When a construction joint is required on a wall on wall or column on column pour the joint line can cause problems with deflection, grout loss and achieving a true straight edge to the joint.
Deflection is the biggest issue and should not be ‘feathered in’ to the concrete plane of the pour below. It may appear to be a solution but the concrete will always look worse if this is attempted. It will always appear to be ill considered and look funny to the eye. The only solution is to continue the plane of the concrete and form a true straight joint line. The joint line, even though it is not flush, will help the repair to be more accepted by the eye (see image).
Grout loss will also be present but this can be resolved but protect the pour below!
If the wall from the previous pour is not ‘struck off’ to a straight line with the formwork then this will also require the re-instatement of a new joint line as a wobbly line will prevail. Finishing the top face of a pour to flatness is important...
This week we’ve been busy repairing some deflected construction joint lines on columns on a major fair faced project in London. This will be the next Concrete Repair Category with some before and after images.
I also written an article on in situ polished concrete flooring for a major publication. Along with a previous article on concrete repair works we hope to have two pieces published this month. We’ll keep anyone who follows this blog informed when these come out.
Also this week I gave an intimate two-hour CPD on Specifying Visual Concrete (Floors, Furniture and Tadelakt) to Belsize Architects http://www.belsizearchitects.com which according to feedback, was really informed and full of practical information. This is what it’s about. I hope that it facilitates future projects for this dynamic group. Thanks for the invitation…
There will be more to come of course on the Visual Concrete Finishes series focusing on Polished Concrete Flooring.