Accelerated aging laboratory tests for the evaluation of the durability of hydrophobic treated and untreated andesite with respect to salt crystallization, freezing–thawing, and thermal shock

The processes of deterioration related to the interaction of the petrographic, physical, and mechanical characteristics of the rocks with physical and chemical actions of water are important. The aim of the article was to study the deterioration of andesite by accelerated weathering tests. For this purpose, laboratory studies were carried out in two stages. First, the main characterization analysis of the andesite was performed. Main technical values and parameters such as mineralogical–petrographic (polarize microscope, XRD, and SEM), chemical (XRF), and mechanical–physical properties were studied. Moreover, calculations on some physical and mechanical tests as well as the resistance to dry weight change caused by weathering were assessed. The change of rock strength and ultrasonic wave velocity measurements were experimented. These experiments were carried out on untreated and hydrophobic treated andesite before and after accelerated alteration tests such as cyclic freezing–thawing, salt crystallization, and thermal shock. The ultrasonic wave velocity and uniaxial compressive strength test results on the samples subjected to salt crystallization and freezing–thawing tests showed decreased values for all the andesite samples. However, the physical integrity of the andesite samples did not deteriorate. Laboratory test results showed that all andesite samples were suitable for use as building stones in a humid and salty environment. It was found that treated samples were less affected by the destructive effect of accelerated weathering tests compared with the untreated samples. Therefore, for the outdoor use of these stones, it is recommended that the block surfaces are to be treated with chemicals against weathering.