Experimental study of the effect of saline water on weathering of rocks in Robat Namaki region of Khorramabad

The salty running water from Gachsaran Formation in Robat Namaki region, north of Khorramabad city, has caused salt weathering of some rocks in the region. Salt weathering due to the salty running waters of the region is one of the reasons for changing the geomechanical properties of rocks, and as a result reducing their durability. In current research, the effect of salty running waters on the geomechanical properties of outcropping rocks in Robat Namki region has been studied by conducting salt weathering tests. For this purpose, two samples of limestone and sandstone have been prepared and salt weathering tests have been performed on them for 30 cycles in salty running water, spring water and saturated salt solution. After every 5 cycles, the point load index and porosity of the samples were determined. Fitting curves between salt weathering test cycles with point load index and porosity were developed for all three test solutions, and parameters of decay constant and half-life were obtained from them. The effect of the three test solutions on the samples has been evaluated using these parameters, as well as the percentage of changes of the point load index and porosity. The results show that saturated salt solution, spring water and salty running water had the greatest to least effect on the changes of point load index and porosity of the samples, respectively. Also, data analyses shows that sandstone is more affected by salt weathering due to its higher porosity and layered than limestone.