Effects of Slaking fluid pH on the Index Properties of Carbonate Rocks

The physical and chemical characteristics of water critically influence the mechanical and chemical breakdown of rocks. The physical properties of rocks, such as porosity (n), water content (w(a)), apparent specific gravity (G(s(A))), and dry and saturated densities (rho(d), rho(s), respectively), may be adversely affected by the acidity/alkalinity of water. This study aimed to investigate the variability of certain physical properties of carbonate rocks using the second-cycle slake durability index (second-cycle SDI, I-d2) under acidic and alkali conditions. Laboratory SDI tests were conducted on 21 rock samples (seven from each of the Rus, Asmari, and Dammam carbonate rock formations) using slaking fluids with various pH levels, i.e., 2-14 (acidic to basic). Results show that the n and w(a) values were negatively correlated with pH for carbonate rocks from the Rus, Asmari, and Dammam Formations. However, the G(s(A)), rho(d), and rho(s) values of carbonate rocks from the Rus Formation showed decreasing trends with pH, whereas increasing trends were observed for the Asmari and Dammam Formations. This may have been either due to variations in the mineralogical and textural features of the carbonate rocks or chemical reactions with CaCO3 caused by the different pH levels of the slaking fluid, especially under acidic conditions. Such findings will likely improve our understanding of the durability of carbonate rocks in the study region and elsewhere.

Automated summary

This study investigated the variability of certain physical properties of carbonate rocks under acidic and alkali conditions. Results showed that the physical properties of carbonate rocks from different formations exhibited different trends with pH levels, possibly due to variations in mineralogical features and chemical reactions. These findings contribute to a better understanding of the durability of carbonate rocks in various geological environments.