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Photos (WIMR PROJECT):
Time-Tested Concrete Waterproofing Technology
Used in Two University Medical Building Projects
Xypex® Concrete Waterproofing by Crystallization™
VANCOUVER, BC – An established technology to waterproof, protect and repair concrete structures for a wide variety of new and existing applications – Xypex® Chemical Corporation’
The three project phases for the WIMR facility will consist of three towers–the first of which serves as headquarters of the UW Carbone Cancer Center. The tower also is home to imaging sciences, with medical physics occupying the lower level and radiology on the first floor.
Conrad Ettmayer, P.E., LEED® AP, is the structural engineer overseeing the project.
Part of his attention focused on an underground concrete utility tunnel below the entire structure (including the tower’s first two floors, which also are underground)
“When you have high-pressure steam lines, chilled lines and electric lines all winding through a tunnel where people have to walk,” Ettmayer said, “it would be dangerous from a safety standpoint for water to infiltrate through the concrete walls. Not to mention, that water penetration can lead to concrete and interior steel corrosion. At the same time, the lines themselves can produce water or humidity which can attack the concrete from the interior.”
Ettmayer and the general contractor, Oscar J. Boldt Construction, decided the challenge of rendering the tunnel watertight was beyond the capability of an exterior membrane alone, and wanted a “belt-and suspenders” approach. They decided to formulate the tunnel’s concrete with Xypex Admix C-1000 crystalline waterproofing admixture to prevent water intrusion.
Jeff Niesen, vice president for construction management at Boldt, said the site of the project itself presented unique water challenges. “The variety of soils on-site couldn’t easily be made to resist the groundwater pressure from the adjacent Lake Mendota—the surface of which is about level with the worksite—so they had to change the site dewatering method from suction to deep well,” Niesen explained.
The initial concern was that the tunnel, being submerged, could possibly float, thus endangering some of the research and medical-care operations. To prevent that eventuality, the tunnel was overbuilt with extra-thick concrete casing for weight to keep it from moving. In addition, the concrete was formulated with the crystalline waterproofing admixture to prevent water intrusion.
Niesen said seeing is believing. “As expected, the tunnel’s interior has remained dry,” Niesen said. “The way the Xypex technology works allows you to see where it has done its job. You can actually see where the crystallization has occurred to plug a hairline crack.”
According to Niesen, the university informed him that it is committed to continue using Xypex. “They’re sold on it,” he said.
Ettmayer said his engineering firm shares the sentiment. “Now, it’s standard operating procedure that when we have a tunnel, especially below the water table, Xypex is specified” he said. “I’m a believer in it.”
The Xypex crystalline technology also was recently used in another university-owned medical research and services building in Albuquerque, NM: The University of New Mexico’s Tri-Services Laboratories building. The complete building measures 187,000 square feet. Adjacent to the University of New Mexico Health Sciences campus, the $86 million, five-story building (one partially below grade) will accommodate the New Mexico Department of Health Scientific Laboratory Division, the New Mexico Department of Agriculture Veterinary Diagnostic Services and the New Mexico Office of the Medical Investigator.
George H. Bradley, PE, Principal Senior Partner of Chavez-Grieves Consulting Engineers, Inc. in Albuquerque, served as the project’s structural engineer. “The Tri-Lab building has a lower level that is has full soil retaining at one end and no soil retaining at the other end of the building due to the slope of the site,” Bradley said.
“The architect was concerned about water intrusion into this lower level,” Bradley said. “Of course, waterproofing was provided at the outside of the concrete retaining walls as well as a vapor barrier below the slab-on-grade. However, since this building was a high profile state office building, he was looking for additional waterproofing to be certain of its success. We suggested that Xypex be utilized as an admixture in the concrete walls and the concrete slab-on-grade. It was utilized and as far as we are aware, it is performing satisfactorily.”
Concrete waterproofing by crystallization–
The crystalline waterproofing technology can be easily introduced into new concrete as an admixture, a dry-shake product, or a surface-applied coating. For existing (i.e., cured) concrete, surface-applied coatings are used.
Because concrete is permeable to liquids and gases, porous conditions can create multiple problems within a building or other structure due to moisture penetration. The infiltrating water, and harmful chemicals dissolved within, also can compromise the concrete.
The crystalline technology uses water in the capillary tracts as a diffusing medium to carry waterproofing chemicals into the concrete. The chemicals migrate through the waterways of the saturated pore network, where they react and grow non-soluble, needle-like crystals that plug the pores. Within a couple weeks of crystal growth, liquids can no longer pass through and the transmission of gases is significantly restricted. The effect is integral and permanent.
Concrete waterproofing by crystallization is generally less costly and more convenient than external barrier approaches. Crystalline waterproofing makes the construction process greener by eliminating the need for membranes manufactured with plastics, asphalt, polymer resins, solvents, aromatics and other materials with high energy manufacturing costs.
The Xypex crystalline waterproofing technology is non-toxic, contains no VOC's (volatile organic compounds), and is NSF-61 approved for potable water.
Xypex Chemical Corporation (www.Xypex.com)
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Xypex Chemical Corporation is one of the world’s leading manufacturers of products to waterproof, protect and repair concrete structures, a proven solution for both new and existing applications.