ASSESSMENT OF CRITICAL-STATE SHEAR STRENGTH PROPERTIES OF COPPER TAILINGS

Abstract

Philippines, with a total of 7,107 islands, have one of the largest mineral resources in the
world. The copper and gold deposits are considered to be among the largest in the world (Bureau of East
Asian and Pacific Affairs, 2010). Mining minerals generate waste material called mine tailings.
Impoundment of mine tailings is normally done to store these waste materials. One of the most common
types used in impounding tailings is raised embankments because of its low economic cost. This
impoundment uses natural soil, tailings, and waste rocks as the construction material. There are cases that
raise embankments experience stability failure which can affect the environment and well-being of the
community where it is situated.
It is the interest of this study to assess the possibility of using mine tailings, specifically copper tailings, as a
construction material. Index properties were first established following ASTM standards. From this, it was
established that the copper tailings has plasticity. Unconsolidated undrained, consolidated undrained and
consolidated drained test were conducted to determine the critical shear strength of the copper tailing. The
copper tailings were tested having two relative densities namely, 60% and 90%. The effective critical angle
of friction was found to have a range of 21°-28°. Since critical-state parameters are considered in the study,
Cam clay model can be implemented so that to its behavior and failure mechanism can be predicted.