On rare occasions we are asked to extend the dimensions of concrete either because the initial setting out was incorrect or because the piece just didn't fit into the space properly. Growing concrete is a great remedial work to undertake because it resolves big issues fairly simply. The repairs also look impressive which is a bonus.
The key to any good repair is respecting the plane of the existing material, getting a seamless flush finish and good texture match. Any hint of disparity here will drag the eye into disbelieving discourse with the brain and the repair will fail…. no matter how good the colour match is.
Columns, walls, window reveals can all be cultivated in this way. In this case precast treads were given the ‘gardening treatment’ to get a neat inserted finish into a stone lime washed wall. There were 17 treads in all with plenty of other post finishing to add to the mix. All good fun…
Precast concrete that is generally blemish free raises the stakes considerably when it comes to delivering a top class repair. The same could be said for self compacting in situ concrete.
Whilst as with any remedial work the key starting point is flush, true and texture appropriate filling, colour matching such good original work up’s the anti to dizzy heights. Achieving a close colour match in terms of tone is not an issue per se. It is the successful diffusing of minute tonal variation to convince the eye to believe.
If the concrete is pre cast or site batched in steel shuttering then this adds a significant advantage as the surface quality of steel formed concrete tends to have a nice balance of light reflectivity. Not too shiny and not too dull.
The images here are the before and after of construction damage on a pre cast column for BP. It is irrelevant to the repair process but it is probably a PFA blended mix. The blotchy marks have come from differential curing not the casting p...