Abstract
The effect of incorporation of wood bark on three-phase composition of soil, soil resistance, hydraulic conductivity, and water retention was investigated on clayey soil and sandy soil. Application of wood bark was arranged at 0.0 %, 1.0 %, 2.0 %, 3.0 %, 4.0 %, and 5.0 % of wood bark to soil (dry weight basis). Soil resistance was determined with a hand-held cone penetrometer (Yamanaka-shiki Koudokei), the hydraulic conductivity by using the variable head test technique, and water retention by the hanging water column method and centrifuge method. The remarkable result was found in sandy soil such that incorporation of 5 % wood bark produced reduction of 31 % solid phase. The soil resistance was higher in compaction stage than cutting off stage at both soils. In clayey soil, it decreased from 14.4 kgf/cm2 (0 % wood bark) to 10.5kgf/cm2 ( 5 % wood bark) in compaction stage, but it varied in cutting off stage with maximum at 9.7 kgf/cm2 ( 1 % wood bark) and minimum at 7.4 kgf/cm2 (3% wood bark). Hydraulic conductivity in clayey soil reached to the maximum ( 3.5 × 10-4 cm/s) with incorporation of 5% wood bark, however in case of sandy soil it changed inconsistently as addition of wood bark. The increase in water content by 3% wood bark was kept almost constant as 4.13% even in low suction at pF 0.8 ( -0.60 kPa) and as 4.01 % in high suction at pF 5.5 ( -31 MPa) in clayey soil, while in sandy soil, it diminished from 1.40 % at pF 0.8 ( -0.60 kPa) to 0.01% at pF 4.2 ( -1.5MPa). This study demonstrated that incorporation of wood bark influenced the physical properties of clayey and sandy soil.
