OSMOSIS

In a few cases severe blistering of thin synthetic resin floorings occurs between 3 months and two years after laying.  These blisters commonly vary in size from a few mm in diameter up to 100 mm, with heights up to 15 mm.  When drilled into or otherwise broken the blisters are found to contain an aqueous liquid under very high pressure.  The mechanism of their formation is not fully understood but it is assumed because of their physical state that they are caused by a process of osmosis.  Blistering which occurs soon after the flooring is installed is unlikely to be caused by osmosis and is more likely to result from water contained in the structure. 

Osmotic blisters only occur with thinner synthetic resin floorings, resin coatings and flow applied systems, up to about 6 mm in thickness.  The problem has not been observed with trowel applied resin floorings probably because of their higher resistance to deformation and greater lateral permeability. 

..............................Please refer to FeRFA Guidance Note No 2: Osmosis in Resin Flooring ISBN 0 9538020 5 1

Because the mechanism is not fully understood it is not possible to be specific about the steps which should be taken to avoid osmotic blistering.  However it is considered good practice to take the following steps in order to minimise the risk.

a) In new construction ensure the base concrete has low soluble salts by avoiding poorly washed aggregates and by curing the concrete well immediately after laying to prevent premature surface drying out; 

b) Allow the concrete to dry out thoroughly after curing, preferably for a minimum of 21 days. 

c) By the use of mechanical rather than chemical means of preparing the concrete surface.  In particular by avoiding the use of acid etching; 

d) By avoiding washing the concrete surface with detergent solutions as part of the preparation procedure.

e) By the complete removal of all contamination from existing floors:  this may prove very difficult where the concrete has been saturated for long periods with water soluble materials.

f) Any levelling screeds should preferably be polymer-modified to minimise permeability and salt migration.

g) By the use of water vapour permeable floorings.

h) By the use of solvent-free primers rather than water-borne systems, under impervious resin floorings.

j) By ensuring that the synthetic resin flooring is precisely proportioned, either by weight or volume as specified by the product manufacturer. 

Where osmosis has occurred, techniques which have proved successful in preventing the problem reappearing, after cutting out the affected area and mechanically cleaning the exposed concrete, include: 

a) Double application of a penetrating primer to the base to ensure complete coverage and

maximum adhesion of the replaced flooring.

b) Replacing with a trowel applied flooring at a thickness of at least 6 mm; 

c) Hot compressed air blasting of the exposed concrete coupled with the application of a

penetrating primer whilst the concrete is still warm. 

d) By the use of water vapour permeable floorings.

Many thanks to Google.com, FeRFA, Doc88.com from where the details were taken.

IS 15477 : 2019 – Tile adhesive testing standard

Adhesives have been classified into five types namely, Type 1, Type 2, Type 3, Type 4 and Type 5 based on Tensile adhesion strength and Shear adhesion strength and of course in consideration of type of tile/stone to be installed along with the substrate nature and situation.

Type 1 Adhesive: This adhesive is suitable mainly for tiles with apparent porosity greater than 3 percent. It is suitable for most of the clay and ceramic (non-vitrified) tiles of small dimension (size not more than 300 mm x 300 mm) and the majority of cement based backgrounds (substrates) like cement plaster, cement concrete, cement screed, etc, and for interior dry area applications only. Below values are in N/mm^2

Type 2 Adhesive: This adhesive is suitable mainly for tiles with an apparent porosity less than or equal to 3 percent. It is suitable for vitrified/fully vitrified tiles, glass mosaic tiles, all stones, dense and large dimension (More than 300 mm × 300 mm size) tiles and stones (slabs), and where background and location is more demanding like wet areas, submerged areas, etc. This type of adhesive is recommended for both interior floor and wall applications, and for exterior floor applications. Below values are in N/mm^2

Type 3 Adhesive: This adhesive is suitable mainly for tiles and stone tiles on exterior wall substrates like plaster or concrete. It is suitable for tiles like ceramic, clay tiles, basalt tiles, vitrified, glass mosaic tiles and porcelain tiles and all natural stone tiles. Below values are in N/mm^2

Type 4 Adhesive: This adhesive is suitable mainly for tiles and stone tiles which are included in Type 1, Type 2 and Type 3 (except metal tiles or engineered stones) but intended for installation on dry wall board substrates like gypsum boards, plywood, wood, calcium silicate boards, medium density fibre boards, fiber cement boards, cement boards, bison panel, etc. For all tiles/stones of size more than 600 mm × 600 mm, the adhesive shall also comply with ‘S1’ category of transverse deformation. For all tiles/stones of size more than 1200 mm × 1200 mm, the adhesive shall also comply with ‘S2’ category of transverse deformation.

These polymer modified adhesive can be achieved by the addition of a liquid admixture to the standard general purpose adhesive which is called as polymer fortified adhesive. Below values are in N/mm^2

Type 5 Adhesive: This adhesive is suitable for all types of tiles including engineered stones (manufactured stones) which are intended for installation on glass or metallic substrates like, grid iron, mild steel, stainless steel, aluminium or copper, etc. It is suitable for metal tiles, glass tiles, engineered stones or for all types of tiles and stones to be installed on different cement based substrates like cement screeds, plaster, concrete, drywall boards like gypsum boards, plywood, wood, metals composite boards, modified backer boards and the metallic substrates. Below values are in N/mm^2

These adhesive is generally a mixture of synthetic resin, mineral fillers and organic additives in which hardening occurs by chemical reaction. They are available in one or more component forms and in essence, these cover polyurethane adhesive, epoxy adhesives, Furane based adhesive, etc.

Along with this, some other test has to be performed and declared accordingly. Like:

      a.       Annex C, the open time shall not be less than that stated by the manufacturer.

      b.       Annex D, the adjustment time shall not be less than that stated by the manufacturer.

     c.       Annex E, the slip shall not be more than 0.5 mm. Slip resistant adhesives shall be                  designated as ‘T’.

     d.       Annex F, the deformability shall be within the range mentioned below for a particular class as stated by the manufacturer:

                                 I.            Deformable adhesive, S1 : > 2.5 mm, <5.0 mm

                               II.            Highly deformable adhesive, S2 : >5.0mm

 

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TA - 1T

SS - 1T

GS - 2T - C1T

DS(G/W) - 3T - C2TS1

PSW - 4T - C2TES1

Afs1 (G/W) - 4TS1 - C2TES1

Afs2 - 4TS2 - C2TES2

EG - IS 4832

FR - IS 4832

Flex - __ - C2ES2 

WA91 - 

Determination of transverse deformation for cementitious adhesives and grouts

The test explained here is as per BS EN 12004 and BS EN 12002, and as follows:

1. Standard conditions shall be (23 ± 2)°C and (50 ± 5)% R.H. and air velocity in the working area of less than 0,2 m/s

2. Place the plastic sheet and apply adhesive in the template of 280 X 45 X 5mm and compact the adhesive by placing in flow table and then get the sample adhesive using Template B of 300 X 45 X 3mm. After 48 Hrs, remove the template.

3. Condition the test units at (23 ± 2)°C. After 12 days remove them from the plastic container and condition them for 14 days in air in standard conditions.

4. Remove the specimens from the polyethylene film and measure their thickness at the middle and (50 ± 1) mm from each end. If the three values fall within the required tolerance of (3,0 ± 0,1) mm calculate the average value; discard any specimen which falls outside the required permissible thickness.

5. Place the test specimen on the test jig, deform it with a transverse load applied by the anvil at a rate of 2 mm/min until failure occurs. Record the deformation in millimetres. When no cracking occurs, report the maximum force and deformation.

6. The transverse deformation is determined to 0,1 mm, by calculating the average value of the deformations obtained in the test.