Arab Construction World – March 2007
Knowledge Village is an upscale area in Dubai located close to Internet City, Media City and the Dubai Marina. The Village is well known for representing some of the world’s most reputed academic institutes and colleges in one geographical area. Inside Knowledge Village, next to Sheikh Zayed Road, (one of UAE’s busiest highways) there is an office building owned by Armada Holdings FZ LLc.
Before construction began for the building’s below-grade parking structure, the contractor, AI Kaitoob Building Contracting, was concerned with the amount of time associated with installing membranes and protection boards for waterproofing the concrete. Although membranes and protection boards are commonly used, they are a time-consuming and expensive method of waterproofing due to high labor and opportunity costs.
The project team understood that in below-grade structures such as the parking garage, the sight of cracked concrete is common. While the impact of these leaks is not as dramatic as leaks in water containment structures, the team was concerned that repairs would be time-consuming and costly. Also, the team was concerned that the leaks would be aesthetically displeasing and possibly allowing the corrosion of the reinforcing steel and eventual deterioration of the structure’s integrity.
Selecting the right waterproofing solution
With a wide range of waterproofing systems available on the market today, the project team had many choices, including:
After weighing the options, the Knowledge Village project team selected an integral crystalline waterproofing system because it offered a number of key advantages over the other alternatives in providing a completely tanked waterproofing solution such as:
Even when properly applied, external membrane systems have a finite useful life. They eventually dry, crack, peel or otherwise deteriorate as a result of exposure to hot/dry conditions and ultraviolet light. The result is a structure that is vulnerable to water leakage and/or contamination. When an external membrane is compromisd, water becomes trapped between the concrete and the membrane and leaks will occur at the path of least resistance in the concrete. Once the crack is repaired, trapped moisture will then find the next path of least resistance and a new leak will appear. This pattern will repeat itself during the life of the structure, deteriorating it and compromising its integrity. Crystalline systems improve with time and exposure to moisture. A key advantage of the best systems is the ability to reactivate to seal fresh cracks in weeks, months, even years after the application. In addition, crystalline is highly resistant to hydrostatic pressure and will not break down over time. Providing long-term protection against water damage reduced maintenance costs and peace of mind.
Advantages of Integral crystalline Waterproofing for tanking a below-grade structure
Along with superior waterproofing and self-sealing properties, integral crystalline waterproofing offers a number of advantages over conventional membrane systems. These are:
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 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 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.
Results from using Integral Crystalline Waterproofing
The project team selected Kryton International’s Krystol® waterproofing system for waterproofing 1530 cubic meters of concrete on the raft slab and 200 cubic meters of the retaining walls. The Krystol Waterstop System™ was also used in all the construction joints to complete the watertight tanked structure.
In addition to saving 35-days of construction time (approximately US$16,000.00) the use of ICW eliminated the following steps for waterproofing:
AI Kaitoob Building Contracting was extremely pleased with the results of using Kryton’s Complete Waterproofing System™ and additional revenues were realized in allowing his company to move on to new projects at a faster rate than usual.
How is ICW applied?
Integral crystalline waterproofing products are usually supplied as an easy-to-use, dry powder comprised of Portland cement, silica sand and special chemicals that can simply be added to the ready mix truck at the plant or jobsite to create a powerful moisture barrier in slabs and walls. There is no need for any sort of surface application at the construction site – ICW can be simply added to the concrete.
Such systems can also be surface-applied to existing walls and slabs and incorporated into construction joints during construction or after the fact.
In building a concrete tanked structure such as the below-grade parking facility at Knowledge Village, extra care must be taken when waterproofing construction joints, since these areas are the most vulnerable to water intrusion. Until recently, the best option for waterproofing joints was to place a plastic barrier or Bentonite strip into the joint before the adjoining wall was poured.
However, this method can be unreliable since physical barriers easily become dislodged or damaged during subsequent concrete pours, rendering them ineffective and leaving joints susceptible to leakage.