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Climate change is one of the most challenging problems that humanity has ever faced. With the rapid development in technology, a key feature of 5G networks is the increased level of connectivity between everyday objects, facilitated by faster internet speeds with smart facilities indicative of the forthcoming 5G-driven revolution in Internet of Things (IoT). This study revisited the benefits of 5G network technologies to enhance the efficiency of the smart city and minimize climate change impacts in Singapore, thus creating a clean environment for healthy living. Results revealed that the smart management of energy, wastes, water resources, agricultures, risk factors, and the economy adopted in Singapore can remarkably contribute to reducing climate change, thus attaining the sustainability goals. Hence, future studies on cost-effective design and implementation are essential to increase the focus on the smart city concept globally.
Ghasan Fahim Huseien; Kwok Wei Shah. Potential Applications of 5G Network Technology for Climate Change Control: A Scoping Review of Singapore. Sustainability 2021, 13, 9720 .
AMA StyleGhasan Fahim Huseien, Kwok Wei Shah. Potential Applications of 5G Network Technology for Climate Change Control: A Scoping Review of Singapore. Sustainability. 2021; 13 (17):9720.
Chicago/Turabian StyleGhasan Fahim Huseien; Kwok Wei Shah. 2021. "Potential Applications of 5G Network Technology for Climate Change Control: A Scoping Review of Singapore." Sustainability 13, no. 17: 9720.
Buildings account for about 30% of the final energy consumption and nearly one-third of the global carbon emissions. The reduction of energy use in buildings has therefore become a pressing issue. Building envelopes such as windows, roofs, and walls determine the cooling energy demand to a considerable extent. Nanomaterials with their remarkable reflective and emissive properties have found to be effective in developing energy-efficient building envelopes with excellent passive cooling performance. Such functional nanomaterials include gold, silver, zinc oxide, tin oxide, vanadium oxide, silica, silicon carbide, titanium dioxide, hafnium oxide, etc. This chapter presents an in-depth overview of the recent advances in these nanomaterials, nanocomposites, and nanosized structures for reducing building heat gain. The focuses are particularly put on two promising technologies which include transparent solar reflective nanocoatings and nano-based daytime radiative cooling. The former can be used for near-infrared shielding of glass, while the latter has a great potential to emit excess solar heat to outer space. For each technology, it starts with a brief introduction of the fundamental principles and followed by the commonly used materials, structures, as well as the characterization results. Then, the state-of-the-art applications in cool windows and cool roofs are reviewed with analyzing the technological feasibility and prospects. Furthermore, the benefits, limitations, and challenges of these emerging passive cooling nanotechnologies have been identified, and the future outlook is also outlined.
Kwok Wei Shah; Teng Xiong. Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes. Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications 2021, 2621 -2648.
AMA StyleKwok Wei Shah, Teng Xiong. Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes. Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications. 2021; ():2621-2648.
Chicago/Turabian StyleKwok Wei Shah; Teng Xiong. 2021. "Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes." Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications , no. : 2621-2648.
Uses of novel technologies for improving the durability and lifespan of the construction materials have emerged as viable solutions toward the sustainable future wherein the coating industry plays a significant role in economy growth and better livelihoods. Thus, the continual innovation of various technologies to introduce diverse market products has become indispensable. Properties of materials like color stability under UV, elevated temperatures and aggressive environments, and skid and abrasion resistance are the main challenges faced by commercial coating materials, leading to more demand of natural materials as sustainable agents. Lately, nanostructured core–shell pigments with unique compositions have widely been utilized in composite materials to enhance their properties. Core–shell particles exhibit smart properties and have immense benefits when combined with building materials. Based on these facts, we comprehensively overviewed the state-of-the-art research of core–shell nanomaterials in terms of their preparation and performance evaluation methods, as well as feasible applications. The first part of this article discusses effective shell materials, including most common silica and titanium oxides. In addition, nanotechnology enabling the production and patterning of low-dimensional materials for widespread applications is emphasized. The second part deals with various potential core materials used to achieve core–shell nanostructures. The third part of this paper highlights some interesting mechanisms of core–shell structures in the modified systems that display high stability, durability, efficiency, and eco-friendliness. Finally, different applications of these core–shell nanostructures are underscored together with their test methods to evaluate their performances.
Kwok Shah; Ghasan Huseien; Harn Kua. A State-of-the-Art Review on Core–Shell Pigments Nanostructure Preparation and Test Methods. Micro 2021, 1, 55 -85.
AMA StyleKwok Shah, Ghasan Huseien, Harn Kua. A State-of-the-Art Review on Core–Shell Pigments Nanostructure Preparation and Test Methods. Micro. 2021; 1 (1):55-85.
Chicago/Turabian StyleKwok Shah; Ghasan Huseien; Harn Kua. 2021. "A State-of-the-Art Review on Core–Shell Pigments Nanostructure Preparation and Test Methods." Micro 1, no. 1: 55-85.
To effectively utilize marine resources and promote sustainable development in the construction industry, an innovative building material, namely, alkali-activated slag mortars prepared with seawater and coral sand (SC-AAMs), was proposed in this paper, and its workability, setting time, compressive strength, flexural strength, and drying shrinkage were studied. The effects of the modulus of sodium silicate (Ms), Na2O-to-binder (N/B) ratio by weight, replacement ratio of the coral sand for sea sand (Rs), and water-to-binder (W/B) ratio were considered using the Taguchi orthogonal experimental design method. The experimental results indicated that an increased alkali activator modulus and alkaline contents improved the compressive and flexural strengths, however, resulting in a decreased setting time and an increased drying shrinkage. According to the results from the aforementioned orthogonal experiments, the optimum mixtures for SC-AAMs were determined to be an Ms = 1.2, a N/B = 4%, a W/B = 0.45, and a Rs = 100%. Then, the microstructure and crystalline phases in the SC-AAMs prepared with this optimum mix proportion were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively, and the cement mortar mixed by seawater and coral sand was selected as the reference. It can be concluded that the utilization of the alkali-activated materials changed the reaction hydrate products of the mortars and improved the interfacial microstructures between the coral sand and slurry. In addition, the existence of the coral sand reduced the drying shrinkage of the AAMs due to the self-curing effect inside the coral aggregate.
Bai Zhang; Hong Zhu; Kwok Wei Shah; Pan Feng; Zhiqiang Dong. Optimization of mix proportion of alkali-activated slag mortars prepared with seawater and coral sand. Construction and Building Materials 2021, 284, 122805 .
AMA StyleBai Zhang, Hong Zhu, Kwok Wei Shah, Pan Feng, Zhiqiang Dong. Optimization of mix proportion of alkali-activated slag mortars prepared with seawater and coral sand. Construction and Building Materials. 2021; 284 ():122805.
Chicago/Turabian StyleBai Zhang; Hong Zhu; Kwok Wei Shah; Pan Feng; Zhiqiang Dong. 2021. "Optimization of mix proportion of alkali-activated slag mortars prepared with seawater and coral sand." Construction and Building Materials 284, no. : 122805.
This paper experimentally and numerically investigated the thermal performance of cementitious composites containing polystyrene/n-octadecane microcapsules (MPCM-CCs). The focus was placed on the passive cooling and heating, and the peak load reduction and shifting of MPCM-CCs subjected to extreme temperature conditions (10–50 °C). Adding microcapsules with a latent heat of 142.9 J/g effectively improved the heat storage and thermal insulation performance of MPCM-CCs, thereby mitigating the temperature fluctuations of inner surface and indoor air by up to 17.5 °C and 10.7 °C, respectively. The peak load was reduced and shifted by up to 260 W/m2 and 675 s in the heating process (1130 s), and 436 W/m2 and 465 s in the cooling process (1750 s). Further, this study evaluated the influence of differential scanning calorimetry (DSC) scanning rate on the phase change properties of microcapsules and the consistency between the simulation and experimental results of MPCM-CCs. Due to the low thermal conductivity of polystyrene shell, the phase change temperatures of microcapsules varied significantly with DSC scanning rates. Consequently, the simulation results based on improper scanning rates deviated from the experimental results, which highlights the importance of considering the difference between the temperature change rates of building components and DSC analysis.
Teng Xiong; Kwok Wei Shah; Harn Wei Kua. Thermal performance enhancement of cementitious composite containing polystyrene/n-octadecane microcapsules: An experimental and numerical study. Renewable Energy 2021, 169, 335 -357.
AMA StyleTeng Xiong, Kwok Wei Shah, Harn Wei Kua. Thermal performance enhancement of cementitious composite containing polystyrene/n-octadecane microcapsules: An experimental and numerical study. Renewable Energy. 2021; 169 ():335-357.
Chicago/Turabian StyleTeng Xiong; Kwok Wei Shah; Harn Wei Kua. 2021. "Thermal performance enhancement of cementitious composite containing polystyrene/n-octadecane microcapsules: An experimental and numerical study." Renewable Energy 169, no. : 335-357.
The concepts of smart building (SB) and smart facilities management (SFM) are crucial as they aim to uplift occupants’ living standards through information and communication technology. However, the current network possesses several challenges to SFM, due to low bandwidth, high latency, and inability to connect a high amount of IoT (Internet of things) devices. 5G technology promises high-class network services with low latency, high bandwidth, and network slicing to achieve real-time efficiency. Moreover, 5G promises a more sustainable future as it will play a crucial role in reducing energy consumption and shaping future applications to achieve higher sustainability goals. This paper discusses the current challenges and benefits of implementing 5G in various use cases in SFM applications. Furthermore, this paper highlights the Singapore government rollout plan for 5G implementation and discusses the roadmap of SFM use case development initiatives undertaken by 5G Advanced BIM Lab (Department of Building, National University of Singapore) in alignment with the 5G implementation plan of Singapore. Under these 5G SFM projects, the lab seeks to develop state-of-the-art 5G use cases in collaboration with various industry partners and developed a framework for teaching and training to enhance students’ learning motivation and help mid-career professionals to upskill and upgrade themselves to reap multiple benefits using the 5G network. This article will serve as a benchmark for researchers and industries for future progress and development of SFM systems by leveraging 5G networks for higher sustainability targets and implementing teaching and learning programs to achieve greater organizational excellence.
Michael Chew; Evelyn Teo; Kwok Shah; Vishal Kumar; Ghassan Hussein. Evaluating the Roadmap of 5G Technology Implementation for Smart Building and Facilities Management in Singapore. Sustainability 2020, 12, 10259 .
AMA StyleMichael Chew, Evelyn Teo, Kwok Shah, Vishal Kumar, Ghassan Hussein. Evaluating the Roadmap of 5G Technology Implementation for Smart Building and Facilities Management in Singapore. Sustainability. 2020; 12 (24):10259.
Chicago/Turabian StyleMichael Chew; Evelyn Teo; Kwok Shah; Vishal Kumar; Ghassan Hussein. 2020. "Evaluating the Roadmap of 5G Technology Implementation for Smart Building and Facilities Management in Singapore." Sustainability 12, no. 24: 10259.
Kwok Wei Shah; Ghasan Fahim Huseien. Inorganic nanomaterials for fighting surface and airborne pathogens and viruses. Nano Express 2020, 1, 032003 .
AMA StyleKwok Wei Shah, Ghasan Fahim Huseien. Inorganic nanomaterials for fighting surface and airborne pathogens and viruses. Nano Express. 2020; 1 (3):032003.
Chicago/Turabian StyleKwok Wei Shah; Ghasan Fahim Huseien. 2020. "Inorganic nanomaterials for fighting surface and airborne pathogens and viruses." Nano Express 1, no. 3: 032003.
Climate change is anticipated to have a major impact on concrete structures through increasing rates of deterioration as well the impacts of extreme weather events. The deterioration can affect directly or indirectly climate change in addition to the variation in the carbon dioxide concentration, temperature and relative humidity. The deterioration that occurs from the very beginning of the service not only reduces the lifespan of the concretes but also demands more cement to maintain the durability. Meanwhile, the repair process of damaged parts is highly labor intensive and expensive. Thus, the self-healing of such damages is essential for the environmental safety and energy cost saving. The design and production of the self-healing as well as sustainable concretes are intensely researched within the construction industries. Based on these factors, this article provides the materials and methods required for a comprehensive assessment of self-healing concretes. Past developments, recent trends, environmental impacts, sustainability, merits and demerits of several methods for the production of self-healing concrete are discussed and analyzed.
Kwok Wei Shah; Ghasan Fahim Huseien. Biomimetic Self-Healing Cementitious Construction Materials for Smart Buildings. Biomimetics 2020, 5, 47 .
AMA StyleKwok Wei Shah, Ghasan Fahim Huseien. Biomimetic Self-Healing Cementitious Construction Materials for Smart Buildings. Biomimetics. 2020; 5 (4):47.
Chicago/Turabian StyleKwok Wei Shah; Ghasan Fahim Huseien. 2020. "Biomimetic Self-Healing Cementitious Construction Materials for Smart Buildings." Biomimetics 5, no. 4: 47.
Passive daytime radiative cooling represents one of the boldest answers to tackle the future cooling needs of the built environment and to mitigate urban heat island effects. Recent developments in the field targeted sub-ambience with several successful examples. On the other side, heating demands may get exacerbated unless effective countermeasures against overcooling are identified, especially in wintertime or heating-dominated climates. This review aims at collecting state-of-the-art technologies and techniques to dynamically control the heat transfer to and from the radiative emitter and ultimately modulate its cooling capacity. Potential solutions are selected from different applicative fields, including spacecraft thermal control, thermal camouflage and electronics. Environmentally-responsive solutions are analyzed in depth given their perfect match with radiative cooling design requirements. Among them, VO2-tuned Fabry-Perot resonators are given particular emphasis, owing to their proven applicability. Active solutions are presented for completeness, but in less detail. Underlying principles, structural composition and experimental/simulated results are detailed and discussed to identify prominent pathways towards technically and economically effective integration in the built environment.
Giulia Ulpiani; Gianluca Ranzi; Kwok Wei Shah; Jie Feng; Mattheos Santamouris. On the energy modulation of daytime radiative coolers: A review on infrared emissivity dynamic switch against overcooling. Solar Energy 2020, 209, 278 -301.
AMA StyleGiulia Ulpiani, Gianluca Ranzi, Kwok Wei Shah, Jie Feng, Mattheos Santamouris. On the energy modulation of daytime radiative coolers: A review on infrared emissivity dynamic switch against overcooling. Solar Energy. 2020; 209 ():278-301.
Chicago/Turabian StyleGiulia Ulpiani; Gianluca Ranzi; Kwok Wei Shah; Jie Feng; Mattheos Santamouris. 2020. "On the energy modulation of daytime radiative coolers: A review on infrared emissivity dynamic switch against overcooling." Solar Energy 209, no. : 278-301.
To adequately develop the application of marine resources for island construction and effectively promote the sustainability of industrial resources, this paper investigates the feasibility of using seawater and coral or sea sand as replacements for freshwater and river sand in alkali-activated mortars (AAMs) containing ground blast furnace slag (GBFS), fly ash (FA), and silica fume (SF). Five different mortar mixtures were designed: seawater and coral sand alkali-activated mortar (SC-AAM), seawater and sea sand alkali-activated mortar (SS-AAM), freshwater and river sand alkali-activated mortar (FR-AAM), seawater and coral sand cement mortar (SC-OPC), and freshwater and river sand cement mortar (FR-OPC). The differences in the workability (slump), setting time, compressive strength, flexural strength, and drying shrinkage of the prepared cement mortars and AAMs were compared. Then, the microstructure and crystalline phases of the mortar samples were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The experimental results indicated that the utilization of seawater and coral or sea sand promoted the formation of C-S-H gel phases. Additionally, the existence of coral sand decreased the slump and initial setting time of the mortars due to the high water absorption and porosity of the coral aggregate. The SC-AAM exhibited higher compressive and flexural strengths at an early age and had a lower drying shrinkage than other AAMs, which can be attributed to the natural internal curing effect of the coral sand and the dense interfacial transition zone between the aggregate and the binders. The weak strength of coral sand had no effect on the strength development of the mortars in AAM production. However, the SS-AAM had a relatively low compressive strength and a large drying shrinkage in comparison to other mortar samples due to the existence of more free water.
Bai Zhang; Hong Zhu; Kwok Wei Shah; Zhiqiang Dong; Jie Wu. Performance evaluation and microstructure characterization of seawater and coral/sea sand alkali-activated mortars. Construction and Building Materials 2020, 259, 120403 .
AMA StyleBai Zhang, Hong Zhu, Kwok Wei Shah, Zhiqiang Dong, Jie Wu. Performance evaluation and microstructure characterization of seawater and coral/sea sand alkali-activated mortars. Construction and Building Materials. 2020; 259 ():120403.
Chicago/Turabian StyleBai Zhang; Hong Zhu; Kwok Wei Shah; Zhiqiang Dong; Jie Wu. 2020. "Performance evaluation and microstructure characterization of seawater and coral/sea sand alkali-activated mortars." Construction and Building Materials 259, no. : 120403.
As a promising climate change mitigation technology, radiative cooling presents an economical and environmental-friendly approach to alleviate cities from overheating and urban heat island. Based on the fundamental theory, this study comprehensively reviews the materials composition and nano/microstructures underlying the radiative cooling technology. The study summarizes the primary six properties of the selective emitting material, reflecting material, back-mirror material, matrix material, insulation material and dynamic switching material, in terms of their morphologies, substrates, properties, and performances. The configuration of radiative cooling systems mostly follows the two essential designs, namely “multi-layered structures” composed of multiple continuous nano/micro-layers or “nano/micro-particle structures” consisting of discrete nano/microparticles or a combination of both. Cooling potential and end-applications on buildings were reviewed, including cool roofs, PV cooling and water cooling. At the end of this review, we present our recommendations on the combining “multilayer” and “nanostructure” designs for better design radiative cooling composites from a materialistic perspective. Unlike previous studies, our review provides a unique overview of nanomaterials and composite structures, leading to better design configuration and optimisation of radiative cooling end-applications.
Wenxin Li; Yanru Li; Kwok Wei Shah. A materials perspective on radiative cooling structures for buildings. Solar Energy 2020, 207, 247 -269.
AMA StyleWenxin Li, Yanru Li, Kwok Wei Shah. A materials perspective on radiative cooling structures for buildings. Solar Energy. 2020; 207 ():247-269.
Chicago/Turabian StyleWenxin Li; Yanru Li; Kwok Wei Shah. 2020. "A materials perspective on radiative cooling structures for buildings." Solar Energy 207, no. : 247-269.
Buildings account for about 30% of the final energy consumption and nearly one-third of the global carbon emissions. The reduction of energy use in buildings has therefore become a pressing issue. Building envelopes such as windows, roofs, and walls determine the cooling energy demand to a considerable extent. Nanomaterials with their remarkable reflective and emissive properties have found to be effective in developing energy-efficient building envelopes with excellent passive cooling performance. Such functional nanomaterials include gold, silver, zinc oxide, tin oxide, vanadium oxide, silica, silicon carbide, titanium dioxide, hafnium oxide, etc. This chapter presents an in-depth overview of the recent advances in these nanomaterials, nanocomposites, and nanosized structures for reducing building heat gain. The focuses are particularly put on two promising technologies which include transparent solar reflective nanocoatings and nano-based daytime radiative cooling. The former can be used for near-infrared shielding of glass, while the latter has a great potential to emit excess solar heat to outer space. For each technology, it starts with a brief introduction of the fundamental principles and followed by the commonly used materials, structures, as well as the characterization results. Then, the state-of-the-art applications in cool windows and cool roofs are reviewed with analyzing the technological feasibility and prospects. Furthermore, the benefits, limitations, and challenges of these emerging passive cooling nanotechnologies have been identified, and the future outlook is also outlined.
Kwok Wei Shah; Teng Xiong. Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes. Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications 2020, 1 -28.
AMA StyleKwok Wei Shah, Teng Xiong. Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes. Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications. 2020; ():1-28.
Chicago/Turabian StyleKwok Wei Shah; Teng Xiong. 2020. "Nanomaterials and Nanocomposites for Energy-Efficient Building Envelopes." Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications , no. : 1-28.
Dispersing thermally conductive nanostructures is an effective method to improve the thermal performance of phase change materials (PCMs). For this purpose, nanocarbons, nanometals, and nano metal oxides have been used to develop nano-enhanced phase change materials (NePCMs) with unique thermal properties. However, review papers focusing on the numerical simulations of NePCMs are still scarce. The present review provides a comprehensive overview of the latest numerical studies on NePCMs for thermal energy storage (TES). These studies are mainly based on single-phase approaches, and the simulation results largely depend on the used prediction models of effective thermophysical properties. Accordingly, the most common numerical methods and prediction models are reviewed to address their advantages and limitations. Then, the focus is placed on melting and solidification of NePCMs inside different containers, including rectangular cavities, tubes, cylinders, spheres, and annulus. In-depth insights are given into the effects of nanostructure type, morphology, size, and concentration on heat storage and release performance. The pros and cons of dispersing nanoparticles and other heat transfer enhancement techniques are also compared, such as mounting fins and using porous foams. Moreover, a critical discussion is presented to identify the reasons for the discrepancy between simulation and experiment, as well as the research gaps and future directions. This review aims to update the existing NePCM studies using different simulation techniques, and to reveal the basic phase change behavior of NePCMs from the reported results.
Teng Xiong; Long Zheng; Kwok Wei Shah. Nano-enhanced phase change materials (NePCMs): A review of numerical simulations. Applied Thermal Engineering 2020, 178, 115492 .
AMA StyleTeng Xiong, Long Zheng, Kwok Wei Shah. Nano-enhanced phase change materials (NePCMs): A review of numerical simulations. Applied Thermal Engineering. 2020; 178 ():115492.
Chicago/Turabian StyleTeng Xiong; Long Zheng; Kwok Wei Shah. 2020. "Nano-enhanced phase change materials (NePCMs): A review of numerical simulations." Applied Thermal Engineering 178, no. : 115492.
The recycling of millions of tons of glass bottle waste produced each year is far from optimal. In the present work, ground blast furnace slag (GBFS) was substituted in fly ash-based alkali-activated mortars (AAMs) for the purpose of preparing glass bottle waste nano-powder (BGWNP). The AAMs mixed with BGWNP were subsequently subjected to assessment in terms of their energy consumption, economic viability, and mechanical and chemical qualities. Besides affording AAMs better mechanical qualities and making them more durable, waste recycling was also observed to diminish the emissions of carbon dioxide. A more than 6% decrease in carbon dioxide emissions, an over 16% increase in compressive strength, better durability and lower water absorption were demonstrated by AAM consisting of 5% BGWNP as a GBFS substitute. By contrast, lower strength was exhibited by AAM comprising 10% BGWNP. The conclusion reached was that the AAMs produced with BGWNP attenuated the effects of global warming and thus were environmentally advantageous. This could mean that glass waste, inadequate for reuse in glass manufacturing, could be given a second life rather than being disposed of in landfills, which is significant as concrete remains the most commonplace synthetic material throughout the world.
Mostafa Samadi; Kwok Wei Shah; Ghasan Fahim Huseien; Nor Hasanah Abdul Shukor Lim. Influence of Glass Silica Waste Nano Powder on the Mechanical and Microstructure Properties of Alkali-Activated Mortars. Nanomaterials 2020, 10, 324 .
AMA StyleMostafa Samadi, Kwok Wei Shah, Ghasan Fahim Huseien, Nor Hasanah Abdul Shukor Lim. Influence of Glass Silica Waste Nano Powder on the Mechanical and Microstructure Properties of Alkali-Activated Mortars. Nanomaterials. 2020; 10 (2):324.
Chicago/Turabian StyleMostafa Samadi; Kwok Wei Shah; Ghasan Fahim Huseien; Nor Hasanah Abdul Shukor Lim. 2020. "Influence of Glass Silica Waste Nano Powder on the Mechanical and Microstructure Properties of Alkali-Activated Mortars." Nanomaterials 10, no. 2: 324.
Nowadays, alkali-activated binders based industrial and agricultural wastes have been introduced as the environmental friendly materials with high durability performance. We evaluate the performance of alkali-activated mortars (AAMs) incorporated with fly ash (FA) and ground blast furnace slag (GBFS) as surface repair materials useful in construction sector. Various levels of GBFS replacing FA were blended and activated via low concentration of the alkaline activator solution. The fresh and hardened state properties of these AAMs including the flow and setting time, compressive, flexural and tensile strengths, abrasion resistance, bond strength and compatibility with the base concrete substrate (NC) tests were performed. The microstructures and related characteristics of such mortars were also examined. The bond strength and other mechanical properties of the AAMs were enhanced when FA was replaced by GBFS in the presence of low alkaline solution contents. The early bond strength after 24 h was increased from 1.8 MPa to 2.4 MPa when the GBFS level was raised from 30 to 70%, respectively. This increase in the AAMs bond strength and improvement in the compressive strength as well as microstructure were ascribed to the formation of more C-(A)-S-H due to the increase in the calcium content. The obtained excellent abrasion-erosion resistance, freeze-thaw cycling resistance and high compatibility with the concrete substrate confirmed the effectiveness of the proposed AAMs as high performance repair material effective for the damaged concrete surfaces.
Ghasan Fahim Huseien; Kwok Wei Shah. Performance evaluation of alkali-activated mortars containing industrial wastes as surface repair materials. Journal of Building Engineering 2020, 30, 101234 .
AMA StyleGhasan Fahim Huseien, Kwok Wei Shah. Performance evaluation of alkali-activated mortars containing industrial wastes as surface repair materials. Journal of Building Engineering. 2020; 30 ():101234.
Chicago/Turabian StyleGhasan Fahim Huseien; Kwok Wei Shah. 2020. "Performance evaluation of alkali-activated mortars containing industrial wastes as surface repair materials." Journal of Building Engineering 30, no. : 101234.
This study explored rheological and hardened-state properties of self-compacting alkali-activated concrete (SCAAC) incorporating ceramic tile powder waste (CPW) for construction activities. Samples containing 100% ground blast furnace slag (GBFS) were used as reference. Test data revealed that the mini-slump flow enhanced, while the plastic viscosity of SCAAC reduced when 50% or higher concentration of CPW was mixed with GBFS. Also, CPW affected the workability and plastic viscosity considerably when used in higher concentration. The strength decreased as GBFS substitution with CPW increased. In conclusion, the chemical structure, capacity and water assimilation of GBFS underpinned the rheological behaviour of SCCAC.
Ghasan Fahim Huseien; Abdul Rahman Mohd Sam; Kwok Wei Shah; Jahangir Mirza. Effects of ceramic tile powder waste on properties of self-compacted alkali-activated concrete. Construction and Building Materials 2019, 236, 117574 .
AMA StyleGhasan Fahim Huseien, Abdul Rahman Mohd Sam, Kwok Wei Shah, Jahangir Mirza. Effects of ceramic tile powder waste on properties of self-compacted alkali-activated concrete. Construction and Building Materials. 2019; 236 ():117574.
Chicago/Turabian StyleGhasan Fahim Huseien; Abdul Rahman Mohd Sam; Kwok Wei Shah; Jahangir Mirza. 2019. "Effects of ceramic tile powder waste on properties of self-compacted alkali-activated concrete." Construction and Building Materials 236, no. : 117574.
Nowadays, geopolymer with alkali activation binders are introduced as alternative environmentally friendly construction materials to the ordinary Portland cement for solving the carbon dioxide emission and high energy consumption problems. In the construction sectors worldwide, the durability of concrete is the major concern. Concretes produced by recycling the agricultural and industrial wastes were shown to be environmentally friendly with improved durability performance. In this view, present paper examines the effects of fly ash (FA) as replacement agent to GBFS on the durability performance of synthesized self-compact alkali-activated concrete (SCAACs). Six concrete mixes each with a different percentage of FA (30, 40, 50, 60 and 70%) in place of GBFS were designed. A control mixture with 100% GBFS content was used as base specimen to compare other five mixes. Properties such as filling and passing ability, compressive strength, drying shrinkage, carbonation depth and resistance to sulfuric acid were measured. The life cycle of proposed SCAACs were assessed in terms of CO2 emission, cost and saving energy. The resilience and the workability of the SCAAC mixtures were improved when FA was substituted with GBFS at 40%, 50% and 60%. Addition of FA could largely enhance the SCAACs durability and exhibit superior performance against sulphuric acid attack. Likewise, concrete mixtures containing FA of 50% and above showed reduction in CO2 emission over 20%, cost about 15% as well as energy consumption almost 18%. It was concluded that by substituting GBFS by FA a potential solution to the issue of trying to reduce CO2 emission and contribution to a healthier environment can be achieved.
Ghasan Fahim Huseien; Kwok Wei Shah. Durability and life cycle evaluation of self-compacting concrete containing fly ash as GBFS replacement with alkali activation. Construction and Building Materials 2019, 235, 117458 .
AMA StyleGhasan Fahim Huseien, Kwok Wei Shah. Durability and life cycle evaluation of self-compacting concrete containing fly ash as GBFS replacement with alkali activation. Construction and Building Materials. 2019; 235 ():117458.
Chicago/Turabian StyleGhasan Fahim Huseien; Kwok Wei Shah. 2019. "Durability and life cycle evaluation of self-compacting concrete containing fly ash as GBFS replacement with alkali activation." Construction and Building Materials 235, no. : 117458.
Organic materials have gained considerable attention for electrochromic (EC) applications owing to improved EC performance and good processability. As a class of well-recognized organic EC materials, viologens have received persistent attention due to the structural versatility and property tunability, and are major active EC components for most of the marketed EC devices. Over the past two decades, extensive efforts have been made to design and synthesize different types of viologen-based materials with enhanced EC properties. This review summarizes chemical structures, preparation and EC properties of various latest viologen-based electrochromes, including small viologen derivatives, main-chain viologen-based polymers, conjugated polymers with viologen side-chains and viologen-based organic/inorganic composites. The performance enhancement mechanisms are concisely discussed. The current marketed viologens-based electrochromic devices (ECDs) are briefly introduced and an outlook on the challenges and future exploration directions for viologen-based materials and their ECDs are also proposed.
Kwok Wei Shah; Su-Xi Wang; Debbie Xiang Yun Soo; Jianwei Xu. Viologen-Based Electrochromic Materials: From Small Molecules, Polymers and Composites to Their Applications. Polymers 2019, 11, 1839 .
AMA StyleKwok Wei Shah, Su-Xi Wang, Debbie Xiang Yun Soo, Jianwei Xu. Viologen-Based Electrochromic Materials: From Small Molecules, Polymers and Composites to Their Applications. Polymers. 2019; 11 (11):1839.
Chicago/Turabian StyleKwok Wei Shah; Su-Xi Wang; Debbie Xiang Yun Soo; Jianwei Xu. 2019. "Viologen-Based Electrochromic Materials: From Small Molecules, Polymers and Composites to Their Applications." Polymers 11, no. 11: 1839.
Transparent nanomaterial-based solar cool coatings (nSCCs) are composite materials made up of transparent thin-layered substrates incorporated with nanosized additives for the purpose of reducing solar heat gain and passive cooling in buildings. This review summarizes recent state-of-the-art development of transparent nSCCs from a nanomaterial’s perspective and their key applications in buildings. It is well known that solar heat gain into buildings through building envelopes is the dominant factor accounting for up to 60% of cooling loads, resulting in significantly high building energy consumption. Therefore, there is a strong interest in the research into nSCCs as a solar heat gain reduction and passive cooling method for building energy savings. To date, very few reviews have been reported for such nSCCs from the view of nanostructured materials; this review consequently seeks to highlight the roles of nanotechnology and nanomaterials in enhancing the performance of solar cool coatings. Since opaque cool coatings have been widely reviewed in the past and the related applications are limited to concrete walls and rooftops, only transparent clear nSCCs are discussed here, predominantly due to the fast gaining popularity of transparent glass facades and glazed building envelopes. Consequently, in this review transparent clear nSCCs are classified based on the types of nanosized additives and solar reduction mechanisms, followed by the discussion with respect to their synthesis techniques, morphologies, optical performance and their key building applications. This review would be useful for the scientific community and building industry to better understand the applications of nanomaterials in building and construction.
Long Zheng; Teng Xiong; Kwok Wei Shah. Transparent nanomaterial-based solar cool coatings: Synthesis, morphologies and applications. Solar Energy 2019, 193, 837 -858.
AMA StyleLong Zheng, Teng Xiong, Kwok Wei Shah. Transparent nanomaterial-based solar cool coatings: Synthesis, morphologies and applications. Solar Energy. 2019; 193 ():837-858.
Chicago/Turabian StyleLong Zheng; Teng Xiong; Kwok Wei Shah. 2019. "Transparent nanomaterial-based solar cool coatings: Synthesis, morphologies and applications." Solar Energy 193, no. : 837-858.
The discovery of the aggregation-induced emission (AIE) phenomenon in the early 2000s not only has overcome persistent challenges caused by traditional aggregation-caused quenching (ACQ), but also has brought about new opportunities for the development of useful functional molecules. Through the years, AIE luminogens (AIEgens) have been widely studied for applications in the areas of biomedical and biological sensing, chemosensing, optoelectronics, and stimuli responsive materials. Particularly in the application of chemosensing, a myriad of novel AIE-based sensors has been developed to detect different neutral molecular, cationic and anionic species, with a rapid detection time, high sensitivity and high selectivity by monitoring fluorescence changes. This review thus summarises the recent development of AIE-based chemosensors for the detection of anionic species, including halides and halide-containing anions, cyanides, and sulphur-, phosphorus- and nitrogen- containing anions, as well as a few other anionic species, such as citrate, lactate and anionic surfactants.
Ming Hui Chua; Kwok Wei Shah; Hui Zhou; Jianwei Xu. Recent Advances in Aggregation-Induced Emission Chemosensors for Anion Sensing. Molecules 2019, 24, 2711 .
AMA StyleMing Hui Chua, Kwok Wei Shah, Hui Zhou, Jianwei Xu. Recent Advances in Aggregation-Induced Emission Chemosensors for Anion Sensing. Molecules. 2019; 24 (15):2711.
Chicago/Turabian StyleMing Hui Chua; Kwok Wei Shah; Hui Zhou; Jianwei Xu. 2019. "Recent Advances in Aggregation-Induced Emission Chemosensors for Anion Sensing." Molecules 24, no. 15: 2711.