Integrated Assessment of Cost and Embodied Carbon in Parking Lot Pavement Design

Abstract

The construction sector significantly contributes to global greenhouse gas emissions, with rigid pavement systems forming a substantial portion of urban infrastructure. Although structural performance has traditionally guided pavement design, there is a growing need to incorporate environmental and economic considerations, particularly embodied carbon and construction costs, into early-stage design decisions. This study aims to identify the optimum rigid pavement configuration for parking lots by evaluating the influence of concrete compressive strength and lean concrete subbase thickness on the structural thickness, embodied carbon, and cost. Twelve pavement configurations were analysed, varying in concrete grade (20–40 MPa). Subbase conditions (0, 50, and 100 mm of lean concrete), under a uniform subgrade condition (CBR 6%) and 40-year design life based on ACI 330 Traffic Spectrum C. Pavement thickness was determined using PavementDesigner.org, and a cradle-to-gate Life Cycle Assessment (LCA) was conducted in accordance with BS EN 15978 to quantify embodied carbon. Construction cost estimation followed a unit-price approach using standardised data from the Indonesian Ministry of Public Works (PUPR). The results revealed that designs using 25–30 MPa concrete without a subbase offered the best performance trade-off, achieving the lowest embodied carbon (48.2–48.3 kgCO2e/m2) and construction cost (US$9.2–9.3/m2), while still satisfying design reliability. In contrast, high-strength concrete (40 MPa) with a 100 mm subbase increased emissions and cost by up to 50% and 52%, respectively, with a marginal structural benefit. These findings highlight the need to avoid excessive overdesign. They show moderate-strength concrete with a minimal subbase, which offers a structurally sound, cost-effective, and environmentally friendly solution for urban parking lot pavements.