Xypex Chemical’s Concrete Waterproofing Achieves 40th Year Milestone
VANCOUVER, BRITISH COLUMBIA, CANADA - June 1, 2011 - WastewaterPR.com - Xypex Waterproofing by Crystallization uses concrete’s inherent water permeability to deliver crystalline chemicals that plug the material’s pores and bridge micro-cracks that occur as the concrete dries and shrinks.
An established green technology to waterproof, protect and repair concrete structures including wastewater treatment plants (WWTP) and piping – Xypex® Chemical Corporation’s proprietary Concrete Waterproofing by Crystallization™ – has reached a significant milestone: its 40th year of use in thousands of construction projects around the world.
Four decades is a period traditionally cited in the construction industry as the “proof” of a sophisticated technology’s effectiveness. The Xypex Crystalline Technology is judged to be one of the most effective, efficient and economical solutions to protect concrete from water ingress for a wide variety of new and existing applications.
Xypex has been observing the technology’s 40th anniversary in stages, reflecting the fact that, since 1970, the technology has been has been successfully specified in more than 70 countries.
Xypex Waterproofing by Crystallization uses concrete’s inherent water permeability to deliver crystalline chemicals that plug the material’s pores and bridge micro-cracks that occur as the concrete dries and shrinks.
Concrete structures in sanitary sewers and waste treatment plants are vulnerable to attack from hydrogen sulfide gas (H2S), which causes not only a “rotten egg” odor but also corrosion. The control (elimination or reduction) of hydrogen sulfide is a big concern for managers of wastewater collection systems, especially in warm climates or in systems with low velocity.
If a concrete sewer is only partially full, the damp surface above the water line attracts aerobic bacteria that oxidize the H2S and produce sulfuric acid (H2SO4). The acid attacks the calcium carbonate constituents of concrete. Corrosion is most severe at the crown of the pipe, where the acid collects. This leads to a weakening of the pipe and, if left unattended, could also cause a collapse. The key is integral density–keeping out the bacteria that causes the problem.
“When done right,” said Paul Steward, PE, Vice President, Structural Engineering Services for Thatcher Engineering in Minneapolis, “concrete waterproofing by crystalline technology does an excellent job of densifying the concrete, making it more resistant to chemical attack.” Steward is a veteran of more than 50 wastewater treatment plant (WWTP) projects, from new construction to forensic corrective work.
Matt Raysin, a civil and environmental Division Engineer for Genesee County (Michigan) Water and Waste Services, said the Xypex crystallization technology was used for critical areas of a 21-mile long sewer extension project (54-inch and 72-inch pipe) completed in 2006.
“The crystallization product was the mechanism we chose to protect the concrete from developing hydrogen sulfide-induced corrosion,” Raysin said. “There was a noticeable increase in density in the concrete.”
The Xypex concrete waterproofing chemistry draws praise for its application in a large number of WWTP elements, a fact reflected in the comments of Doug Harned, Project Manager for RMCI, Inc., in Albuquerque, New Mexico. Harned’s company was contracted by the nearby City of Aztec to construct a new WWTP. The main component was a 3.5 million gallon system of above-ground cast-in-place concrete basins. Concrete waterproofing by crystalline technology was applied to all interior surfaces of each basin.
“During leak testing of the structures, the majority of the cracks/leaks sealed themselves in less than a week’s time,” Harned said. “This result exceeded our expectations and was superior to results we’ve had with other similar products.”
The crystalline waterproofing chemistry 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 Xypex 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 few weeks of crystal growth, liquids can no longer pass through and the transmission of gases is significantly restricted.
The effect is permanent. In fact, the technology will even self-seal new micro-cracks if and when they occur years after the original application, a fact referenced in a November 2010 report (ACI 212.3R-10) by the American Concrete Institute®.
The ACI report also notes “the crystalline deposits develop throughout the depth of the concrete and become a permanent part of the concrete mass… [and] resist water penetration against hydrostatic pressure.”
The Xypex crystalline technology delivers an integral waterproofing system without the exposure disadvantages (from tearing or detachment) presented by external barrier/membrane solutions. It also is generally less costly and more convenient than external barrier approaches.
Crystalline Waterproofing protects the environment from contamination caused by wastewater leakage and 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 by NSF International, a widely-accepted, independent source of public health and safety standards around the world.