WORK METHODOLOGY OF TERRACE SLAB WATERPROOFING
Option – 01: Waterproofing with two part component
Cementitious waterproofing
Option – 02:
Waterproofing with Solvent Based Polyurethane ( PU ) membrane
Option – 01: Waterproofing with two part component
Cementitious waterproofing
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 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 3
days ponding test has to be carried out, if the leakages are observed then
repeat the above procedure till to achieved water tight toilet area
STEP- 02 : SEALING OF PIPE INLET / OUTLET
DRAINAGE PIPES AND FILLING CUTOUT HOLES
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 Top level of the waterproofing shall be marked.
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 or 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.
STEP-
4 : BRICK BAT COBA FOR FILLING OF SUNKEN AREA or TERRACE SLAB;
Ø Level pad shall be prepared as per the required slop
towards nahani trap as per drawing or specification.
Ø Bricks selected for using as brick bat coba shall be
either full brick or ¾ brick made out of one complete brick by breaking into
required sizes using mallets.
Ø Brick bat shall be soaked thoroughly for about 15 minutes
prior to their placing.
Ø A thin layer of cement slurry shall be laid on cleaned
slab prior to laying of brick bats, cleaning to be ensured before laying the
brick bat.
Ø On applied cement surry, 10 to 20mm thick layer of cement
sand mortar in the proportion 1:4 mixed with compatible waterproofing compound
shall be laid.
Ø Approved integral waterproofing admixture shall be mixed
with cement mortar as per data sheet.
Ø Mortar shall be mixed properly and same shall be used
within 60 minutes from its mixing time.
Ø Broken brick bats of required size shall be placed over
the cement mortar bed by hand packing having minimum 15 to 20mm gap between
broken bricks.
Ø Pre-soaked brick bats shall be laid in radial by
inserting brick bat s to a depth of about 10mm by light tamping.
Ø Mortar shall be ratio of 1:4 shall be used for filling of
gaps between broken bricks.
Ø Cement mortar shall be filled up to 2/3rd height of the
broken bricks.
Ø Laying of brick bats should proceed from one corner and
shall be laid in radial pattern to drain off any water which has seeped through.
Ø Thiyyas / Level Pad for the same shall be given by
operation engineer, Brick bat shall be laid accordingly.
Ø Brick bat each layer will be cured for minimum 3 days
Ø Post Curing, remaining 1/3rd height filling of brick bat
and 20mm thick cement mortar screed / cement mortar plaster shall be provided
in a single layer.
Ø Sand mortar in the proportion 1:4 with waterproofing
compound (as per mix ratio)
Ø Top coat shall be of neat cement slurry of adequate
consistency and shall be monolithic with brick bat.
Ø Waterproofing plaster shall be extended upto 500 mm (from
RCC slab Top) on vertical surface/ parapet wall.
Ø Average thickness of brick bat coba shall be maintained
as per project specification.
Ø Top level shall be maintained as per drawing & slope.
Ø Pond Curing shall be done for 7days and leakage shall be
checked.
Option – 02:
Waterproofing with PU membrane
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.
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