Crack width calculation for swimming pool.

[cyphos168]

Hi all,

Need some advice on crack width requirement for swimming pool structure. The pool is located on an upper floor level. Some literature state crack width of 0.1 and 0,2 depending on the length of water tightness tests to be conducted. SO I am assuming 0.2mm being the limit of crack that is allowed to form in the structure. Is this limit set based on normal concrete or with waterproofing membrane in place? I would have thought if a waterproofing membrane is going to be used to line the pool, crack width limit would be higher but not too high as to cause the lining to fail. Thanks.

Regards,

Chong

 

[Agent666]

Definitely it can be relaxed if there is a liner/membrane. Watertightness is no longer provided by the "structure". Just remember though ultimately if the liner fails the concrete is the second line of defence, not such a concern for an in ground pool, but perhaps more of a concern for an indoor elevated pool.

Also if the pool soffit is exposed to view you might still want to adopt the more stringent criteria, depending on the depth the loads are pretty high, and you also deal with a lot of restraint, thermal expansion/contrsction, etc, so more likely to crack and determining crack widths are not an exact science.

 

[cyphos168]

Hi Agent666,

Thanks for your quick response. Yes its probably going to be waterproofed with crystalline waterproofing system like Krystol or Penetron. And due to the issue with depth of beam constraint, I might advice the owner to line it as well. FYI depth of pool is 1.2m high.

Chong

 

[hokie66]

Those crystalline "waterproofing systems" only work to seal cracks after they form, and it takes a while. So don't depend on them for waterproofing if leaking on anything below will be a problem. Crack control, and consequently leak control, is best managed in an elevated pool by using plenty of reinforcement...about 0.6% Ag.

 

[cyphos168]

Hi Hokie66, as per my response, would double defense work in this case? Liner and water proofing. It will be expensive but in view of the limitation in beam depth due to limited headroom, I see no other choice but to go this way. I am going to use a lot more steel without exceeding the maximum area permitted by the code to control total deflection and crack width. I am getting down to around 0.2mm at the moment.