Energy conservation and carbon emission reduction of cold recycled petroleum asphalt concrete pavement with cement-stabilized phosphogypsum

Abstract

Phosphogypsum, a byproduct generated during the production of chemical fertilizers, can pose a significant environmental threat when not managed appropriately. This study endeavors to explore the potential repurposing of phosphogypsum by incorporating it into the cement-stabilized base of asphalt concrete pavement. We conducted an in-depth study of an optimized scheme using a specific engineering project as a case study. This scheme substitutes phosphogypsum for part of the cement in the original cement-stabilized base, creating a cement-stabilized phosphogypsum mixed material (CSPM) base for road construction. The primary aim is to assess the energy consumption, carbon emissions, and environmental implications throughout various construction phases within the optimized scheme by the life cycle assessment (LCA). Additionally, a sensitivity analysis is conducted to scrutinize the influence of the underlying layer, base layer thickness and material transport distance on energy consumption and carbon emissions. The results indicate a noteworthy reduction, showing a 42.5% decrease in energy consumption and a 12.7% decrease in carbon emissions. Moreover, crushed stone (CS) and milling planer material (MPM) have the greatest impact on energy consumption during the material transportation stage. Notably, the material production phase yields the most substantial benefits, demonstrating a 48.0% decrease in energy consumption and a 67.5% decrease in carbon emissions. The optimized scheme facilitates the reuse of reclaimed asphalt pavement (RAP) materials and phosphogypsum, resulting in a 44.3% reduction in mineral usage, a 6.9% reduction in petroleum asphalt, and preventing 16.859 square meters of waste occupancy.