3.2 Particle shape, roundness and grain surface texture
The shape and the roughness of grain surfaces also the friction angle and the slope stability of dumps. Robinson and Friedman (2002) found that increased angularity of grains increased the friction angle. In fact grain texture is dependent upon material composition, grain formation, separation from the matrix, transportation, and depositional environments (Cho et al., 2006). Similar investigation made by Barton (2008) suggest that strength of dump material is similar to the strength of rockfill and rock joints, because these materials have similar strength envelopes due to the effects of point of contacts. There has been a profound effect of roughness and particle size on shear strength as well. As roughness increases so does the friction angle.