A trade-off between rock crushing and enhanced performance of concrete roads based on life cycle assessment and cost analysis

While the role of aggregate angularity in the asphalt concrete is well understood, the same is not established for paving concrete mixes. This study evaluates the mechanical, structural and environmental trade-offs associated with aggregate angularity in rigid pavements. Aggregates with angularities (round, sub-angular and angular) maintaining similar sphericity and surface texture were used in two paving concrete mixes (water-to-binder ratios of 0.36 and 0.45). Mechanical properties, porosity and resulting pavement slab thicknesses were assessed for traffic levels ranging from 1,000 to 10,000 commercial vehicles/day and linked to embodied energy and emissions through a cradle-to-gate life-cycle assessment. Higher angularity improved flexural strength and modulus, enabling slab thickness reduction of approximately 15 to 20 mm. Although additional crushing increased emissions, reduced concrete volume resulted in net energy and CO2 reductions of 3-11% per km. A scenario incorporating crusher fines further improved material efficiency, reduced environmental impacts and decreased sensitivity to transportation distance.