METHODOLOGY / PROCEDURE OF BASEMENT WATERPROOFING

METHODOLOGY / PROCEDURE OF BASEMENT  WATERPROOFING

 

CONTENT

SL NO	ACTIVITIES
1	INSTALLATION OF HDPE MEMBRANE BELOW RAFT / ABOVE PCC
2	INSTALLATION OF SBS SELF ADHESIVE MEMBRANE ON OUTER SIDE OF RETAINING WALL
3	WATERPROOFING TREATMENT INSIDE THE RETAINING WALL OF BASEMENT

1.    INSTALATION OF HDPE MEMBRANE BELOW RAFT / ABOVE PCC

STEP-1. SURFACE PREPARATION:

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 must be repaired with approved repairing materials.

Ø  All cracks below 5mm shall be cut opened, cleaned and shall be filled with shrink free crack filling material,

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

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

 

STEP-2. INSTALATION OF HDPE MEMBRANE

Ø  Film side HDPE membrane to be placed on the PCC substrate with adhesive (if required )

Ø  Sand layer side up facing towards the concrete or Raft pour.

Ø  End lapping positioning of HDPE membrane will be done as per manufacturer's guideline.

Ø  It is essential to achieve continuous bond without creases and with a heavy roller to roll firmly on joint of HDPE membrane.

Ø  All the overlaps and end laps to be secured additionally by applying over the joints in opposite direction with double sided tapes to ensure watertight joints.

Ø  After completion of installation of HDPE membrane, reinforcement fixing and concreting activities can be started.

Ø  Termination of HDPE membrane shall be done on side of raft, from where SBS membrane will be started.

 

STEP-3. FIXING OF PRESSURE RELEASE PIPE (PRP)

 

Ø  Provide Pressure Release Pipe (PRP) and with washed gravels at the time of laying of PCC.

Ø  Galvanized Iron pipes (PRP) of 25mm diameter inside the pocket 50mm length, 50mm width and 50mm deep need to be provided

Ø   The mouth of the pipes need to be closed with tough plastic cover to avoid blockage of the pipes from pouring concrete.

Ø  The length of the pipe shall be such that it remains outside the raft level.

Ø  Each PRP shall be wrapped and dressed at the PCC top with Non-shrink grouting material / non-shrink mortar and shall be terminated with metallic Jubilee clip and PU sealant at joint location.

Ø  The Pre-bond HDPE membrane shall be terminated over the PU flashing.

Ø  The PRP shall be hold in position at the time of laying PCC so that the PRPs remain in vertical position.

Ø  The mouth at the top of PRPs shall be covered with tough plastic cover so that the pipes does not get blocked at the time of concreting,

 

 

2.    INSTALATION OF SBS SELF ADHESIVE MEMBRANE ON OUTER SIDE OF RETAINING WALL

 

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- 3 : AAPPLICATION OF PRIMER AND SBS MEMBRANE

 

Ø  Solvent based bituminous Primer need to be applied on the entire surface of RCC wall as per manufacturer guideline.

Ø  After priming of RCC surface, approved SBS membrane shall be installed or fixed on primed surface.

Ø  Minimum time gap must be maintained between applying of primer and fixing of membrane as per manufacturer guideline.

Ø  SBS membrane application shall be started from bottom of the wall.

Ø  Lapping of HDPE membrane (Which comes from bottom of the raft) and SBS membrane shall be done properly as per manufacturer guideline.

Ø  Lapping of SBS membrane shall be done as per manufacturer guideline.

Ø  Termination of the SBS membrane shall be done at 200 mm above the ground level.

Ø  Aluminum termination bar shall be fixed at termination location i.e. minimum 200 mm above Ground level & shall be fixed with non-corrosive fastener @ 4 nos per rm.

Ø  Sealing of termination bar shall be done by applying of PU Sealant.

Ø  The joints of the corners (Internal and external corners) shall be sealed by returning the membrane a minimum of 100mm and sealing with Pre-Bond Tape.

 

STEP- 4 : PROTECTION OF SBS MEMBRANE

Ø  Installed SBS membrane shall be protected by using of 11mm thick dimpled board / protection board.

Ø  Dimpled board / protection board shall be fixed to avoid any physical damage of membrane during soil filling.

Ø  Fixing of dimple board shall be done as per manufacturer guideline.

 

3.    WATERPROOFING TREATMENT INSIDE THE RETAINING WALL OF BASEMENT

 

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 during or after 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 (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.

 

 

B.   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.