Investigation of Concrete Deterioration Due toSulfate Attack--A Case History
Appears on pages(s):
chemical tests; chlorides; corrosion; deterioration; ettringite; expansion; exposure; gypsum; magnesium sulfates; marine atmospheres; reinforced concrete; reinforcing steels; salt water; seawater; sodium chloride; subsurface structures; sulfate attack; D
In coastal areas of Saudi Arabia underground reinforced concrete structures are frequently exposed to aggressive action of saline water and sulfate-bearing groundwater. The extent of deterioration varies from negligible to very severe depending on the type of exposure and the concentration of sulfates and chlorides, as well as the quality of concrete. Deterioration of concrete is mainly due to aggressive action of magnesium sulfates, mitigated by chloride ions, and the decomposing effect of calcium sulfates from sulfate-bearing groundwater. The procedures employed to evaluate nature, extent, and rate of deterioration consisted of a condition survey, chemical analysis of groundwater and water-borne precipitates, petrographic analysis of concrete cores, and structural evaluation of the in-place concrete. After unsound concrete is replaced and deficiencies repaired, protection from further deterioration can be achieved by tanking the surfaces with several layers of hot-applied coal tar reinforced with felt and by the installation of a subsurface drain system.