ACCELERATED WEATHERING TESTS ON TWO HIGHLY POROUS LIMESTONES

Abstract

A major cause of weathering of building and historic monuments constructed using limestones is associated with the salt crystallization. This may typically occur at the surface (due to efflorescence) or in subsurface layers while limestones are drying. Due to this reason structural damage or material loss (granular disintegration, flaking, contour scaling) may occur. In this paper, imbibition-drying cycles are carried out with pure water and solutions of NaCl with different concentrations to simulate the weathering effect on two limestones with similar total porosity values. The imbibition kinetics of these limestones was significantly influenced by the number of applied imbibition-drying cycles. In addition, imbibition kinetics was also dependent on the concentration of salt solutions, the mineralogical composition as well as on the pore-size distribution of these two stones. The structural and textural modifications that arise in the limestones due to the influence of imbibition characteristics of drying cycles are qualitatively confirmed by scanning electronic microscope (SEM) and quantitatively with helium pycnometry measurements.