METHODOLOGY / PROCEDURE OF OHT WATERPROOFING

METHODOLOGY / PROCEDURE OF OHT  WATERPROOFING

( INSIDE & OUTSIDE OF OHT )

 

STEP-1: `SURFACE PREPARATION:

 

Ø  Concrete surfaces should be fully cured (minimum 28 days) prior to application.

Ø  The concrete surface shall be cleaned thoroughly of all contaminants like dust, traces of curing compound, oil and grease.

Ø  All surface imperfections, protrusions, structurally unsound and friable concrete must be removed and repaired with a suitable concrete repair mortar.

Ø  All surface cracks, undulations and voids shall be repaired appropriately before application.

Ø  All cracks above 5mm deep,  shall be cut opened, cleaned and shall be filled with shrink free crack filling material. i.e. GP2 or equivalent.

Ø  Filling up of tie rod holes shall be done with non-shrink cementitious grout i.e. GP2@ or equivalent.

Ø  The entire surface to be coated must be in SSD condition prior to application of coating.

Ø  All the construction joints need to be opened and treated with polymer modified mortar (Cement: sand: SBR Latex) or ready to use modified mortar.

Ø  Injection grout shall be done at all construction joints. Nozzle shall be fixed @ 500mm centre to centre at all construction joints.

Ø  Wall surface shall be cleaned by Compressed air cleaning to make the surface free of dust, debris, laitance etc. for proper bonding with RCC surface.

 

STEP- 02 : SEALING OF PIPE INLET / OUTLET DRAINAGE PIPES AND CORE FILLING

Ø  The surface of the pipe shall be free from dust, laitance, oil and water.

Ø  The core cut shall be free from debris, dust or any foreign materials.

Ø  Bath seal tape need to be unrolled to required length and wrap around the pipe by removing release film from one side of the tape.

Ø  The length of the tape shall be taken in such a way that the overlap of tape maintains to be 150mm.

Ø  Pipe need to be inserted with Bathseal tape or equivalent wrapped into the core and support it with formwork from below the slab or support from the periphery of the wall so that the gap around the pipe and the core shall be uniform throughout.

Ø  The bore packing shall be done with Non-shrink free flow cementitious grout, , so that there is no air entrapment / voids creating

 

 

STEP- 3:  APPLICATION OF TWO PART COMPONENT ACRYLIC POLYMER BASED CEMENTITIOUS COATING

Ø  The entire surface to be coated must be in SSD condition prior to application of coating acrylic polymer based cementitious coating as per approved brand.

Ø  Mixing: Using a slow speed mechanical mixer and a clean suitable mixing vessel, slowly add the powder component to the liquid polymer and stir until a smooth and homogenous slurry is achieved.

Ø  Allow the mixed slurry to stand for 5 – 10 minutes to remove air bobble created during mixing.

Ø  Do not dilute with water at any time of  mixing.

Ø  Apply mixed cementitious slurry by brush, roller.

Ø  Allow the first coat to dry completely for 6 – 8 hours before applying the second coat.

Ø  Apply second coat at right angles to the first coat.

Ø  Coating to be applied as per recommendation of manufacturer regarding application tool.

Ø  Allow the coating to cure for 3 – 4 days before application of protection layer.

Ø  Cure the applied cementitious slurry for period of 7 to 10 days. Or minimum of 3 to 5days if further activities starts immediately.

 

STEP- 4 : PROTECTION OF COATED SURFACE

 

A.   Protection to waterproof coating (Horizontal Surface)

 

Ø  Cement sand mortar to be laid for protection to the coating laid to slope to the drainage point.

Ø  This mortar shall be minimum 30 to 40mm thick and shall admixed with integral waterproofing compound as per approved brand.

Ø  Cement mortar for base coat shall be used minimum ratio of 1:4.

Ø  Curing shall be done at least for 7 to 10 days.

 

 

B.   Protection to waterproof coating (Vertical Surface)

 

Ø  After chemical coat, a rash coat shall be applied for better bonding with cementitious mortar bedding.

Ø  Protection Layer or base coat will be carried out.

Ø  This mortar shall be minimum 15 to 20mm thick and shall admixed with integral waterproofing compound as per approved brand.

Ø  Cement mortar for base coat shall be used ratio of 1:4 .

Ø  Top of base coat shall be trowel finish to receive the block / brick bat upto required level.

Ø  Curing shall be done at least for 7 to 10 days.