Laboratory Study of Manganese Mining Overburden Mixed with Lime as a Paving Subbase Layer

This chapter presents the results of a laboratory investigation comprising geotechnical characterization, CBR, and resilient modulus tests carried out on a manganese overburden, in the natural state and mixed with 3% and 4% lime, to evaluate the suitability of the materials for road construction. The test results were used to calculate the allowable stresses for a typical Brazilian flexible asphaltic pavement for low-volume roads. Allowable stresses considering a subbase built with lime-amended manganese overburden were compared to the stresses calculated for a lateritic clayey sand subbase to evaluate the efficacy of the manganese overburden and its mixture with lime. The allowable stresses were converted in N (number of equivalent single axle loads—ESAL). The results of the investigation indicated that the manganese sterile with 3% lime addition and 7 days of curing time achieved slightly higher N values than the typical lateritic subbase road for the same cross-section: N increased from 1013 to 1014 using the alternative material. This is a promising reuse alternative to introduce manganese in the circular economy and to preserve natural soils from exploitation.