XYPEX-F.A.Q. Coating


1. Can paint and other finishing materials be applied over a Xypex coating?

Yes. In most circumstances paint, epoxy coatings, cement parge coats, plaster and stucco can be applied over a Xypex coating. For further information concerning the interface of the Xypex coating with paint and other finishing materials, consult with a Xypex Technical Services Representative..

2. Can the Xypex coating be applied to the negative side of a structure?

Yes. Although applied as a coating, Xypex is not relying on its surface bonding capability to achieve its waterproofing effect. By means of diffusion, the reactive chemicals in the Xypex coating migrate through the capillary tracts within the concrete to become an integral part of the concrete mass. Therefore, the Xypex coating can be applied to either the positive (water side) or negative side even against strong hydrostatic pressure.

3. Can the Xypex coating be applied while the concrete is wet?

Yes. In fact, the concrete must be wet or moist before applying the Xypex slurry coat. Xypex requires moisture to generate the crystalline growth in concrete. The presence of moisture is also necessary to ensure proper bonding of the slurry coat to the concrete substrate.

4. How is the Xypex coating system different from other cementitious coatings?

Most cementitious coatings are simply surface treatments and are totally dependent on maintaining a proper bond to the concrete surface. Such coatings usually incorporate a latex modifier which makes the coating less permeable and acts as a bonding agent for better adhesion to the surface. They are surface treatments only, and have the added disadvantage of limiting breathability of the concrete. They do not form crystals within the concrete substrate (contrary to what is sometimes represented) and are not effective when applied against hydrostatic pressure.

5. How resistant is Xypex-treated concrete to aggressive chemicals?

Based on independent testing according to ASTM C 267 “Chemical Resistance of Mortars”, the Xypex-treated concrete is not affected by a wide range of aggressive chemicals including mild acids, solvents, chlorides and caustic materials. Because Xypex is pH specific (not chemical specific) it will protect concrete from any chemical whose pH range is 3.0 to 11.0 constant contact, or 2.0 to 12.0 periodic contact.

6. Is the Xypex affected by temperature, humidity, ultraviolet and oxygen levels?

When applied according to specifications, Xypex performs at 100% efficiency within -25°F to +265°F (-32°C to +130°) constant temperatures or within -301°F to +2786°F (-185°C to +1530°C) periodic temperatures. Humidity, ultraviolet and the oxygen level (oxidation) have no effect on a Xypex coating.

7. Is the Xypex coating suitable for use on surfaces other than concrete?

Xypex is totally compatible with the chemistry of concrete, whether cast-in-place, precast or shotcrete. It is not suitable for application to cut-limestone, clay brick, wood, metals, asphalt or other non-concrete building materials.

8. Is there a preference when choosing between the positive or negative side?

Generally, it is recommended that the Xypex coating be applied to the positive side (water side), if accessible, so as to ensure maximum benefit. Therefore, new construction specifications almost always call for the use of the Xypex coating on the positive side (water side). If, however, the positive side is not accessible e.g. tunneling projects or rehabilitation of existing structures, the Xypex coating will be specified for use on the negative side against the hydrostatic pressure.

9. What are the installation advantages to using a Xypex coating system instead of membranes?

The crystalline nature of the Xypex waterproofing system provides many installation advantages over traditional barrier products:

  1. Xypex does not require a dry surface; in fact, a wet surface is necessary.
  2. Xypex does not require dry weather to be applied.
  3. Xypex does not require costly surface priming or leveling prior to application.
  4. Xypex cannot puncture, tear or come apart at the seams.
  5. Xypex does not require protection during backfilling or during placement of steel, wire mesh or other materials.
  6. Xypex can be applied on either side of a concrete surface – the negative or the positive side.
  7. Xypex does not require sealing, lapping and finishing of seams at corners, edges or between membranes.
  8. Xypex is less costly to apply than most other methods.

10. What is the appearance of a Xypex coating?

A Xypex coating normally produces a grey-colored, cementitious surface. However, Xypex “White” is also available.