An investigation of the pore size distribution variations with salt crystallization tests of Dӧǧer tuff (Afyonkarahisar-Turkey)

The present study included the effect of four salt types and their four different concentrations on the pore size distribution of Döğer tuff which was subjected to salt crystallization tests. For this purpose, laboratory studies were carried out in three stages. First, the main technical values and parameters were studied such as mineralogical–petrographic (polarizing microscope, XRD, and SEM), chemical (XRF), physico-mechanical, and pore size distribution properties. Second, salt crystallization tests were performed to examine the pore size distribution change. The salt concentrations were prepared as 2, 5, 10, and 14% for each salt solution. Last, the pore size distribution changes of Döğer tuff after the salt crystallization tests were investigated through the SEM and the mercury porosimeter method. Fresh Döğer tuff with 36.67% porosity exhibited a unimodal pore size distribution, with a pore size range of 0.01–5 µm. The experimental results corroborate the theoretical supposition that micropores smaller than 0.1 µm in diameter are a critical influence on salt crystallization damage. The size of the pores and total porosity in Döğer tuff increased in parallel with the increase in salt concentrations. The maximum pore increased because deterioration was 42.11% in 14% sodium sulfate solution. The 14% solutions of the potassium chloride, magnesium sulfate, and sodium chloride salts constituted porosity ranging from about 41.05, 38.77, and 38.77%, respectively. The test results indicated that salt types and concentrations play a very important role in both salt uptake and pore size distribution.