The silent destroyer
At the Ramdeobaba Salt Weathering Lab, located on the campus of Shri Ramdeobaba College of Engineering and Management, researchers study one of the most persistent and destructive forces in geology: salt. The local sandstone is exceptionally vulnerable to a process called haloclasty, or salt weathering. This phenomenon is a primary cause of decay in stone monuments and buildings around the world. The process starts when saline water penetrates the stone's porous structure. Nagpur's climate, with its intense dry seasons and wet monsoons, creates a perfect engine for destruction.
During dry periods, the water within the stone evaporates, leaving behind salt crystals. As these crystals grow within the rock's microscopic pores, they exert immense pressure on the confining mineral grains. This internal stress, known as crystallization pressure, can exceed the tensile strength of the sandstone, forcing the grains apart from within. The damage is not a one-time event. With each new influx of moisture from rain or humidity, the salts dissolve, only to recrystallize with greater destructive force when the next dry spell begins. Common salts like sodium sulfate are particularly damaging; they can change their hydration state with temperature shifts, causing the crystals to expand and contract, further weakening the stone. This relentless cycling makes the weathering in this region so accelerated.