Search

Cement is traditionally regarded as an energy and emission intensive construction material. The reduction of environmental impacts in the cement industry has gained increasing concern worldwide for environmental sustainability. As a resource-scarce city, cement production in Hong Kong is associated with high CO 2 emissions, thus contributing significantly to the high environmental impacts in the construction industry. This study herein has been conducted to comprehensively assess the energy consumption and global warming potential impacts of different types of cement manufactured in Hong Kong using life cycle assessment (LCA) techniques. Two sustainable strategies for the reduction of energy consumption and greenhouse gases emission in the cement industry were then proposed. The LCA results showed that ordinary Portland cement production has high environmental impacts mainly due to the import of associated raw materials and burning of fossil fuel. The use of alternative material, such as fly ash would help to reduce the environmental impacts. Significant impacts reductions associated with cement production can be further achieved by strategies such as the use of glass powder from locally generated waste glass bottles as part of the raw materials, and the use of a bio-fuel produced from locally generated wood wastes as a co-fuel with coal. The assessment results indicated that about 12% of the total greenhouse gases emission and 15% of energy consumption can be reduced from the cement industry in Hong Kong by using waste materials to replace virgin materials (clinker/coal). [ABSTRACT FROM AUTHOR]

The possibility of recovering energy from biomass residues has attracted a lot of research interest due to the environmental problems associated with burning coal. Wood wastes generated from construction and demolition activities and other wood product wastes can be a good potential source of renewable energy. The present study was conducted by using Hong Kong as an example to assess the environmental sustainability of converting recycled wood wastes (from construction and demolition activities and other wood product wastes) to produce wood pellets for direct energy generation. The chemical and physical characteristics of different types of wood product wastes were tested. An attributional lifecycle assessment approach was used to assess and compare the environmental impacts and sustainability for heat generation from the pelletized bio-fuel and coal. The test results showed that the energy content, chemical compositions and the trace metal concentrations all met the relevant standards. The results also showed that significant impacts on health, ecosystem, climate change and resources damage can be potentially avoided by using wood pellets instead of coal for energy generation. The overall findings demonstrated that the proposed “energy recovery” approach for using wood pellets as a bio-fuel in Hong Kong is environmentally sustainable, which can provide an alternative route for managing wood product wastes with the added benefits of energy recovery, and may be more applicable in mega cities especially when city-based incineration is a concern. [ABSTRACT FROM AUTHOR]

Substantial amount of resources is consumed by pavement systems, which have resulted considerable environmental impacts. Understanding the environmental impacts would provide opportunity for reducing resource consumption and informing decision-makers in the process of designing sustainable pavement. There is a lacking of comprehensive and comparative sustainability assessment of pavement systems in highly urbanized context currently. Therefore, this study aims to design and comprehensively evaluate the environmental performance of the commonly adopted pavement systems in highly urbanized context using lifecycle assessment (LCA) technique through a case in Hong Kong. According to the codes and practices of Hong Kong, two pavement systems including flexible and rigid pavements were designed based on the same road section. After that interviews with structured questionnaire were conducted to collect relevant practical information of pavement construction and maintenance from the relevant professional bodies and experts for the subsequent LCA of such designs. The LCA results reveal that the two mid-point impacts of global warming potential and mineral extraction are 21% and 54% higher for rigid pavement than for flexible pavement. Yet, the end-point results indicate that flexible pavement is associated with 64%, 65%, and 69% higher human health impact, ecosystem quality damage, and resource damage, respectively. Material production and transportation contribute significantly to the total impact in the two pavement systems. For instance, it is about 57% and 97% of the total global warming potential for flexible and rigid pavements, respectively. The overall results demonstrated that 49% higher total impact was found for flexible pavement than rigid pavement. Therefore, the use of more recycled and environmentally friendly materials can potentially enhance the environmental sustainability of both pavement systems. The findings should provide useful information to the design and selection of sustainable pavement structures in resource-scarce highly-urbanized cities. [Display omitted] • Designed two commonly used pavement systems based on the existing practices in Hong Kong. • Evaluated the environmental sustainability of pavements in an urban context using LCA. • Considerably higher impact was associated with frequent maintenance in flexible pavement. • About 49% higher total impact was found for flexible pavement than the rigid pavement. [ABSTRACT FROM AUTHOR]

• Evaluated the techno-environmental feasibility of using natural pozzolana in concrete production, • Comparable compressive strength was found for the use of VA against conventional SCMs, • VA significantly reduced environmental impacts of concrete compared to OPC and other SCMs, • 11–30% lower GHG emissions was found for VA concrete compared to other cementitious materials. With increasing environmental sustainability concerns in the construction industry and a demand for producing more durable and sustainable concrete, effort is devoted to producing concrete with Ordinary Portland cement (OPC) being substituted by alternative binder materials. By considering the compressive strength, the comprehensive environmental performance of natural pozzolana in concrete was evaluated comparatively by developing six mix-designs of concrete with OPC, and commonly used industrial by-products as supplementary cementitious materials such as fly ash (FA) and ground granulated blast furnace slag (GGBS) based on the lifecycle assessment (LCA) approach. The results show that comparable compressive strengths can be achieved for the use of 20% and 30% volcanic ash (VA) against conventional SCMs. Using the volume as functional unit, the LCA results have demonstrated that higher environmental savings are associated with VA concrete compared to that of OPC, GGBS (30%) and FA (25%), but almost similar when 50% GGBS is used. For example, 15–24% and 10–19% lower global warming potential are associated with VA concretes compared to that of OPC and FA concretes, respectively, but much higher saving is found when considering the strength of the concrete, as they are about 11–12%, 10–11% and 29–30% compared to that of GGBS, FA and OPC concretes, respectively. The results can be used as valuable guidelines for VA-based in sustainable concrete production, which would further enhance the sustainability of the concrete industry. [ABSTRACT FROM AUTHOR]

Sustainable construction is widely regarded as one of the best decisions to reduce the environmental impact of the buildings. Numerous scientific efforts have been devoted to promoting sustainability by adopting different techniques such as life cycle assessment (LCA) and building information modeling (BIM). The recent circular economy (CE) agenda is prioritizing in different sectors including construction due to increasing concern on the materials efficiency and resources consumption. Therefore, this study aimed to identify the implications, considerations, contributions and challenges of BIM integrated LCA and the CE adoption in the industry by critically analyzing the recent literature. A scientometric analysis was applied to the selected studies to show the knowledge among BIM, LCA and CE relationships. With a comprehensive analysis of major challenges and opportunities of LCA and BIM for construction sustainability, key drivers for sustainable building design were identified and analyzed. A prospective integrated framework for CE adoption into BIM-based LCA of buildings and an evaluation method are proposed by analyzing the contemporary issues. It is believed that the analyzed critical issues, identified future research direction and proposed frameworks and this methodology should contribute to effective implementation of CE into the building for promoting sustainable construction. [ABSTRACT FROM AUTHOR]