Arab Construction World – January 2008
In order to prevent water damage and preserve the integrity of concrete structures, it is essential to use a proven waterproofing system for your foundation to avoid costly problems in the years to come. Whether your foundation needs to be damp-proof or fully waterproofed against hydrostatic pressure, Integral Crystalline Waterproofing (ICW) is changing the way concrete structures around the world are repaired and waterproofed, providing a quick and cost-saving alternative to traditional membranes. While conventional waterproofing involves applying a coating or membrane to the concrete surface, ICW permanently seals concrete by plugging its natural pores and capillaries and blocking the movement of water. It also reacts with incoming water to self-seal the cracks that inevitably develop in concrete, protecting structures against the water and contaminants that can weaken or destroy concrete and corrode steel reinforcement.
How does Integral Crystalline Waterproofing work?
When applied to existing concrete, crystalline chemicals are absorbed into the concrete by capillary action (the natural wicking movement of liquids through a porous structure) and diffusion (the natural movement of chemical molecules.) Once inside the concrete, crystalline chemicals begin growing crystals and filling the spaces between concrete particles. As long as moisture remains present, crystals continue to grow throughout the concrete, reaching lengths of many centimeters over time. Once the concrete has cured, the crystalline chemicals sit dormant until another dose of water (such as through a new crack or rising water table) causes the chemical reaction to begin again.
The ability to reactivate in the presence of water gives crystalline-treated concrete the ability to “self-seal”. When cracks form due to curing shrinkage, settling, seismic activity, etc., water entering through them causes new crystals to form and grow, blocking and filling the cracks. Its ability to self-seal cracks is one of crystalline technology’s most unique and useful features, and can help to dramatically reduce the long-term maintenance and repair costs of a concrete structure. In a hot weather, external membrane systems can become brittle and deteriorate when exposed to prolonged heat, resulting in leaks and increased repair and maintenance costs. Crystalline is unaffected by climate and remains effective for the life of the structure. Also, the soil in hot or tropical climates found in Jeddah, may contain high levels of sulphates, chlorides and other chemicals that decrease concrete’s integrity and corrode steel reinforcements. By blocking the penetration of water that can carry these contaminants and safeguarding concrete and reinforcements against corrosion, crystalline systems will prolong a structure’s useful life.
The Al Mashfa Group, a much-respected medical company, built as a 10-storey full-service private hospital in Jeddah. The project team excavated a 12-m pit for a two-level parking garage beneath the hospital in a mixture of soil and sand that had a high concentration of sulphates, due to its proximity to the Red Sea. Salt water and its ability to corrode the steel and compromise the integrity of the structure was a key concern for the cold joints, as was extreme head pressure (92 m). The team also hit an underground lake that was too large to pump out, which meant the team required a waterproofing solution that could be installed in wet conditions. Finally, construction of the hospital was already behind schedule; the project team could not afford further costly delays.
Selecting the right waterproofing solution
The Al Mashfa project’s team compared traditional membrane systems with the Krystol Concrete Waterproofing System, a worldwide leader in crystalline waterproofing technology. The team discovered that in addition to employing Kryton to completely waterproof and tank the hospital, they would also save time and thousands of dollars in waterproofing and cold-joint construction.
The Krystol system employs advanced integral crystalline waterproofing technology to transform porous concrete into a permanent, water-resistant barrier and provides a guaranteed defense against water damage and steel reinforcement corrosion, through constant head pressure. When combined with water and concrete, Krystol causes millions of needle-like crystals to grow and spread concrete particles to permanently block the movement of water and waterborne contaminants. If cracks form later on, incoming water causes additional crystals to grow, filling the cracks and ensuring that the structure’s waterproofing barrier is protected. Krystol technology provides maximum flexibility and can be used any time before, during, or after the construction process. It can be applied in wet or dry conditions, and unlike external waterproofing membranes originally specified for the Al Mashfa Private Hospital, Krystol will not deteriorate – it is guaranteed to last the lifetime of the structure. “The implementation of all typical waterproofing methods would have been near impossible for our project,” said Mr. A. Hamis Elmas, Project Manager & Architectural Consultant, Al Mashfa Group. “Particularly, given the challenges we incurred during excavation: the 12-me cutoff wall and extreme head pressure. We required an advanced waterproofing system that could withstand all of these obstacles especially during the casting of the matt slab.” The Krystol Concrete Waterproofing System at the Al Mashfa Private Hospital included:
Krystol Internal Membrane HS (KIM-HS), an admixture suitable for new concrete construction. KIM-HS was used in the 1.6m-thick basement slab, along the slab perimeter and in the walls.
The Krystol Waterstop System (KWS), an advanced joint design system that provides both chemical and physical waterproofing barriers. KWS was used in all the cold joints of the slab and walls.
Predictably, when the team first turned off the dewatering pumps, water trickled in, due to the intense head pressure. However, after a few weeks, Krystol’s crystalline technology self-sealed and left the structure dusty dry. “I can say with complete confidence that if Kryton had not been involved in this project, we would still be looking for a waterproofing solution that would meet the demands of our project. I will specify Kryton on all my future projects,” he concluded. More than 25,215kg of KIM-HS® treated 6,413m3 of concrete covering an area of 4,045.5m2. Over 551 lineal meters of KWS™ was used for all the cold joints. The Al Mashfa Group saved 48 days by employing the Kryton concrete waterproofing products service.
Take the time to assess each system, bearing in mind the specific requirements and challenges of your project. Before you select a waterproofing system, ask lots of questions, carefully review brochures and literature and speak with manufacturers’ technical service reps if you need additional information. It may even be worthwhile to have a manufacturer’s field rep visit the site. Investing the time to research, compare and select the best waterproofing system for your structure will save you a lot of time and expense in years to come.