Works we undertake

Cleaning

All dirt, grease and other surface contaminants should be removed, including any moss, lichens or algae etc. This is best achieved by pressure water jetting, streamcleaning or wax free detergent and clean water scrubbing.

Any existing, deteriorated or inadequate surface coatings should be removed along with cement laitence or other containants. Any surface defects such as cracks, honeycombing, blowholes etc should be fully exposed. This is undoudtedly best achieved by abrasive blastcleaning, however, if environmental constraints prevent this, then alternative mechanical means such as power tools may be employed.

 

Repair

i) Mechanically break out all visibly damaged concrete, together with other areas identified by engineer, back to a sound, alkaline base.

All cracks in the surface should be identified and cut out (chased) to ensure that reinforcement is not corroding. Moving cracks should be stabilised or the degree of movement ascertained by the engineer before proceeding.

N.B. Feather edging should be avoided and any loose aggregates should also be removed.

Any steel reinforcement uncovered should be fully exposed along its corroding length. it is not necessary to cut behind non-corroding bars bedded in sound, alkaline concrete, but if in doubt it is preferable to do so.

N.B. The removal of concrete from behind reinforcement bars should only be carried out with the approval of the engineer.

The exposed steel reinforcement should be thoroughly cleaned; abrasive blastcleaning is the best and most efficent way of achieving this, but if environment constraints prevent this, alternative mechanical means such as power tools may be employed

ii) Immediately after cleaning (within 24 hours) the reinforcing bars to be given two coats of STEEL REINFORCEMENT PRIMER, the second coat to be thoroughly blinded with QUARTZ SAND to ensure a physical key for the subsequent repair. Where part of the reinforcing bar remains embedded in sound, alkaline concrete the primer should be overlapped onto concrete by approximately 10 mm.

STEEL REINFORCEMENT PRIMER is a two componet , high build, thixotropic, solvent free epoxy resin and finely ground cement clinker (sulphate free) combination. It has a density of 1.8 kgs/litre and should be applied at approxiamtely 0.7 kgs per square metre per coat (normal 350 microns per coat). QUARTZ SAND to kiln dried, washed quartz river sand with rounded profiles and of granulation 0.7-1.2mm

This is to provide a dense, impervious, highly alkaline, protective coating around the reinforcement.