically plastic? These will be basically expansion slots, should I really have to cut the re-bar mesh, cause its being poured (hopefully) along with the 40 centimeter Kan (foundation trench) which contains 9mm steel.

Originally Posted by mellow

Elwood: There is also a plastic type of material a friend of mine has seen used here in Thailand. The problem is to find out what it's called and where to purchase it. But I'm looking. Should have more luck tomorrow, its Monday. Happyman: If I can't find the commercial type of material for the job, I will more than likely go with your idea. Did you buy the wooden laths as is? Polythene bags are what? Basically plastic? These will be basically expansion slots, should I really have to cut the re-bar mesh, cause its being poured (hopefully) along with the 40 centimeter Kan (foundation trench) which contains 9mm steel.

Bought the laths and used "as cut"
Polythene was to stop the concrete sticking to the rough wood and stopping them coming out easily, and came out with the wood .

Panels were about 12 'long X 10' wide and 6-7"thick laid on hard compacted sand (in Saudi) and used daily by a 1.5 ton forklift truck for warehouse access.

Thanks for the info Happyman.

Local roads department will know a source of bitumen

Went to a construction company where I buy some of my materials from, and they said that they use styrofoam. So I got some half inch panels of that, and will cut it about 4 centimeters deep and use that. Couldn't find the bitumen. talked to my workers about it and at first they considered using pvc, then they opted for the styrofoam.

Originally Posted by geoff

Another thing to watch for, is a material which is a repellant to insects, aspecially termites, as they will come up and eat their way through it and continue on until they find something else to eat. Usually it is good to spray, or treat the ground before pouring the concrete. Unless you are laying a parking area or driveway, where you don't mind the beasties coming through.

Did that with the house, also put in underground pvc in order to feed them insecticide periodically.

Originally Posted by mellow

Did that with the house, also put in underground pvc in order to feed them insecticide periodically.

Wise move!!
They didnt do that when they built the house i live in ( rented so I dont really give a f*ck ) but when termites started to eat the skirting boards the landlady got some "cowboys" in who drilled holes in the tiled floor - breaking a few at the same time - and pumped some crap in .
They sealed the holes and patched up the tiles using some sort of plaster which after a few weeks turned to powder !!.
I got it all dug out and grouted properly and sent the landlady the bill ! A bit of forethought like you have would have saved all the trouble !!