Gilsonite for Bridge Deck Waterproofing

Water and de-icing salts penetrating bridge decks corrode reinforcement. Waterproofing layers prevent this.

Systems

• Mastic asphalt layers
• Bituminous sheet membranes
• Liquid-applied membranes

Gilsonite role

Hardens mastic and membrane compounds, improving resistance to indentation from traffic and hot asphalt surfacing.

Why bridge decks need special attention

Chloride from de-icing salts and sea spray penetrates concrete and corrodes reinforcement. Repair of a bridge deck is expensive and disrupts traffic, so the waterproofing layer must last as long as the surfacing.

Requirements for deck waterproofing

• Strong bond to the concrete deck
• Resistance to hot asphalt surfacing (often laid at 160–180 °C)
• Resistance to indentation from heavy wheel loads
• Ability to bridge small cracks

Role of gilsonite

Gilsonite raises the hardness and softening point of mastic and membrane compounds, so the layer does not soften excessively when hot asphalt is laid on it and resists indentation under traffic.

Good practice

• Shot-blast the deck to remove laitance.
• Apply primer and check pull-off adhesion on test areas.
• Protect the membrane from traffic until the surfacing is placed.
• Detail joints, drains and kerbs carefully – most leaks start at details.

See waterproofing grade gilsonite and gilsonite in mastic asphalt.