Concrete contraction/expansion in Swimming Pool Slab-on-grade

[megmain]

Forensic Question about Concrete contraction/expansion in Swimming pool: A swimming pool with 8" thick reinforced concrete slab-on-grade has expansion joints approximately 40 feet apart. At the joint the concrete is 12" thick. Under and around the walls of the pool, a layer of 6 inches of clean crushed stone is present. The pool has experienced significant water loss. Caulking materials at the joints had deteriorated at some areas and ceramic at both edges of the joint has separated and cracked. The pool was built about 1.5 years ago. There has been water leakage from adjacent surge tank towards the pool and concrete sections adjacent to the pool at pool deck also heaved 3 to 4 inches at joints near the walls during cold weather. The heave has subsided after temperature risen, during the same time pool level went a few feet down (not sure if uplift is a factor).

Soil borings showed that the materials under pool and deck is silty sand. No signs of plastic soils any where. No groundwater below the slab.

 

[hokie66]

Pools are best built without joints, as the joints always cause problems. Now that the pool is built, and the joint seals have failed, the fun begins.

Sounds like the deck was uplifted by freezing, but 3 to 4 inches seems a lot.

A forensic investigation such as this will typically arrive at a number of contributing factors, and I doubt that this forum will be able to assist you greatly without a lot of additional detailed information.

As the pool is only 1.5 years old, is it under warranty?

 

[JAE]

OK - you described everything...what is your question?

 

[megmain]

Question?: I am looking for feedback on what could be the possible reasons for the heave. Would saturated soils below 4 inches of concrete could create this much heave or would there be other contributing factors that I need to explore.