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Core drilling is used to evaluate the quality of bonding, adhesive thickness and any lack of adhesion in bulk adhesion applications such as concrete bridge refurbishment.
To evaluate the quality of bonding, thickness of adhesive layer and any lack of adhesion
Cores are drilled out of the bonded structure. These are prepared and examined using optical metallographic methods.
Core drilling was used to evaluate the bond quality following refurbishment of the M5 Quinton expressway in Birmingham in 1975, the first application in the UK of such refurbishing methods.
A number of core samples were obtained from the bridges at Quinton to provide samples for this forensic investigation of the adhesive joint. The Quinton bridges appear to be performing satisfactorily, apart from areas subject to persistent leakage and consequent washing of water over plated areas. Clearly it is important to divert running water and to fill cracks in the deck, prior to plating, through which water might migrate to bondlines.
The steel/steel bondlines were found to be between 0 and 1.5mm thick; the steel/concrete bondlines were between 0.5 and 5.0 mm thick. Adhesive was absent in some areas, including an important zone close to the end of a plate. Such areas had not been detected in any of the tapping surveys.