Infrastructure Engineering - Research Publications

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    New circularity indicator for decision making in the stockpile management of construction and demolition waste: Perspectives of Australian practitioners
    Pilipenets, O ; Hui, K ; Gunawardena, T ; Mendis, P ; Aye, L (Elsevier BV, 2024-07-01)
    Despite the increasing popularity of the circular economy, there remains a lack of consensus on how to quantify circularity, a critical aspect of the practical implementation of this model. To address this gap, this article examines the industry's perspective and efforts toward implementing the circular economy in real-world scenarios. We conducted 40 interviews with engineers, project leaders, and top-level managers in the Australian construction sector. Using Saldaña's coding approach, we analysed their views on circular economy practices and efforts within their organisations. Our findings reveal while waste minimisation, reduction of greenhouse gas emissions, and cost considerations are widely regarded as essential indicators of a successful circular economy model, the significance of waste storage and long-term stockpiling while awaiting treatment has been overlooked or under-emphasised in industry practices and academic literature. Stockpiling of waste has often been seen as a staging process in waste treatment. However, based on industry insights, it accumulates to the point of mismanagement when it becomes a safety and environmental concern. Addressing this oversight, we propose a storage circularity indicator that allows incorporating waste storage and stockpiling in circular economy models. Our research contributes to various environmental and waste management aspects, supporting policies and strategies for solid waste management and excessive stockpile prevention. By emphasising the significance of storage circularity, we clarify waste prevention techniques and address socio-economic issues such as the urgent need to reduce long-term stockpiling of solid waste. This work highlights the importance of decision-support tools in waste management to facilitate the implementation of circular economy principles. Our proposed storage circularity indicator promotes industrial collaboration, aligning with the concept of industrial symbiosis to optimise resource use and minimise waste generation. By discussing these topics, we aim to contribute to the advancement of more robust waste management strategies and policies that promote sustainable production and consumption practices.
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    Mechanical properties and life cycle greenhouse gas analysis of textile waste fibre-based concrete
    Jayalath, A ; Sofi, M ; Ginigaddara, T ; Gou, H ; Mendis, P ; Aye, L (Elsevier BV, 2024-05-17)
    The application of textile waste as an aggregate in concrete enhances sustainability in construction and promotes circular economy. This work develops a novel fibre-based concrete incorporating textile waste fibres. The experiments showed that including textile waste fibres reduces flowability of concrete and improves its tensile and compressive strengths, alongside strain resistance. The fibres enhance concrete’s ductility and resilience against environmental damage. Textile waste fibre exhibits a lower greenhouse gas emissions compared to other non-polymer fibres. This work emphasises the benefits of textile waste in enhancing construction sustainability and highlights the need for expanded exploration.
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    Upcycling opportunities and potential markets for aluminium composite panels with polyethylene core (ACP-PE) cladding materials in Australia: A review
    Pilipenets, O ; Gunawardena, T ; Hui, FKP ; Nguyen, K ; Mendis, P ; Aye, L (ELSEVIER SCI LTD, 2022-11-28)
    Many buildings worldwide have high fire-risk materials as part of their cladding. As governments in Australia strive to make buildings safer, it is expected that a large volume of end-of-life dangerous cladding will be replaced with safer materials. This high volume of hazardous materials might be upcycled into value-added products. This article presents a systematic market analysis and literature review in identifying current and potential uses for the raw materials used in hazardous ACP-PE cladding. The most promising areas were identified to be non-food-contact packaging (US$228 M p.a.), non-pressure pipes (US$30 M p.a.), footwear (US$5.29 M p.a.) and 3D printer filament (US$2.73 M p.a.)
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    Designing Post COVID-19 Buildings: Approaches for Achieving Healthy Buildings
    Navaratnam, S ; Nguyen, K ; Selvaranjan, K ; Zhang, G ; Mendis, P ; Aye, L (MDPI AG, 2022-01-12)
    The COVID-19 pandemic forced the accessibility, social gathering, lifestyle, and working environment to be changed to reduce the infection. Coronavirus spreads between people in several different ways. Small liquid particles (aerosols, respiratory droplets) from an infected person are transmitted through air and surfaces that are in contact with humans. Reducing transmission through modified heating, ventilation, and air conditioning (HVAC) systems and building design are potential solutions. A comprehensive review of the engineering control preventive measures to mitigate COVID-19 spread, healthy building design, and material was carried out. The current state-of-the-art engineering control preventive measures presented include ultraviolet germicidal irradiation (UVGI), bipolar ionization, vertical gardening, and indoor plants. They have potential to improve the indoor air quality. In addition, this article presents building design with materials (e.g., copper alloys, anti-microbial paintings) and smart technologies (e.g., automation, voice control, and artificial intelligence-based facial recognition) to mitigate the infections of communicable diseases.
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    Airborne and impact sound performance of modern lightweight timber buildings in the Australian construction industry
    Jayalath, A ; Navaratnam, S ; Gunawardena, T ; Mendis, P ; Aye, L (Elsevier BV, 2021-12)
    Timber usage in the Australian construction industry has significantly increased due to its strength, aesthetic properties and extended allowances recently introduced in building codes. However, issues with acoustic performance of lightweight timber buildings were reported due to their inherit product variability and varying construction methods. This article reviews the recent literature on the transmissions of impact and airborne sounds, flanking transmission of timber buildings, and the state of computer prediction tools with reference to the Australian practice. An in-depth analysis of issues and an objective discussion related to acoustic performance of timber buildings are presented. Timber is a lightweight material and shows low airborne sound resistance in low frequency range. Attenuation of sound transmission with addition of mass, layer isolation, different products like cross-laminated timber and prefabrication are discussed. Challenges in measuring sound transmissions and reproducibility of results in low frequency ranges are discussed. Well-defined measurement protocols and refined computer simulation methods are required. The serviceability design criteria for modern lightweight timber applications in Australia need to be re-evaluated in the area of impact generated sound. Developing computer tools to predict airborne and impact sound transmission in lightweight timber buildings is quite challenging as several components such as timber members and complex connections with varying stiffnesses are non-homogeneous by nature. Further, there is a lack of experimentally validated and computationally efficient tools to predict the sound transmission in timber buildings. Computer prediction tools need to be developed with a focus on mid-frequency transmission over flanks and low-frequency transmission of timber and prefabricated buildings.
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    Fire resistance of a prefabricated bushfire bunker using aerated concrete panels
    Nguyen, T ; Ngo, DT ; Tran, P ; Mendis, P ; Aye, L ; Kristombu Baduge, KS (Elsevier, 2018-06-20)
    Prefabricated lightweight aerated concrete (PLAC) panels provide low thermal conductivity, potentially high stiffness-to-weight ratios, cost-effective material and structural systems and rapid modular construction. These panels can be utilised as floor slabs or external walls for various applications in building construction. The fire performance of the PLAC panel is examined in this work for a particular case, namely a prefabricated emergency bushfire shelter, which is one of the key applications of PLAC panels. Since, bushfires have unique heating curves, standardised tests are not useful and the system needs to be tested in a manner such that the heat flux of an actual bush fire can be reproduced. In this study, the fire performance enhancement of dual-skin bushfire bunkers, which are comprised of lightweight concrete and base metal thickness (BMT) steel, are examined experimentally and validated numerically. The Speedpanel PLAC modular panel explored in this work is a lightweight wall system primarily used for acoustic and thermal insulation purposes. Burning experimental studies of a single panel and dual-skin bunkers are carried out on a full scale. The experimental results are compared with fire safety codes for building materials to identify the key areas for improvements. A fire dynamic numerical model has been developed in this work using the Fire Dynamics Simulator (FDS) to simulate the burning process of PLAC structures. Numerical results of heat production are presented in comparison with experimental observations for validating the computational model. The proposed numerical model is used to predict the fire performance of a dual-skin bushfire bunker, demonstrating the need to have at least two PLAC layers to ensure fire safety compliance.
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    Optimisation and financial analysis of an organic Rankine cycle cooling system driven by facade integrated solar collectors
    Wu, D ; Aye, L ; Tuan, N ; Mendis, P (ELSEVIER SCI LTD, 2017-01-01)
    The use of a solar cooling system has the potential to reduce the amount of energy required for cooling buildings. One of the most important methods of improving energy efficiency in buildings is by carefully designing building façades. A façade integrated evacuated tube collector (ETC)-organic Rankine cycle (ORC)-vapour compression cycle (VCC) was applied in this study. To optimise the design parameters of ORC, a steady-state semi-empirical model was developed in Engineering Equation Solver (EES). The optimum number of plates in each heat exchanger is obtained by maximising the net present value (NPV) of electricity savings. The financial performance of the optimised system was assessed through a unit cooling cost (UCC) analysis. It was found that the UCC of the optimised facade integrated ETC-ORC-VCC system is $0.24 per kWhr of cooling effect.
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    Effects of phase change material roof layers on thermal performanceof a residential building in Melbourne and Sydney
    Jayalath, A ; AYE, L ; Mendis, P ; Ngo, T (Elsevier, 2016-04-05)
    This paper assesses the effectiveness of Phase Change Materials (PCMs) for the improvement of the thermal performance and the thermal comfort of a residential building in Melbourne. The incorporation of PCMs in buildings with their significant heat storage capacity can delay the heat transfer and reduce the cooling and heating loads. Numerical simulation is a useful tool for comprehensive assessments and optimization of PCM applications in buildings. Thus an available TRNSYS component, PCM Wall: Type1270, was implemented with Type56 (Multi zone component). PCM Wall TRNSYS component has been validated with some experimental data published in the open literature. The validated model was then utilised to simulate the thermal performance of a residential building which has a PCM roof layer. The building is a typical single-storey, three bed room residential building in Melbourne. It was found that the PCM roof layer can reduce the cooling and heating loads whilst providing better thermal comfort for occupants with reduced indoor temperature fluctuations.