Ecologically based hybrid life cycle analysis of continuously reinforced concrete and hot-mix asphalt pavements Murat Kucukvar, Omer Tatari ⇑ Department of Civil, Environmental, and Construction Engineering, University of Central Florida, Orlando, FL 32816, United States article info Keywords: Environmental life cycle assessment Asphalt pavements Concrete pavements Monte Carlo simulation abstract An ecologically-based hybrid life cycle assessment model is used to evaluate the resource consumption and atmospheric emissions of continuously reinforced concrete and a hot- mix asphalt pavements. The cumulative mass and ecological resource consumption values are lower for continuously reinforced concrete, but the median values of cumulative energy and industrial energy consumption were lower for hot-mix asphalt. In addition, the use of reclaimed asphalt pavement results in a higher sensitivity for the ecological resource consumption of hot-mix asphalt compared to that of fly ash when use on the nat- ural capital utilization of continuously reinforced concrete pavement. The cumulative and industrial exergy consumption values are significantly reduced with increases in reclaimed asphalt pavement and fly ash, and the use of low fuel transportation modes. Ó 2011 Published by Elsevier Ltd. 1. Introduction Roads have a significant impact on the environment, economy and society, and the selection of pavement type thus has wide ranging implications. All phases of road development, from construction to operations, consume large amounts of eco- system goods and services, and generate waste and emissions. Life cycle assessments (LCA) in various forms, have been used to study the effects of pavements on the environment but there is been little focus on concentrated on ecosystem goods and services. Most studies on have utilized process-based (P-LCA), economic input–output (EIO-LCA), or hybrid LCA models to estimate the environmental impacts by quantifying energy consumption, atmospheric emissions, and waste generation. Di- rect and indirect roles of ecological resource consumption have, however, generally been excluded in these studies. Due to the large consumption of natural resources during the production of pavements, there is a need to account for the natural capital of pavement designs. Thus an ecologically-based LCA (Eco-LCA) model is used here to account for ecological good and services used by continuously reinforced concrete (CRCP) and hot-mix asphalt (HMA) pavement by enlarging the system boundary to include not only the national economy, but also ecological good and services. 2. Methodology The developed hybrid Eco-LCA model evaluates pavement designs on the basis of materials extraction and processing, transportation of pavement materials to mixing plant, mixing plant operations, transportation of mixtures to the construc- tion site, and placement of the pavements. Materials and energy used are quantified, and then a hybrid LCA model devel- oped. The emissions during material transportation and mixing plant operation are calculated by the P-LCA model, and are augmented to the results of the Eco-LCA model to account for direct process-based analysis and indirect economic and ecological analysis. 1361-9209/$ - see front matter Ó 2011 Published by Elsevier Ltd. doi:10.1016/j.trd.2011.05.006 ⇑ Corresponding author. Tel.: +1 407 823 2841. E-mail address: tatari@ucf.edu (O. Tatari). Transportation Research Part D 17 (2012) 86–90 Contents lists available at ScienceDirect Transportation Research Part D journal homepage: www.elsevier.com/locate/trd