Slab spalling caused by fertilizer application?
Slab spalling caused by fertilizer application?
(OP)
One sub-freezing day this winter, a customer of mine, here in Atlanta, used fertilizer on his year-old driveway instead of de-icing compound. Shortly thereafter the areas of the driveway where the the fertilizer was the heaviest developed severe spalling. I have since heard that certain kinds of fertilizer can cause this condition. My customer maintains it is a flaw in the driveway pour (i.e. a warranty-service problem), even though the driveway was in excellent condition prior to this event. He contends that "some of his neighbors used fertilizer with no problems". Any comments?





RE: Slab spalling caused by fertilizer application?
If the slab surface has spalled, then a pre-existing condition is present in the slab. The de-icing procedure probably caused the 'spalling' or delamination to occur rapidly rather than slowly. Several ACI & PCA publications deals with the several causes of 'spalling' and delamination. My experience in Colorado is that a variety of finishing techniques, coupled with weather and concrete mix proportions and additives, can result in slab surface deterioration. Ice (freeze-thaw)and aggresive De-icing usually just speeds up the process. Actually determining what went wrong can be a challange. The combinations of finishing, curing, weather, mix proportions and additions is quite large.
If the concrete surface has deteriorated due to chemical attack, the chemistry of the fertilizer will give indications. Please note that sulfate (gypsum) and I believe some compounds containing ammonia can be very hard on concrete. Again, ACI & PCA have a lot of information.
Good Luck
RE: Slab spalling caused by fertilizer application?
The differences between chemical attack and expansive spalling are readily apparent...chemicals usually attack the paste, while expansive spalling will usually split the aggregate as well as the paste.
RE: Slab spalling caused by fertilizer application?