Macro-mechnical charakteristics and their control on the strenght of sandstones of western Indo-Burmese Rangers, NE India

Abstract

Mechanically strong sandstones consider as a potential construction material which can withstand modest load and not associated with any geologic fractures. This work is about understanding the macro-mechanical properties of sandstones by studying several petrographic parameters, which could provide evidence of their influence on mechanical strength. Here the authors were considered the Bhuban sandstones of western Indo-Burmese Ranges (IBR) of north-eastern India to investigate the above criteria. The result shows that sandstones have a mean grain size between 108 to 208 μm. Moderate to poorly sorted (phi scale ranges 0.56-1.5) grains show greater content of rounded constituents (43-68 %) with sphericity between 0.65-0.85; along with moderate packing properties (packing density 54-77 %; packing proximity 32-70 %). The grains join by mostly straight (20-54 %) and concavo-convex (13-45 %) contacts; with lesser point (5-13 %) and sutured contacts (8-44 %). Schmidt Hammer rebound values (R-values) were used to calculate and analyse the uniaxial confined stress (UCS); which again validated with UCS testing of core samples. The comparison between macro-mechanical parameters and the UCS shows interrelationship among rock constituents which hold the key to the mechanical strength of the rock. The presence of angular grains and semi-angular spherical grains diminish the macromechanical strength to some extent. Moreover, FETEM-EDX analysis confirms the microweathering of the angular grains, which have a deformed lattice setting. These findings show that macro-mechanical and micro-nano scale properties of sandstones influence the rock strength.

Petrographic and geotechnical evaluation of Ogwashi-Asaba ferruginised sandstone, Niger Delta, as aggregates for construction

“…The research work of Chioma et al (2021) on the quality of crushed Amasiri Sandstone suggests the possibility of using marginally suitable sandstone for construction purposes, provided that adequate design is made to compensate for their defects. Rakshit et al (2021) while investigating the influence of micromechanical properties of sandstones of Western Indo-Burmese Ranges, Northeast India, opined their strength reduction to be a result of the presence of angular and semi-angular spherical grains. Similarly, Monsees et al (2021) while investigating the relationship between diagenetic alteration and mechanical properties of Permian Siliciclastic sandstones suggested optical porosity which was linked to diagenetic alteration as a significant factor influencing its mechanical properties.…”