Performance of coated floats in different soils
1990
Canillas, Campanero Emmanuel
Experiments were conducted in a laboratory soil bin to evaluate the performance of coated floats in different soils. Floats with 15 cm width and 30 cm length were fabricated from 0.32 cm mild steel plate. The three floats each were coated with enamel and Teflon and the three were uncoated. Three soil types viz. clay, loam and sandy soil were used for testing. The drag forces required to pull the floats over the soil surface were measured with the help of load cells. The normal loads were varied to 24.5, 44.1 and 63.7 N. The effect of moisture content was evaluated by varying the soil moisture from 21.2 to 62.4 % (db) for clay soil, 16.6 % to 36.1 % (db) for loam soil and 0.7 % to 13.8 % (db) for sandy soil. All tests were conducted at a constant float speed of 0.20 m/s. The performance of the enamel coated floats was superior to Teflon and uncoated floats in all soil conditions tested. The drag force increased with normal load for all floats. In clay and loam soils, the drag force increased initially until the soil moisture content reached the plastic limit. However, the drag force showed a decreasing trend once soil moisture exceeded the plastic limit. For sandy soil, however, the drag force increased with moisture content. Depending on the normal load and soil moisture content, the overall reduction for the enamel coated float compared to uncoated float were from 4 to 64 % in clay soil, 16 to 46 % in loam soil and 26 to 45 % in sandy soil. Besides this superior performance of the enamel coated float compared to the other floats, it showed excellent resistance to wear due to abrasion and scouring. Considering the above findings, the use of enamel coating in clay, loam and sandy soil is recommended.
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