ACTFLEX PROSWELL Swellable sealant
Hydrophilic swellable polyurethane joint sealant
Gun-applied water-swellable sealant that seals rough concrete joints and beds PRESWELL strip.
ACTFLEX PROSWELL coverage, coats and cure times
Grey moisture-curing polyurethane paste in a 600 mL sausage pack, applied with a caulking gun. It expands by more than 70% on contact with water to form a compression seal in below-ground construction joints.
- Water swell
- > 70%typicalof original volume on contact with water · TDS p3
- Pack
- 600 mLsausage pack, for a standard caulking gun · TDS p3
- Skin time
- 65 minat 25°C and 50% RH · TDS p3
- Pour after
- 8 h / 24 hhand-placed cover / large-scale pour · TDS p3
- Cure rate
- 3.5 mm / 24 happroximately, from the surface inward · TDS p3
- Apply at
- 5–35°Cambient · TDS p3
- Service temp
- −10 to +65°Ctypicalrange in service · TDS p3
- Elongation
- 700%typicalat break, GB/T 528 · TDS p3
- Per pack
- 6.0 mat a 10 × 10 mm bead, theoretical, real use is higher · TDS p5
From the FORSPEC data sheet, TDS-PROSWELL · Revision 1 · 25 August 2026. Times are at 25°C and 50% relative humidity unless the data sheet says otherwise. Typical = FORSPEC’s own typical value, not a laboratory-certified one.
Where ACTFLEX PROSWELL is used
Use it for
- Concrete construction joints and cold joints, below ground
- Sealing and bedding PRESWELL HYDROPHILIC WATERSTOP on rough concrete
- Basements, lift pits and below-ground structures
- Retaining walls and blockwork walls
- Pipe and service penetrations through concrete
- Precast panel joints and segment joints
Know before you start
- Not a waterproofing membrane: it seals a joint, not a structure
- Not for continuous immersion, or for expansion and movement joints
- Joint must be damp, not wet: no standing water and no pre-soaking
- Does not stop running water: stop active flow with ACTFLEX HYDROPLUG first
How to apply ACTFLEX PROSWELL
- 01
Prepare
Clean the joint of dust, dirt, oil, curing and release agents. Damp but not wet, with no standing water. Repair large voids and honeycombing with a FORSPEC concrete repair product.
- 02
Check
Ambient 5°C to 35°C and no heavy rain. Where water is entering the joint, stop it with ACTFLEX HYDROPLUG first.
- 03
Load
Put the 600 mL sausage pack in a caulking gun and cut the nozzle to suit the joint width.
- 04
Apply
Run a continuous bead along the full joint and tool it to touch both faces. Butt beads together with no gaps, and fill voids on rough concrete with extra sealant.
- 05
Penetrations
Run the bead round the full circumference of each pipe or service and return it into itself.
- 06
Cure and pour
Protect from rain and groundwater. Pour from 8 hours for hand-placed cover and from 24 hours for a large-scale pour, without displacing the bead.
A short guide from the data sheet. Read the full ACTFLEX PROSWELL TDS before you start.
ACTFLEX PROSWELL test reports and compliance
- AS/NZS 4858 and AS 4654.1
- Not applicable, a joint sealant not a membraneNo classification
- DIN 53504 tensile strength
- 1.4 N/mm² approximatelyForspec R&D, indicative
- DIN 53505 Shore A hardness
- 23 approximatelyForspec R&D, indicative
- DIN 53479 density
- 1.35–1.45 ± 0.05 kg/LForspec R&D, indicative
- GB/T 528 elongation at break
- 700%Forspec R&D, indicative
Results as stated in the data sheet, TDS-PROSWELL · Revision 1 · 25 August 2026. Warranty up to 25 years, depending on the system: ask FORSPEC which term applies to your system.
ACTFLEX PROSWELL questions
How does PROSWELL seal a joint?
It swells by more than 70% when wet. Confined in a cast joint it cannot expand freely, so it pushes against both concrete faces and forms a compression seal.
How do I use it with PRESWELL?
Smooth concrete: fix the PRESWELL strip, then run a PROSWELL bead along both edges. Rough or uneven concrete: lay a PROSWELL bead along the joint first and press the strip into it.
How long before I can pour concrete?
From 8 hours for hand-placed concrete cover and from 24 hours for a large-scale pour, at 25°C and 50% RH. A deep bead takes longer to cure through.
How many cartridges do I need?
Metres per 600 mL pack equals 600 mL divided by the bead volume per metre. A 10 × 10 mm bead gives 6.0 m, 20 × 10 mm gives 3.0 m and 25 × 15 mm gives 1.6 m. Real use is routinely higher, so trial a length.
Does it work on wet concrete?
No. The joint must be damp but not wet. Do not apply into standing water, and do not pre-soak the sealant.
Can it stop a leak?
Not running water. Stop active flow with ACTFLEX HYDROPLUG first, then seal.
Used with ACTFLEX PROSWELL
ACTFLEX PROSWELL TDS and SDS
Always work from the current data sheet. Every FORSPEC TDS and SDS →
Specify it. Or buy it.
Send the drawings or photos and FORSPEC comes back with the system, the details and the quantities. Or find a FORSPEC stockist for ACTFLEX PROSWELL.