Concrete Waterproofing Retrofit products for pervious concrete walls  Anyone who has had damage from water seepage knows that it is a costly and time-consuming process to repair. An effective and inexpensive way to help prevent water seepage is by using crystalline concrete waterproofing. This method uses a catalytic reaction to seal the pores, capillaries and shrinkage cracks that occur naturally in concrete. Crystalline waterproofing penetrates several inches in concrete. As hairline cracks form over the life of concrete, crystalline waterproofing continues to activate in the presence of moisture and seal additional gaps.
Long available for industrial applications, crystalline waterproofing is now ready for use in residential applications. It consists of a dry powder compound of Portland cement, very fine treated silica sand, and proprietary chemicals. Combining the product with water and applying it to the surface of concrete results in a catalytic reaction that forms several inches of non-soluble crystalline fibers within the pores and capillary tracts of concrete. This seals the concrete against the penetration of water or liquids from all directions. Crystalline waterproofing replaces traditional solvent-based waterproofing on foundation walls. Its most cost effective application is a waterproofing for concrete floor slabs and basement walls of existing homes that are seeping water. 
 | According to the manufacturers, it may be applied to the interior side of a leaky basement wall or on-grade slab floor. This would eliminate the cost and trouble of re-excavating existing foundations to seal a leak. The product is nonflammable and odorless, and it cleans up with water. |  | Crystalline waterproofing is known for its strength and effectiveness as waterproofing for reservoirs, sewage and water treatment tanks, and tunnels. The manufacturers claim that it is more durable than conventional waterproof coatings. Crystalline waterproofing can withstand aggressive environments such as salt spray or harsh chemicals. |
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The waterproofed concrete product can be tested for compliance with the appropriate ASTM standards for strength, bonding, abrasion resistance, freeze/thaw, fungus growth resistance, and breathability. If building code approval is not available, it can be used in combination with approved methods.
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Crystalline waterproofing is available as a dry powder, mixed with water to form a slurry, sprayed or brushed onto porous concrete surfaces or applied to newly poured concrete, and worked into the surface. Surfaces must be sound, clean, and free of any other materials that may impair its bond to concrete. The sealant reacts with the concrete and cures over a two- to three-day period. The waterproofing coating must remain moist during the process to assure that there is sufficient water available to complete the catalytic reaction. Periodically wetting the surface with a water mist sprayer, covering with wet burlap, or backfilling a foundation with moist soil after 24 hours can complete the reaction. In contrast to other waterproofing materials, crystalline waterproofing applied to the surface prior to the concrete curing saves construction cycle time and allows quicker backfilling. It should be noted that crystalline waterproofing products can be applied to either side of a wall and still effectively waterproof the wall. Crystalline product's effectiveness decreases when applied to older concrete. The newer the concrete, the higher effectiveness of the product. If backfilling is not feasible, cementitious waterproof coatings may require repeated wetting for a few days, which may mean repeated trips to the job site. To facilitate curing, application should occur at temperatures above 40 to 45 degrees F and with protection from rain. Some applications may require two coats. On smooth concrete surfaces, sandblasting or roughening of the surface may be required prior to the application of the product. It is always recommended that crystalline products be applied to a properly prepped surface. Crystalline products cannot use acrylic bonding agents as the acrylic can inhibit the crystalline growth. Consequently, the materials are reliant on a mechanical bond. The prep of the surface is the step that is most often performed incorrectly. It is recommended that home owners have a qualified contractor apply the crystalline products.
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Crystalline waterproofing is known for its strength and effectiveness as waterproofing for reservoirs, sewage and water treatment tanks, and tunnels. The manufacturers claim that it is more durable than conventional waterproof coatings. Crystalline waterproofing can withstand aggressive environments such as salt spray or harsh chemicals. It allows concrete to "breathe," so that moisture does not buildup. Backfilling does not damage the crystalline waterproofing treatment and it does not separate from the concrete surface over time. According to the manufacturers, it may be applied to the interior side of a leaky basement wall or on-grade slab floor. This would eliminate the cost and trouble of re-excavating existing foundations to seal a leak. The product is nonflammable and odorless, and it cleans up with water. The material price for crystalline waterproofing averages about $0.40 per square foot, while installed cost can range between $1.30 to $2.50 per square foot, depending on number of coats and surface preparation. Maximum labor savings may be possible by using some products as an admixture added to the concrete mix, which is claimed to cost about $0.75 per square foot for an 8" thick concrete wall. | 
