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LACK of rebar support

LACK of rebar support

LACK of rebar support

What are the standards for placing rebar support chairs for a driveway in a commercial construction application.  I am asking because I have evidence that the contractor ran out of chairs and went forward with the pour because of major pressure from the construction manager.  I represent the client, but before I escalate this issue I need to make sure I am right.  I have attached a picture that shows a worst case scenario.


RE: LACK of rebar support

Take a series of cores and locate the rebar in the slab.  The tolerance on vertical position will govern whether or not to accept the slab.  Chairs are usually not specified, just location of reinforcement.

RE: LACK of rebar support

Great advice.  You are correct, the placement of the chairs is not specified - just the location of the reinforcement.  I will report back the conclusion, the testing begins possibly next week.

RE: LACK of rebar support

Normally the requirement for support chairs, type and spacing is in the specification for commercial construction. For small construction projects, it often is not specified.

RE: LACK of rebar support

The CRSI Manual of Standard Practice recommends a minimum support spacing of 4'.

However, ACI-318 gives no minimum support spacing; the code gives the required clear-cover.  Thus the number of required support chairs is the number needed to support the rebar at the required clear-cover.  The code doesn't care if it's one support chair or 1000 support chairs.  

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