Bentonite clay. Environmental properties and applications / Бентонитовые глины. Экологические свойства и область применения

Have you tried to walk across a farmer’s field in Montmorillon in France on a rainy October day? Marcel and Bertrand, his father, tried to do so in the fall of 1881 with fatal consequences. We will return to this terrible true story in the first chapter of this book for explaining how the soil at this place made it happen, continuing throughout the rest of the book by explaining how the dreadful soil, in fact, also has extremely beneficial properties in other contexts, like isolation of very hazardous waste. The place gave name to the mineral montmorillonite, which belongs to a group of clay minerals called smectites, which have tremendous ability to adsorb water; this property transforms the clay from being stiff in dry weather to becoming soft sticking mud after long periods of rain, from which you cannot pull your feet and legs out. The harder you try to get them up, the deeper you work yourself down because intense movement reduces the strength of the clay and makes it fluid. But a minute’s rest for breathing makes the thixotropic* material stiffen and lock you up, so that you cannot start moving again (Figure I.1). French farmers in this region and in numerous other areas with this type of clay cannot complete cultivation or even inspect their land in the rainy season. Much the same kind of clay is found on the island of Sardinia, Italy, where such clay is in abundance. People in the churchyard visiting the grave of their deceased relatives are never sure of placing flowers on the right grave since the graves move about in all directions with the seasonal variation in water content of the ground. This preface concludes with a comment relating this property of montmorillonite to a perspective on life and death. <...>