Life-Cycle Sustainability Assessment of Using Rock Dust as a Partial Replacement of Fine Aggregate and Cement in Concrete Pavements

Abstract

The use of recycled materials and industrial by-products in pavement construction and rehabilitation can achieve substantial benefits in saving nature resources and reducing energy consumption as well as greenhouse gas (GHG) emissions. Alternative geological origin rock dust for the partial replacement of fine aggregate and/or cement in Portland cement concrete (PCC) pavements may provide positive environmental and economic benefits. The objective of this study was to quantitatively assess the life-cycle economic and environmental impacts when rock dust is used in PCC pavement roadway construction. Previous studies have primarily focused on the economics and/or environmental impacts during the material production process. Thus, a methodological framework considering all stages (such as material production, transportation, construction, maintenance, rehabilitation and end of life), involved in the life-cycle assessment of concrete pavements is proposed when using recycled materials/by-products. The life-cycle assessment (LCA) was conducted on a pavement project representative of typical construction practices in Poland to quantify such benefits. The alternative sustainable construction strategies considered partially replacing fine aggregate and/or cement with rock dust of basalt origin in PCC pavements. The LCA results indicate that using rock dust to replace 20% FA and 10% cement provided a reduction of 6.5% in cost, 10% in CO2 emissions and 11% in energy consumption. This study also provides significant insights on the specific contribution of material production, construction processes and the transportation of materials to the overall environmental benefits and cost savings. The suggested approach for LCA analysis in pavement construction can be adopted elsewhere for quantifying the sustainability benefits of using alternative recycled materials in roadways.