Disintegration of concrete construction induced by acid mine drainage attack

Abstract: In this paper, microanalytical investigation was conducted on disintegrated field concrete that had been used to construct a weir within a coal mine in South Africa. The concrete was in contact with polluted mine water, commonly referred to as acid mine drainage (AMD). Accordingly, the concrete weir had been exposed to dynamic conditions associated with flowing AMD. Investigations were conducted by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). The field concrete samples examined consisted of soft broken concrete chunks and whitish powdery substance that had crystallized and formed a surface coating on the widely cracked locations of the deteriorated concrete. No evidence of sulphate attack or pyrite oxidation was found in the investigation; acid attack mechanism was diagnosed