nicholls-colton-half-joint

Half-joint investigations

Half-joint investigations are vital as the joints have commonly been used in bridge deck construction, in order to simplify design and construction techniques.  However problems have been found associated with the failure of deck expansion joints allowing chloride rich moisture to enter the inner surfaces of the joint, leading to a possible deterioration in the condition of the concrete and hence reinforcing steel, reducing the long term serviceability of a structure.

Areas of the bearing shelf and re-entrant angles of the joint are frequently affected, their relatively inaccessible positioning causing problems with inspection and maintenance works that may be required.

Nicholls Colton have undertaken numerous Half-joint investigations utilising routine concrete condition testing to deck surfaces and soffits surrounding a half joint, along with more specialist activities to access the internal sections of the joint.  Cores to the edge of the joint drilled vertically down from the deck and/or up from the soffit provide access to the vertical faces of the joint and area of the bearing shelf.  By the use of an endoscope, a visual inspection can be made of these surfaces identifying defects such as spalling and cracking which would be indicative of deterioration of the concrete.  Depending on the level of endoscope used, still photographs or video footage can be made of these inspections, systems also being available to allow the measurement of the width of any cracking observed.

As well as visual inspection, specially adapted equipment can be used to determine the half-cell potential of concrete vertical faces allowing an assessment of corrosive potential to these areas of the structure.  Cores taken can be tested for chloride contamination along with other chemical properties and also subject to petrographic examination if required.

A full factual report of our findings along with photographic record (video footage being provided electronically if taken) is provided.