A sprayed waterproofing membrane is a liquid-applied protective coating system that is sprayed onto surfaces in tunneling and underground structures to provide a seamless and durable barrier against water infiltration.
Definition:
A sprayed waterproofing membrane is a liquid-applied protective coating system that is sprayed onto surfaces in tunneling and underground structures to provide a seamless and durable barrier against water infiltration. It is typically composed of a polymer-based material that forms a continuous and flexible membrane when applied.
Uses/benefits:
Sprayed waterproofing membrane is used in various construction applications to provide a seamless, waterproof layer that protects surfaces from water damage. Some of the uses and benefits of sprayed waterproofing membrane include:
1. Waterproofing: The primary use of sprayed waterproofing membranes is to prevent water ingress into underground structures, such as tunnels, basements, and underground parking garages. They create a seamless barrier that protects the structure from moisture, preventing potential water damage and corrosion.
2. Protection against chemical attack: In addition to water resistance, sprayed waterproofing membranes also offer protection against chemical attacks. They can withstand exposure to various chemicals present in the surrounding soil or groundwater, enhancing the durability of the structure.
3. Crack bridging: Sprayed waterproofing membranes possess excellent crack-bridging properties, meaning they can span small cracks and gaps that may occur in the substrate. This capability helps to maintain the integrity of the waterproofing system, even in situations where the substrate may experience slight movement or cracking.
4. Seamless application: The liquid nature of sprayed waterproofing membranes allows for seamless and uniform application on complex and irregular surfaces. It can conform to different shapes, contours, and penetrations, ensuring complete coverage and eliminating potential weak points.
5. Flexibility: These membranes exhibit high flexibility, allowing them to accommodate structural movements, settlement, or vibration without cracking or delamination. This flexibility ensures long-term performance and durability of the waterproofing system.
6. Adhesion to various substrates: Sprayed waterproofing membranes adhere well to a variety of substrates, including concrete, steel, and masonry. This versatility makes them suitable for different types of underground structures.
7. Fast application and curing: The application of sprayed waterproofing membranes is typically faster compared to traditional sheet membranes. They can be sprayed using specialized equipment, allowing for quick and efficient installation. Moreover, these membranes have fast curing times, allowing for faster project completion and reduced downtime.
Specifications:
Sprayed waterproofing membrane comes in various specifications, depending on the application requirements. The most common specifications are:
1. Thickness: The sprayed waterproofing membrane should be applied at a specified thickness to ensure effective water resistance and durability.
2. Curing time: The membrane should have a specific curing time to achieve the desired properties and become fully functional.
3. Adhesion strength: It should have sufficient adhesion strength to bond to the substrate and create a durable and long-lasting waterproofing barrier.
4. Crack bridging capacity: The membrane should possess good crack-bridging capabilities to accommodate potential movements and minor cracks in the substrate.
5. UV resistance: If the membrane will be exposed to sunlight, it should have UV resistance to prevent degradation and maintain its performance over time.
Types:
There are several types of sprayed waterproofing membrane, including:
1. Polyurethane (PU) sprayed waterproofing membranes: These membranes are commonly used in tunneling and underground structures due to their excellent adhesion properties, flexibility, and resistance to water and chemicals.
2. Polyurea sprayed waterproofing membranes: These fast-curing membranes provide high tensile strength, flexibility, and abrasion resistance. They are suitable for applications where quick installation and fast return-to-service times are required.
3. Acrylic sprayed waterproofing membranes: These membranes offer good UV resistance and weatherability, making them suitable for exterior applications where exposure to sunlight is a concern.
4. Bitumen-based sprayed waterproofing membranes: These membranes are composed of bitumen and polymers, providing excellent water resistance and durability. They are commonly used in below-ground applications.
ITAtech Design Guidance For Spray Applied Waterproofing Membranes, is a guidance document provides a set of information for the use of of spray applied waterproofing membrane in excavated Tunnels and shaft helps in assisting tunnel designers, contractors and owners. It also presents guidance regarding the drawing and design details specifications.