Material properties is one of the most significant variables in terms of efficiency. The sediment
layer in a coal pit mine has a possibility of sticking to the equipment bucket and reducing its productivity,
especially in the disposal area. Consequently, stickiness has a close definition of adhesivity level; thus it may
be associated with geomechanical properties. Various soil classification in the disposal area was investigated
to identify the relationship between adhesivity and geomechanical properties such as water content, density,
cohesion, and internal friction angles. Multivariate regression analysis and statistical test (F-test and t-test)
were used to investigate geomechanical properties related to adhesivity on each disposal area. Primary data
was taken from a standard and modified laboratory testing. The results showed that disposal materials were
high-plasticity materials with different grain-sizes. The dominant grain size on disposal 1, 2, and 3 were clay,
sand, and clay, respectively. Based on regression analysis, the adhesivity on each disposal was increased along
with the water content until its optimum value. Using a statistical test with a significance level of 95% (P-value
0.04), water content, cohesion and internal friction angle affected the adhesivity level on disposal 1 by 99%
(adjusted R
2
0.99). Adhesivity level in disposal 2 was only affected with density by 63% (adjusted R
0.63).
Meanwhile, in disposal 3, the significance level of 33
% (P-value 0.50) was used to define that water content,
cohesion, and internal friction angle as parameters affecting adhesivity level by 33% (adjusted R2 0.33)