Experimental investigation of the influence of precipitated salts on the liquid transport properties of brick using an organic liquid

The transport properties of porous materials change considerably when soluble salts precipitatein the pores. The porosity decreases, the connectivity between pores and pore size change, thesurface properties are altered, etc. Hence, the precipitation of salts has an influence on allaspects of liquid moisture transport such as storage capacity, liquid retention and liquidpermeability. One of the difficulties to study these phenomena, are the interactions betweenwater and precipitated salt. In order to obtain information about the influence of the presenceof these salts without ongoing precipitation or redissolution, a series of tests were performedusing an organic liquid (decane) which is immiscible with water and in which the salts are notsoluble. Besides capillary absorption tests, mercury intrusion porosimetry was performed. Thesubstrate is a fired clay brick contaminated with different amounts of NaCl, NaNO3 andNa2SO4. It was noticed that porosity decreases at the lower defined introduced salt contentwhile it increases when the salt content increases because the brick dilates due to crystallisationpressure. Capillary absorption coefficient and capillary liquid content decrease, as is the casefor the dominant pore size. The different behaviour of the three salts is demonstrated andhypotheses are formulated about the governing mechanisms.