A71 Calder Road, Edinburgh
Wet blasting, using the Quill Falcon system, of approx 1000 metres of railings to Sa2.5 in preparation for a four coat Highways Agency paint system with Ameron Coatings. Approx 2000 sq metres of underpass walls and soffits cleaned in preparation for concrete repairs and preparation to receive two coats Ameron PSX 700 polysiloxane coating which being very tough and glossy has excellent anti-graffiti qualities. Work being carried out under adverse conditions, it was -9 deg C one morning. This is a contract for Edinburgh City Council.
Blast Cleaning
The cold and wet weather increased the flash rusting so much that we have reverted to traditional dry blasting using fine copper slag. Using our 3 bag pot from Airblast Ltd of Peterborough powered by a 550cfm compressor supplied by Speedy Hire in Glasgow. This has been fitted with an air cooler which effectively reduces the moisture content of the air and has almost eliminated down time caused by blockages.
Priming
Getting the primer (Amercoat 4376) PPG Protective and Marine Coatings applied immediately after removing any flash rusting presents an additional hazard in that it is then subject to airborne dust and debris not only from the nearby blasting work but from waterborne debris thrown up by the traffic which is no more than 2 metres away. We have had to rub down and apply a second coat of primer to all the sections subject to this hazard. This has one advantage in that it helps to achieve the required dry film thickness of the completed paint system.
Concrete Repairs
One of the underpasses presented us with deteriorated substrate. Some years ago the walls have been coated with a textured material which has in places de-laminated from the original smooth concrete finish. We have removed all the material which can be removed manually. Using Weber Keycoat and Fairing coat we are repairing the surfaces and then skimming the whole surface of both walls to restore the original smooth finish.
Despite the unfriendly weather conditions throughout January and February we have successfully removed all the graffiti and defective paint coatings from all four underpasses approximately 2000 square metres of subway walls. We have carried out concrete repairs particularly around rusting rebar which has been blast cleaned, primed and repairs carried out using Weber HB40 epoxy repair mortar.
Containment and Dust Control
We have built on site a custom blast chamber using scaffold tube and sheeting. To this we have added a powerful dust extraction set up designed and built by Michael Williams Engineering Ltd of Cambridge. This extracts all dust, debris and abrasive material from the blast area. The spent material and debris can then be bagged or skipped for removal off site and disposal. In order to reduce costs and environmental damage about 25% of the abrasive material is sieved and re-used.
This contract is going well and with the lengthening days and hopefully better weather we will recover the time lost during the winter weeks. The painting inspector is satisfied with the quality of the work and the customer is happy with the way in which our team on site have dealt with the various challenges and conditions they have had to work in.
