Waterproofing

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Components Classification

Based on the characteristics and the basic material, waterproofing systems can be generally classified into 3 main categories, namely: [1]

Preformed membrane/Sheet/Roll

This type is suitable for large area with minimum protrusions, thus in Singapore it is not commonly used in the internal wet area. It is practicable to be used in area such as concrete bridges, flat roof, basement and tunnels. It’s either self adhesive or bonding agent has to be used.

The base of this system can be either Bituminous (i.e. Asphalt, Bitumen, modified Bitumen) or Non Bituminous (i.e. Ethylene-Copolymer Bitumen (ECB), Polyvinyl Chloride (PVC), Polyethylene (PE), Chlorinated Polyethylene (CPE), Butyl Rubber, Ethylene Proplyene Diene (EPDM), Neoprene, Polysobutylene (PIB), and Bentonite clays.)

Liquid applied membrane

Liquid applied system are preferred to be used in the internal wet area, due to its continuity between horizontal and vertical planes, around projections and penetrations and some of them come in self-leveling property.
The base of this system can be either Bituminous or Non Bituminous (i.e. Acrylic, Epoxy, Polyurethane (PU), Polyisorene/ rubber, Cementitious, etc).

However, generally Liquid applied system can be classified into water based and solvent based.

It can be applied by brush (as coating), dry shake, or as admixture.

Untreated Concrete Initiation Mature

Density

Depending on the type of waterproofing, the density is ranged from 1.2-1.6 g/cm³.

Preformed membrane Generally quite dense and sometimes its self-weight may become a deterent factor due to creep when installed on vertical surfaces such as basement walls.
Liquid-applied Generally low density.
Cementitious Can be relatively dense due to the cement and aggregate contents

Thermal Conductivity

About 0.691 W/ m²K.

As all waterproofing membranes are relatively thin ( 0.6 to 4 mm) thermal conductivity is normally insignificant and for roofs, this is usually provided by using a layer of insulation material such as extruded polystyrene, etc.

Water Vapour Transmission

Herewith is the general comparison between different types of waterproofing in terms of water vapour transmision:

Preformed membrane Depending on the generic types ie bitumen based generally very low vapour permeablity while PVC types usuall are formulated with relative high vp
Liquid-applied As above except that vapour permeability is usually affected by the thickness of the membrane and liquid systems tend to have lower thickness therefore generally better vapour transmission
Cementitious Good vapour permeability due to its structure

The range of water vapour transmission value for different types of waterproofing system (for sheet membrane and liquid applied only):

Self adhesive membrane (thk : ±1.5mm) 5-15 g/m².24 hr
Bituminous membrane (torch on, thk:3-4mm) 5-15 g/m².24 hr
Liquid applied roof waterproofing (thk: 0.8-1mm) 40-80 g/m².24 hr
Flexible cementitous membrane (thk: 0.8-1mm) < 30 g/m².24 hr
Elastomeric wall coating (thk: 0.2 mm) > 80 g/m².24 hr

In SS 374: the WVT requirement is < 12g/m².24h. If the amount of water vapour in the substrate is high and it has to permeate the film of low WVT, there will be a pressure on the film which can cause debonding from the substrate, resulting in blistering which is common among liquid applied roof coating.

For liquid applied elastomeric wall coatings, the specification is >80g/m².24h

Elastomeric wall coating have higher WVT due to the lower applied film thickness and therefore reduce the risk of debonding from the substrate, caused by the high pressure of water vapour.

Tensile Strength

Range about 4 – 6 N/mm²

Preformed membrane Generally high especially if reinforced
Liquid-applied Medium to low depending on generic types and also whether reinforced.
Cementitious Generall low tensile strength and normally not reinforced except at detailing.

Modulus Elasticity (elongation at break)

Preformed membrane Generally good for non-reinforced. Elongation however is affected by types of reinforcements (range 50 to 1000%)
Liquid-applied Average from medium to high depending on generic types (range 50 to 700%) ie.

  • bitumen based: low.
  • rubber-based: high.
Cementitious Low, normally at around 150 % for polymer modified type

Reinforcement

Base reinforcements Benefits Limitations
Woven glass fibre tissues and mats
  • High modulus (300-1000 N/mm)
  • Dimensional stability
  • Rot proof
  • Low elongation (3%)
  • Fragile
  • Low tear resistance
  • Capillary action along strand
Glass / polyester (mixed non-woven fibres)
  • High modulus (400 N/mm)
  • High dimensional stability
  • Rot proof
  • Improved resistance to crack propagation.
  • Low elongation
Polyester
  • Modulus (100-300 N/mm)
  • High elongation (over 20%)
  • Rot proof
  • High puncture resistance
  • High tear resistance
  • Moderate dimensional stability
  • Less flexible (stiff)
  • Heavier weights.

Source: CITI training note; Certificate in Waterproofing Supervision. [4]

With courtesy from Hitchin Pte Ltd

Property APP modified SBS modified SS 374 : 1994 requirements
Nominal thickness in mm. include surfacing glass* polyester** glass* polyester**
Dimension stability
(both longitudinal & transverse) %		 4 mm 4 mm 4 mm 4 mm –
Tensile strength

longitudinal (N/mm2)

transverse (N/mm2)

  

0.1%

  

+ 0.14%

– 0.10 %

  

0.2%

  

0.3%

  

+ 0.5 %

– 0.5 %
Elongation at break

longitudinal (%)

transverse (%)

  

2%

2%

  

45%

45%

  

2%

2%

  

45%

45%

  

both max.
min 45 %
Tear strength / shear,

longitudinal (N/mm)

transverse (N/mm)

  

80

100

  

175

210

  

110

130

  

180

220

  

Tensile shear at joints –

failure occur outside (>500N)
Water absorption
( % )		 0.5 % 1.3 % – – < 1.0 %
Vapour penetration
resistance		 40,000 46,000 70,000 50,000 Water vapour transmission in g/hr-m2 (<0.5)
Hydrostatic test 2 bars 2 bars 2 bars 2 bars > 3 bars – no leakage observed
 Low temperature flexibility,max. ºC  – 15  – 18  – 25  – 25  NA
Heat resistance, max. ºC +130 +155 +100 +100 NA

*glass fibre 50 gm./m²
**polyester mat 180 gm/m²
Source: CITI training note; Certificate in Waterproofing Supervision. [4]
With courtesy from Hitchin Pte Ltd

Property PVC* EVA** ECB*** SS 374 : 1994
Membrane thickness mm 1.2 1.2 2.0
Dimensional stability %

longitudinal

transverse

  

0.0

0.0

  

< 0.4

0

  

< 1.0

–

  

±2.0 % without ageing
Tensile strength ( max )
in N / mm²longitudinaltransverse		  

15.4

15.6

  

12.5

12.5

  

6

4

  

> 15.0 N/mm2
Elongation at break %

longitudinal

transverse

  

250

270%

  

320%

320%

  

350%

490%

  

>300%

>240%
Vapour permeability coefficient <15,000 <20,000 <80,000
Water vapour transmission g/m2.24hr 11.4 1.65 0.25 vapour transmission
<12 g/m2.24hr
Water absorption after 24 hours % 0.11 NA 0.31ª < 1.0 %
Resistance to water penetration 4 bars 4 bars 6 bars > 3 bars – no leakage observed
Low temperature flexibility °C – 30 – 20 – 20
Root resistance tested NA tested

* PVC membrane reinforced with polyester scrim
** ECB membrane glass fleece backing
*** EVA membrane non-reinforced
ª water absorption after 7 days
Source: CITI training note; Certificate in Waterproofing Supervision. [4]
With courtesy from Hitchin Pte Ltd

Property EPDM CSPE SS 374 : 1994
Membrane thickness
in mm		 1.2 0.9
Dimensional stability %

longitudinal

transverse

  

±2

–

  

< 0.4

0

  

±2.0 % without ageing
Tensile strength ( max )
in N / mm²longitudinaltransverse		  

11.7

–

  

10.4

–

  

> 15.0 N/mm2

ASTM D412 requires

> 9 N/mm2
Elongation at break %

longitudinal

transverse

  

475%

–

  

500%*

–

  

>300%

>240%
Water vapour transmission g/m2.24hr 0.25 2.1 vapour transmission
< 12 g/m2.24hr
Water absorption after 7 days % 2.0 1.25 < 1.0% after 24 hours
Low temperature flexibility °C – 65 – 45

* Elongation of rubber only, fabric elongation at 35%.
Source: CITI training note; Certificate in Waterproofing Supervision. [4]
With courtesy from Hitchin Pte Ltd

Recommended Testing Method

Applicable for cementitious membrane waterproofing:

Item Test method Specification
Characterization of Polymer FTIR, DTA & TGA FTIR, DTA & TGA graphs used as fingerprint records for future comparison of subsequent testing
Initial hardness (Shore A)

* 7 days curing

 ASTM D2240 min 40
Crack bridging ASTM C836 No cracking at 2mm width.
No crack after 10 cycles of stretching & closing at 1mm width.
Adhesion to substrate
* Condition as cast		 ASTM D4541 min 0.3 N/mm2
Tensile strength
a) Condition as cast
Change in strength (%)
b) After ageing at 50ºC for 14 days
c) After 72h chemical immersion at room temperature:
i) 0.5% (v/v) NaOCl
ii) 1.25% (v/v) NH4OH
iii) 3.7% (v/v) HCl		 ASTM D412 min 1.5 N/mm2

min 1.3 N/mm2

& negative change max. 40%

}
} No limit for positive change
}
Elongation
a) Condition as cast
Change in elongation (%)
b) After ageing at 50ºC for 14 days
c) After 72h chemical immersion at room temperature:
i) 0.5% (v/v) NaOCl
ii) 1.25% (v/v) NH4OH
iii) 3.7% (v/v) HCl		 ASTM D412 min 150%

min 120%

& negative change max 40%

}
} No limit for positive change
}
Chloride Content ISEA Method min 0.1%
Resistance to water penetration Adopted DIN 1048 : Pt 5 No water penetration allowed at 0.2kgf/cm² for 6 hours
Set to touch time
RH 65 ± 5% & 30 ± 2ºC		 ASTM D1640 Touch dry within 2 hours

Source: CITI training note; Certificate in Waterproofing Supervision. [4]
With courtesy from Hitchin Pte Ltd