BASEMENT or any below-ground structure that is formed by a base slab, walls and a top slab, is partially or fully exposed to the surrounding soil and groundwater, resulting in specific exposure and stress from the prevailing permanent or temporary environmental conditions. Today new building owners generally request a service life of 50 years or more, and for structures such as tunnels up to 120 years. Any lack of water tightness severely reduces the long-term durability of a building or other below-ground structure and badly affect its planned use as water ingress will result in physical attack and deterioration of the concrete. This leads to expensive structural repair works, damage or loss of interior finishes and goods, operational downtime, or serious impact on the internal environment from damp and condensation.
WATERPROOFING SYSTEMS for below ground structures are faced with more stringent requirements regarding durability, exposure and stress conditions, construction method and sequence, ease of application and total cost management. In addition, sustainable system solutions are becoming more important in order to save natural resources, energy and water, plus reduction of CO2, etc. As the global leader in providing structural waterproofing solutions, Sika has the most complete and comprehensive range of products and systems that are designed and can be adapted to meet the specific needs and requirements of owners, architects, engineers and contractors on site.
The selection of the appropriate waterproofing method, the project specific design of the chosen waterproofing system and its correct installation on site are key elements in minimizing the Total Cost of Ownership. A waterproofing system typically amounts to less than 1% of the total constructions cost, yet the selection of a high quality waterproofing solution can easily save this amount or more, in future maintenance and repair costs over the service life of the structure.
Sika provides full range of technologies and systems used for below ground waterproofing. This includes highly flexible membrane systems, liquid applied polymeric membranes, watertight concrete admixtures, joint waterproofing systems, waterproofing mortars and coatings, as well as injection sealing grouts. All of these solutions are designed to be used together to meet the specific needs and requirements of owners, architects, engineers and contractors on site.
Type of Exposure and Stress
Below ground structures can be subject to many different exposure conditions including:
- Different levels of water exposure and pressure (e.g. damp soil, percolating water or water under hydrostatic pressure, and open water)
- Aggressive ground water containing chemicals (commonly sulphates and chlorides in solution)
- Unequal static forces (due to load, settlement or uplift, etc.)
- Dynamic forces (e.g. from settlement, earthquake, explosion, etc.)
- Temperature variations (frost during the night/winter, heat during the day/ summer)
- Gases in the ground (e.g. Methane and Radon)
- Aggressive biological influences (plant roots/growth, fungal or bacterial attack)
Owner’s Project Requirements
To define the appropriate waterproofing strategy and type of system for a specific project, it is important to consider not only the ground conditions but also the project requirements of the owner: Functionality and future use, the service life and the total cost of ownership.
BASEMENT WATERPROOFING – CONCEPT
Integral Waterproofing System
A waterproofing system integrated into the concrete structure. Liquid water penetration is stopped by the structure itself and cannot entirely pass through into the basement. Typical products are admixtures for watertight concrete combined with appropriate joint sealing systems for connection, construction and movement joints.
- Grade of watertightness: Grades 1 –3
- Application: New construction
- Protection provided: Waterproofing
- Durability: Very high durability (for non-aggressive ground water)
External Waterproofing System
A waterproofing barrier applied on the external surfaces that are exposed to ground water (positive side). The structure is protected against water ingress and also against any aggressive substances or influences. For some materials such as post applied waterproofing mortars and coatings, access to the external surfaces is required for application after concreting.
- Grade of watertightness: Grades 1 – 3 plus additional requirements
- Application: New construction
- Protection provided: Waterproofing & concrete protection
- Durability: Low to high durability
- Internally Applied Waterproofing System
A waterproof barrier is applied on the internal surfaces of the structure (negative side). These systems do not prevent damage to the structure from water ingress, nor concrete damage due to aggressive chemicals. Generally these systems are applied as coatings or sheet membrane linings, and is only recommended for refurbishment works in example where access to the directly exposed surfaces is not possible.
- Grade of watertightness: Grades 1 – 3
- Application: Generally for refurbishment only
- Protection provided: Waterproofing
- Durability: Limited durability (as the structure is unprotected)
Leak Sealing Solutions
Leaking concrete structures below ground such as basements and civil engineering structures, can have a greatly reduced service life due to steel corrosion and concrete damage, in addition to any reduced functionality and use. In order to avoid the expensive costs of repairs to the structure, or to water damaged interior finishing’s, furnishings or other goods, plus the costs of any operational downtime, these leaks can often be securely sealed and waterproofed by injection.
Sika provides an extensive range of injection systems for all types of leak sealing applications in concrete, masonry and natural stone structures. These can be used at any time, including during the initial construction works, or later to extend the service life during any subsequent refurbishment, according to the specific project’s requirements. Sika injection systems can not only close, flexibly bridge, seal and make leaking structures watertight for the long term, some can also be used to increase or restore structural integrity and load bearing capacity, thereby providing complete and durable maintenance solutions.
Sika’s high performance injection materials are also fully compatible with Sika’s complete Engineered Waterproofing range and they can be used for the repair and sealing of cracks, voids, joints, hoses and compartment systems in many different structures. As a prerequisite, all of Sika’s injection products are also fully tested and conform to all of the relevant global standards.
Sika Injection Solutions for Repair and Refurbishment Works
In situations with water ingress due to localised damage of the waterproofing system, appropriate repairs to seal the leaking areas have to be undertaken. These can often only be done by injection, because of inadequate access to the waterproofing system itself in most basements and below ground structures. According to the type of damage / leakage (i.e. through joints, cracks or honeycombed areas, etc.) and the waterproofing requirements, the right materials have to be used. Successful and durable repairs by injection are ensured by the combination of Sika’s expert diagnosis, using Sika materials and recommended equipment, plus Sika trained installers.
There are three primary success factors involved in ensuring the effectiveness and durability of injection works. It is essential that the right combination of injection materials, injection equipment and injection method must be selected and this is what Sika’s extensive technical and practical experience provides:
The selection of the right injection material and indeed the right specific injection product for the defined project requirements is the first key factor for success. This especially means the materials viscosity, flexibility and behaviour in contact with water that can all significantly influence the effectiveness of the injection.
Appropriate equipment for the selected injection material, including for the correct preparation, mixing and delivery of the material is the second key success factor. This means everything from the initial dosage and mixing, through delivery from a suitable pump, to use of the right packers/ports/connectors.
Injection Method / Application
Thirdly, the correct injection method and application techniques must be used by trained, competent and experienced contractors, in order to ensure the success and provide complete and permanent leak sealing solutions.
INJECTION MATERIAL TECHNOLOGIES
Polyurethane Foam Resins
Polyurethane foaming resins are designed to expand with water to temporarily block the passage of water through the crack or void. Their fast expansive reaction with water forms a tough and flexible / elastic foam. For permanent waterproofing, these polyurethane foaming resins are re-injected with a suitable non-foaming injection resin – usually also based on polyurethane as below.
Polyurethane resins are hydrophobic, flexible and used for the non-structural injection sealing and waterproofing of voids, cracks and joints. Their low viscosity allows good penetration into the concrete structure to seal the leaks and achieve a durable elastic seal. Polyurethane resins seal with very good edge adhesion to concrete and their hydrophobic characteristics. In voids, cracks and joints with high water ingress, pre-injection as temporary waterstopping with a Polyurethane foaming resin as mentioned above is required.
Acrylate resins are hydrophilic, very flexible and used for non-structural injections of cracks, joints and voids, including for injection hose systems, compartment systems and area (e.g. Grid and Curtain) injection works. For application Acrylate resins have an extremely low viscosity (similar to water) and therefore have ideal penetration abilities. Their reaction (hardening) time is also adjustable, which allows flexibility in adaptation of the injection material to the prevailing conditions on site (e.g. temperature and injection distance, etc.). Acrylate resin based materials seal and waterproof leaks through their hydrophilic swelling behaviour in contact with water. The injection equipment is also easily cleaned with water.
Epoxy resins have relatively high tensile and compressive strengths in relation to concrete, they are generally regarded as ‘rigid’ materials and widely used for structural repairs by injections of cracks and voids in load bearing reinforced concrete structures or elements. Their low viscosity allows excellent penetration into cracks in the structure and this also helps to ensure permanent and durable load transfer based on their excellent adhesion to the concrete. Epoxy resin based materials are suitable for many different structural injection requirements and applications in dry and slightly damp.
Microfine Cement Suspension
Microfine cement suspensions are non-flexible and therefore non-movement accommodating, rigid, polymer modified, injection materials (also often known as Microfine cement grouts), which are based on blends microfine cements. They are now widely used for structural injection works to seal non-moving cracks, voids and day work joints for example. Due to their polymer modification, these cement based materials can also have high flow characteristics and very good penetration ability.
Basements and below ground civil engineering structures protected with Sika waterproofing solutions have increased living comfort and wider possibilities for use, plus the total cost of ownership is reduced and increase the durability increased for the entire service life of the project.
Our fully integrated and compatible system solutions are sustainably produced and well proven in practice for many decades all over the world, plus they are fully tested and certified to all leading national and international standards. This gives owners and their project specifiers and contractors the security of clearly defined performance characteristics for all of Sika’s waterproofing solutions to be used for their specific requirements.
For further details:
Sika India Pvt. Ltd.
501 & 502, B Wing, Lotus Corporate Park Off. Western Express Highway Goregaon East Mumbai – 400063
Ph: +91 22 6270 4038,
Fax: +91 22 6270 4039