Evaluation of long-term durability of carbonate building stones after freeze and thaw cycles using CART method

The freeze and thaw cycles are one of the most important factors in physical weathering of stones, which substantially can influence the long-term durability and service life of building stones. To evaluate the long-term durability of stones against freeze and thaw cycles, two parameters of decay constant (λ) and half-life index (N1/2) can be applied. To determine these two parameters, the freeze and thaw test should be done, which is a difficult, time-consuming and expensive process. Therefore, development of indirect models to estimate these two parameters without performing freeze and thaw test can be useful for fast and low-cost evaluation of stones’ long-term durability. In this paper, considering the P-wave velocity (VP) of stones during the freeze and thaw process for 22 types of Iran’s carbonate building stones, two parameters of λ and N1/2 were determined. Then, based on obtained data and using regression analysis and classification and regression tree (CART) techniques, models were developed to predict these two parameters. The results indicated that the developed models using CART technique have higher accuracy and precision than the regression models. These models are able to present acceptable prediction of λ and N1/2 based on the initial porosity of stone.