Laboratory simulation of gypsum rock dissolution at different pressures, water-flow velocities and pH ranges

Abstract

Sulfate rocks, particularly gypsum rock as its most common near-surface form in the Earth's crust, are among the evaporitic rocks that due to their solubility can cause serious problems if they are present in the foundations and abutments of reservoir dams. To investigate the solubility of gypsum, gypsum blocks were taken from Gachsaran Formation outcrops located at a reservoir dam construction site in Iran. To perform the rock-dissolution experiments under pressure and water-flow conditions, a pneumatic–hydraulic pressure vessel with internal water circulation was designed and manufactured. Dissolution simulation experiments were performed at a constant temperature (25°C) and for a range of pressures, water-flow velocities and water acidities, the solution-rate constants for the experimental conditions considered. The results confirmed, first, that there are strong direct increasing relationships between pressure and the water-flow velocity with the solution-rate constant, while these relationships with increasing pH are reversed. Secondly, the values obtained from the rock-dissolution experiments under atmospheric conditions cannot be trusted as design parameters for dam foundation or abutments because the solution-rate constant values at the affected depth below reservoir dams can be several times higher than the surface value.

Nonlinear Optical Studies of Water at Gypsum–Air and Gypsum–Aqueous Interfaces

“…27,28 Gypsum dissolution as a function of aqueous phase pH and ionic strength has been studied in a controlled laboratory setting to gain more understanding of its adverse effects on environmental water quality. 29,30 For example, gypsum dissolution is responsible for high ground and surface water salinity in landscapes dominated by evaporite karst structures, such as those commonly found in the Rocky Mountain West, especially in areas where the local overburden has been disrupted from open-air coal mining activity. 31 While many gypsum dissolution studies have focused on bulk gypsum dissolution rates, surprisingly, little is known about water behavior at the gypsum−aqueous and gypsum−air interfaces.…”

Effects of groundwater and distilled water on the durability of evaporitic rocks

“…The SDI test is required for sustainable, durable, reliable and safe engineering structures and provides a critical index parameter (I d ) for estimating the mechanical and chemical breakdown characteristics of rocks under cyclic (I d1 -I d4 ) drying and wetting conditions with various slaking fluids. The mineralogical and textural features of rocks and the slaking fluid properties greatly control the rock degradability [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] .The study of evaporitic rocks is valuable in basic geology, mineral deposits, petroleum geology, and engineering geology of which its dissolution has been a research highlight for several decades [17][18][19][20][21] . Subsurface evaporitic rocks are susceptible to being dissolved in water and forming cavities, sinkholes, and karst features, which can lead to unfortunate disasters due to the collapse of infrastructure, foundations, and dams [22][23][24][25][26] .…”

“…The study of evaporitic rocks is valuable in basic geology, mineral deposits, petroleum geology, and engineering geology of which its dissolution has been a research highlight for several decades [17][18][19][20][21] . Subsurface evaporitic rocks are susceptible to being dissolved in water and forming cavities, sinkholes, and karst features, which can lead to unfortunate disasters due to the collapse of infrastructure, foundations, and dams [22][23][24][25][26] .…”