The investigation of static and dynamic capillary by water absorption in porous building stones under normal and salty water conditions

Abstract

The presence of water in building stones is one of the main factors in deterioration. Capillary rise is the most usual mechanism of water penetration into building materials. In this study, the kinetics of the capillary rise phenomenon was studied for three porous building stones: two tuff stones and andesite. For each of the examined natural stones the capillary water absorption, pore size distribution, mineralogical–petrographic (optical microscope, XRD, SEM), chemical (XRF) and mechanical–physical properties were determined. The mechanism of capillary water absorption depends mainly on the pore size and the shape of the pore system. The pore size distribution was determined by means of high pressure mercury porosimetry. Iscehisar andesite, Ayazini tuffs and Seydiler tuffs have pore sizes ranging from about 0.01 to 10, 0.01 to 20 and 0.01 to 4 µm, respectively. The capillary water absorption of the building stones was determined on the basis of TS EN 1925. The effects were analyzed with a static and dynamic capillary by water absorption under normal and salty water conditions of porous building stones. Water content was determined by weighing after 1, 3, 5, 10, 15, 30, 60, 480, 1440 min until the free saturation was reached and the liquid uptake stopped. The results indicated considerable differences in the water absorption shown as a function of elapsed time. NaCl crystals are observed under SEM in pores and surface of the tested stones. According to the results, capillary absorption of salty water value is bigger than pure water in all stones at the end of test. It could be shown that primarily moisture properties, i.e., capillary and sorptive water uptake and salt crystallisation can be addressed to the deterioration processes.