Evaluation of the durability of Gerdoee travertine after freeze-thaw cycles in fresh water and sodium sulfate solution by decay function models

The reduced durability and service life of stones subjected to freeze-thaw action are significant and ongoing problems in stones used for commercial purposes such as building stones. Consequently, evaluating the durability of building stones subjected to freeze-thaw action is important for selecting of an appropriate stone for outdoor applications in cold climatic conditions, which involve excessive freeze-thaw cycles. In this research, the durability of Gerdoee travertine (northwest of Iran), after freeze-thaw cycles in fresh water and sodium sulfate solution (Na2SO4), was evaluated using its mechanical properties as well as decay constant (A) and half-time (N-1/2) parameters. For this, freeze-thaw tests in fresh water and sodium sulfate solution were carried out up to 60 cycles, and the uniaxial compressive strength, Brazilian tensile strength, point load strength and ultrasonic wave velocity (quantifying by P-wave velocity) of the travertine were determined after every 10 cycles. Finally, regression models were developed between the measured mechanical properties and various cycles of tests. The models postulate a first order process, and provide meaningful parameters of decay constant (lambda) and half-time (N-1/2) for the integrity loss of travertine's mechanical properties, and thus its durability, after freeze thaw action. Using data analysis, the variation in the travertine's mechanical properties and their decay constant (lambda) and half-time (N-1/2) show that the travertine's durability after the freeze-thaw action in fresh water and sodium sulfate solution was different. Further, it was found that the effect of freeze-thaw action on the travertine's durability was more severe in sodium sulfate solution as compared with fresh water. (c) 2016 Elsevier B.V. All rights reserved.