Reduce, Reuse, Resilient? Life-Cycle Seismic and Environmental Performance of Buildings with Alternative Concretes

This paper investigates the impacts of alternative structural concretes on the life-cycle sustainability and resilience of a reinforced concrete building in a high seismic region. To do so, we conduct a life-cycle environmental impact assessment, quantifying greenhouse gas emissions associated with building construction and seismic performance, accounting for potential earthquake damage and subsequent repairs. The unit of analysis is a modern code-designed reinforced concrete frame building, designed with seven different types of concrete: a conventional concrete mix, 3 concrete mixes in which varying quantities of fly ash replace cement, and 3 concrete mixes in which varying quantities of recycled concrete replace virgin coarse aggregate. The findings suggest that replacing cement with fly ash can be an effective tool to improve building sustainability over the entire life cycle, reducing greenhouse gas emissions during both construction and service life (seismic) life-cycle stages, without compromising seismic performance (i.e., resilience). However, replacing virgin coarse aggregate with recycled concrete aggregate can have unintended consequences in terms of worsening seismic performance and hence making the overall life-cycle sustainability calculus unfavorable in terms of greenhouse gas emissions. This paper is one of the first to link life-cycle seismic and environmental performance of buildings designed with alternative (and potentially green) concretes and to demonstrate the importance of considering tradeoffs between resilience and sustainability in design and selection of alternative structural materials. In addition, this study illustrates a framework that can be applied for life-cycle assessment and evaluation of structural concrete material choices.