Effects of Sodium Chloride (NaCl) On Historical Bridges and Treatment with Bentonite

Abstract

In this study, the effects of bentonite clay were investigated in the cleaning of the andesite stone samples used in the restoration of historical Çobandede Bridge and some historical buildings contaminated with sodium chloride salt. The stones of historical buildings are exposed to harmful salt effects for various reasons. Especially in regions where terrestrial climate dominates, the sodium chloride salt sprinkled on the icy roads for thawing may infiltrate over time into soil and then arrives at the historic bridges’ stones. In this way, because of capillarity of the stones and ionic osmos, the salt accumulates in the pores of the stones and the hygroscopic nature of NaCl damages the historic bridges’ stones on the road route. This physically damages the stone and reduces the life of historic bridges. Therefore, the removal of salt entering the structure of the stone is very important to increase the durability of the stones. In order to model this situation, a sum of bentonite clay paste prepared in liquid limit was implemented to artificially polluted andesite stone samples. The clay pastes applied to the stones were removed from the stones surfaces after a certain period of time and analyzed. X-ray Fluorescence Spectrometry (XRF) analyzes showed that bentonite clay gave positive results for sodium chloride removal from historical building stones exposed to NaCl salt.