Epoxy-Resin-Base Bonding Systems for Concrete

[TRAN QUOC HOANG]

Dear All.

Now im dealing with a problem. Our mat foundation is 4000mm thickness, we are planing to cast this foundation in 2 times (2 layers, layer 1 is 2m and layer 2 is 2 meters).

Now im dealing with the shear flow resistance at the shear plan (the interface between 2 casting layers).

Option 1: using shear friction reinforcement prosed in ACI or EC2 code.

Option 2: using expoxy (chemical) for eliminating the shear reinforcement and help saving cost.

But for the option 2, im worrying about the durability of expoxy by the time.

Please advise me some infor for the durability of expoxy resin base.

 

[BridgeSmith]

I would find it surprising if using an epoxy would be less expensive than rebar. That being said, the way to do it with virtually no cost increase is to form keyways into the bottom part of the slab so that the two concrete pours interlock.

 

[hokie66]

First placement, concrete hardens. Then epoxy, which hardens. Second placement, concrete hardens. No connection between the two, as the epoxy will form a perfect bond breaker.

Hot Rod is correct, keys are effective in this type structure. There should be some reinforcement as well.

 

[TRAN QUOC HOANG]

Hi All, but ACI code, Designation: C 881 – 99, Standard Specification for
Epoxy-Resin-Base Bonding Systems for Concrete1. It state that we can use expoxy for that type of structure.

 

[hokie66]

That would be what I would call very poor advice. But if you don't want to take our advice, I suggest you contact Sika or one of the other companies who make these products. Explain what you want to achieve, and ask them how to do it. I predict they will say that it will be impossible to control the timing of the bonding application with the concreting. These bonding agents can work for small areas, but not something like your mat foundation.

 

[dik]

Hokie's right on... keyways are the only way to provide a positive attachment... and, make sure the existing concrete surface is dry.

Dik

 

[TRAN QUOC HOANG]

I had worked with some suppliers (like BASF), and they surely told that this method by using expoxy is possible.

They said that this method will be the same with using epoxy for FRP (strengthening of structure by FRP).

 

[hokie66]

Unfortunately, sometimes supplier representatives will tell you what you want to hear, or enough to convince you to buy some product, then leave you high and dry. Ask the supplier for some references for similar projects.