Chapter 6. Evaluation of Pyrite-Bearing Construction Aggregates for Acid Rock Drainage
Fred H. Shrimer
WSP Golder, Vancouver, Canada
Testing of aggregate materials in connection with construction projects has traditionally involved evaluation of their engineering properties to determine whether they satisfy various specifications for durability, strength and resistance to in-service performance related to loading, abrasion, weathering and so on. This work is usually conducted as a prequalification of the material prior to acquisition of a new quarry site, for permitting and opening of a new aggregate source, or as ongoing, routine quality control testing. These testing regimes are intended to benefit both the aggregate producer and the eventual user of the material/Owner of the construction project, by ensuring that the aggregate products are ‘fit for purpose.’ Over the last few decades, however, it has become increasingly common that project Owners and specifying agencies may or will require evaluation of the potential for Acid Rock Drainage (ARD) and metals leaching (ML) of aggregates that contain sulfide minerals. Since most aggregate materials are composed of natural geologic products, the characterization of these materials typically follows a geologic assessment-based route. Geological characterization thus plays an important first step in ARD/ML assessment and forms the basis for further testing. In the case of ARD, an understanding of the likelihood of sulfide minerals in the rock and their relative proportions are centrally important. In this chapter, we present and discuss some cases of ARD prediction for aggregate materials that start from a geological perspective.
Keywords: sulfide, construction aggregate, geology, Acid Rock Drainage, ARD prediction
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