Expanded obsidian as a soil aerator, its porosity, physical and mechanical characteristics

Abstract

Today, the decline in soil fertility progress, therefore, special attention paid to the search for new, including non-traditional sources of raw materials that allow cultivating agricultural crops. It is propose to use expanded obsidian as a soil aerator. Obsidian is a volcanic rock, consisting of volcanic glass in which water content does not exceed 1%. A characteristic feature of this stone is the ability to expand under heat treatment. The expansion of obsidian is possible to implement at temperatures of 1050… 1150 °C. It has been shown that due to obsidian expansion it is possible to obtain a light porous filler with an average density of 200… 350 kg/m3, where the heat treatment of 5… 10 mm grains should be performed under temperatures from 1050 to 1150°C, during 3…5 minutes. The mechanical strength of the expanded obsidian is due to the thickness of the internal partitions of the pores and depends on the total porosity. Increased porosity decreases the strength of the expanded obsidian grains as the internal partitions of the pores become thinner. Relatively high mechanical strength develop grains with less porosity, ie lower coefficient of expansion. At the same time, the nature of the external surface of the grain has a significant influence on the mechanical strength. The melted surface,under other equal conditions provides mechanical strength increase of the expanded obsidian.