Concrete Waterproofing with Crystalline Technology

Crystalline chemicals improve concrete durability, lower maintenance costs, and extend building life cycles
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Sponsored by XYPEX Chemical Corp.

How Crystalline Waterproofing Technology Works

Crystalline technology improves the durability and performance of concrete structures, lowering their maintenance cost and extending their lifespan by protecting them against the effect of aggressive chemicals. These high performance qualities result from the ways in which the crystalline technology works, when used with concrete.

Crystalline Technology waterproofs and improves the durability of concrete structures by filling and plugging the pores, capillaries and micro-cracks with a non-soluble, highly resistant crystalline formation. The waterproofing effect is based on two simple reactions, one chemical and one physical. Concrete is chemical in nature. When a cement particle hydrates, the reaction between water and the cement causes the concrete to become a hard, solid mass. The reaction also generates chemical by-products such as calcium hydroxide, sulfates and carbonates of sodium potassium and calcium as well as un-hydrated or partially hydrated cement particles all of which reside in the capillary tracts of the concrete.

Crystalline waterproofing introduces another set of chemicals to the concrete. When these two chemical groups, the by-products of cement hydration and the crystalline chemicals, are brought together in the presence of moisture, a chemical reaction occurs. The end product of this reaction is a non-soluble crystalline formation.

This crystalline formation can only occur where moisture is present, thus it will only form in the pores, capillary tracts, and shrinkage cracks of the concrete. Wherever water goes, crystalline waterproofing will form filling the pores, voids and cracks.

When crystalline waterproofing is applied to the surface, either as a coating or as a dry-shake application to a fresh concrete slab, a process called chemical diffusion takes place. The theory behind diffusion is that a solution of high chemical density will migrate through a solution of lower chemical density until the two equalize.

Thus, when concrete is saturated with water prior to applying crystalline waterproofing, a solution of low chemical density is introduced into the porosity concrete. When crystalline waterproofing is applied to the concrete surface, a solution of high chemical density is created, triggering the process of chemical diffusion. The crystalline waterproofing chemicals must migrate through the water (the solution of low density) until the two solutions equalize.

When the crystalline waterproofing chemicals spread into and through the concrete they become available to the by-products of cement hydration thus allowing the chemical reaction to take place forming a non-soluble crystalline structure. As the chemicals continue to diffuse through the water, the crystalline growth will form behind the advancing chemical front. The reaction will continue until the crystalline chemicals are either depleted or run out of water. Chemical diffusion can carry these chemicals up to 12 inches into the concrete. If water has permeated two inches into the substrate, then the crystalline chemicals can only diffuse to this depth but, they still have the potential to penetrate 10 inches further.

Instead of reducing the porosity of concrete, like water reducers and superplasticizers, the crystalline formation fills and plugs the voids in concrete becoming an integral and permanent part of the structure.

Scanning electron microscope (SEM) view of a concrete pore

Image courtesy of Xypex

SEM view of a concrete pore filled with crystalline formation

Image courtesy of Xypex

Because these crystalline formations are within the concrete and are not exposed at the surface, they cannot be punctured or otherwise damaged like membranes or surface coatings. 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 -25 degrees Fahrenheit (-32 degrees Centigrade) and 265 degrees Fahrenheit (130 degrees Centigrade) in a constant state. Humidity, ultraviolet light, and oxygen levels have no impact on the products ability to perform.

Crystalline waterproofing offers protection against the following agents and phenomena:

  • Inhibits the effects of CO, CO2, the gasses responsible for the corrosive phenomenon known as ‘carbonation’ a process in which exterior gasses create a corrosive phenomenon that softens the surface layers of the concrete. Carbonation testing shows that the crystalline formation in the capillary tracts reduces the flow of gases into concrete, thus significantly retarding carbonation.
  • Protects concrete against alkali aggregate reactions (AAR) by denying water to those processes affecting reactive aggregates.
  • Chloride ion diffusion testing shows that crystalline waterproofing reduces the diffusion of chlorides in concrete structures. This helps protect reinforcing steel and prevents deterioration that could occur from oxidation and expansion of steel reinforcement.

Michael Brown, P.E., principal with Golder Associates in Seattle, has used crystalline waterproofing in numerous applications, but notably on the Blackbird mine remediation project near Salmon, Idaho, which has very low pH acidic mine water flowing through concrete structures. "We use crystalline waterproofing technology as an additive to concrete to reduce permeability and provide protection for the epoxy coated reinforcing bar," said Brown.

More traditional methods of protecting concrete still leave it open to chemical and water damage. Membranes and other coatings are susceptible to errors caused by faulty workmanship such as pinholes, improperly sealed seams, blistering, delamination and damage during backfilling. Unlike crystalline waterproofing, they also deteriorate over time and lose their effectiveness.


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Originally published in November 2011