Highway Bridge Waterproofing

Thurmont-MD

PROJECT DETAILS
System: Guardian BD
Completion Date: October 2025
Type: Renovation

PROJECT TEAM
Client: Maryland DOP
Location: Thurmont-MD
Sub‑Contractor: Spray Teq LLC
Technical Service Director: Michel Francisco

PRODUCT DETAILS
FT‑6160 Epoxy Primer – High‑performance primer formulated to maximize adhesion to prepared steel and concrete substrates.
FT‑2202 Polyurea – Rapid‑curing waterproofing membrane that meets AREMA requirements as a stand‑alone barrier layer.
FT‑2202 SS Polyurea – Slow‑curing waterproofing membrane that meets AREMA requirements with an extended gel time and tack-free time to accept aggregate broadcast.

OBJECTIVE
The objective of this project was to waterproof the concrete surface of a highway bridge located in Thurmont, Maryland.
The application of the polyurea coating system aimed to prevent water infiltration into the concrete structure, thereby extending the service life of the bridge deck and providing a durable and flexible barrier against weathering, de-icing salts, and mechanical wear.

SURFACE PREPARATION
Prior to coating application, the concrete substrate underwent a complete surface preparation process to achieve proper adhesion and cleanliness.

Preparation steps included:
• Abrasive blasting using steel shot to remove contaminants, laitance, and weak surface layers.
• Thorough cleaning and vacuuming to eliminate dust and residual particles.
• Inspection to confirm that the surface met the required cleanliness and profile standards before primer application.

This procedure ensured an ideal surface condition for maximum bonding strength and coating performance.

PRIMER APPLICATION
Following surface preparation, the concrete surface was primed with Epoxy Primer FT-6160.
The primer was chosen for its excellent adhesion to concrete and moisture resistance, providing a reliable base for the subsequent polyurea layers.
The primer was applied evenly, ensuring full coverage and uniform film thickness before the polyurea application.
Due to low temperatures at the site, additional attention was required to control the curing process.

POLYUREA COATING SYSTEM
After the primer had cured, the surface was coated with Polyurea FT-2202, applied to a total thickness of 60 mils (≈ 1.5 mm).

This high-performance polyurea system provides:
• Excellent waterproofing and crack-bridging capability.
• Strong chemical and abrasion resistance.
• Rapid curing time, suitable for short construction windows.
• High elasticity and flexibility, ideal for bridge deck applications.

A final layer of Polyurea FT-2202SS was then applied, to a total thickness of 30 mils serving as a sealing coat and bonding interface.
While still tacky, gravels were broadcast onto the surface to promote better mechanical bonding of the asphalt pavement layer applied later on top of the polyurea system.

PROJECT CHALLENGES
The project was executed under several challenging conditions, which required careful planning and field management:

Traffic Management and Execution Phasing
• The highway could not be fully closed to traffic, requiring the work to be performed in two separate phases:
o Phase 1: Left lane closure.
o Phase 2: Right lane closure.
• Each phase was executed within a tight timeframe of two days, demanding efficient coordination of equipment, materials, and crew activities.

Climatic Conditions
• The project faced low ambient temperatures, typical of the Maryland winter, which negatively affected the curing time of the epoxy primer FT-6160.
• Temperature monitoring and environmental control were implemented to ensure proper curing and adhesion between layers.

Despite these conditions, the system was successfully applied within schedule, meeting all performance and quality standards.
Application Area

The total surface area coated with the polyurea system was approximately 4,500 square feet (≈ 418 m²).
Results and Conclusion

The FT-6160 / FT-2202 / FT-2202SS polyurea waterproofing system was successfully applied, providing the following benefits:
• Complete waterproofing of the bridge deck.
• Strong adhesion and seamless integration with the subsequent asphalt pavement layer.
• Durability and resistance to moisture, temperature variation, and traffic wear.
• Timely completion of the project despite challenging environmental and operational conditions.

The application ensured long-term protection of the bridge structure, contributing to extended service life, reduced maintenance, and improved safety for road users.

Gallery

The FreedomTuff® product line is a revelation of what Polyureas, Polyurethanes, Polyaspartics and Epoxies are about. When so many products have been “made” for maximum impact, at Freedom® Chemical Corporation we’ve been content to let our products speak quietly. No need to shout when you have something special to say.