Investigating the use of iron ore tailings as subbase material for pavements.

Abstract

Mining of Iron ore results in large quantities of iron ore tailings (waste) and disposing of such large quantities of waste poses tremendous challenges for the mining industry and significantly impact the environment. On their Website, The World Counts estimates that every year, approximately 55 billion tons of fossil energy, minerals, metals, and biomass are extracted from the earth. Mineral extraction from the earth is coming at a steep environmental cost. Due to a ban on the exportation of unprocessed iron ore, the iron mining sector in Uganda has been rather slow. While meeting NRM youth leaders from the Kigezi region on 13th December 2020, the president promised that the government was going to implement its plan of constructing a steel factory in Rubanda district very soon to exploit the approximately 580 million tones of the country’s iron ore resources. This large scale operation of mining will result in the generation of huge amounts of iron tailings and the so many problems associated with these tailings will require sustainable and economically viable options. Therefore this study is about assessing the suitability of Iron ore Tailings for use in Sub bases of Flexible Pavements. Assessing the suitability of iron ore tailings as a sub-base material will help to determine whether or not these tailings can be put to profitable use. In case they are found to be suitable, then the study will not only have cut down on the negative impacts meted on to the environment as a result of iron ore tailings (i.e. sedimentation, acid mine drainage, destruction of bio-diversity) but will also provide an alternative material (which will most likely be cheaper since it’s waste) to the commonly used gravel material for sub-bases. To assess the Engineering properties of the Iron Ore Tailings, Unconfined Compressive Strength, California Bearing Ratio, Particle size distribution (Sieve Analysis), Liquid limit, Plastic limit, Plasticity index, USCS, Specific Gravity, Grading Modulus, Compaction tests were conducted in the Highways lab at Makerere University. Electron microscope analysis was also carried out to characterize the sample. We also stabilized the sample using cement to improve its strength properties. The results of our study are presented in chapters 4 and 5 whereby the California Bearing Ratio of the neat sample (30.5%) qualifies it to be used as G30 material. The Unconfined Compressive Strength of the sample increases with the increase of the stabilizer content (Cement) and any cement content > 1.2% gives a UCS greater than 0.75MPa which qualifies it to be used as a G45 material