Dewatering, waterproofing and drainage - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 222

- Bitumen solutions are solutions of bitumen in solvents, which vaporise after applica-
tion.
- Bitumen emulsions are mixtures of finely distributed bitumen in water, which evapo-
rates after application [79].
- Asphalt is a mixture of bitumen and minerals, most frequently with 22 % bitumen for
better plasticity.
Bituminous masses have a very good sealing and waterproofing effect but little strength.
A backing medium is therefore normally provided in the form of fibrous organic material
(wool felt board, jute), inorganic textiles (fibreglass mat), bitumen roll material with metal
inlays such as aluminium or copper foil or corrugated copper band as reinforcement. Bitu-
men polymer waterproofing membranes (predominantly polyisobutylene (PIB) according
to DIN 16 935). All organic fibre materials must be impregnated with bituminous material
on order to provide a waterproofing effect and against rotting.
Commonly available products are:
1. Felts: felt impregnated with bitumen but without a bituminous covering layer is called
“roofing felt”. This material is described according to the weight of the unimpregnated
raw felt (500 denotes 500 g/m²).
2. Hot-applied bitumen (FSK-Bahn, DIN 52130): Bitumen waterproofing material with a
bitumen covering layer on one or two sides each about 1.5 to 2.5 mm thick; Inlays of
glass fibre, jute or polymer mats, metal bands or plastic foils; applied hot.
3. Bitumen latex (BL): Bitumen mixed with 15 to 20 % by volume addition of latex rub-
ber, mostly based on chloroprene, to improve the mechanical properties of the bitumen.
BL waterproofing is normally sprayed as an emulsion in many layers. Plastic sheet
material, for example CSM, is used as a carrier insert [86].
Waterproofing layers and application process. Waterproof coating: Applied with brushes
or brooms or sprayed. Primer (normally liquid without heating) followed by many layers
of waterproofing (applied hot or cold, trowelled as a paste). Waterproof coatings cannot
achieve permanent protection and are thus not of significance in tunnelling [127].
Trowelled: Mixtures of bitumen and rock dust/natural asphalt raw dust and also possibly
asbestos fibres or similar as filler are applied hot or cold as a viscous mass in one or more
layers with wooden spreaders or trowels. Each layer should be at least 8 mm thick. This is
only of significance in tunnelling for repair work.
Brushed application according to DIN 4122: The support and waterproofing membrane
are painted with bituminous adhesive at 180 to 200 °C, the material is rolled out and
pressed down. The consumption is about 2 to 4 kg/m² per layer. In tunnelling, this is nowa-
days only interesting for cut-and-cover construction.
Poured and rolled-in process according to DIN 4122: Bitumen adhesive at 200 °C is
poured between the layers and a roller is used to press down. For overhead application, the
adhesive mass is poured onto the hanging end of the roll. This process is laborious but reli-
able when mixed correctly. The process is only be used for cut-and-cover tunnels today.
Welded process (also flamed melting adhesion or flamed process): requires waterproofing
roll material with a sufficiently thick layer of bitumen (1.5 to 2 mm each side). After the
application of a primer coat, the material is heated with a propane torch to make it sticky