Evaluation of petrographic number methods efficiency in quality determination of some carbonates rocks

Document Type : Original Research


Department of Geology, Faculty of Science, University of Isfahan, Isfahan, Iran


Several regulations and manual have been presented for assessing the resources of rock aggregate for use of rock in breakwaters and shore protection structures. Although there are differences between these regulations, many experiments are required, which are often time-consuming, costly and sometimes difficult to implement in the early stages of the project. One of the fast, easy and low-cost methods is the Petrographic Number (PN) method, which according to rock thin sections, has suggestions for expressing the quality of rock materials. In this paper, the application of the PN method in some of the sources of rock aggregate in Iran has been addressed. For this purpose, 33 samples of carbonate rocks used in marine protection structures on the south coast and inland dams were collected. More than 350 experiments were carried out on these specimens. Also, in order to determine the PN, rock thin sections were prepared and the percentage of the components of the petrography including the type of allochem, porosity, cement and matrix, carbonate and non-carbonate minerals are obtained. Then, in order to evaluate the accuracy and efficiency of the PN method, correlation coefficient and comparison of the results of PN with the results of Iranian regulation has been used. Results have shown that a link between the PN with regulations and testing results. The results indicate a significant correlation between some of the engineering properties of samples with the PN. There is also a good correlation between the PN and the total score of the Iranian manual with R2=0.86. However, a single method cannot replace the set of experiments, but for the early stages of the aggregate resource study, it can provide a proper view of the quality of carbonate rock resources.