Ammonium Nitrate corrodes concrete; fresh concrete even more rapidly. Once it has penetrated or been absorbed by concrete, it can remain dormant until suitable environmental conditions are established for it to start a chemical attack. Contaminated concrete cannot be assumed to have stopped deteriorating, nor can it be protected or delayed by coverings of paint or render.
It is essential to detect A.N. attack in its early stages, by establishing routine inspections of foundations, process drainage, and A.N. dust-laden overhead structures, specifically to search out and identify contamination and monitor its significance.
Recognition of the symptoms, therefore, is important, but also it is essential to properly prepare contaminated concrete before any remedial work is attempted.
Coatings, patch mortars, overlays, admixes and other protective applications have their uses, but great care must be exercised in their application, as very often, if wrongly applied, or even correctly applied in the wrong circumstances, they can do much more harm than good.
It is not intended to specify a guaranteed remedy or repair procedure, (as this largely depends on the repair location or environmental conditions) but rather to focus on the effectiveness of completed repairs and their associated problems, as a guide to those who may encounter similar problems in the future, and to promote a wider exchange of information, and by this exchange avoid wasteful duplication of effort or expense by those presented with the problem of repair.