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.