FOR IMMEDIATE RELEASE to Environmental Science & Engineering

FOR IMMEDIATE RELEASE to Environmental Science & Engineering

Contact: Nick Murosky, LarsonO’Brien Marketing Group

Phone: 412.831.959 x123 E-mail:

Contact: Les Faure, XYPEX Chemical Corporation

Phone: 604.273.5265 E-mail:

Date: August 17, 2011

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Increasing Service Life of Concrete Water and Wastewater Structures

Integral Protection through Crystalline Waterproofing Technology

by Les Faure

Largely due to economic and environmental advantages, concrete is the world’s most widely used building material for water and wastewater systems. Yet despite all of the advantages, concrete’s porous nature renders it permeable to liquids and gases making it susceptible to deterioration caused by the acid produced by hydrogen sulfide gas (H2S), sulfate attack and water ingress—all of which will jeopardize the integrity of the structure and result in increased operating, maintenance and environmental costs. To gain advantages, concrete must be protected from deterioration.

Time-tested waterproofing solution, such as Concrete Waterproofing by Crystallization™, a proprietary technology developed by Xypex® Chemical Corporation, merges the fields of environmental science and materials engineering to waterproof, protect and repair wastewater treatment plants, sewer pipe, as well as pump stations and access manholes.

Waterproofing solutions have been used in thousands of new and existing concrete structures around the world. It is easy to use, considerably less costly and more convenient than barrier/membrane solutionswithout the disadvantages, such as puncturing, blistering or detachment.

How it works

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 insoluble, 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 restricted.The effect is permanent. In fact, the technology self-seals new micro-cracks if and when they occur—even years after the original application.

Crystalline waterproofing chemicals can be introduced into new concrete in three different ways: as an admixture, dry-shake, or surface-applied coating.

Crystalline waterproofing chemicals added during concrete batching requires no effort, expertise or labor on the part of the contractorbecausethey are added to the ready-mix truck at the batch plant. Curing of the concrete is simultaneous with the curing of the waterproofing application. There is no coating or residue to remove afterwards. Concrete with crystalline waterproofing can achieve higher compressive strength than similar “standard” mixes.

Using the dry-shake method, new concrete slabs can be dosed with crystalline waterproofing during finishing. After the concrete reaches initial set, waterproofing powder is troweled on a wet surface as part of finishing.

For existing (cured) concrete, concrete surfaces must be clean and free of laitance, dirt, film, paint, coating or other foreign matter prior to treatment. For the most benefit, surfaces must have an open capillary system to provide “tooth and suction” for the coating to adhere and gain access to the pore network.

In all cases, the crystalline waterproofing technology is non-toxic, contains no volatile organic compounds (VOCs), 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.

Self-sealing edge

The chemical formulations of crystalline waterproofing products are a manufacturer’s trade secret, but in all cases, these materials react with the byproducts of cement hydration such as calcium hydroxide—commonly called “lime”—and other minerals within the cement matrix.

The growth of the waterproofing crystals is a gradual process, requiring two to three weeks to reach maturity. The result is the formation of a microscopic, mesh-like barrier as the crystals grow across the diameter of the concrete’s pores, which plugs them against the flow of liquids, even against extreme hydrostatic pressure.

Although crystal formation largely matures in two to three weeks, the process can continue virtually as long as there is water in the concrete. Cessation usually occurs due to natural drying of the concrete. The reaction effectively never runs out of lime, meaning that if water re-enters the concrete years later, it automatically reactivates the waterproofing chemicals—and new crystallization begins.

At the micro-level, shrinkage-cracking from drying potentially creates passageways for moisture infiltration. If the passageways occur while crystals are still forming, the waterproofing system can bridge micro-cracks as small as 0.4 mm. If the passageways occur later and allow water infiltration, the water reactivates the waterproofing chemicals to self-heal the concrete on the micro scale.

Concrete waterproofing chemistry as a self-healing product draws praise for its application in a number of WWTP projects. Consider the comments of Doug Harned, Project Manager for RMCI, Inc., in Albuquerque, New Mexico. The 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.”

Crystalline connections

Crystalline technology is also a critical component of the South District wastewater treatment plant (WWTP),alandmark project now under construction in Miami-Dade County, Florida, USA, that will serve about one-third of Miami-Dade’s 2.5 million residents.

Miami-Dade Water & Sewer Department is upgrading South District WWTPto a high-level disinfection facility with a peak flow capacity of 285-million gallons per day (mgd), an increase of 27 percent. It is the largest domestic wastewater injection site, and one of the largest deep bed sand filter plants in the country.In Phase 1, over 52,000-sq-ft of surface area was treated with a two-coat crystalline chemical system manufactured by Xypex Chemical Corporation to waterproof and protect the transfer pump station, flocculation tanks and filters.

Phase 2 of the project will also incorporate crystalline technology as an admixture for waterproofing and protection of an oxygenation train, four new clarifiers, associated splitter boxes and a pump station.An estimated 400,000 lbs of the Xypex product is required for a substantial portion of 70,000-cu-yds of poured-in-place concrete.

“We think it [crystalline technology] brings value to this project by increasing the concrete’s density,” said JohnHoffman, PE, Construction Manager for Phase 2 on behalf of the Miami-Dade Water & Sewer Department.

Acid defense

The Achilles heel ofconcrete structures in sanitary sewers and waste treatment plants is hydrogen sulfide gas (H2S), which causes not only a “rotten egg” odor but also results in chemical attack and corrosion. The control (elimination or reduction) of hydrogen sulfide is particularly challenging, 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 is an open invitation to aerobic bacteria that oxidize the H2S and produce sulfuric acid (H2SO4). The acid attacks the concrete surface causing deterioration. It also penetrates the capillary tracts and reacts with calcium hydroxide and calcium silicate hydrate (CSH) initiating an expansive sulfate reaction, resulting in the self-destruction of the concrete.

Corrosion is most severe at the crown of the pipe, where the acid collects. The acid causes a weakening of the pipe and, if left unattended, could cause the pipe to collapse. The solution is either to reduce bacterial action or to protect the concrete from chemical attack.

“When done right, concrete waterproofing by crystalline technology does an excellent job of densifying the concrete, making it more resistant to chemical attack,” said Paul Steward, PE, Vice President, Structural Engineering Services for Thatcher Engineering in Minneapolis. Steward is a veteran of more than 50 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, recalled that 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.”

Global appeal

Crystalline waterproofing has been applied on concrete water and wastewater treatment systems around the world.

In Canada, crystalline waterproofing products were used on projects such as the $430 million Pine Creek Wastewater Treatment Plant, which can treat up to 100 mega-liters of wastewater per day (ML/d), the Seymour-Capilano Water Filtration Plant in Metro Vancouver (not only Canada’s largest, but also the world’s largest UV disinfection facility).

For companies interested in building concrete structures, including WWTPs, in the Middle East North Africa (MENA) region, Xypex Concentrate iscompliant with the Water Regulations Advisory Scheme (WRAS) for potable water at a temperature up to 50°C, as per MENA region Water Authorities statutory requirement. (WRAS Test Report MA4049/K).

Adding to its appeal in the MENA region, Xypex crystalline treatment is pH specific, not chemical specific. Its ability to prevent deterioration due to aggressive chemicals is measured by its ability to withstand a pH range of 3.0 – 11.0 constant contact (and 2.0 – 12.0 in periodic contact).

The Ras Laffan Reservoir in Qatar, part of the highly prestigious Ras Laffan-C Integrated and Independent Water and Power Projects (IWPP), holds 65 million gallons and produces 275,000 cubic meters of potable water per day. It is one of the largest single-structure potable water reservoirs in the world, serving 40 percent of Qatar’s water requirements. The two-coat system of Xypex concentrate was used to waterproof and protect 37,999 square meters of potable water tanks.

The benefits of waterproofing, enhancing structural durability and the ability to resist aggressive chemicals—in this case, a very high salt content—made products employing the crystalline concrete waterproofing products the preferred choice for this project.

The effectiveness of crystalline waterproofing in the field is backed up by extensive independent laboratory testing for permeability, crack sealing and chemical resistance. Permeability testing in accordance with U.S. Army Corps of Engineers (ACE) CRD C-48-73, Permeability of Concrete, demonstrated that crystalline-treated concrete could withstand up to 405 ft (123 m) of head pressure–1.2 MPa (175 psi), which was the limit of the testing apparatus.

Long-term benefits

Chemically waterproofed water and wastewater systems have clear advantages over traditional barrier methods in terms of application, convenience and cost. Because this technology involves the growth of crystals to block the pore network of the concrete, it is not instantly effective. Crystal formation can take 2-3 weeks to fully mature. However, it offers a long-term solution to many water-infiltration vulnerabilities, since its affects are permanent, and it can be re-activated by water at any time to self-seal new points of infiltration.

Crystalline technology has been used effectively for 40 years on concrete projects of all shapes and sizes—a period of time that has traditionally been cited in the construction industry as the “proof” of a mature technology.

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How vital is it for the world to produce water and wastewater treatment systems that do their jobs properly?

The U.S. Centers for Disease Control and Prevention (CDC)—citing figures from the World Health Association (WHO) and UNICEF—provides disheartening information about the global state of water, sanitation and hygiene:

• Unsafe drinking water, inadequate availability of water for hygiene and lack of access to sanitation together contribute to about 88 percent of deaths from diarrheal diseases, or more than 1.5 million of the 1.9 million children younger than 5 years of age who perish from diarrhea each year, mostly in developing countries. This amounts to 18 percent of all the deaths of children under the age of five and means that more than 5,000 children are dying every day as a result of diarrheal diseases.

• Worldwide, 884 million people do not have access to an improved water source.

• According to the World Health Organization and UNICEF, improved sanitation could save the lives of 1.5 million children per year who would otherwise succumb to diarrheal diseases.

• An estimated 2.6 billion people lack access to improved sanitation (more than 35% of the world’s population).

• The impact of clean water technologies on public health in the U.S. is estimated to have had a rate of return of 23 to 1 for investments in water filtration and chlorination during the first half of the 20th century.

• Water and sanitation interventions are cost effective across all world regions. These interventions were demonstrated to produce economic benefits ranging from (in U.S. dollars) $5 to $46 per $1 invested.

• Improved water sources reduce diarrhea morbidity by 21 percent; improved sanitation reduces diarrhea morbidity by 37.5 percent; and the simple act of washing hands at critical times can reduce the number of diarrhea cases by as much as 35 percent. Improvement of drinking-water quality, such as point-of-use disinfection, would lead to a 45 percent reduction of diarrhea episodes.

The above CDC statistics and other information can be found at

In the United States, where antiquated infrastructure is a growing concern, the scope of the challenge can feel overwhelming. In a 2004 report, the U.S. Environmental Protection Agency (EPA) estimated that 34.4 billion gallons of wastewater were transported and treated each day in the United States by more than 21,600 publicly owned treatment works (serving 78 percent of the U.S. population). The EPA estimates the network of sewer lines underground in the United States measures 1.2 million miles.

Seems like plenty of work ahead for both environmental scientists and engineers alike—not to mention everyone in the business of making and using concrete.

Les Faure, Advertising and Promotion Director for Xypex Chemical Corporation (), has been working with concrete waterproofing by crystalline technology for 25 years.