Class 2 formwork finish

[nicam]

Had a job here that the architect specified class 2 formwork finish. The builder is now saying the plastic reinforcement chairs are showing up through the concrete finish. any ideas on how to fix this?

 

[civeng80]

Reinforcement must be supported with something and plastic tipped chairs would be what I would be using. If they show up it would have negligable effect, nothing can really be done to fix this.

 

[LittleWheels]

Plastic chairs generally have a bigger 'footprint' than plastic tipped steel chairs (which are less durable). I've found fibre cement chairs to be a better option for high quality architectural finishes and in aggressive environments than either.

At this point, there is no good fix; bagging probably will show up even more.

 

[nicam]

Thanks, if the chairs are still visible would you still consider it a class 2 finish?

 

[RHTPE]

Where does find the definition of "Class 2" finish? It does not sound like an ACI term.


Ralph
Structures Consulting
Northeast USA

 

[hokie66]

It is an Australian term.

 

[kelowna]

It is also a Canadian term.

Class 2 finish should be defined in the code or standard of the place Nicam is from. In B.C., Canada, it even defines the number and maximum size of bugholes.I would be very surprised if it is not so in his area

 

[LittleWheels]

There is nothing in the AS3600 formwork finishes that refers to the visibility or otherwise of bar chairs. You may be able to incorporate that aspect into another section of the table but that interpretation would probably be subject to negotiation, more difficult after the fact.

A proper Class 2 finish is quite challenging for a lot of contractors more used to producing Class 3 or worse. What are the test panels like? Establishing and maintaining a standard for a high class finish is difficult without prior test panels (you did it good enough last time, why not this time). Is a Class 2 finish necessary and appropriate, per the architect's intent?

Photos make it a lot easier to judge whether your situation is acceptable or not, of course.