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Leak-Proof FLEX (Single Component) 1gal
Leak-Proof FLEX 1gal Leak-Proof FLEX
[Johnson Group Online]
 USD $99.00 
Availability:  Usually ships in 1-2 business days

Flexible Single Component PU Grout  
1 gal

Leak-Proof FLEX is a 100% solids, single component polyurethane grout.  It will cut-off water flows by displacing the water and producing a tough, flexible closed cell foam with excellent adhesion to the concrete. This PU grout is highly adjustable with the use of the required activator called Leak-Proof FLEX-ACT.


Leak-Proof FLEX is a low toxicity,hydrophobic MDI based polyurethane grout which forms a very durable closed cell grout foam with a very uniform structure.  This product does not contain TDI's. The cured material is also flexible enough to withstand future joint movement without losing adhesion to the surface due to its superior bonding capabilities to wet or dry surfaces.

An overall excellent injection grout.



  • Leaks in new tunnel construction.
  • Cracks in concrete basements or foundations.
  • Maintenance of transportation subways.
  • Settlement cracks in concrete pools and tanks.
  • Cracks in water dams and reservoirs.
  •  Leaks in concrete pipes.
  • Highway barrier wall shrinkage crack sealing.
  • Parking garages.

This product does not have unpleasant odours which may cause problems in commercial and residential applications. The cured material has excellent cut resistance, high elongation and is
virtually unaffected by corrosive environments.

How to Choose a Grout:

Select the grout to use based on:

    • Required end product flexibility.
    • Viscosity in relation to crack/joint width.
    • Expansion required (adjustable with activators).
    • Hydrophobic (does not incorporate water into product), or hydrophilic (does incorporate water into final product).

Mixed VISCOSITY 600 cps @ 25°C
Heating will greatly lower viscosity for injection into tight cracks.
(Viscosity is an important factor in the products ability to flow. The lower the viscosity of a particular grout, the easier it will be to "push" it along in a tight crack or joint. Low viscosity means lower injection pressures and better travel.
Conversely, if the crack or joint is wider than, lets say the thickness of a pencil, the low viscosity product may run out of the crack or drop to the bottom of the crack before it can begin to react and foam. This may cause a poor injection. In selecting your grout for a particular project, you should give proper consideration to the viscosity of the product based on the width of the crack. You may temporarily close up the crack by jamming hydraulic cement into it.)  


UNCURED RESIN         Leak-Proof FLEX               Leak-Proof FLEX-ACT
VISCOSITY                  600 cps @25°C                  5 cps @ 25
°C                ASTM D-1638
SOLIDS                        100%                                100%                             ASTM D-1010
SPECIFIC GRAVITY      1.05                                  1.02                              ASTM D-1638
FLASH POINT               >150
°C                              >125°C                           ASTM D-93
MIX RATIO (A:B)           100                                   1 to  5%
WORKING LIFE             .....................25 seconds to 8 minutes.............................
MIXED VISCOSITY @ 5% accelerator...................600 cps @ 25

CURED FILM             
100% Modulus               130 psi                                                        ASTM D-412
200% Modulus               265 psi                                                        ASTM D-412
TENSILE STRENGTH     325 psi                                                       ASTM D-412
ELONGATION                 245%                                                          ASTM D-412
°C                                                          ASTM D-2137
SHRINKAGE                     <4%                                                           ASTM D-1042
TOXICITY                      NON-TOXIC

Five (5) gallon (18.9 ltr.) metal pail (46Lbs or 20kg), closed head with flex spout.
One (1) gallon (3.78 ltr.) plastic jugs (9.2 Lbs or 4kg)

Requires:      This product requires an Activator called Leak-Proof FLEX-ACT. Ordered separately. The activator is mixed into the Grout just prior to use. Use 1% - 10% ratio to get the desired results.1000ml (1.056 Quarts) of activator is plenty for a 5 gal pail of grout. That is just over a 5% ratio of grout to activator. We recommend using a 4-5% ratio for standard cracks. The more activator, the faster the reaction when it touches moisture. You need to balance the speed of reaction against the depth of penetration into the crack. The crack (or section of crack) should be filled with non-reacted grout before the reaction begins.

CAUTION - pH NOTICE:     All water that is to be used to "activate" Polyurethane Grouts must be in the range of ph 3 - 10 for proper chemical reactions of the product to take place.

Surface Preparation

Low Pressure Injection - Use Leak-Proof Ports n Plugs and fit the fat end into 5/8" holes drilled straight into the crack about 1/3 to 2/3 the depth of the crack.

High Pressure Injection - Use Leak-Proof HD Packers (3/8's Plastic Hammer-In Ports) in 3/8" holes.

Drill the holes at a 45o angle to intersect the crack approximately 4" below the concrete surface for a 8 inch thick wall.  These holes should be drilled alternately on opposite sides of the crack allowing an 8" distance between them.  This should ensure intersection of the crack. Alternatively, the holes can be drilled straight into the crack to a depth 2/3 the thickness of the wall, spaced every 3 inches for very tight cracks. (This method allows for higher injection pressures without damage to the concrete through blowouts.) Coat the packer or port with the grout prior to insertion into the cleanly water flushed drill hole for a superior seal.

After fitting injection ports or packers, the drill holes should be flushed out using water delivered through a 1/4" hose from a pressure pot (low pressure) or a high-pressure pump or grease gun (high pressure).

Be careful to check that each of the holes intersects the crack and a path is available for subsequent injection.  Where no travel is evident then additional holes should be drilled to provide the necessary access to the crack.

Mixing and Application:     The single component pump is the preferred equipment for grouting with Leak-Proof FLEXLeak-Proof FLEX should be fully mixed by pouring the required amount into a clean, moisture free mixing vessel and mixing by hand or with a low speed power mixer (200-300 rpm) until the activator is thoughly blended in.  Scrape the sides and bottom of the mix container to ensure a complete mix is obtained.

It is advisable to mix just a part of the unit initially - 1 litre would be appropriate - to determine rate of travel of the resin and to confirm how much material can be used well within the pot life.

Injection of the mixed Leak-Proof FLEX is then carried out, commencing at the lowest injection point.  As the Leak-Proof FLEX moves into the crack, water is displaced ahead of it.  Once all the water is released then Leak-Proof FLEX will follow the water - when this is observed, injection should move on to the next packer and the same process continued along the crack until it is completed.  Excess Leak-Proof FLEX appearing at the surface of the crack can be easily removed after it has completed foaming, using a sharp knife. Adjust the speed of activation by adding the required amount of activator (up to 5% by volume). Tight cracks should use less activator while wide ones will need a faster foam to offset the running out of the product from the crack.

Clean Up:      All equipment must be cleaned immediately after use. Thorough and repeated flushing is required using Leak-Proof PUMP CLEANER.  The equipment lines should then be filled with Leak-Proof PUMP CLEANER to eliminate air/moisture from the lines. Cured material should be mechanically removed.

Safety and Toxicity:     Leak-Proof FLEX is an MDI based single component polyurethane.  These recommendations are common with all MDI based polyurethanes. Within the generic group of polyurethane polymer technology the MDI based polyurethanes are considered the safest in terms of safety and toxicity.  Isocyanates are designated substances and are capable of producing a severe allergic breathing problem in some people.  If any difficulty at all with breathing is experienced the person should immediately vacate the work area.  Particular care should be taken to avoid mixing and application in confined areas.  Avoid breathing vapours at any time.   Precautions must be taken to prevent prolonged or repeated skin contact and it is essential to protect the eyes from splashes.
Repeated skin contact can also cause sensitization.  Protective clothing, rubber gloves and chemical goggles should be worn when working with these products.  A facemask with organic cartridge and a particulate filter is usually adequate.  Air supplied mask is suitable for use in confined areas.
Refer to MSDS for details. MSDS is availble on request.

Although reactive chemicals are needed to form Leak-Proof FLEX the final cured material is a non-toxic polyurethane foam.

Storage:     Store in heated area and on pallets.  Do not allow products to freeze.  Shelf life in unopened containers is one year.  Once opened, then dependent on humidity, shelf life may be reduced to as little as 3 months.

Injection at Low Temperatures:      Low temperatures will greatly lower viscosity and initial cure times. To minimize this effect, store the product at normal room temperature for a minimum period of 24 hours prior to use. If site temperatures are extremely low, heat bands may used on the pails before and during use to maintain the products temperature, lower the viscosity and improve penetration. Avoid splashing water into open containers, as the material is water activated. DO NOT EXCEED 26.5 degrees Celsius (80F) WHEN WARMING.

Made in Ontario, Canada and exclusively supplied through Johnson Group Online for internet sales at Our internationally renowned manufacturer produces high quality products for Johnson Group Online under exclusive agreement.

Warranty:   All information and statements are intended for persons having the required skill and know-how and do not relieve the user from verifying the suitability of the information and statements given for a specific purpose prior to use. The information, and in particular, the recommendations relating to the application and end-use of our products, are given in good faith based on Johnson Group Online Inc. and its manufacturers current knowledge and experience of the products when properly stored, handled and applied under normal conditions, within their shelf life, but accuracy and completeness of said information is not guaranteed and are not to be construed as a warranty either expressed or implied. In practice, the differences in materials, substrates and actual site conditions are such that no warranty in respect of merchantability or of fitness for a particular purpose, nor any liability arising out of any legal relationship whatsoever, can be inferred either from this information, or from any recommendations, or from any other advice offered. Users should always refer to the most recent issue of the Technical Data Sheet and the MSDS for the product concerned, copies of which will be supplied on request or can be accessed in the internet under

Neither seller nor manufacturer shall be liable to buyer or any third person for any injury, loss or damage directly or indirectly resulting from use or inability to use this product. The proprietary rights of third parties must be observed. All orders are accepted subject to our current terms of sale and delivery.

Johnson Group Online Inc. warrants its products to be manufactured free of defects and will replace or, at our option, refund the purchase price of any materials proven to be defective. Seller’s and manufacturer’s sole responsibility shall be to replace that portion of the product of this manufacturer which proves to be defective. This limited warranty is in lieu of any other guarantee, expressed or implied, including warranties of merchantability or fitness for a particular purpose.  In no event will Johnson Group Online Inc. or our suppliers and manufacturers be liable for incidental or consequential damages nor shall liability, if any, extend beyond the purchase price of the material.



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Johnson Group Online Inc.
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This product was added to our catalog on Monday 23 July, 2007.
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