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Austria is full of small and large dams that exploit the natural presence of water in the territory. These basins are exploited for the production of electricity, making Austria one of the most advanced countries for the use of renewable energies. Pumping plants and canals connect different basins to each other increasing efficiency and production capacity of the plants.Kelag is one of the most important producers of energy in the country and is the owner of many mountain basins. Wurtendamis situated near Flattachon the slopes of the glacier Mölltaler, famous for his famous for its ski slopes and lifts. The dam is part of a linked system that connect sevral other basin l ike Feldsee dam, Oscheniksee, Innerfragant basin and other.The Fragant group of power plants, located in the Möll Valley in Upper Carinthia, Austria, are owned and operated by Austrian util ity Kelag. The plants have an installed output of 334MW and annual generation of 550MkWh, with the Innerfragant power plant storing a further 100MW. Construction of the plants began in 1964, with work completed in 1984 with commissioning of the Wölla power plant. The most significant plants in the group are the high levelZirknitz plant, the main level Innerfragant power plant with the Wurten and Oschenik power plants, plus the low level Ausserfragant plant.
Two reservoirs, Wurtenalm and Feldsee, are part of the power plant group and have been in existence for over 30 years.The Feldsee currently serves as a distant storage reservoir for the Hochwurten - Grosssee reservoir system, with the stored water pumped into the reservoir system by means of several small pumping stations.Kelag is now planning to extend the Fragant group by developing the Feldsee pumped storage hydro power plant using the existing Wurtenalm and Feldsee reservoirs.The dam has been constructed at 1700 m s.l . , it is 65 meters high and it has an upstream facing slope of 1,75/1. The total surface of the upstream facing to waterproof was 14.000,00 m2.The surface before the renovation works presented blistering. Works consisted in the removal of the old l ining of asphalt and renovation of the facing.The choice was to remove only the dense layer up to not damage the old binder layer, butdue to the lower condition of binder even 4.000 m2 of 5 cm new binder layer was realized. CEA realized 14.000 m2 of new dense layer in addition to the final completion of the crown road.
The Wurtendam experience Austria 2019
Mix design
To refine and prepare the mixture the mix design is a crucial phase and a very delicate operation. The grading envelope, the bitumen content, the coefficient of permeabil ity, the void index and the characteristics of the concrete, of the bitumen and of the aggregates, are described in the specifications. The executor should refine the mixture with the materials available near the site.Below are resumed the main characteristics of the mixture for the binder and the sealed coats of the Wurtenspeicher Dam (Table 1), and the fol lowing diagram describe the project grading envelope and the obtained mixture for the 8cm waterproof layers with the al lowed tolerances (Image 2).
Table1: Main characteristics of the Bituminous Layers of the Wurtenspeicher Dam
8 cm
From 10 % to 15 %
4 %
> 10 mm 15 - 17 %
1–- 10 mm 59 - 64 %
0,1 - 1 mm 10 - 12 %
< 0.1 mm 5 - 7 %
8 cm
1
< 3 %
6,1 - 6,4 %
> 10 m (0 - 15 %)
1 - 10 m 75 - 85 %
0,1 - 1 mm 16 - 20 %
< 0.1 mm 11 - 14 %
According to the available materials and other relative conditions, the mix design can take few days or several weeks. It is very important to arrive at a satisfactory definition before commencing the l ining, because a mistake during this phase can jeopardize the entire work.
The aggregates
Being the coating not subject to traffic wear, it is more l ikely to use aggregates with high bitumen adhesion, both for the binder and the outer impervious layer.
The preliminary tests on the aggregates are described in Table 2
Table1: Main characteristics of the Bituminous Layers of the Wurtenspeicher Dam
SAMPLING LOCATION
AGGREGATES
COARSE D 692
FINE 1073
TEST NORM
Classification
Specific gravity ASTM C 127/128 - BU 64
Sieve analysis
Specific gravity cnr TEST
Unit weight and voids in aggregates
Soundness
Abrasion (Los Angeles)
Plasticity Index
Flakiness & elongation
Adhesion test
Free from unfavourable amounts of clay
Sand equivalent
UNI 10006
ASTM C 136
CNR BU 63
ASTM C 29
ASTM C 88
ASTM C 131
ASTM D 4318
BS 812 part 105,1
ASTM d 1664 - CNR 138/92
ASTM D 1073
AFNOR NF - P - 18 598
Table1: Main characteristics of the Bituminous Layers of the Wurtenspeicher Dam
SAMPLING LOCATION
FILLER D 242
TEST NORM
Specific gravity
Plasticity index ASTM 4318 Method B
Sieve analysis
Free from organic impurities
Organic impurities
Fineness
Sriffening power
ASTM 128 - CNR BU 63
ASTM D 546
ASTM D 2974
ASTM C 40
ASTM C 204
CNR 122
BitumenThe bitumen Penetration Test is determined by the l imit conditions, especial ly the facing slope and the cl imatic conditions of the structure’s location. Dams with steeper slopes wil l need Bitumen with lower penetration values, to avoid the coating to flow down. Nevertheless, temperature heavily influences the flow values, thus the dam’s location must be given a particular attention. A dam built in cold countries, or in high mountain, wil l need softer Bitumen because, on the one hand the concrete must be able to sl ide too much, on the other it must not be too hard, or cracks wil l form in the coating. The Wurtenspeicher Dam is located in a cold country but at 1700 m.s. l . ,that’s why it has been opted for a class 70-100 Bitumen, available on site, and delivered to the construction site in heated containers.Once refined the mixture, we usually prepare a test layer on the horizontal plane to test on site the permeabil ity with a vacuum gauge, and extract core samples to analyse them, before the final approval of the mixture to be layered in the facing is granted (Table 3 and 4)
Table 3: Bitumen Preliminary Tests
Table 3: Bitumen Preliminary Tests
SAMPLING LOCATION
BITUMEN
TEST NORM
Penetration
Softening point ASTM D 36
Specific gravity
ASTM D 5
ASTM D 70
SAMPLING LOCATION
TRIAL TEST
ALL LAYERS
TEST NORM
ASTM D 1188
V A
ASTM 2172
ASTM C 136
ASTM D 1559
ASTM C 127/128 - BU 64
Shell V A
V A
V A
SPT cliente
ASTM D 2172 B U n°38
ASTM C 136
ASTM D 1559
V A CNR BU 39
Shell V A
V A
ASTM D 1075
ASTM 1188
Density 3 samples during trial test
% voids 3 samples during trial test
Bitumen content 1 sample + 1 core during trial test
Sieve analysis 3 samples + 1 core during trial test
Marshall stability and flow 3 samples during trial test
Permeability 3 samples + 1 core during trial test
Resistance to flow on slope (stability) 3 samples during trial test
Flexibility of asphaltic concrete 1 sample during trial test
Kind mix
Bitumen content
Sieve analysis of aggregates
Marshall stability and lfow
Specific gravity
% voids
Permeability
Resistance to flow on a slope (stability)
Effect of water on cohesion of bitumen mix
Density
3
4.0
IR - MOBAWurtendamm - Austria 2019Thermophoto
To ensure the longevity of the work it is necessary to carry out it with extreme care. This is why our paver machines are equipped with electronic instruments (IR MOBA thermometer sensor) that measure continuously the temperature of the asphalt recording the data that can be analyzed at any time. In addition, compaction is verified during the roller by using PQI (Pavement Quality Indicator) which give the same results as Troxler test but unlike it is a no-nuclear source, could be used immediately even with warm material and give results in 3 seconds.Other instruments like thermos-camera, drone, laser-scanner allow a meticulous control on every processing, ensuring the achievement of a very high quality.
Mill inghigh depth
Spain 2018
Edolo - Italy 2017
Italy 2008
Sierra Leone 2006
Italy 2004 and 2007
Italy 1993
Austria 2019
Austria 2019
Austria 2019
3 4
Feldsee
Kelag
Cooperativa Edile Appennino
Feldsee
Summer 2019
m 2.200
m 270
4,5
1,7:1
m 34
m2 6.000
cm 26
cm 10
--
cm 8
cm 8
Wurtendamm Austria 2019
Kelag
Cooperativa Edile Appennino
Wurtendamm
Summer 2019
m 1690
m 280
5
1,65:1
m 65
m2 14.000
cm 26
cm 10
--
cm 8
cm 8
3 5
AlmendraSpain 2018
Iberdrola
Cooperativa Edile Appennino
Almendra
Summer 2018
m 740
m 1700
4
1,75:1
m 50
m2 50.000
cm 17
cm 4
--
cm 6
cm 7
3 6
3 7
m 720
m 655
4
2,5:1
m 27
Italy 2017
Restoring the efficiency of the existing impervious asphalt layer
Edolo
Enel
Cooperativa Edile Appennino
Edolo
2017
3 8
3 9
4 0
4 1
COOPERATIVA EDILE APPENNINO SOC. COOP.
HeadquarterVia Bacciliera 10/1240012 Calderara di Reno (BO)ItalyPhone +39 051 4135811 Fax +39 051 [email protected]
Registered OfficeVia degli Artigiani 640063 Monghidoro (BO)Italy
Dams DivisionHead of DepartmentEng. Leonardo [email protected]
CEA General DevelopmentHead OfficeMarco [email protected]
