Experimental study on salt weathering of dolostones (case study: Falak-Ol-Aflak castle, Khorramabad, Iran)

Carbonate rocks have been used as a building material for centuries all around the world. Construction and reconstruction projects still commonly employ them, particularly for replacing damaged ashlars in monuments. Unfortunately, Carbonate rocks are highly vulnerable to salt weathering, leading to their eventual breakage. This study focuses on analyzing how dolostones used in the construction of Falak-ol-Aflak castle behave when exposed to salt crystallization weathering. To achieve our goal, we conducted 40 salt crystallization test cycles on the selected dolostones using Na₂SO₄ and MgSO₄ solutions. After every 10 cycles, we assessed the visual changes and physico-mechanical properties of the salt-crystallization samples. We measured the damage rate (DR) of weight (W), P-wave velocity (V_p), porosity (n), and point load index (PLI) to determine these properties. SEM observations were conducted to examine the structural changes of the building stones resulting from the salt crystallization tests. Based on the findings, it can be concluded that saline solutions containing Na₂SO₄ cause more damage to samples than those containing MgSO₄.