Characterization of mine tailings in their natural state and stabilized with cement, focused on construction

This work presents the physical-chemical, geotechnical and mechanical characterization of a sample of mine tailings from the state of Zacatecas, Mexico with the objective of evaluating their possible use as a construction material for pavement support layers or as an aggregate of a hydraulic concrete. The material analyzed was classified as a poorly graded silty sand (SP-SM) according to the USCS classification and is composed mainly of quartz and calcite. The analyzed sample satisfies the necessary requirements, according to current Mexican regulations, to be used as i) a subgrade layer in a pavement, without the addition of virgin aggregates, or ii) as fine aggregates in the production of hydraulic concrete, previously sieved to correct its grain-size distribution. The mining residues studied do not require stabilization because the material transported in the leaching process is below the permissible limits for heavy metals according to Mexican regulations; this may be caused by the neutral pH of the sample, demonstrating a high adsorption of the heavy metals that avoids potential leaching. However, the sample was stabilized with Portland cement with 3 and 5 % respectively to corroborate the decrease in heavy metal transport based on the consulted bibliography; the concentrations of the analyzed elements decreased except for chrome due to its presence in the stabilizing material and an increase in the pH value was observed.