Life-Cycle Analysis of Proposed Performance-Based Specifications for Structural Concrete and Portland Cement Concrete Pavement in Georgia

Increasing adoption of performance-based specifications (PBS) rather than conventional prescriptive specifications for concrete mixes is a paradigm shift that is expected to increase the use of more innovative and durable materials. The adoption of PBS could result in meaningful changes to mix designs and qualification processes for concrete by state agencies [e.g., Departments of Transportation (DOTs)] and other owners, including allowing higher proportions of cement replacement, additional performance benchmarks, and shifting to site-specific designs. The shift in specifications could affect outcomes outside the performance specification, such as emissions and maintenance costs, over the life cycle of concrete-based infrastructure projects. These outcomes can be quantitatively evaluated to inform owners and producers during this transition. This paper examines proposed durability-focused PBS for concrete pavement and structural elements with a range of potential concrete mix designs for the Georgia Department of Transportation, using environmental life-cycle analysis and life-cycle cost analysis. Specifically, this analysis evaluates cradle-to-gate and cradle-to-grave environmental and cost impacts for both prescriptive and performance-based specifications over 30- and 40-year lifespans for concrete pavement and structural concrete applications. Concrete designed under the proposed PBS has projected lower lifetime climate impact relative to the existing prescriptive specifications, with a reduction in greenhouse gas emissions ranging from 11% to 13% (pavements) and 9% to 10% (columns). PBS adoption carries a modeled benefit–cost ratio of 1.3–1.7 (pavements) and 5.7–8.3 (columns). This analysis supports a recommendation that DOTs adopt such PBS for concrete mix design, largely due to expected reduced maintenance needs due to higher durability.