Large Scale Central

Question on joining concrete roadbed sections

General Discussion
#1

I’m about to pour a concrete pad for two new switches directly next to an existing pad [See This Thread for details]

Should I tie the two pads together - or let them float in the ground independently?

I could drill the end of the existing pad and set some rebar in place to tie it to the new pad - OR - I could install an expansion joint between them -OR- I could just pour the new one tight to the old one.

I’m concerned that if I don’t tie them together I may end un with height difference at the joint after a winter or two. On the other hand, if they are tied together movement of one may cause the other to crack.

What would you do ?

I have to go find Cozad’s article on Concrete Roadbed (if I’m still allowed to read it) and see what he does.

#2
Jon Radder said:
I'm about to pour a concrete pad for two new switches directly next to an existing pad [See [url=http://www.largescalecentral.com/LSCForums/viewtopic.php?id=11215]This Thread[/url] for details]

Should I tie the two pads together - or let them float in the ground independently?

I could drill the end of the existing pad and set some rebar in place to tie it to the new pad - OR - I could install an expansion joint between them -OR- I could just pour the new one tight to the old one.

I’m concerned that if I don’t tie them together I may end un with height difference at the joint after a winter or two. On the other hand, if they are tied together movement of one may cause the other to crack.

What would you do ?

I have to go find Cozad’s article on Concrete Roadbed (if I’m still allowed to read it) and see what he does.


I would drill the existing and use some rebar it can’t hurt, I did it with a patio extension about 4 years ago and it is still ok. I would bet if you don’t that it will shift all the mow strips I have put in through the years have moved. Yep no rebar.

#3

Any cracking is supposed to be relieved by the expansion joint. Just having the two separate slabs will allow for expansion/contraction. Most modern large slab pours are made monolithic and joints are saw cut in after a short cure.

Rather than rebar etc, if it is a small slab, just drill and screw in some TapCon type screw fasteners. Use a fiber glass admixture to help control cracking versus steel rod.

#4

Jon,
I would pour two separate pads.
Remember you are not building a space shuttle launch pad here. :slight_smile: :slight_smile:
A little leveling with a rubber mallet now and then and you are back in business.

My switches set on those pre-fabbed 8 x 16 x 2 concrete slabs, with a tamped sandy base.
No problemo’s.
You don’t even have to mix or pour anything.

#5
David Hill said:
Any cracking is supposed to be relieved by the expansion joint. Just having the two separate slabs will allow for expansion/contraction. Most modern large slab pours are made monolithic and joints are saw cut in after a short cure.

Rather than rebar etc, if it is a small slab, just drill and screw in some TapCon type screw fasteners. Use a fiber glass admixture to help control cracking versus steel rod.


Ditto. See David and I can agree on something too. :wink:

-Brian

#6

Thanks guys.

John, you’re outnumbered :smiley:

My original plan was to tie them, but then had second thoughts. I like the screw idea too. Sounds much easier.

Back to Homely Depot to look for the fasteners.

#7

Let me throw my 2 cents in.

I use the paving block method for my switches. I float the block on some ballast, level it at final grade, then install the switch over it.

Rarely do I have to fuss with it. I think that over the years, I’ve had to adjust only 2 or three of them, period.

#8
Steve Featherkile said:
Let me throw my 2 cents in.

I use the paving block method for my switches. I float the block on some ballast, level it at final grade, then install the switch over it.

Rarely do I have to fuss with it. I think that over the years, I’ve had to adjust only 2 or three of them, period.


That’s what I said as well, Steve.
Just trying to save Jon some work. :slight_smile: :slight_smile: :slight_smile:

#9
Brian Donovan said:
David Hill said:
Any cracking is supposed to be relieved by the expansion joint. Just having the two separate slabs will allow for expansion/contraction. Most modern large slab pours are made monolithic and joints are saw cut in after a short cure.

Rather than rebar etc, if it is a small slab, just drill and screw in some TapCon type screw fasteners. Use a fiber glass admixture to help control cracking versus steel rod.


Ditto. See David and I can agree on something too. :wink:

-Brian


+1

:wink:

#10

Hay I like that paver ideal. I have a ton of the 2 x6 x12 pavers. I will have to do that when I add my rail clamps this year.

Thanks guys for finding more work for me.

#11

CRAP !

Picked up a small pack of Tapcon screws and a bit. Drilled 8 holes and put in 8 screws on the butt-end of the existing pad. Then started digging around the sides to overlap the form for the new section. There was a small crack on the surface which turned out to be the butt joint between two pours. My digging popped the section loose :frowning:

I forgot that the existing pad was multiple pours. Looks like I didn’t worry about tying them together 6-7 years ago when I poured them.

So now I have this 8 inch long x 4 inch thick chunk of roadbed with 8 Tapcon screws in it floating loose. I was able to float it back pretty tight and level with the rest of the roadbed, but now I’m questioning the logic of tying this small chunk to the new 40 inch section.

Maybe I’ll just pull out the short section and tie back to the original slab. Lots of effort wasted drilling and installing those screws.

#12
Jon Radder said:
CRAP !

Picked up a small pack of Tapcon screws and a bit. Drilled 8 holes and put in 8 screws on the butt-end of the existing pad. Then started digging around the sides to overlap the form for the new section. There was a small crack on the surface which turned out to be the butt joint between two pours. My digging popped the section loose :frowning:

I forgot that the existing pad was multiple pours. Looks like I didn’t worry about tying them together 6-7 years ago when I poured them.

So now I have this 8 inch long x 4 inch thick chunk of roadbed with 8 Tapcon screws in it floating loose. I was able to float it back pretty tight and level with the rest of the roadbed, but now I’m questioning the logic of tying this small chunk to the new 40 inch section.

Maybe I’ll just pull out the short section and tie back to the original slab. Lots of effort wasted drilling and installing those screws.


Can I refer you to the second post in this thread :(. Oops forgot Outnumbered, well actually If it were me I would pull out the screwed up cemento and go with the floating block on ballast, no holes, on screws and no trips the local HD.

#13
John Neal said:
Jon Radder said:
CRAP !

Picked up a small pack of Tapcon screws and a bit. Drilled 8 holes and put in 8 screws on the butt-end of the existing pad. Then started digging around the sides to overlap the form for the new section. There was a small crack on the surface which turned out to be the butt joint between two pours. My digging popped the section loose :frowning:

I forgot that the existing pad was multiple pours. Looks like I didn’t worry about tying them together 6-7 years ago when I poured them.

So now I have this 8 inch long x 4 inch thick chunk of roadbed with 8 Tapcon screws in it floating loose. I was able to float it back pretty tight and level with the rest of the roadbed, but now I’m questioning the logic of tying this small chunk to the new 40 inch section.

Maybe I’ll just pull out the short section and tie back to the original slab. Lots of effort wasted drilling and installing those screws.


Can I refer you to the second post in this thread :(. Oops forgot Outnumbered, well actually If it were me I would pull out the screwed up cemento and go with the floating block on ballast, no holes, on screws and no trips the local HD.

Wait John - I think you need to re-read your own post…

John Neal said:
I would drill the existing and use some rebar it can't hurt, I did it with a patio extension about 4 years ago and it is still ok. I would bet if you don't that it will shift all the mow strips I have put in through the years have moved. Yep no rebar.
You suggested drilling and adding rebar and I agreed with you :D The John who was outnumbered was John Bouck ! Now you are changing sides and suggesting I float it!

No problemo. The places where I have poured concrete road bed are the least troublesome of all. I will be experimenting with ladder for this new loop. I plan to make a joint for the ladder at the end of my concrete pour. I can salvage the Tapcon screws and drill new holes. It’s only labor.