What is the Xypex process?

The Xypex process is unique and involves waterproofing by crystallization, whereby the addition of Xypex to concrete, with water as the catalyst, reacts to generate a non-soluble quartz-like crystal which grows in the bleed tracts and capillaries within the concrete.

One of the benefits of this reaction is that of a secondary hydration process, which fills naturally occurring voids with the quartz-like crystals. In this manner concrete becomes impermeable to the penetration of liquids.

How does Xypex work?

When a cement particle hydrates there is a reaction between water and the cement that causes it to become a hard, solid mass but there are also chemical by-products given off which lay dormant in the concrete. With Xypex we introduce a second set of chemicals.

When we combine the by-products of cement hydration and the chemicals in Xypex in the presence of moisture, a chemical reaction takes place and the product of this reaction is a nonsoluble, dendritic, crystalline structure.

This crystalline structure can only take place when moisture is present and thus Xypex tends to form this crystalline material in the bleed water tracts, capillary tracts and shrinkage cracks in concrete. Wherever water is present, Xypex crystals will form.

Does Xypex add Durability & Protection?

Impermeability against liquids. 50mm thick Xypex treated concrete has withstood hydrostatic pressure equivalent to 405 feet of head pressure. This was the limit of the testing apparatus. Xypex treated concrete is impervious to: water, chlorinated water, diesel, fuels and other petroleum products.

As the crystals are a silica, which is a mineral and not an organic product, Xypex significantly increases the chemical resistance of concrete. Numerous tests have shown that Xypex treated concrete is not affected by a wide variety of aggressive chemicals.

Xypex protects concrete against chloride attack. The growth of Xypex crystals into the concrete will help protect reinforcing steel by blocking microcracks and capillary pathways used by migrating chloride ions. The concrete becomes impermeable and prevents further entry of chlorides or other chemicals. Normally during the course of spalling repairs to concrete structures, chlorides are still trapped and active within the concrete in areas which have not been repaired. Independent tests have shown Xypex not only prevents further penetration of chlorides, but also reduces the level of chloride ion activity within existing structures to below the level required to promote electrolytic corrosion. As a side benefit, the presence of crystalline growth within the concrete also tends to directly interfere with corrosion reactions on imbedded steel.

Xypex crystalline growth reduces carbonation in concrete structures by a factor of up to 40%.

The filling of capillaries within the concrete significantly increases strength. In Admix treated concrete, the increases in strength are typically 5 - 20%. Xypex Admix promotes an extended hydration process within concrete thereby achieving its design strength at around seven (7) days.

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 does Xypex stand up to harsh conditions?

pH Range
From 3.0 to 11.0 constant contact
2.0 to 12.0 periodic contact
Temperature Range
From -25 °F to + 265 °F constant
From -301°F to + 2786 °F periodic
No effect
No effect
Oxygen level (oxidization)
No effect

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. Several are listed below:

  • NSF International
  • Swiss Federal Health Service
  • Japanese Ministry of Public Welfare
  • United Kingdom Water Fittings Bylaws
  • Singapore Institute of Standards and Industrial Research

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.

What are some typical Xypex applications?

  • Water/Waste water treatment plants
  • Reservoirs/Tanks
  • Secondary Containment Structures
  • Foundation Slabs
  • Below-grade work
  • Parking Structures
  • Tunnels/Manholes
  • Underground Vaults
  • Swimming Pools
  • Elevator Pits

How is Xypex different from other products?

Xypex the material and its technology is completely unique in the market, not one other product or combination of products creates the same crystalline growth within cementitious materials.

  • 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.
  • Xypex will seal hairline cracks up to 0.4mm.
  • Xypex is not subject to the deterioration problems encountered by membranes.

What are the 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 leveling 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 the concrete surface, the negative or the positive (water pressure) side.
  • Xypex does not require sealing, lapping and finishing of seams at comers, edges or between membranes.
  • Xypex is less costly to apply than most other methods.

Are there additional benefits to Xypex?

  • Resists extreme hydrostatic pressure from either positive or negative surface of the concrete
  • Becomes an integral, permanent part of the substrate
  • Self healing capacity for static cracks up to 0.4mm in width.
  • Corrosion protection
  • Neutralizes chloride ion activity
  • Highly resistant to aggressive chemicals
  • Reduces carbonation
  • Prevention of alkali aggregate reaction
  • Gains in concrete design strength
  • Added durability
  • Allows concrete to breathe
  • Non-toxic
  • Less costly to apply than most other methods
  • Increases flexibility in the construction schedule

Is Xypex used to waterproof cracks, joints and other defects in concrete?

Yes. Xypex has a specific repair system that utilizes its unique crystalline waterproofing technology to stop water flow through cracks, faulty joints and other defects. In the case of expansion joints or chronic moving cracks, a flexible sealant is recommended.

Does Xypex have limitations?

Yes. Xypex will not heal moving cracks. Moving or unsettled ground causes cracks to move and Xypex will not work. Xypex will not work with non-cementitious material. Xypex requires Portland cement to create the crystals.

How long will Xypex last?

A Xypex application, unlike most other systems, is permanent. Its unique, dendritic crystalline growth will not deteriorate under normal conditions.

What are the cost savings of Xypex treatments?

There are numerous cost savings other than the initial price for the treatment. The long term benefit of the Xypex treatment may only be fully realized by our children's children.


Applied to concrete, Xypex products cause a catalytic reaction which, in contact with moisture, forms crystals of dendritic fibers in the natural voids and capillary tracts of the structure. This nonsoluble crystalline growth is so small as to ensure that water cannot pass through.

The ability of chloride ions to migrate through concrete is dependent on salt solutions penetrating into the structure. The integral waterproofing achieved by Xypex Crystallization prevents the ingress of such solutions. Once treated with Xypex, concrete structures are protected from penetration.

Xypex FAQ