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Harbor
Concrete Repair Materials
NFESC considers shrinkage as important a control parameter for
concrete repair material as strength. Excessive strain will result
in cracking, which will hasten deterioration of the structural upgrade.
Tensile strain capacity is related to shrinkage, creep, and the
modulus of elasticity. The contractor was required to select repair
materials and procedures that control cracks by controlling shrinkage.
The approval of a suitable material for concrete repair was a time
consuming process and it preceded all other project tasks. Shrinkage
tests took more than 35 days to complete by a testing laboratory
with the facilities to conduct the tests at 46 to 54 percent relative
humidity at 70 to 76?F (21? to 25?C). The process was started well
in advance of concrete demolition. Fortunately, the contractor proposed
to use Sikatop 111 Plus? and Sikatop 123 Plus? prepackaged materials
that were used earlier in the NASVSTA San Diego Pier 12 upgrade.
Therefore, the qualifying tests on the prepackaged materials were
significantly simplified. Tests were conducted on the prepackaged
material mixed with aggregate prior to using the mix on the site.
The tests produced shrinkage well below the required 0.05 percent
maximum allowable (See Appendix A for detailed results).
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