THE ROLE OF QUARTZ MICROSTRUCTURES ON THE MECHANICAL AND ELASTIC PROPERTIES OF QUARTZITES : A STUDY FROM THE HIMALAYA

The Himalaya is undergoing rapid developmental activities mainly because of the exploitation of hydropower potential which requires theconstruction of roads, bridges, dams, tunnels etc. Thus, the demand for good quality rock material for the construction purpose is increasing at a faster rate. Of the various rock types available in the Himalaya, quartzite is the most common choice for engineering works mainly in the construction projects because of its widespread occurrence and its highly resistant ability to weathering. Quartzite may be of sedimentary or metamorphic origin. The sedimentary origin quartzite termed as ‘orthoquartzite’ is formed by diagenetic processes whereas, metamorphic origin quartzite termed as ‘orthoquartzite’ is formed by metamorphic recrystallization of sandstone. Metaquartzite exhibits distinctive microfabrics which are produced at varying pressure-temperature regimes and operation of different mechanisms of recrystallization. These distinctive microfabrics result in the large variation in the mechanical and elastic properties of quartzite.

In order to study the role of different microfabrics on the mechanical and elastic properties of the quartzites, we have investigated the mechanical and elastic properties along with their quantitative microfabrics of the ortho- and meta- quartzites of the lesser and higher Himalayas. These are mainly termed as the ‘Pandukeshwar quartzite’, ‘Tapovan quartzite’ and ‘Berinag quartzite’.

The results demonstrate that the mechanical and elastic properties of quartzites are greatly controlled by their microstructures. Grain size is the most dominant factor that controls the elastic behavior of quartzite. It has also been observed that orthoquartzites exhibit higher strength than the metaquartzites, thus are better suited construction material. The study helps to identify the suitable construction material for the engineering works which is of great demand in the Himalaya.