Deep protection possible
Diffusion occurs when concrete is saturated with water prior to the application of crystalline waterproofing. In this way, the water creates a solution of low chemical density within the concrete. When a slurry mixture of crystalline waterproofing is applied to the concrete, it represents a solution of high chemical density on the surface that triggers the process of chemical diffusion. The crystalline waterproofing chemicals are now chemically compelled to migrate through the water (i.e. the solution of low density) until the two solutions equalize.
The crystalline waterproofing chemicals now spread through the concrete and become available to the byproducts of cement hydration allowing the chemical reaction to take place. A crystalline structure is formed and as the chemicals continue to migrate through the water this crystalline growth will form behind this advancing front of chemicals.
This reaction continues until the crystalline chemicals are either depleted or run out of water. Chemical diffusion can take these chemicals about 300 mm (12 in.) into the concrete. If water has only soaked 50 mm (2 in.) into the surface then the crystalline chemicals will only travel 50 mm and stop but, it still has the potential to travel 250 mm (10 in.) further if water re-enters the concrete at some point in the future and reactivates the chemicals.
Unique benefits with crystalline protection
Instead of just reducing the porosity of concrete, like water reducers, plasticizers, and super plasticizers, the crystalline formation engages the material filling and plugging the voids in concrete to become an integral and permanent part of the structure (Figure 2).
Crystalline waterproofing works the same way whether it is mixed in new concrete as an admixture or applied to the concrete surface as a slurry coating for repairs or as a waterproofing treatment. Crystalline waterproofing becomes a permanent part of the concrete and will continue to work for the life of the structure, preventing the ingress of water from any direction and sealing static hairline cracks and pores up to 0.04 mm (1.5 mils). When applied as a coating to a concrete surface and moisture cured for two to three days, the active chemicals in crystalline waterproofing diffuse into the concrete surface.
Since this crystalline formation is occurring throughout the concrete matrix and not just at the surface, the waterproofing protection cannot be punctured or otherwise damaged like membranes or surface coatings. Crystalline technology also improves the durability of concrete structures, lowering their maintenance cost and extending their lifespan by protecting them against the effect of aggressive chemicals.
Crystalline waterproofing is highly resistant to chemicals where the pH range is between three and 11 under constant contact and two to 12 under periodic contact. Crystalline waterproofing will tolerate temperatures between –32 C (–25 F) and 130 C (265 F) in a constant state. Humidity, ultraviolet (UV) light, and oxygen levels also have no impact on the products ability to perform.
Crystalline waterproofing offers protection in the following ways:
- by blocking the ingress of liquids, crystalline waterproofing protects concrete against accelerated deterioration caused by dissolved acids such as those produced by microbial-induced corrosion (MIC) in sewer collection and treatment structures;
- by preventing the diffusion of chlorides which protect the reinforcing steel and prevent the deterioration that could occur (i.e. oxidation and expansion of the steel reinforcement);
- by inhibiting the effects of carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), and nitrogen dioxide (NO2), the gasses responsible for the corrosive phenomenon known as ‘carbonation’ (carbonation testing shows crystalline waterproofing also reduces the flow of gases into concrete, thus retarding carbonation at the surface and thereby helping to prevent the drop in alkalinity that can soften the surface layer); and
- by protecting concrete against alkali aggregate reactions (AAR) by denying water to those processes affecting reactive aggregates.
Traditional methods of protecting concrete such as membranes and other coatings may still leave it susceptible to water and chemical damage. Only with the addition of crystalline technology can the pores and micro-cracks, which normally result from the process of setting and curing concrete, be sealed.
All information listed in this section was submitted by Xypex Chemical Corp.
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