Your brand new pool may not show signs of structural distress now. But poorly placed shotcrete will result in issues in the future. It may take a few years or a decade - but they will appear.
Shrink Cracks vs Structural Cracks
Shrink cracks are evident in almost every concrete structure. As moisture evaporates from the concrete, the concrete shrinks in volume. Small hairline cracks may develop. As long as these cracks remain tight, there is usually no negative effect.
Structural cracks result from a structure that is too weak, shotcrete that is too thin or from stresses placed upon the structure. A home's new room addition that moved closer to the pool, may place additional stress upon the structure - more than it's design capacity. A second story addition may increase the surcharge upon the pool, that is was not designed for. A poorly engineered pool, where considerations were not made for an upslope or expansive soils, will develop cracks as well.
Forensic Testing
The only way to know for sure if your pool has adequate reinforcing steel, a thick enough shell and sufficient coverage over the reinforcing steel is to perform testing.
Radar imaging is inexpensive and can quickly determine the reinforcing steel placement and shotcrete coverage. It cannot determine the diameter of the reinforcing steel or how well it is encapsulated.
Drilling cores and removing them from the structure, will allow an inspector to evaluate a cross section of the shell, reinforcing steel encapsulation, shotcrete placement and compressive strengths.
Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at:
info@aquatictechnology.com or 408-776-8220.
Visit his website at: www.aquatictechnology.com.
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