Expansion Joint-kind of bond dreaker to use?

[Galway11]

Hello everyone,

I need to seal 20mm x 20mm expansion joints with hot applied modified bitumen sealant. This is for a lightly trafficked outdoor concrete hardstanding.

The problem is the filler is closed cell polyethlyene foam (as specified by designers), which I'm told will be melted by hot applied sealant. Cold pour is not an option due to cost...

The best solution I can find is to use 3m 7130 masking tape as a bond breaker (heat resistant to 170 degrees C supposedly). But I haven't done this before so I don't know if it will work or not!!!

Anybody done this before? Is it likely to work?

Thanks in advance for any replies...

 

[Ron]

High temp masking tape works fine. Even regular masking tape will work in many cases.

 

[cvg]

wouldn't it be better to RFI the designer and ask to use a different backer rod since the specified product is not suitable?

 

[Galway11]

I've spoken to the designers and sent them material data sheet for the masking tape, they know even less about it than me to be honest! It's the clients detail which they copied and pasted onto their drawing. The company also can be slow to pay so I'm not going to suggest anything expensive.

There isn't a backer rod, it's 20mm wide x 175mm deep strips of closed cell polyethylene with a 20mm tear out at the top...I suppose it could be raked down and a backer rod put in...the only backing rods I've seen are made from the same material though.

I've been looking up bond breaker tape material on the net. I've seen polythene tape, polyethylene tape, duct tape and metal foils mentioned. Which is the best to use?

I may also have to do the same with 10mm wide isolation joints, designers haven't given a detail yet though. Would this be too small for hot applied sealant? I'm planning on using a Type N1 sealant to BS 2499 (Coljoint N1). These joints are an afterthought in a 75mm thick walkable concrete area!

Thanks for your replies

 

[Ron]

I doubt that polyethylene will withstand the heat. Polyester or PTFE will work, but those are significantly more expensive than masking tape.

Keep it simple. Masking tape will work. Don't let the contractor overheat the sealant. Duct tape will work, also.

Many state Departments of Transportation specify masking tape.

 

[Galway11]

Thanks for your answers, much appreciated