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Most geopolymer research claims a substantial reduction in carbon dioxide emissions compared with ordinary portland cement concrete. However, geopolymer concretes are not all equally eco-friendly. The environmental benefits of geopolymer concrete cannot be taken for granted. Modeling emissions is necessary to assess the environmental impact of each geopolymer mix. Unfortunately, only studies concerned with carbon dioxide emissions care to provide sophisticated emissions modeling. Such modeling is practically nonexistent for other geopolymer studies; because function-oriented geopolymer research tends to assume the environmental eminence of their designed mixes. This research reviews the last 7 years of geopolymer concrete research to assess the sustainability of the mixes designed by researchers worldwide and to highlight any bad environmental practices in the mix design. The nominal CO2-e equivalent emissions for geopolymer concrete mixes varied from 56 to 661 kg-CO2/m3 for the surveyed mixes. SOx and NOx emissions reached 1,865 g-SOx/m3 and 1,161 g-NOx/m3 , respectively. Finally, this paper recommends a simple method for estimating a nominal carbon dioxide emissions value, which can be easily implemented in future geopolymer research. [ABSTRACT FROM AUTHOR]

Water distribution networks (WDNs) confront momentous challenges, including the need to meet continuously increased demand, combat unforeseen disruptions, and reduce carbon emissions. Developing efficient plans for resilience enhancement of WDNs thus is essential recognizing the ubiquitous nature of WDNs and increased frequency and destructive severity of hazardous events. This paper presents a resilience-driven multiobjective optimization model to maximize the resilience of WDNs while minimizing the life-cycle cost and carbon emissions. Enhancement actions first are determined and clustered into work packages, and then an optimized schedule is generated considering various operational and managerial factors. A real WDN in the city of London, Ontario, was utilized to demonstrate the proposed model's practicality. The resilience increased by 24% with CAD 1.6 million investment. Additionally, cost saving of about 33% is achievable if the proposed model is employed instead of a currently utilized practice. The developed model is expected to help city managers establish optimal resilience enhancement plans, considering tight available budgets and limited workforce. [ABSTRACT FROM AUTHOR]

Given the urgent need for decarbonization of the construction industry due to its pivotal role in global greenhouse gas emissions, industrialized construction (IC) has emerged as a promising technique to change the productivity, quality, and sustainability of construction. Although some evidence and case studies reveal that IC has distinct decarbonization advantages compared with traditional construction, there still is a need to analyze best practices, opportunities, and challenges in order to guide industry practitioners and to define key knowledge gaps. A systematic review was conducted following the three core steps: database search; research gap identification, analysis according to key lifecycle stages, and decarbonization themes. This synthesized existing academic works at the intersection of industrialized construction and decarbonization to provide a comprehensive understanding of decarbonization in IC. The findings show that although a significant amount of research focused on emissions during project stages A1–A3, there is a noticeable research gap in evaluating the carbon emissions associated with transportation, operations, and end-of-life attributes of IC. Moreover, the absence of real-time assessments during the B6–B7 operational stages impedes optimal carbon emission assessment. The verbosity of carbon estimation and tracking methodologies also adds challenges to ensuring that additional carbon impacts of IC are adequately offset by improved efficiency and lower onsite emissions. The potential of decarbonization of IC can be explored further by future research on the standardization of life-cycle assessments, development of continuous carbon-tracking methodologies, and application of alternative materials and new technologies. Practical Applications: The effectiveness of IC practices in reducing carbon emissions may vary, as deduced from the reviewed literature. However, the conscientious selection of materials characterized by low embodied emissions can contribute to a reduction in carbon emissions, applicable to both IC and non-IC projects. IC projects are uniquely positioned to achieve an even greater reduction in carbon emissions because of a unique process that innately offers waste reduction and product quality improvements. Although a considerable volume of research has focused on estimating carbon emissions, there appears to be a gap in tracking the precise quantity of emissions across various life-cycle phases within IC. Although there is considerable research on decarbonization in prefabricated components, research on specific life-cycle phases still is lagging. Furthermore, future research should prioritize investigating similar opportunities for three-dimensional (3D) volumetric systems. [ABSTRACT FROM AUTHOR]