Concrete Dams
Concrete dams are vital structures where Repairs and Waterproofing are crucial aspects of dam maintenance for several reasons:
- Environmental factors: Over time, exposure to rain, wind, and freezing temperatures can cause cracks and spalling (chipping) of the concrete surface. This is especially true in places with harsh winters where water repeatedly freezes and thaws within the concrete, causing it to expand and crack
- Chemical degradation: Environment chemicals can seep into the concrete and cause corrosion of the steel reinforcement bars inside. This corrosion expands the steel, causing cracks in the concrete and weakening the structure.
- Overload and wear: The weight and constant vibration from heavy traffic can put stress on the bridge, leading to cracks and wearing down the concrete surface.
- Design and construction flaws: Sometimes, problems can arise from errors made during the design or construction of the bridge. For instance, inadequate concrete cover over the reinforcing steel can make it more susceptible to corrosion.
Waterproofing:
- Seepage control: Dams are designed to hold back water, but concrete is not perfectly impermeable. Seepage, the slow passage of water through the dam, can erode the foundation and weaken the structure. Waterproofing helps prevent excessive seepage.
- Longevity: Water exposure and harsh environments can deteriorate concrete over time. Effective waterproofing protects the dam from these elements, extending its lifespan
- Safety: Dam failure can be catastrophic. Waterproofing minimizes the risk of water infiltration, which can lead to structural weaknesses and potential breaches.
Repair:
- Crack sealing: Cracks in the concrete can allow water to penetrate deeper into the dam and weaken it. Repairing cracks with appropriate materials helps maintain the dam's structural integrity.
- Reinforcement protection: Waterproofing and repairs also aim to protect the steel reinforcement bars embedded within the concrete. Corrosion of these bars due to water ingress can significantly weaken the dam.
Here are some common methods used for repairs and waterproofing of concrete dams:
- Concrete admixtures: These are additives mixed into the concrete during construction to improve its water resistance.
- Membrane waterproofing: These are sheets or coatings applied to the dam's surface to create a barrier against water infiltration
- Crack injection: For existing cracks, specialists may inject special materials like epoxies or polyurethane grouts to seal them
- Sprayed Polymer mortar: This technique involves spraying a thin layer of polymer modified high strength modified mortar onto the damaged area for repair.
The specific repair and waterproofing methods chosen will depend on the type of dam, the extent of damage, and the budget.