METHODOLOGY / PROCEDURE OF PODIUM SLAB WATERPROOFING

METHODOLOGY / PROCEDURE  OF PODIUM  WATERPROOFING

 

 

APPLICATION OF SOLVENT BASED POLYURETHANE (PU) MEMBRANE ON PODIUM SLAB

 

STEP-1: `SURFACE PREPARATION:

Ø   

Ø  The surface needs to be clean, dry and sound, free of any contamination, which may harmfully affect the adhesion of the membrane.

Ø  Maximum moisture content should not exceed 5%. Substrate compressive strength should be at least 25 MPa, cohesive bond strength at least 1.5 MPa.

Ø  New concrete structures need to dry for at least 28 days. Old, loose coatings, dirt, fats, oils, organic substances and dust need to be removed by a grinding machine. Possible surface irregularities need to be smoothened.

Ø  Any loose surface pieces and grinding dust need to be thoroughly removed.

Ø  WARNING: Do not wash surface with water.

Ø  All surface cracks, undulations and voids must be repaired before application using a suitable repairing material.

Ø  Substrates must be surface dry prior to application.

Ø  During surface preparation all fittings of drain outlets work must be completed.

 

STEP-2 : PRIMING OF RCC SURFACE

Ø  Prime absorbent surfaces like concrete, cement screed with PU Primer and allow the primer to air cure according manufacturer’s technical instruction.

Ø  Allow the primer to cure for 6 – 8 Hrs to tacky condition

 

STEP-3 : APPLICATION OF PU MEMBRANE

Ø  Stir well before using of PU solvent.

Ø  Apply the PU solvent onto the primed surface and lay it out by roller or brush, until all surface is covered.

Ø  Airless spraying method can be allowed a considerable saving of manpower.

Ø  After 12-18 hours (not later than 48 hours) apply another layer of the PU solvent.

Ø  For best results, the temperature during application and cure should be between 5ºC and 35ºC.

Ø  Low temperatures retard cure while high temperature speed up curing. High humidity may affect the final finish.

Ø  The coverage shall be maintained at 1.8 Kg/sqm to achieve Dry Film Thickness of    1.5mm.

Ø  The membrane (both the coats) shall be applied over the angle fillet and shall be extended over the vertical wall (i.e. Parapet wall ) upto height such that it is terminated at 300mm above Finish Floor Level or Soil Filling Level.

Ø  Allow the membrane to air cure for minimum 3 – 4 days before any activity over it.

Ø  Allow the coating to cure for 2 – 3 days.

 

STEP- 4 : PONDING TEST OF APPLIED PU MEMBRANE (If required)

Ø  Make bund wall and fill water to pond the area as per the site requirement and allow the water for 72Hrs.

Ø  Remove water after 72 Hrs after inspection. Allow to dry for 24 Hrs.

 

STEP- 5: PROTECTION OF PU MEMBRANE (HORIZONTAL SURFACE)

 

Ø  Provide  200 GSM geotextile membrane over the waterproofing membrane to create a separation layer as well as protection layer from screeding.

Ø  The geotextile layer shall have 100 mm overlap and spot bonded and shall be extended at the wall up to 100mm above the slab floor.

Ø  Lay Concrete screed of minimum M20 grade concrete (RMC) over the geotextile membrane. 12mm poly-propylene fibers at 0.9Kg/cum may be added to avoid shrinkage cracks of concrete.

Ø  Provide slope of 1:1000 or as recommended by client.

Ø  The slope shall be provided in such a way that there is 40mm minimum thickness at the point of drain outlet.

Ø  The screed shall be finished rough with broom and in shape of watta / rounding at the wall and floor junctions.

Ø  The screed shall be cured with water for minimum 07 to 10 days.

Ø  After the screed is cured remove all the water, cut joints in screed with grinder of 10mm wide and 25 mm deep to form panels of 4M X 4M.

Ø  Clean the joints with compressed air to make it dust free and leave it for 1 or 2 days to remove the moisture from the joints.

Ø  Pack in backer rod of round cross-section inside the joint upto 10 mm depth left at top.

Ø  This joint shall be applied with PU primer. Allow to dry for minimum 2 – 3 Hrs to tacky condition. Then fill the joints with PU sealant.

Ø   Allow the sealant to air cure for 2 – 3 days before covering or laying of further tiles / pavers if applicable.

 

STEP- 6: PROTECTION OF PU MEMBRANE (FOR VERTICAL SURFACE SURFACE)

 

Ø  Over the waterproofing membrane apply 2 coats of Epoxy Bonding Agent conforming to Shear Bond strength as per ASTM C 881.

Ø  Sprinkle sand over the primed surface at 2 – 3Kg/sqm when the bonding agent is wet.

Ø  Allow it to dry to form firm key for the plaster.

Ø  Lay 15 to 20mm thick plaster in two coats over the prepared surface of cement sand mortar mixed with integral waterproof compound conforming to IS 2645-2003.

 

FOR LANDSCAPE PORTION (i.e. Grass & Trees height upto 2mts):

 

Ø  The Rolled matrix Drainage layer with filter media shall be laid over the protection screed before soil filling as per specification of Landscape architect / engineer.

 

FOR PLANTER BOXES: Separate Anti-Root Treatment above the screed

(If Trees height is more than 2 mts.):

 

Ø  Prime the surface with solvent based bituminous primer.

Ø  Stick peel and Lay SBS modified cold applied preformed Anti-root membrane over the primer.

Ø  The overlaps shall be minimum 50 to 75 mm selvedge and self-sticking.

Ø  The Rolled matrix Drainage layer with filter media shall be laid over the protection screed before soil filling as specified by Landscape architect / engineer.