Experimental Study of Fly Ash Concrete Attacked by Sulphuric Acid

Abstract

Experiments were conducted to study fly ash concrete (FAC) attacked by sulphuric acid. The cubes with dimensions of 100 mm were cast and immersed in sulphuric acid solution with different pH values of 2, 3 and 4, and tested at exposure times of 28 d, 56 d, 90 d, 150 d and 365 d respectively. The compressive strengths of concrete were tested, and the SO42- contents of concrete at different depths were measured with powder samples by the chemical titration method. The results show that FAC has certain ability to resist corrosion of sulphuric acid though exposed surfaces were damaged at long-term exposure times, the concrete strength at same exposure time decreases with the increasing density of sulphuric acid solution, the SO42- mainly contains in shallow layer of concrete while the content decreases obviously with the increasing depth of concrete. With the increasing density of sulphuric acid solution, phenomena of surface cement paste peeling off surface of concrete and crystal CaSO4 separated out of concrete became seriously. The deterioration mechanisms of FAC attacked by sulphuric acid are discussed.