The effect of moisture content on physical and mechanical properties of rice (Oryza sativa L.)

The objective of this study was to investigate some physical and mechanical properties of Osmancik-97 rice variety wi¬despread cultivated in Turkey in order to determine needed designing parameters for handling and storage facilities. In this study, some physical and mechanical properties were evaluated as a function of moisture content in the range of 10¬14% d.b. Length, width, thickness, arithmetic and geometric mean diameter ranged from 8.27 to 9.01 mm, 3.10 to 3.48 mm, 2.05 to 2.26 mm, 4.47 to 4.92 mm, 3.75 to 4.13 mm, respectively as the moisture content increased; sphericity, grain volume, surface area, true density and porosity increased from 43 to 45%, 130.97 to 160.32 mm3, 38.68 to 46.91 mm2, 939.0 to 962.1 kg m-3, and 36.61 to 41.97%; bulk density decreased from 595.5 to 560.5 kg m-3; the angle of internal fric¬tion increased linearly from 29.70° to 32.53° with the increase of moisture content; the static coefficient of friction in¬creased from 0.764 to 0.972, 0.524 to 0.702 and 0.576 to 0.764 for concrete, galvanized steel and wood surfaces, respec-tively; the poisson ratio and pressure ratio decreased linearly with the increase of moisture content. The data obtained from the study will be useful in the structural design of rice bin to calculate loads on bins from the stored material.