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The Fourth International Conference on

Non-Destructive Testing in Civil Engineering

Liverpool 1997

Bar-Sizing of Reinforcement in Concrete -- Comparison of Available Methods

John C Alldred MA, MSc, Protovale (Oxford) Ltd

Abstract

Cover meters, by definition, are required to measure the concrete cover to reinforcing bars of known diameter. It is also desirable to be able to measure cover to bars of unknown diameter.
A third practical requirement is the wish to measure reinforcing bar diameter: strictly speaking, this is outside the remit of a cover meter of basic specification, but a number of methods of achieving this aim have become available over the years.

This paper summarises and compares six methods that have been published during the period 1977 to 1996 for the measurement of diameter and cover to bars of unknown size.

Originally it had been assumed that such methods should result in a simultaneous solution for diameter and cover; but it has recently become apparent that this approach tended to yield ambiguous results.
This paper confirms that it is important to first choose between one of two requirements:

and then choose and use an appropriate method which best achieves the desired result.
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