Zenith performed an inspection and strengthening works to a 61m high concrete chimney at a refinery in Scotland.

The works comprised the following sequence:

• Access was gained to the 37m level of the chimney by installing temporary ladders and a full circumference scaffold platform.
• An inspection of the concrete windshield shell where excessive horizontal cracking had been found.
• Core samples were taken through the concrete to investigate the extent of the cracking.
• The cracking was found to extend completely through the concrete for the full circumference.
• Zenith engineers then produced a report and investigated the cause of the cracking. They then developed a repair scheme to strengthen the chimney. Full calculations and design checks were performed.
• Crack sealing work was performed to the outside of the crack for the full circumference.

Carbon fibre plates were bonded to the outside of the chimney windshield in a vertical orientation to strengthen the shell at this location.