Sulfate Corrosion of Concrete with Fly Ash or Slag in Saline Soil Environment

LI Guo; CHEN Jianzhuang; GUO Dongqin

doi:10.3969/j.issn.1674-358X.2015.03.012

Abstract：T he soil containing sulfate w as used to simulate saline soil environment ,and sulfate corrosion of concrete with fly ash or slag replacement and normal concrete for comparison were studied through half embedding in saline soil combining with sulfate solution wetting and drying cycles .With the proceeding of corrosion ,ultrasonic velocity ,macro‐and micro‐morphology and corrosion products of specimen concrete a‐bove and beneath soil interface were tested .The results show that the sulfate corrosion mechanism and cor‐rosion rate of concrete above and beneath soil interface in saline soil environment are obviously different . Corrosion of concrete above the soil interface belongs to physical crystallization corrosion ,and the corrosion products are sulfate crystallization .While corrosion of concrete beneath the soil interface belongs to chemi‐cal corrosion ,and the corrosion products are ettringite and gypsum .Corresponding different sulfate corro‐sion mechanisms ,effects of fly ash and slag are also different .The replacement of fly ash is not beneficial to the resistance of concrete sulfate physical crystallization corrosion ,w hile the replacement of slag is not beneficial to the resistance of concrete sulfate chemical corrosion .For the same kind of concrete ,the sulfate corrosion rate of concrete above the soil interface is significantly higher than that beneath the soil interface .