Slutrapport (PDF) - NordFoU

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8 Foto 0.6a. Ny Rånåsfoss bru i Norge. Foto 0.6b. Ny Rånåsfoss bru udført 1988 med monolitisk betonslidlag.
Summary This project will show the advantages and disadvantages of concrete bridges without bitumen-based waterproof insulation. Can these bridges be built more cheaply and more rapidly than bridges with such insulation? The most important point is whether they can have a durability corresponding to that of insulated bridges. The project is described in the following two reports: • Insulation-free bridges 1 – Insulation of concrete bridges in the Scandinavian countries – State-of-the-art • Insulation-free bridges 2 – Concrete wearing course – Investigations of condition and recommendations. The present report (Report 2) covers the results of condition investigations carried out on over 20 Scandinavian bridges in the period July 2007 to July 2008. The bridges are all constructed with concrete as the wearing course- i.e. are so-called insulation-free bridges. It should be mentioned that there are two types - monolithic wearing courses cast wet-on-wet with structural concrete, and wearing courses cast later than the structural concrete, typically added to existing bridges when the wearing course is replaced, i.e. during repairs. The object was to document the durability of the concrete wearing course with regard to external actions such as wear from winter tyres of vehicles, penetration of chlorides from thawing salt and the related risk of corrosion of the reinforcing bars. Finally, the concrete quality was investigated with the object of comparing the older types of concrete with the concretes used today. In this way it is made clear whether experience with the older concretes can be transferred to modern concrete. Petrographic (macro- and micro) analyses have shown that high-quality concrete was used for the wearing course of the bridges investigated. The quality of wearing course concrete is equal to the quality of modern concrete used in bridges in extremely aggressive environments. Crushed rock, usually granite,is generally used as coarse aggregate. The sand fraction is of similar material. Alkali-reactive aggregates were found in very few cases. Fine to mediumfine Portland cement was used in the Norwegian, Swedish and Finnish bridges. In Denmark, low-alkali sulfate-resistant Portland cement was generally used. The water-cement ratio of the concretes are in the range 0.35 – 0.45, corresponding to a dense and strong paste. The low watercement ratio often resulted in an internal shrinkage that caused the formation of micro-cracks. There was no clear correlation between the extent of micro-cracking and the water-cement ratio, though there is a tendency for the extent of micro-cracking to be associated with a low water-cement ratio. The observed extent of micro-cracking was similar to that normally seen in this type of high-quality concrete today, and is not considered to have any influence on durability. Visible cracks were observed on a few small areas of the wearing courses examined, typically in the wearing courses that were not fibre-reinforced. The cause is probably movement over the supports. However, they can also result from early shrinkage of the concrete or temperature movements that take place during hardening. 9
Page 1 and 2: Isoleringsfrie broer 2 Betonslidlag
Page 3: Isoleringsfrie broer 2 Betonslidlag
Page 6 and 7: 4 Foto 0.1. Brånsbroen i Sverige (
Page 8 and 9: 6 Fibre anvendes i større eller mi
Page 12 and 13: 10 Fibre is used to a greater or le
Page 14 and 15: 12 eller hovedlandevej til bebyggel
Page 16 and 17: 14 Undersøgelser og prøvningsmeto
Page 18 and 19: 16 Foto 1.4. Illustrerer hvordan ud
Page 20 and 21: 18 Bro Land Klima Trafik Betonslidl
Page 22 and 23: 20 Foto 2.1a. Mjøsbrua i Norge. Fo
Page 24 and 25: 22 derfor sammenfattet under ét i
Page 26 and 27: 24 Foto 2.3. Makroundersøgelse af
Page 28 and 29: 26 Venstre side af foto består af
Page 30 and 31: 28 Figur 2.1. Eksempler på kloridp
Page 32 and 33: 30 233 Galvapulsmålinger Der er fo
Page 34 and 35: 32 24 Konklusion for Mjøsbrua Beto
Page 36 and 37: 34 Diffusionskoefficient (10 -13 mm
Page 38 and 39: 36 hold) er typisk bedre end felsis
Page 40 and 41: 38 Figur 3.1. Prognose for sporslid
Page 42 and 43: 40 Foto 3.2. Kerne fra Gullmarsplan
Page 44 and 45: 42 Bro Mjøsbrua Monolitisk slidlag
Page 46 and 47: Bro Bredalbroen Monolitisk slidlag
Page 48 and 49: 46 Bro v/c-forhold Middelværdi Sta
Page 50 and 51: 48 34 Slidlagets vedhæftning til k
Page 52 and 53: 50 Kloridindhold (vægt-%) Kloridin
Page 54 and 55: 52 Kerne Beskrivelse af revne Indtr
Page 56 and 57: 54 Kloridindhold (vægt % Cl) 0,7 0
Page 58 and 59: 56
Page 60 and 61:
58 Trafik I Lav II Middel III Høj
Page 62 and 63:
60 43 Betonkvalitetens betydning 43
Page 64 and 65:
62 AR er en beton, der opfylder Vej
Page 66 and 67:
64 Kloridindhold [% af betonvægt]
Page 69 and 70:
5 Støbning med fiberbeton 51 Prøv
Page 71 and 72:
Foto 5.2. Der blev anvendt stav- og
Page 73 and 74:
Foto 5.4. Kerne HL2 - overfladen tv
Page 75 and 76:
I alle prøveemner ses indesluttet
Page 77 and 78:
Foto 5.6. Afslutningsvis blev beton
Page 79:
indtil betonkernen har samme temper
Page 84:
Vejdirektoratet Niels Juels Gade 13
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