Obsidian expansion kinetics

Abstract

According to the modern terminology, the term «perlite» means natural glassy mountainous rock that has the expansion feature when heated causing high porous pumice-like material. Scientifically, in the first place, perlite (containing different quantities of water) itself that is hydrated volcanic glass, in the second place, pechstein that is even and fairly strong hydrated glass, in the third place, obsidian that is glass containing little water, in the fourth place, the so-called porous perlite that is scientifically regarded as little porous pumice, can be pertained to technical perlite. Thus, in Armenia according to technical significance «perlite», glassy mountainous rock, divided into perlite and obsidian. The igneous rock consists of volcanic glass the water content of which does not exceed 1%. In Armenia, in ancient times obsidian was expanded and used in the upper layers of the dome of the three-floored temple Zvartnotc. Expanded obsidian can be used as artificial porous aggregate for lightweight concrete of different designation. Obsidian is expanded at temperature of 1050-1150°C. The lowest average density of 200-350 kg/m3 (in a piece) is obtained at thermal processing of obsidian with the coarseness from 5 to 20mm and the duration of 3-10 minutes. On the basis of expanded obsidian heat-insulating and acoustic materials can be developed: lightweight and cell concrete and plastering with cement and gypsum.