Carbonate building materials and engineering constructions are exposed to severe seasonal environmental fluctuations and result in a full or partial disintegration, especially in cold regions, and employment of nondestructive methods for evaluating the durability of building materials subject to frost weathering is gaining great significance. This research aims to obtain reliable relationships between unconfined compressive strength decrease and nondestructive parameters variations of limestone types under frost conditions and provide useful information regarding their durability in order to ensure the long-term viability or sustainability of these materials used for constructions against frost conditions. In this study, five important types of Chinese limestone used as construction materials were subjected to 50 frost cycles. Unconfined compressive strength, compressional wave velocity and spatial attenuation, and porosity were obtained at the end of every 10 cycles. As a result of progression in frost cycles, the increase and decrease rates were determined at the end of every 10 cycles, and the relationships between them were obtained to predict the loss ratios of unconfined compressive strength (RDσc). Results indicated that at the end of 40th cycles, there was a high correlation between RDσc and spatial attenuation loss with an R² of 0.8584. Furthermore, there was also a strong relationship between RDσc and compressional wave velocity decrease after the end of 20th and 50th cycles with an R² of 0.9089 and 0.9025, respectively. Therefore, these relations are reliable to provide useful information for durability and viability of studied samples under frost conditions and support the use of the ultrasonic measurements. It can also be successfully used for pre-estimation of unconfined compressive strength loss of studied limestone types against frost weathering without any tests.

The mechanical properties of rocks, such as uniaxial compressive strength and elastic modulus of intact rock, must be determined before any engineering project by employing lab or in situ tests. However, there are some circumstances where it is impossible to prepare the necessary specimens after exposure to high temperatures. Therefore, the propensity to estimate the destructive parameters of thermally heated rocks based on non-destructive factors is a helpful research field. Egyptian granodiorite samples were heated to temperatures of up to 800 °C before being treated to two different cooling methods: via the oven (slow-cooling) and using water (rapid cooling). The cooling condition, temperature, mass, porosity, absorption, dry density (D), and P-waves were used as input parameters in the predictive models for the UCS and E of thermally treated Egyptian granodiorite. Multi-linear regression (MLR), random forest (RF), k-nearest neighbor (KNN), and artificial neural networks (ANNs) were used to create predictive models. The performance of each prediction model was also evaluated using the (R²), (RMSE), (MAPE), and (VAF). The findings revealed that cooling methods and mass as input parameters to predict UCS and E have a minor impact on prediction models. In contrast, the other parameters had a good relationship with UCS and E. Due to severe damage to granodiorite samples, many input and output parameters were impossible to measure after 600 °C. The prediction models were thus developed up to this threshold temperature. Furthermore, the comparative analysis of predictive models demonstrated that the ANN pattern for predicting the UCS and E is the most accurate model, with R² of 0.99, MAPE of 0.25%, VAF of 97.22%, and RMSE of 2.04.

The degradation of natural rocks due to severe environmental conditions can influence their durability over an extended period of time. This research aims to investigate the long‐term durability or disintegration rate of rocks used as construction materials under severe climatic conditions using frost damage action, and the deterioration rate was assessed using mathematical decay function approach. The mathematical model assumes an initial order operation and gives purposeful properties for the deterioration rate of rocks due to frost action. For this reason, six different limestone types used as building materials were quarried from limestone mine in China and subjected to a series of laboratory tests to determine the mineralogical, petrographical, physical, and mechanical characteristics. Then, 50 cycles of frost damage process was performed, and after each 10 cycles, the unconfined compressive strength, point load strength, and Schmidt rebound were determined. The disintegration rate or integrity loss characteristics of each rock type were assessed using the mathematical decay function approach parameters. This approach proved that the disintegration rate varies for the rocks of the same type especially which were extracted from the same areas, the rock durability under frost damage conditions can be estimated with good accuracy, the parameters of this model saved a lot of time and provided important practical features to assess a rapid durability, and hence, there is no need to carry out the frost damage test which is slow and consumes time.

This research aims at investigating the deterioration of limestone rocks due to the influences of thermal quenching and salt crystallization weathering tests and predicting their long-term durability. Therefore, six types of limestones were quarried from different provinces of Egypt and subjected to 50 cycles of thermal quenching and 25 cycles of salt crystallization weathering processes. The porosity, Schmidt hammer rebound hardness, ultrasound pulse velocity, Brazilian tensile strength, and uniaxial compression strength were determined before and after weathering processes. In addition, the mathematical decay function model was developed to evaluate the degradation rate of samples against weathering processes. Results proved that the cyclic salt crystallization deteriorates the physico-mechanical characteristics of the studied limestone more strongly than the thermal quenching cycles do. The decay constant and half-life indexes obtained here indicate that the degradation rate differs for various limestone specimens under thermal and salt weathering processes. This model also showed that the deterioration rate of the studied rocks was higher during cyclic salt crystallization in comparison with thermal quenching. Therefore, the rock degradation rate and or long-term durability under cyclic thermal and salt processes can be estimated accurately. These results show that the studied limestones can be used as building stones in regions exposed to frequent cyclic thermal and salty weathering conditions for long periods without degradation. However, partial attention should be given to LSG limestone rocks characterized by increased porosity and water absorption characteristics.

Salt crystallization is the most important weathering processes that causes problems for rocks used as building stones. Therefore, assessment of the physico-mechanical properties of stones against cyclic salt crystallization is a critical issue for rock engineering applications in salty environmental conditions especially prone to abrasion. This research aims at investigating the relationship between the degradation of various physico-mechanical properties including apparent porosity, point load index, unconfined compression strength and abrasion loss rate for rocks during salt weathering process. For showing rock weathering in the salt crystallization process, five kinds of carbonate rocks were sampled from different areas of Egypt and subject to cyclic salt crystallization, up to twenty cycles. The variation rates of their physico-mechanical characteristics and abrasion loss values were calculated after each five cycles of salt weathering. The results showed that the studied rocks are suitable for use as building and decorative stones in areas prone to crystallization of salts, but attention must be paid to rocks with high porosity and low strength characteristics such as El-Minia limestone specimens. It was also found that there are strong linear correlations between the physico-mechanical degradation parameters and the abrasion loss rate of the studied rock samples at the end of the twentieth cycle of salt weathering. These relationships may be used to estimate the abrasion loss rate of the studied rock types against the cyclic salt weathering conditions and hence to make a rapid evaluation of the stone durability.