Hydrothermal processing of new fly ash cement

The recent Mount Pinatubo volcanic eruption in the Philippines, in which at least 268 people died, shows that volcanic eruptions can be highly destructive. The eruption shot ash and debris over the countryside; six towns near the volcano faced a high risk of devastating mudslides, and nearly 2000 U.S. service members and their families were evacuated from two nearby military bases. However, this paper reports that not all the consequences of volcanic eruptions are bad. Under hydrothermal conditions, volcanic ash can be transformed into zeolitic tuff and, eventually, into clay minerals that constitute agricultural soils. The Materials Research Laboratory (MRL) has recently used some artificial pozzolanas (fly ash) that when mixed with lime, under hydrothermal conditions, also produced a new type of cementitious material. This was categorized as a new fly ash cement. The formation of a new hydrothermally treated wood-fiber-reinforced composite has also been demonstrated. It is apparent, however, that with respect to concerns about detailed knowledge of the reactivity of calcium silicate-based materials under hydrothermal conditions, the application of the technology far outweighs the understanding of the underlying principles of reactivity. It would seem that an understanding of reactions on the molecular level is just beginning, and that more » work on hydrothermal reactions is still a potentially lucrative area of research. « less