Engineering key Point

Tests on Stones To certain the required properties of stones, the following tests can be conducted: (i) crushing strength test (ii) water absorption test (iii) abrasion test (iv) impact test (v) acid test. (i) Crushing Strength Test:   For conducting this test, specimen of size 40 × 40 × 40 mm are prepared from parent stone. Then the sides are finely dressed and placed in water for 3 days. The saturated specimen is provided with a layer of plaster of paris on its top and bottom surfaces to get even surface so that load applied is distributed uniformly. Uniform load distribution can be obtained satisfactorily by providing a pair of 5 mm thick playwoodinstead of using plaster of paris layer also. The specimen so placed in the compression testing machine is loaded at the rate of 14 N/mm2 perminute. The crushing load is noted. Then crushing strength is equal to the crushing load divided by the area over which the load is applied. At least three specimen should be t

The purpose of materials engineering is to obtain knowledge about the materials so that alternate materials with the desired characteristics m ay be produced. The basics of materials engineering relate the requisite properties of the materials with the structure of atoms in that material. The structure of a material and its properties depend upon the chemical elements of the material. The science of materials engineering examines the connection between the structures of materials at molecular scales and their macroscopic characteristics. The materials engineering is a broad based science that includes essentials of chemistry, physics, mechanical, and civil engineering. Due to the advancement of the nanotechnology, the science of materials engineering has obtained significant importance in recent years. Use of Materials In Industry The discipline of materials engineering is used in the industry not only to create perfection in the presently used materials, but also a

The following are the some of commonly used stones: (i) Basalt and trap                 (ii) Granite (iii) Sandstone (iv) Slate (v) Laterite (vi) Marble (vii) Gneiss (viii) Quartzite. Their qualities and uses are explained below: (i) Basalt and Trap: The structure is medium to fine grained and compact. Their colour varies from dark gray to black. Fractures and joints are common. Their weight varies from 18kN/m3 to 29 kN/m3. The compressive strength varies from 200 to 350 N/mm2. These are igneous rocks. They are used as road metals, aggregates for concrete. They are also used for rubble masonry works for bridge piers, river walls and dams. They are used as pavement. (ii) Granite: Granites are also igneous rocks. The colour varies from light gray to pink. The structure is crystalline, fine to coarse grained. They take polish well. They are hard durable. Specific gravity is from 2.6 to 2.7 and compressive strength is 100 to 250 N/mm2. They are used pri