FREQUENTLY ASKED QUESTIONS
Can paint and other finishing materials be applied over a Xypex Coating?
Yes, paints and epoxy coatings, cement parge coats, plaster and stucco or similar coatings can be applied and are applied over Xypex treated concrete or coatings. But conditions and specific preparation/applications times may be required. Refer to our product data sheets and method statements for further information. Or alternatively, contact your local Xypex Representative for recommendations.
Can Xypex Admix C-Series be used in concrete containing fly as, micro-silica or slag cement?
Yes, the reactions which take place to form the crystalline structure are very complex. During the cement hydration process, the crystalline complex reacts with various metal oxides and salts as well as, but not only with, calcium hydroxide found in the concrete regardless of the cement type used.
Can Xypex be applied against extreme hydrostatic pressure?
Yes. Because Xypex is not dependent upon adhesion to the concrete surface and instead becomes an integral part of the concrete mass through crystallization, it is capable of resisting extreme hydrostatic pressure from either side (positive or negative) of the concrete.
Does Xypex protect reinforcing steel?
Yes. By preventing the intrusion of chemicals, salt water, sewage and other harmful materials, Xypex protects concrete and reinforcing steel from deterioration and oxidation.
Does Xypex protect concrete against freeze/thaw damage?
Yes. By blocking the intrusion of water into concrete, Xypex helps protect the concrete from the damaging effect of repeated freeze/thaw cycles.
How resistant is Xypex to aggressive chemicals?
Based on independent testing according to ASTM C267-77 "Chemical Resistance of Mortars", Xypex 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.
In what forms are Xypex products available?
Xypex crystalline technology is available in three forms: as a coating (for new or existing structures); as a dry shake material (for fresh horizontal surfaces); and as an admixture (added at the time of concrete batching). These three options will prove an asset to the value-engineering process and to the flexibility of the construction schedule.
Can Xypex 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 the concrete. The presence of moisture is also necessary to ensure proper bonding of the slurry coat to the surface.
What are some typical Xypex applications?
Typical Xypex applications include large infrastructure such as bridges, tunnels, structures with high durability outcomes, concrete waterproofing, reservoirs, sewage and water treatment tanks, secondary containment structures, underground vaults, foundations, parking structures, roof decks, swimming pools, and below grade construction.
What is the recommended dosage rare for Xypex Admix C-Series?
Consult with the manufacturer's technical department or your local Xypex representative for assistance in determining the appropriate dosage rate and for further information regarding enhanced chemical resistance, optimum concrete performance, or the specific requirements and conditions of your project.
When is Xypex Admix C-Series introduced to the concrete mix?
Xypex Admix C-Series should be added to the concrete at the time of batching. The sequence of procedures for addition will vary according to the type of batch plant operation and equipment.
Is Xypex suitable for use on surfaces other than concrete?
Xypex is totally compatible with the chemistry of concrete, whether poured-in-place, pre-cast or concrete block. It is not suitable for application to cut-limestone, clay brick, wood, metals, asphalt or other non-concrete building materials.
How deep does the Xypex Crystalline formation penetrate the concrete?
The Xypex Chemical reactions initially take place at the concrete surface or immediately adjacent with the presence of moisture. The reaction will continue deep into the concrete structure where moisture is present. Xypex Admixture is homogeneous within the concrete matrix and consequently, the chemical reactions occur throughout the concrete ensuring complete waterproofing of the concrete. Xypex coatings have independent testing that indicates Xypex crystalline technology can penetrate 30cm into a  concrete block. This testing placed Xypex Concentrate on the top surface and was left in ambient conditions for 12 months.
How is the setting time, strength and temperature of the concrete affected by the addition of Xypex Admix C-Series?
The setting time of concrete is affected by the chemical and physical composition of ingredients, temperature of the concrete and climatic conditions. Extension of set time may occur when using Xypex Admix C-Series. The amount of extended set will depend upon the concrete mix design and the dosage rate of the Admix. Concrete containing Xypex Admix may develop higher ultimate strengths than plain concrete. Trial mixes should be carried out under project conditions to determine the setting time and strength of the concrete.
How long does Xypex last?
A Xypex application, unlike most other systems, is permanent. Its unique dendritic crystalline growth will not deteriorate under normal conditions.
How is Xypex different from other products?
The Xypex crystalline system for concrete waterproofing is substantially different from traditional barrier products (membranes, cementitious coatings):
  • Xypex creates a crystalline structure deep within the pores and capillary tracts of the concrete mass to prevent the penetration of water and aggressive chemicals. In contrast, barrier-type products function only at the surface of the concrete.
  • Because Xypex is not dependent on surface adhesion to achieve its waterproofing effect, it is resistant to extreme hydrostatic pressure.
  • Xypex is not subject to the deterioration problems encountered by membranes.
  • Xypex can seal static cracks up to 0.4mm in width.
  • Xypex is permanent, integrated and reactivates whenever moisture is present.
  • Xypex reduces project risks by promoting self-healing of cracks up to 0.4mm static width and can be poured integrally with the concrete hence reducing the need for coatings and membranes.
How waterproof is Xypex treated concrete?
A major independent testing laboratory performed concrete waterproofing tests on Xypex in accordance with Army Corps Permeability Specification CRD-C48-73. The results showed that a two-coat application of Xypex on 50mm thick 13.8 MPa porous concrete totally eliminates leakage at pressures of at least 123.4 m of head pressure (1.2 MPa), the limit of the testing apparatus.

Xypex Admix treated concrete samples, when tested under the same testing regime as for Xypex Coatings, was tested to 1.05 MPa (106 m head of water) and exhibited no measurable leakage.
Is Xypex affected by temperature, humidity, ultraviolet and oxygen levels?
When applied according to specifications, Xypex performs at 100% efficiency within -32oC to +130oC constant temperatures or within -185oC to +1530oC periodic temperatures. Humidity, ultraviolet and the oxygen level (oxidation) have no effect on a Xypex treatment.
Is Xypex toxic?
No. Xypex contains no volatile organic carriers (VOC) and can be applied safely in enclosed surroundings. Xypex is approved by numerous country and state health and waterworks departments for use on structures which contain potable water or foodstuffs. A few of these agencies are listed below:
  • Australian Water Quality Centre, Australian Standard AS/NZS 4020
  • NSF International
  • Swiss Federal Department of Health
  • Japan Food Research Laboratories
  • United Kingdom (DWI) Drinking Water Inspectorate
  • Singapore Institute of Standards and Industrial Research
  • Slovak Ministry of Health.
Can Xypex Admix C-Series be used in concrete containing a water reducer, a plasticiser or air-entrainment?
Yes, Xypex Admix C-1000 NF, when used with normal set admixtures, will have minimal effect on the set time. However, it should be noted that the use of retarding admixtures at recommended dose rates will cause extensions in set time when used with Xypex Admix C-1000 NF which has a slight retarding effect within itself. Consult with the manufacturer's technical department or your local Xypex representative for assistance in determining the appropriate dosage rate.
Is Xypex used to waterproof cracks, joints and other defects in concrete?
Yes. Xypex unique crystalline waterproofing technology will develop a non-soluable crystal structure in the pores, capillaries and cracks up to 0.4mm static width which stops the water flow and significantly reduce infiltration of deteriorating substances. In the case of expansion joints or chronic moving cracks, a flexible sealant/product is recommended.
What are the application advantages of using Xypex instead of membranes?
The crystalline nature of the Xypex waterproofing system provides many application advantages over traditional barrier products:
  • Xypex does not require a dry surface; in fact, a wet surface is necessary.
  • Xypex does not require dry weather to be applied.
  • Xypex does not require costly surface priming or levelling prior to application.
  • Xypex cannot puncture, tear or come apart at the seams.
  • Xypex does not require protection during backfilling or during placement of steel, wire mesh or other materials.
  • Xypex can be applied on either side of a concrete surface - the negative or the positive (water pressure) side.
  • Xypex does not require sealing, lapping and finishing of seams at corners, edges or between membranes.
  • Xypex is less costly to apply than most other methods.
  • Xypex typically provides higher durability outcomes.
  • Xypex typically can reduce application and construction timeframes due Xypex not requiring specific moisture conditions to be reached before application.
What is the appearance of a Xypex Coating?
A Xypex coating normally produces a grey-coloured, cementitious surface. However, Xypex "White" is also available.