Concrete Coal Tunnels – Gladstone

CQPA Coal Valve Tunnels

3 x 1430m² Applied to geotextile and concrete tunnels

The Situation: Three pre-form concrete conveyor tunnels were being constructed at the Port of Gladstone to facilitate loading coal transport ships. They required protection from acid sulphate soils as well as waterproofing along their joints to protect them from leakage, as the tunnels were to be constructed below the level of the water table.

The Solution: Different treatments were required for different types of joints:

• Over each expansion joint, we tacked geotextile both sides of the slip sheet and pressed it into place, then sprayed it with a nominal 2mm coating of Liquid Boot
• We put a 2mm coat of Liquid Boot over the chamber wall construction joints, with a tack-coated geotextile layer on top for protection.
• Arch unit / chamber wall interfaces had a cant placed in the corner, then a 2mm coating of Liquid Boot sprayed to 250mm up the wall and across the floor, with a tack-coated layer of geotextile fitted over the top.
• We placed backing rod into the arch unit butt joints, followed by tape bond breaker, grout, 2mm Liquid Boot and finally a protective tack-coated geotextile blanket over the lot.
• Arch apex joints were grouted, then covered with Liquid Boot and geotextile.