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:

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.

Integral waterproofing

Integral waterproofing usually refers to admixtures that are supposed to decrease the water permeability of structural concrete. This is not just a matter of concrete mix but also involves issues in structural design and the manner of handling of the concrete in the field. Detailing and lcation of joints and reinforcing steel as well as quality control in mixing, placing, curing, and finishing are more important to watertightness than adding waterproofing agents to the concrete mix.

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

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

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

Modulus Elasticity (elongation at break)

Types
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.

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 ( > 500 N.)
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

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 / mm² longitudinal transverse	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

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 / mm² longitudinal transverse	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%.

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


Untreated Concrete	Initiation	Mature