What is ACTFLEX PU500 used for?

PU500 is a hydrophilic polyurethane crack injection resin for sealing leaks in structural joints subject to movement and vibration - construction joints, expansion joints, and live cracks where active water flow needs to stop immediately.

How does hydrophilic injection differ?

Hydrophilic foam (PU500) attracts water and remains flexible - swells in contact with water but stays open-cell and elastic. Hydrophobic foam (PU200/300) repels water and becomes rigid closed-cell. Choose hydrophilic for live joints with movement.

Viscosity 200-400 mPa·s at 23°C - the lowest viscosity of the PU injection range, giving the best fine-crack penetration. Surface set in 5-15 minutes, tack-free 15-30 minutes.

Active leak response?

PU500 cuts off water in 10-60 seconds under active leak conditions - the fastest water stoppage in the Forspec injection range. Bonds to damp concrete at 1.18 MPa. Elongation greater than 130%.

Service temperature -20°C to +70°C once cured. Resists dilute acids, alkalis, and sewage exposure - suitable for treatment plant and sewer line repairs. 100% solids, no VOC.

Forspec Actflex PU500 One Component Flexible Foam 20kg hydrophobic polyurethane injection foam for sealing active water leaks, cracks, joints, and voids in concrete and underground structures

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ACTFLEX PU500 Hydrophilic 20kg

Name: ACTFLEX PU500 Hydrophilic 20kg
Brand: Forspec Protective Coatings
SKU: AACF519
Price: 550.00 AUD
Availability: InStock

$550.00

or 4 interest-free payments with

Hydrophilic PU injection resin that stays flexible. Seals joints and cracks that move and vibrate.

ACTFLEX PU500 is a one-component hydrophilic polyurethane injection resin for water leaks in structural joints, construction joints and cracks that move. It reacts with water to form a flexible open-cell foam or an elastic gel, depending on how much water it meets, and it keeps that elasticity in the joint. Best in structures that stay damp or get wet regularly.

Where to use it

Structural, expansion and construction joints and dynamic cracks under movement and vibration
Tunnels, basements, retaining walls, diaphragm walls and segmental tunnel linings
Reservoirs, wastewater structures and dams
Precast elements and joints that see changing moisture

Why waterproofers buy it

One component. Inject it neat from the pail
High elasticity. Holds a flexible seal in dynamic joints and vibrating structures
Elastic gel at high water contact, open-cell foam at lower water contact, 6 to 12 times expansion
Seals active leaks in minutes
Bond over 1.18 MPa to concrete, masonry and porous substrates
Elongation over 130% in thick sections, over 110% in thin
20 kg pail. 10 year Forspec product warranty

Coverage

No fixed rate. Consumption depends on crack width, depth and voids. Estimate from crack volume and confirm by trial injection.

Not for

Joints that dry out (the cured gel shrinks under wet and dry cycling), structural crack repair, static dry cracks (use ACTFLEX PU200 or PU300), dry joints unless pre-wetted, below 10°C, UV exposure, large movement joints, or drinking-water structures without written Forspec confirmation.

All times at 25°C and 50% RH. Forspec R&D typical values.

Stays flexible in joints subject to movement and vibration

Elastic gel at high water contact, resilient open-cell foam at lower water contact

Rapid reaction - seals active leaks in minutes, from 20 seconds at high water contact

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ACTFLEX PU500 Hydrophilic 20kg

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Product Details

The formulation exhibits a rapid response, adapting to varying moisture levels by forming a resilient seal with minimal shrinkage. At low water concentrations, it develops a highly elastic structure, while at higher water volumes, it ensures uniform expansion without compromising flexibility or durability.

How to Use

Inject neat from the pail with single-component, high-pressure polyurethane equipment through 10 mm mechanical packers set at maximum 200 mm intervalsAssess the service moisture conditions before selecting the product - the cured gel depends on retained moisture and will shrink under sustained wet/dry cycling
Probe and assess any void of unknown volume before injecting, and confirm the resin quantity by trial injection on the first section
Drill 10 mm holes at maximum 200 mm intervals along the crack, offset from the crack line and angled at 45 degrees
Drill deep enough to intersect the crack at a depth of 60-100 mm, alternating sides of the crack where access allows
Blow or vacuum all dust from the drilled holes
Insert 10 mm mechanical packers with non-return valves, leaving approximately 20 mm of the packer proud of the surface
Tighten each packer firmly with the T-handle wrench to seal against injection pressure
Flush the pump and lines with urethane thinner before charging; never use equipment or lines containing residual water
Where the joint or crack is dry or water content is low, inject clean water through the packers to activate the reaction
Inject ACTFLEX PU500 neat from the pail, no mixing is required
Charge the pump, filling approximately two-thirds of the reservoir before sealing the lid
Begin injection at low pressure and increase gradually
Vertical cracks: inject from the bottom packer upward. Horizontal cracks: inject from the ends toward the centre
Continue at each packer until resin extrudes from the crack approximately 100 mm either side of the packer, then move to the next packer
Do not over-inject
Leave the non-return packers in place to hold the resin under pressure while it cures
Trim and dress the cured gel once it is firm and no longer expanding
Allow 24 hours at 25C and 50% RH for full reaction and a stable seal
Remove the packers and patch the drill holes flush with a FORSPEC repair mortar, FORBUILD 100 or FORCRETE 100 per its TDS
Flush the pump and lines with urethane thinner immediately after use
Record batch numbers, injection dates, packer locations and spacing, injection pressures and resin consumption per packer in the project quality records

Technical Specifications

Product Type: One-component hydrophilic polyurethane injection resin for flexible water sealing
Composition: One-component hydrophilic polyurethane resin
Cured Structure: Open-cell flexible foam or elastic gel, water-dependent
Colour and Form: Light brown, low-viscosity liquid
Density at 25C: 1.06-1.10 g/cm3*
Viscosity at 25C: 500-600 mPa.s*
Foaming Magnification: 6-12 times, water-contact dependent*
Foaming Time at 25C, 50% RH: Approx. 120-300 seconds*
Bond Strength to Concrete: Greater than 1.18 MPa*
Elongation, Thick Sections: Greater than 130%*
Elongation, Thin Sections: Greater than 110%*
Reaction at 25C, 5:1 Water to Resin: Elastic gel, 20-60 seconds*
Reaction at 25C, 10:1 Water to Resin: Foam 5-10 times, 160-190 seconds*
Reaction at 25C, 15:1 Water to Resin: Foam 5-10 times, 90-120 seconds*
Full Reaction and Stable Seal: 24 hours at 25C, 50% RH*
Application Temperature: Greater than 10C, substrate and material
Packer Spacing: 10 mm holes at maximum 200 mm intervals, angled 45 degrees to intersect the crack at 60-100 mm depth
Packaging: 20 kg pail
Shelf Life: 12 months, unopened, 5-30C, protected from moisture
Hazard Classification: Hazardous Chemical, Dangerous Goods, Poisons Schedule S6 under the WHS Regulations and the ADG Code
* Typical Forspec R&D characteristic values, not subject to third-party certification

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System Build-Up Guide

Correct application makes all the difference.

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Pool System Build-Up

1 Concrete Substrate
2 Crack Repair (if required)
3 ACTFLEX FLEXPLUS
4 ACTFLEX HYDROPLUG
5 ACTFLEX AT MESH
6 ACTFLEX 988 CWP (2 Coats)
7 Tile Adhesive
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1 Concrete Substrate
2 Crack Repair (if required)
3 ACTFLEX MS PRO
4 ACTFLEX AT MESH
5 ACTFLEX 988 CWP (2 Coats)
6 Protection Board (Optional)
7 Drainage System
8 Backfill

Tank System Build-Up

1 Concrete Substrate
2 Crack Repair (if required)
3 ACTFLEX FLEXPLUS
4 ACTFLEX AT MESH
5 ACTFLEX 988 WMP (2 Coats)
6 Protective Coating (Optional)
7 Water

Technical overview

ACTFLEX PU500 is a one-component, hydrophilic polyurethane injection resin for sealing water leaks in structural joints, construction joints and cracks subject to movement and vibration. On injection it reacts with water to form a flexible, open-cell polyurethane foam or an elastic gel depending on the volume of water contacted. The cured material remains highly elastic, accommodating joint movement while blocking water ingress, and is best suited to permanently damp or regularly wetted environments. No Australian Standard specifically governs polyurethane injection resins for water-stopping, so every performance value published here is a Forspec R&D characteristic value determined on standard production material and is not subject to third-party certification. The product is not certified for contact with drinking water under AS/NZS 4020.

Key applications

Sealing water leaks in structural joints, expansion and construction joints, and dynamic cracks subject to movement and vibration
Underground structures - tunnels, basements, retaining walls, diaphragm walls and segmental tunnel linings
Flexible injection sealing of water-retaining structures - reservoirs, wastewater structures and dams
Waterproofing precast concrete elements and construction joints exposed to fluctuating moisture conditions
Void filling in permeable substrates where flexibility is required, subject to geotechnical assessment and trial injection

Surface suitability

Concrete structural joints, expansion joints and construction joints
Concrete cracks subject to movement and vibration
Masonry and porous substrates
Precast concrete elements and construction joints exposed to fluctuating moisture conditions
Permanently damp or regularly wetted environments (the cured gel shrinks under sustained wet/dry cycling)
Dry joints and cracks pre-wetted through the packers before injection
Substrate and material temperature greater than 10C

Best suited to permanently damp or regularly wetted environments - hydrophilic open-cell foams may shrink under prolonged wet/dry cycling; assess the service moisture conditions before product selection. The cured gel depends on retained moisture and will shrink under sustained wet/dry cycling. Requires water to react - dry joints and cracks must be pre-wetted through the packers before injection. Flexible water-sealing product only, not a structural repair - use the FORSPEC structural injection range for load-transferring crack repair. Do not apply below 10C substrate or material temperature; cold conditions slow the reaction and reduce expansion. Not certified for contact with drinking water (AS/NZS 4020) - do not use in potable water structures unless confirmed in writing by Forspec. Moisture-sensitive - the resin reacts with atmospheric humidity; keep containers sealed, and keep equipment and lines dry. Not UV stable - for buried and internal concealed applications, not for exposed finishes. Large movement joints require a purpose-designed movement joint system; ACTFLEX PU500 accommodates joint movement but is not a substitute for an engineered movement joint. Injection into voids of unknown volume can consume large resin quantities - probe and assess before injecting. Classified as a Hazardous Chemical and Dangerous Goods, Poisons Schedule S6. Suspected of causing cancer. May damage the unborn child and is suspected of damaging fertility. Causes damage to organs through prolonged or repeated exposure. Toxic to aquatic life with long lasting effects. Obtain special instructions before use.

Technical Specifications

Product Type	One-component hydrophilic polyurethane injection resin for flexible water sealing
Composition	One-component hydrophilic polyurethane resin
Cured Structure	Open-cell flexible foam or elastic gel, water-dependent
Colour and Form	Light brown, low-viscosity liquid
Density at 25C	1.06-1.10 g/cm3*
Viscosity at 25C	500-600 mPa.s*
Foaming Magnification	6-12 times, water-contact dependent*
Foaming Time at 25C, 50% RH	Approx. 120-300 seconds*
Bond Strength to Concrete	Greater than 1.18 MPa*
Elongation, Thick Sections	Greater than 130%*
Elongation, Thin Sections	Greater than 110%*
Reaction at 25C, 5	1 Water to Resin: Elastic gel, 20-60 seconds*
Reaction at 25C, 10	1 Water to Resin: Foam 5-10 times, 160-190 seconds*
Reaction at 25C, 15	1 Water to Resin: Foam 5-10 times, 90-120 seconds*
Full Reaction and Stable Seal	24 hours at 25C, 50% RH*
Application Temperature	Greater than 10C, substrate and material
Packer Spacing	10 mm holes at maximum 200 mm intervals, angled 45 degrees to intersect the crack at 60-100 mm depth
Packaging	20 kg pail
Shelf Life	12 months, unopened, 5-30C, protected from moisture
Hazard Classification	Hazardous Chemical, Dangerous Goods, Poisons Schedule S6 under the WHS Regulations and the ADG Code
* Typical Forspec R&D characteristic values, not subject to third-party certification

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Frequently asked questions

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What is ACTFLEX PU500 used for?

Compatibility
PU500 is a hydrophilic polyurethane crack injection resin for sealing leaks in structural joints subject to movement and vibration - construction joints, expansion joints, and live cracks where active water flow needs to stop immediately.
How does hydrophilic injection differ?

Performance
Hydrophilic foam (PU500) attracts water and remains flexible - swells in contact with water but stays open-cell and elastic. Hydrophobic foam (PU200/300) repels water and becomes rigid closed-cell. Choose hydrophilic for live joints with movement.
Specifications?

Installation
Viscosity 200-400 mPa·s at 23°C - the lowest viscosity of the PU injection range, giving the best fine-crack penetration. Surface set in 5-15 minutes, tack-free 15-30 minutes.
Active leak response?

Compatibility
PU500 cuts off water in 10-60 seconds under active leak conditions - the fastest water stoppage in the Forspec injection range. Bonds to damp concrete at 1.18 MPa. Elongation greater than 130%.
Service environment?

Performance
Service temperature -20°C to +70°C once cured. Resists dilute acids, alkalis, and sewage exposure - suitable for treatment plant and sewer line repairs. 100% solids, no VOC.

ACTFLEX PU500 Hydrophilic 20kg

Frequently bought together

Pool System Build-Up

Retaining Wall System Build-Up

Tank System Build-Up

Technical overview

Key applications

Surface suitability

Technical Specifications

Pool Renovation

Below Ground Retaining Wall

Concrete Water Tank

Commercial Podium

Swimming Pool Construction

The Waterproofing Shop?

Frequently asked questions

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