● Tiling and screeds

BIOSET under water. The test results.

11 Nov 20262 min readFORSPEC Technical Team

The short version

After 20 days in water, ACTFLEX BIOSET held 1.453 N/mm². The pass mark for a C2 adhesive is 1.0.
Bonded to ACTFLEX 989 CWP, the pair passed adhesion, water tightness and crack bridging tests to AS ISO 13007.5.
BIOSET can now be used for immersed tiling over a cured ACTFLEX 989 CWP or 988 CWP system. It has not yet been tested in chlorinated water.

A tiled pool, cut away: shell, membrane, adhesive, tile.

A tile adhesive in a pool spends its life under water. The question a pool builder asks is simple: does it still hold after it has been soaked? Two reports from XTec Gen, an accredited test lab in South Australia, now answer that for ACTFLEX BIOSET.

The adhesive on its own

Report 571-2, issued 6 May 2026, tested BIOSET to AS ISO 13007.2, the test method standard for tile adhesives.

Adhesion, dry: 2.194 N/mm² (needs 1.0)
After 20 days in water: 1.453 N/mm² (needs 1.0)
After heat ageing: 1.771 N/mm² (needs 1.0)
After 25 freeze and thaw cycles: 1.449 N/mm² (needs 1.0)
Bend before breaking: 3.270 mm (S1 is 2.5 to 5 mm)

The report classes BIOSET as C2 S1: an improved cementitious adhesive that can deform. FORSPEC's own lab results add slip resistance on walls (T) and extended open time (E), which is why the data sheet prints C2TE S1 with that note.

The adhesive on the membrane

An adhesive is only as good as its bond to what is under it. Report 568-2, issued 10 June 2026, tested ACTFLEX 989 CWP with BIOSET on top, to AS ISO 13007.5.

Adhesion, dry: 0.82 N/mm² (needs 0.5)
After heat ageing: 0.86 N/mm² (needs 0.5)
After lime water: 0.63 N/mm² (needs 0.5)
Water tightness at 1.5 bar: 1.87 g gain, no water through (limit 20 g)
Crack bridging: 0.89 mm (needs 0.75 mm)

In all three adhesion tests the break was inside the adhesive layer, not at the membrane face. The bond to the membrane was stronger than the adhesive itself.

What this means on a pool

BIOSET is suitable for immersed tiling over a cured ACTFLEX 989 CWP or ACTFLEX 988 CWP membrane system.
Bed every tile at 100% coverage. No hollows behind a tile under water.
Fill no earlier than 10 days after the final membrane coat, and only once the grout has cured.

What has not been tested

Both reports used clean water and lime water. Neither includes a chlorinated pool-water test, and no report yet covers BIOSET over ACTFLEX 988 CWP. A chlorinated-water test is being arranged. FORSPEC will publish that result here when it is back, whichever way it goes.