SLAKING MECHANISMS OF MUDSTONE LINER IMMERSED IN WATER

The purpose of this research is to probe the slaking property of the m udstone meeting with water. The elemental, crystalline, and morphologi c changes in the mudstone with three different water contents were cha racterized using X-ray fluorescence spectrometer (XRF), semi-dynamic l each test, X-ray diffractometer (XRD), and scanning electron microscop y (SEM)/energy-dispersive X-ray analysis (EDAX) techniques. The XRF an d chemical composition analyses indicated that the mudstone contains h igh concentrations of silicon and aluminum and low concentrations of c alcium, iron, potassium, and sodium. The XRD examination showed large amount of quartz and illite, minor calcium aluminate hydrate and calci um silicate hydrate, and small amount of unidentifiable peaks. The res ult of semi-dynamic leach test showed that the release of sodium is ve ry rapid initially and the released calcium species increase largely i n the final subsequent extractions. The microanalysis using SEM/EDAX i ndicated that the petal-like structures increase with the moisture con tent of the mudstone, Thus, it was inferred that the possible mechanis ms of the mudstone meeting with water to lead to the slaking phenomeno n are stated as follows. The sodium sulfate will rapidly dissolve from the mudstone, and the sulfate species and calcium aluminate hydrate f orm the platelet-like solid solution of 3CaO-Al2O3-CaSO4 . 12H(2)O mak ing the mudstone lose its cementing reaction. (C) 1998 Elsevier Scienc e B.V.