Energy and carbon estimation in construction and maintenance of pavements using conventional and alternative...

Pavement construction and maintenance significantly contribute to environmental impacts and infrastructure expenditure. This study evaluates embodied energy (EE), embodied carbon (EC), and construction-maintenance costs for five flexible pavement alternatives and four rigid pavement alternatives designed for traffic levels ranging from 30 to 150 million standard axles (MSA). Flexible pavements were designed according to IRC:37-2018 with varying base and sub-base configurations, while rigid pavements were designed based on IRC:58-2015. The rigid pavement alternatives incorporated design features such as tied shoulders, dowel bars, widened lanes, and Pavement Quality Concrete (PQC) placed over Dry Lean Concrete (DLC). A constant California Bearing Ratio (CBR) was assumed for flexible pavement design, whereas rigid pavement slab thickness was considered independent of CBR. Embodied energy and embodied carbon were estimated for both construction and scheduled maintenance phases over the design period. In addition to conventional materials, alternative scenarios incorporating up to 50% ground-granulated blast furnace slag (GGBS) as cement replacement and up to 30% recycled aggregates were evaluated. Energy and carbon intensity values were obtained from established life-cycle inventory sources, while equipment productivity and cost estimates were derived from standard construction references. The results indicate that EE, EC, and costs increase with traffic loading, whereas the use of alternative materials can reduce EE and EC by approximately 20-30% and overall costs by 5-15%, supporting more sustainable pavement design practices.