Preheater tower structural strengthening for the Bulacan cement plant

A full range of strengthening techniques was used on the preheater tower

• Application of carbon fibre fabric reinforcement and micro-concrete to increase capacity in the concrete structure
• Additional lateral blisters and new elastomeric bearings
• Strengthening of connections between the steel floor beams and the concrete columns.

A challenging working environment

The working environment was challenging for a number of reasons; there was no elevator access to the structure, operatives were working at height, and in temperatures of up to 50°C due to the operation of the preheater. Other subcontractors had to operate alongside, and restricted work spaces were common. Insulating panel shields and fans were used to improve working conditions inside the structure, with water stations provided at every floor.

Critical connections between the steel floor beams and the concrete tower were strengthened where necessary by the addition of lateral blisters around the existing bearings. New stiffeners added to the steel beams ensured that loads could be transferred on to the blisters.

In other places the entire structural connection was revised, with large custom-designed steel elements fabricated and manoeuvred carefully into the restricted space. The existing concrete slab had to be broken out and the new elements adjusted into position to enable the load transfer to be completed.