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In response to the rapid urban expansion and the burgeoning number of landfill sites, managing water infiltration in these areas has become a critical challenge, especially in cities like Shenzhen, Hong Kong, and Singapore where traditional cover materials such as silt, clayey gravel, and sand are scarce. A three-layer (silt/gravelly sand/clay) capillary barrier cover system has been proposed to address this issue in humid climates. As an alternative to scarce traditional materials, using local soils and construction waste (CW) for this system presents a viable solution. However, the real-world performance of this adapted three-layer system, constructed with local soils and CW under natural rainfall conditions, remains to be fully evaluated. This paper presents a field test evaluating the water infiltration behavior of a three-layer capillary barrier landfill cover system under natural conditions. The tri-layered system is comprised of a 0.6 m loose local unscreened soil layer, covered by a 0.4 m CW layer and topped by a 0.8 m heavily compacted local screened soil layer. Monitoring findings reveal that, during the wet season, infiltration through the top two layers was staved off until the third rainfall, after which these layers retained moisture until 15 September 2016. The fluctuation in pore water pressure in the topmost layers showed each rainfall was contingent not only on the day's precipitation but also the hydraulic state. Beyond the hydraulic state's influence, a deeper tensiometer showed resulted in a diminished correlation between the surge in pore water pressure and daily rainfall. This declining correlation with depth can be attributed to the capillary effect and the reduced permeability of the screened soil layer. Rainfall patterns significantly affect percolation, with the combination of a short-duration, intense rainfall and prolonged weak rainfall resulting in a marked increase in percolation. In the foundational screened soil layer, the pore water pressure remained relatively low, with the cumulative percolation over six months (June to December) registering approximately 10 mm. These findings suggest a promising performance of the three-layer capillary barrier cover system, integrating local soils and CW, in the year of the study conducted in a humid environment. [ABSTRACT FROM AUTHOR]

Purpose: The capacity of landfills will reach saturation in the 2020s. There are more than 50,000 buildings in Hong Kong over 30 years old and which may require extensive refurbishment under the Mandatory Building Scheme. Additionally, most new owners/tenants tend to renovate their premises before moving in. Hence, there is an urgent need in Hong Kong, to explore strategies and measures to enable the development of effective refurbishment and renovation (R&R) waste management for such projects. The objectives of this paper are to investigate the process of R&R for identifying the perceived barriers and thereby the strategies for minimisation and management of R&R waste in Hong Kong. Design/methodology/approach: Desktop study, semi-structured interviews, site observations and document reviews were used as the data collection methods to achieve the objectives of this research. Considering the nature and characteristics of the industry structure, the snowball sampling process was deployed for data collection. Thematic analysis and content analysis were used for data analysis. Waste minimisation and management strategies for R&R projects were then discussed and developed by the research team and a focus group meeting was held to validate the research findings. Six strategies were then proposed to the government. Findings: R&R projects contribute 10–20% of the construction and demolition waste. The barriers to recycling of R&R waste can be grouped into six major categories: (1) lack of sorting and storage spaces, (2) high cost, (3) insufficient government supporting policy, (4) complicated recycling processes, (5) immature recycling market and (6) insufficient public education. Also, six strategies are proposed in this study, which include (1) pre-refurbishment audit, (2) development of recycling market, (3) sea reclamation, (4) incineration, (5) government support and (6) education and research. Originality/value: The strategies and measures proposed in this research could most adequately serve as reference for the government officials, building professionals and academic researchers. Such knowledge would make possible the development of effective strategies and measures for minimising and managing R&R waste. [ABSTRACT FROM AUTHOR]

Construction is a major source of carbon emissions. Moreover, it faces various other sustainability challenges, such as construction waste, construction noise, vehicular traffic near construction sites, dust and other air and water pollutants, and safety and well-being of construction workers. Poorly designed and constructed buildings will continue to affect the well-being of their occupants and overall energy efficiency throughout the building lifecycle. Hence, accelerating the transformation of the construction industry towards smart construction or Construction 4.0 is an important topic. The ways that technology can help to achieve smart construction, especially with the adoption of construction methods with increasing construction modularity, should be further explored. Focusing on modular integrated construction (MiC), this paper examines the following questions: (1) How has technology been applied to support MiC development and smart construction in Hong Kong? (2) What are the lessons learned? A case study approach of a building information model (BIM)-enabled multifunctional blockchain-based digital platform is adopted to allow us to systematically consider (1) the main objectives and scope, (2) the stakeholders involved, (3) the key outcomes and processes, (4) the applications of blockchain technology, and (5) the integration with other digital software and management platforms in practice. Drawing upon the experience, we propose a generic four-stage approach in understanding and facilitating the adoption of relevant technology towards smart construction. At Stage One, the technologies of BIM, RFID, and blockchain are applied to support the core elements of MiC production: just-in-time transportation and on-site installation. At Stage Two, the digital platform is extended to serve as an interface for third parties, notably government; monitoring, authentication, and certifications for information sharing; visualization; and real-time monitoring and updating of MiC projects. At Stage Three, the system focuses on people in the construction process, aiming to enhance the safety and well-being of workers and drivers throughout the construction process. Different Internet-of-Thing devices and sensors, construction robotics, closed-circuit television, dashboards, and cloud-based monitoring are deployed. At Stage Four, the full construction lifecycle is the focus, whereby a centralized smart command theatre is set up with multiple sources of data in a city information model. [ABSTRACT FROM AUTHOR]

• Automatic MiC envelopes and layout generation by a novel SSG-MOO method. • Multi-objective optimization formulation for passive MiC design. • A pilot MiC study in Hong Kong produced 5 selected Pareto optima out of 625. • Up to 0.42% energy savings and 9.71% spatial daylight autonomy improvement against the baseline. • A multi-level analysis of results and design strategies for practitioners. Modular-integrated Construction (MiC) is an emerging construction technique promoted in the building sector for high productivity and low waste emission in the construction phase; yet, the standardized modules also bring new challenges, such as balancing passive energy efficiency and spatial daylight autonomy, to the operational phase. This paper proposes a Symmetric Skeleton Grammar-based Multi-Objective Optimization (SSG-MOO) method to formulate parametric MiC envelopes and detailed layout, with the two objective functions being energy efficiency and interior daylight performance in the operational phase. Pareto optima of the SSG-MOO, computed by the Non-dominated Sorting Genetic Algorithm II, are generally verified and analyzed in three levels, i.e., MOO's solution space, SSG layout, and MiC design parameters. A case study of MiC residential building in Hong Kong demonstrated the SSG-MOO method through five new passive MiC designs (i.e., spatial reorganization of three architectural modules, and parameter tuning of the envelops and corridors), achieving up to 0.42% energy savings and 9.71% spatial daylight autonomy improvement compared to the baseline design. The contribution of this paper is two-fold, including a novel and sound SSG-MOO formulation for parametric MiC designs, and offering time-efficient and evidence-based design tactics for MiC designers and industrial practitioners to push boundaries of MiC. [ABSTRACT FROM AUTHOR]

• This study analyzed demolition practices and discussed existing challenges. • BIM is integrated with advanced technologies for building demolition. • Three key services are proposed to facilitate the building demolition. • A case study is provided to demonstrate the proposed framework. • A benefit-cost analysis is used to assess the proposed framework performance. Hong Kong's construction industry, known for its massive building infrastructure, produces an enormous amount of waste every year, the vast majority of which is disposed for landfills. Therefore, some effective operational measures and waste management policies have been implemented. However, enormous waste remains a concern for stakeholders and exert pressure on the limited capacity of Hong Kong's landfills. Though previous research discusses Building Information Modelling (BIM) application for construction waste management enhancement, the BIM model has not been widely implemented for building demolition with waste management. Hence, as a response to the aforementioned shortcomings, this paper develops a conceptual framework that allows collecting, maintaining, and analyzing comprehensive information through Smart BIM that uses advanced technologies such as Internet of Things (IoT) and capable of reacting to user activities such as waste quantitative assessment, demolition process planning, optimal disposal route selection, and waste management strategy are executed. The advantages of the proposed framework are shown in a case study benefit-cost analysis based on three planned reuse and recycling-rate scenarios that explain on- and off-site recycling methods. The results show that the proposed framework will pave the way for generating sustainable waste disposal practices by providing technical and decision-making support functionalities to engineers and planners in the construction industry. [ABSTRACT FROM AUTHOR]

The construction industry has been focused on sustainability, particularly with regards to reducing CO 2 emissions and recycling construction and demolition (C&D) waste. This study focuses on the alternative technology adaptation of carbonized pavement compact production by using waste concrete powder (WCP) which can be a substitute material to concrete and also able to absorb CO 2. While material scientists embraced and developed this technological application, the financial perspective for adopting this technology has yet to be properly addressed. This paper conducts a feasibility assessment, which includes technical, environmental, social, and financial factors, from different stakeholders' perspectives (government, construction contractors, and material manufacturers) to launch the production of carbonized pavement compact by utilizing WCP. The benefit-cost analysis underlies the Evolutionary Game Model functions' formulation, which emphasizes not only the obvious financial benefits from WCP or its carbonized compacts sale but the benefits from the absorption of CO 2 during the compacts production and avoiding WCP disposal at a landfill. The results based on a Hong Kong case (typical multistorey apartment building) identify promising scenarios where a minimum of 2300t of WCP is required for stakeholder interest in recycling, and a WCP wholesale price of 150HKD/t is suitable for the C&D contractor to participate in the recycling market. The study also estimates a cost-effective selling price of finished carbonized WCP compacts, which is competitive with similar products on the market. Important insights are drawn to initiate the WCP market and consequently increase the sustainability of the C&D recycling market. [Display omitted] • Providing a solution for reducing CO 2 emissions during pavements production. • Assessing the feasibility of launching carbonized WCP pavement compact market. • Considering technical, environmental, social, and financial factors for assessment. • Obtaining feasible conditions for carbonized pavement compact production from WCP. [ABSTRACT FROM AUTHOR]

The concept of the circular economy has gained significant political momentum because it offers policymakers a viable approach to tackling resource depletion, reducing waste and promoting economic development all at the same time. Current research, however, only focuses on the technological feasibility of this model, overlooking circularity's inherent contradiction: namely, that it valorizes waste rather than reducing it. This article tackles this limit by questioning the role of the state in what we describe as 'waste valorization'. It interrogates the urban political ecology of construction and demolition waste, the largest stream of inert materials in the world. It analyses CDW's geographies and economic position in urban development and the shifting rationales by which it is governed. To do this, it compares historical shifts in how CDW has been regulated in Hong Kong and Rotterdam. The article shows that waste is no longer an abject residual of urbanization, but a driver of urban development and a burgeoning sphere of accumulation in ecological capitalism. [ABSTRACT FROM AUTHOR]

This research aims to understand the loading patterns of construction waste hauling trucks in Hong Kong and the factors shaping these patterns. It does so by triangulating the analytical results of big data collected from secondary sources and qualitative data from interviews. Firstly, based on the literature review and our engagement with the industry, four hypotheses on the nexus between "loading pattern" and the factors of (1) vehicle, (2) permitted gross vehicle weight, (3) commodity, and (4) ownership. Then, the hypotheses are tested with combined null hypothesis significance test and effect size measure using 13 million construction waste transportation records. Finally, the results are triangulated with interview data to empirically validate the nexus while providing sensible explanations to them. We find that the four hypotheses are all supported. Distinct loading patterns are presented by different types of (1) construction waste hauling trucks with different (2) permitted gross vehicle weights, (3) types of construction waste transported, and (4) ownership. These findings provide valuable evidence for more targeted interventions, e.g., introducing public policies or hauling operation optimization through the avoidance of excessive underloading or overloading. [ABSTRACT FROM AUTHOR]