Evaluation of Point Load Test Effectiveness in Estimation of Long-Term Durability of Some Chinese Limestone Rocks Due to Frost Action

In spite of point load method has been frequently used for assessment of the decay state of stones under weathering agents, its method in estimation of long-term durability of natural rocks remains limited. This study aims to assess the point load method efficiency in evaluation of long-term durability of limestone types due to frost action. For this reason, the frost process up to 100 cycles was applied on different limestone types which quarried from mine in China and the ultrasound properties including compressional wave velocity (Vp) and spatial attenuation (αs) were determined before and after frost cycles and then their variation rates were obtained. The variation rates of Vp and αs including ΔVp and Δαs, respectively, were taken into consideration as a function of the decay state of stones and as indicators of the frost durability action. The results indicated that there are a strong correlations between point load index values (σp) and ΔVp and Δαs with R2 of 0.79 and 0.82, respectively. It was found that the point load method is an effective tool for evaluating the long-term durability of rocks and can be used for a fast and on-field assessment of long-term durability of stones especially at different mine faces. Therefore, it can facilitate the choosing of a highly durable stones for different outdoor applications. Further, the point load index values can be used to make a new classification of rock strength depending on their durability.