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OCR for page 27
17 The system was reported to have been in use since the 1. Deck surface preparation, mid-1980s. Previously, a system of asphalt overlay on a sheet of mastic or glass fleece had been used, but it did not provide 2. Application of a primer to the concrete, the necessary protection against the ingress of water con- taining deicing salts. 3. Installation of the waterproofing membrane, A 2009 scanning study reported that the use of water- 4. Installation of protection board if used, proofing membranes on concrete decks for corrosion pro- tection with epoxy underneath to seal cracking in the young 5. Repair of unacceptable areas resulting from mem- concrete is standard practice throughout Europe (1). The brane thickness inadequacies, and use of waterproofing membranes on integral and continuous bridges is mandatory in the United Kingdom. Its engineers 6. Installation of asphaltic concrete riding surface. were reported to be highly confident of the enhanced per- formance that waterproofing membranes can provide and Figures 11 and 12 show various steps in the installation do not believe that other deck protection strategies can pre- process. clude the use of membranes. The standard deck design in the United Kingdom consists of 8- to 10-in. thick decks with Results from the survey for this synthesis showed that a waterproofing membrane overlaid with asphalt. European 19 of 31 agencies (31%) have specifications for the surface practice, however, is not to use bare concrete decks or decks preparation of new concrete bridge decks prior to applica- reinforced with epoxy-coated, stainless steel clad, or solid tion of the waterproofing membrane system, and 26 of 32 stainless steel bars. (81%) have them for existing bridge decks. These numbers reflect that more agencies use waterproofing membranes for The 1995, 2004, and 2009 scanning studies recom- existing bridge decks than for new bridge decks. In general, mended that further consideration be given to implementing the specifications require that the concrete surface be free of the use of European waterproofing membrane systems in the protrusions or rough edges, all contamination be removed, United States (1, 13, 16 ). and the surface be cleaned of all loose material without the use of water. CONSTRUCTION AND INSPECTION Most specifications do not go into the means and methods to achieve the desired concrete surface. However, the New According to the specifications reviewed for this synthesis, Hampshire specifications for surface preparation for use with bridge deck waterproofing generally consists of the follow- heat-welded and liquid-spray barrier membranes provide more ing steps: details. The specifications require that the deck be shot-blasted FIGURE 10 Bridge deck multiple-level protection system (16 ).
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18 (a) (b) (c) (d) (e) (f) FIGURE 11 Steps in the installation of a preformed sheet membrane: (a) Application of primer to the concrete deck, (b) Laying out the sheet membrane, (c) Heating the sheet membrane with a torch, (d) Sealing the overlap seams with a hand roller, (e) Completed membrane, (f) Compacting the hot mix asphalt [Source : Photos courtesy of Soprema for a, b, c, and e; New York State DOT for d and f].
OCR for page 27
19 (a) (b) FIGURE 12 Application of a liquid membrane: (a) Hand spraying, (b) Machine spraying [Source : Photos courtesy of Stirling Lloyd for a; New York State DOT for b].