Relationship between the rupture modulus and the flexural strength of building and decorative stones of Iran

摘要

Estimation of tensile strength of stones is very important in industry, because its measurement using direct tensile strength test is very difficult. 3 point flexural loading and four point flexural loading are two methods for measurement of flexural strength. The flexural strength is the maximum tensile stress on the bottom of the rock corresponding to peak load. It is calculated from simple beam theory assuming elastic conditions throughout. ASTM C880-06 covers the procedure for determining the flexural strength of stone by using a simple beam using quarter-point loading. The flexural strength is found to be greater than direct tensile strength. ASTM C99-87 is used for measurement modulus of rupture of building and decorative stones. To prevent various names of stones are used in different classifications, the Dunhan System for notation of sedimentary stones the volcanic stones, it is considered the main and subsidiary materials, and also the tissue of the stones. Based on obtained results from these tests all decorative stones in this project can be divided such as that mentioned. Based on geological map of Iran, it is divided in different nine zones such as Alborz, Central Iran, Zagros, Sannandaj -Sirjan, Mokran, Sahand - Bezman, Loot block, Eastern Iran, Kopedagh. The Building and decorative stones are one of those important natural resources of Iran. According to recent statistics, Iran has been listed among the five important producers of building and decorative stones in the world. Approximately all of decorative and building stones located in the following five zones such as Alborz, Central Iran, Zagros, Sannandaj -Sirjan, Sahand - Bezman. All available data of Alborz zone is only four, so it is not enough to set equation upon this. All stones of Central Iran zone are classified, in two groups, granite and calcite. Relationship between both strength on Granite and Calcite groups is linear but difference between correlation of linear and nonlinear equations of Granite group is smaller than Calcite group. All of stones in Zagros zone are classified in Calcite stones group. In this case relationship between flexural strength and modulus of rupture is direct and difference between correlation of linear and nonlinear equations of Calcite stone is approximately 5%. All stones of Sannandaj -Sirjan zone are classified in three groups consisting of granite, calcite and travertine. The relationship between flexural strength and modulus of rupture in each group is considered. Relationship between flexural strength and modulus of rupture are direct but difference between correlation of linear and nonlinear equations on travertine and Granite groups are smaller than Calcite groups. All samples of Sahand - Bezman zone, are classified in three groups consisting of granite, cal-cite and travertine, then relationship between flexural strength and modulus of rupture upon granite stones was considered but it was not considered upon calcite and travertine stones because samples were not enough. Relationship between both of the strength properties are direct and difference between correlation of linear and nonlinear equations of Granite is very little.