Leak Detection in Bridge Decks

Most modern bridge decks are waterproofed in spray-applied pllymeric coatings. Once asphalt has been applied to it, however, the two are inextricably bonded together, so any defects in the waterproofing cannot be rectified. Whilst it is possible to test the waterproofing with the asphalt in-situ, whilst this can provide approximate locations to defects, the action of removing the asphalt is likely to damage the membrane further, thus negating the effects of test.

For this reason it is considered essential that the waterproofing is fully tested beforehand by means of a holiday test, which should preferably be undertaken by an independent authority, such as Thornton Consulting.

 

Although we are principally involved in locating and resolving leaks, our services extend to their prevention (eg by integrity testingof membranes (see above).

In that rspect, there is potential for leaks resulting fromwaterproofing membrane delamination.  Where this occurs, in the bridge deck membrane, the entrapped air will expand by over 800x, the bubble so formed providing a contour fort the asphalt being rolled out. As the asphalt cools, this blister remains in place, thus presenting potential for crack propagation in the asphalt, with ultimate failure of the membrane fully adhered to it and water/ salt damage to the structure.

We at Thornton Consulting can identify delamination in the membrane prior to asphalting by a process known as transient thermography.   This method can also be applied to determine delamination beneath rolled asphalt.  Details are available on request.