Friction rock stabilizers (FRS), such as Swellex* rock bolts are being considered as reinforcement material for the Yucca Mountain Nuclear Repository. Generally, expanded rock bolts are used for rock support in mining and tunneling applications due to various advantages. Expanded Mn24 rock bolts used for rock reinforcement in underground construction are made of High Strength Low Alloy (HSLA) steel. To our knowledge there are no electrochemical potentiodynamic studies performed on expanded Mn24 in the cold worked condition under certain YM environments for the repository. Corrosion behavior was studied from Potentiodynamic polarization tests performed on expanded Mn24 rock bolt with increasing the concentration of simulated YM water and also as a function of temperature under aerated and de-aerated conditions. Increase in corrosion rates were observed in de-aerated and aerated conditions at room temperature as a function of concentration. Increase in Corrosion rates as function of temperature in YM water chemistry under de-aerated and aerated conditions were observed. Corrosion mechanism of passive layer in anodic region was studied for rock bolt at room temperature in de-aerated condition. Corrosion rates of expanded rock bolt in de- aerated are considerably low than the rates in aerated with both increase in temperature and concentration. From the analysis it was found that the uniform and pitting corrosion were the main contributors to the corrosion rate obtained. In this work, we present the corrosion mechanism and corrosion rates of expanded Mn24 rock bolt in different conditions.
Keywords: Yucca Mountain, Expanded Mn24, Potentiodynamic scan, Corrosion. “*Swellex® “Mn 24 rock bolt is the trade mark of Atlas Copco