Lea Navigation
We were instructed by Enfield Council Highway Services Department to carry out surface preparation and remedial painting to exposed corroded sections of beams on the bridge carrying Lea Valley Road A110 over the Lee Navigation canal at Ponders End Lock.
This bridge was built in 1963 by the Cleveland Bridge and Engineering Company.
Work started on the beams at the eastern abutment wall on the east towpath on 14 August using an aluminium access tower, small generator and 110v power tools. On 21 August scaffolding was erected along the towpath adjacent to the western abutment. On 24 August we commenced work on the western abutment bearing shelf.
Once accessed it became apparent that there was much more extensive corrosion to the ends of the beams on the south and north sides of the bridge and in the centre. Using a small breaker and needle gun attachment together with abrasive flap or mop discs, hammer and chisels we worked for two weeks to remove all the rust and scale from the corroded beam ends and bearings. We discovered that the concrete beam above was cracked with several areas showing exposed corroded rebar in one place over 6 metres.
When all areas of rust and corrosion had been abraded back to clean steel, blown free from dust with compressed air and wiped down with solvent ang rags we applied the first coat of Jotamastic 87 epoxy primer. We then washed down all sound paint on the beams using hot water and Zenith Traffic Film Remover Detergent Other than the ends of the beams and the lower face of the bottom flange the remaining surfaces were practically free from corrosion. These surfaces were lightly abraded with orbital sanders and 80 grit abrasive discs. Once sanding was completed we removed all dust with a hot water pressure wash.
Additional coats of Jotamastic 87 were applied in strip coats and full coats to achieve dft readings from 200-250 microns. We followed this with a stripe and a full coat of Jotun Hardtop XP in BS 381C 172 Pale Roundel Blue.
Once this was completed we commenced work on rebuilding the concrete beam where we had exposed, abraded and primed the rebar.
