I want to concrete around a pool inside a courtyard, and have had conflicting advise from concreters, in that I have been told that pins will need to connect the existing pool concrete and the new slab, and I have been told that you don't do this also. I was hoping that I could get an anwser to this or direction to the technical issues as to why or why not pin.
Regards Ray
Dear Ray,
As a rule and in simplistic terms, there are two types of joints in concrete. The first is a construction joint using pins, dowels or the like and this ties the whole structure together and relies on the fact that movement is uniform. The second is an isolation joint that allows for variation in movement between adjoining elements of a structure or building.
In the situation of a slab adjoining a pool there would need to be two considerations , namely:
- If there is differential movement is there a risk of causing a trip hazard due to the uneven surfaces and
- Is there a risk of cracking (the pool or pool slab edge etc,) if there is no allowance for differential movement.
The most worrying long term concern for me would be the latter and I would always advise anyone in your situation to separate the two in a manner that allows differential movement. Therefore I would recommend that there be an expansion joint between the two and the use of dowels not be adopted.
I hope that this helps.
Kind regards,
Mike