An experimental study on the characterization and durability of two building low-porous trachyte and gabbro

The crucial aspect of sustainable construction relies heavily on the durability of the building stones. In this study, the durability of two low-porous Iranian building stones, trachyte and gabbro, was evaluated using various durability tests, including salt crystallization, freeze-thaw, wetting-drying, acid resistance, thermal shock, and combinations of these processes. To monitor the effects of these alteration tests, non-destructive methods such as colorimetry, saturation-buoyancy technique, and P-wave velocity measurement were employed, along with polarized microscopy, chemical analysis, and physical and mechanical testing to understand the behavior of the stones. The samples were tested for durability through 48 cycles to evaluate their resistance. For each durability test, the color variation, dry weight variation, and P-wave velocity variation were calculated at 8, 16, 24, 32, 40, and 48 cycles. Results show that the gabbro sample, mainly composed of plagioclase (> 90%), has better physical and mechanical behaviour than trachyte. The color change for trachyte samples exposed to thermal shock and combination cycles of weathering processes tests and all gabbro samples is higher than 2 (perceptible at a glance). The important parameters in this variation are related to the efflorescence of salt crystals on the surface, type of surface finishing, soluble agents, and degradation of stone minerals. The significant dry weight variation (DWV) observed in trachyte during the salt crystallization test can be attributed to the salt crystallization within the stone’s pores, which exert pressure on the internal structure, leading to material loss and increased degradation. However, in gabbro, a very low reduction is observable in all durability tests. Also, trachyte samples have higher DWV (lower durability) than gabbro samples. The P-wave velocity variation (PWVV) reduction shows a marked decrease (⁓25%) in P-wave velocity for gabbro, whereas trachyte showed no tangible loss (< 5%) in wave’s velocity.