This paper presents a detailed review of wood-cement composites, focusing on their material characteristics, mechanical performance, and evolution as a class of sustainable and cleaner construction material. Formed by combining wood particles with cementitious binders, these composites offer a unique alternative to conventional building materials by utilising renewable resources, supporting cleaner production practices, and reducing embodied carbon. The review is based on an extensive compilation of experimental data drawn from the literature, covering a wide range of studies that examine the effects of wood species, binder types, fabrication methods, and testing protocols on composite performance. Particular attention is given to the influence of binder composition, wood particle size, and mix ratios on key mechanical properties, including compressive strength, flexural strength, density, and toughness. These parameters are critically assessed to establish their role in governing the structural reliability and functional suitability of the composites. The review also addresses production techniques and standardised testing methods, identifying common challenges such as the chemical incompatibility between lignocellulosic materials and cement hydrates, and summarising approaches developed to mitigate these issues. Recent developments, including the use of alkali-activated binders, are examined for their potential to enhance material performance and support cleaner material development. By consolidating existing research and identifying gaps in current knowledge, this paper aims to support further technical advancement and inform the practical implementation of wood-cement composites in environmentally responsible construction.

This study investigated the geometric and thermohydraulic characteristics of flat- and curve-type singleembossed pillow-plate channels (SEPPCs) elaborately for the first time. These examinations revealed that estimating mean hydraulic diameters (MHDs) in various SEPPCs remains a significant challenge, primarily due to the intricate channel structures. Additionally, assuming identical constant wall temperatures for the thinner and thicker plates of SEPPCs causes thermal uncertainties regarding the influence of conduction heat transfer in these plates. This research addresses these challenges in stainless steel, aluminum, and copper SEPPCs. A procedure for hydroforming simulation based on the finite element method was established to model the structure of SEPPCs reliably. By defining novel dimensionless parameters, improved MHD correlations were developed with estimation errors of 13.54 % and -8.68 % for flat- and curve-type SEPPCs, respectively, compared to simulation results. Compared to existing methods, these correlations improved MHD estimations and identified the MHD extremums. Conjugate heat transfer simulations were applied to study heat transfer in the plates of SEPPCs, revealing how material properties, geometric configurations, and fluid convection shaped temperature distributions. Analysis of the periodic-bulk-temperature ratio revealed that simulations using constant wall temperatures were insufficient to accurately represent the behavior of SEPPCs. Moreover, the development of optimized artificial neural networks facilitated the evaluation of the contributing parameters and resulted in accurate predictions of MHDs in both flat- and curve-type SEPPCs, as well as the average channel plate temperatures in flat-type SEPPCs. The findings of this study on MHD estimations and the critical role of channel wall temperatures offer a solid foundation for advancing research across diverse SEPPC configurations in the future.

The complex geometries of outer channels in pillow-plate heat exchangers (PPHEs) pose significant challenges for developing accurate and generalized thermohydraulic correlations, limiting their broader industrial adoption. This study introduced two artificial neural network models, each integrated with a two-stage optimization algorithm, to predict key thermohydraulic parameters-mean hydraulic diameters (MHDs), heat transfer coefficients, and pressure drop factors-across diverse geometric configurations. The first neural network incorporated novel structural parameters and predicted MHDs with a maximum error of 2.22%. Using novel structural parameters, a new correlation was derived for MHD estimation in various outer channels, outperforming the existing method (reducing the maximum MHD estimation error from 23.01% to 2.48%), and enabling extremum MHD determination based on geometry variations for the first time. Such improvements in estimating MHDs directly affect the determination of other thermohydraulic parameters in the outer channel, including Reynolds number. Using computational fluid dynamics simulations, the second network accurately predicted turbulent flow Darcy friction factors and Nusselt numbers, with maximum errors of 8.75% and 9.09%, respectively. Structural parameter analysis performed by neural networks-covering inner and outer channel maximum heights, welding spot diameter, and diagonal spans-highlighted the influence of surface waviness on outer channel thermohydraulic behavior. This waviness resulted in thermohydraulic performance enhancements ranging from 1.2 to 2.4 compared to flat-wall channels. These findings establish a robust framework for precise estimation of thermohydraulic parameters and Reynolds numbers, as well as modeling outer channel behavior in PPHEs, offering a promising foundation for future design.

Recycling industrial waste into construction materials is becoming a fundamental strategy, offering a hopeful path toward sustainable construction practices. This study focuses on the innovative reuse of end-of-service wood and crumb rubber to develop environmentally favorable materials. Their high availability, lightweight properties, and high-energy absorption capacity make them highly suitable as additives in masonry unit production. Furthermore, using them with sustainable binding material, such as geopolymer, enhances the overall sustainability of the masonry, facilitating rapid strength development and enhancing durability while providing increased protection against fire and weathering. The study involved the development of an optimal mix design, which can potentially be used for the production of load-bearing and non-load-bearing masonry units. This was achieved by examining various proportions of wood, as well as combinations of wood and rubber, using a partial–factorial experimental design. The results show that wood-to-binder ratios ranging from 0.2 to 0.4 can potentially be used for the production of wood–geopolymer masonry units. Additionally, a ratio of 0.3 (with 50

The intricate structure of pillow-plate channels (PPCs) in pillow-plate heat exchangers (PPHEs) results in challenges in estimating thermohydraulic features, such as heat transfer coefficients. The existing heat transfer correlations for fluids in the inner channel (within a PPC) and the outer channel (between two adjacent PPCs) are limited to channels with a specific or narrow range of geometric parameters. Moreover, there are no established heat transfer correlations for certain types of outer channels. After two decades, this study overcomes these limitations for the first time by considering the impact of geometric parameters on estimating heat transfer coefficients, proposing generalized modified Dittus-Boelter correlations for the Nusselt numbers in both channels. An accurate hydroforming simulation for PPCs was employed to create the structure of both channels and their fluid domains. Computational fluid dynamics simulations of incompressible single-phase turbulent flows in these fluid domains were used to analyze the Nusselt number dependence in the inner and outer channels against effective dimensionless structural parameters. Subsequently, modified Dittus-Boelter correlations are presented based on simulation results and Reynolds analogy for a broad range of geometric parameters. These correlations consider the impact of channel heights, welding spot sizes, and configurations, and are applicable for turbulent Nusselt numbers (with Prandtl (Pr) numbers between 1 and 13). Using these correlations for various inner and outer channels gave errors between -15.36 % and +14.24 % (for 1000 <= Reynolds (Re) number <= 20,500) and -7.47 % to +7.86 % (for 5000 <= Re <= 20,000), respectively. The generalized Nusselt correlations provide a framework for future developments in enhancing PPHE thermal design algorithms.

Determining the thermohydraulic characteristics in pillow-plate channels (PPCs) is challenging due to their intricate structure. This work introduces novel geometric parameters specific to a flow cross-sectional area in PPCs and employs a two-stage optimized algorithm for artificial neural networks (ANNs) to enhance its thermohydraulic feature predictions significantly. These parameters enable practical consideration of various PPC structures and help develop a new mean hydraulic diameter (MHD) correlation. Besides the general parameters in PPCs, the novel parameters are incorporated into two two-stage optimized ANNs to predict thermohydraulic characteristics. The traditional method for approximating MHD neglects the actual channel structure and only considers the maximum channel height, leading to deviations of −16.93% to +52.00% from finite element simulated PPCs. Our new MHD correlation and the first ANN, which consider the channel structure, yield more accurate results with deviations of −6.97% to +13.07% and −7.85% to +13.21%, respectively. The second ANN predicts Nusselt numbers and Darcy friction factors with errors of less than 13.04% and 15.83%, respectively, across a wide range of geometric and thermohydraulic conditions. These promising results and presenting the maximum and minimum possible MHD in PPCs by the novel correlation pave the way for more accurate future studies and industrial development of PPCs.

Masonry units have been fundamental to building construction for over 6,000 years, making them one of the oldest and most widely used materials in the industry. However, their production using ordinary Portland cement has significant environmental impacts, including high carbon dioxide emissions and depletion of natural resources. This highlights the need for more sustainable alternatives. One promising option is the use of recycled aggregates from construction and demolition waste in masonry unit manufacturing. This paper investigates the use of chipped waste timber as aggregates, bound together with geopolymer cement made from industrial by-products such as fly ash and slag. The result is a new type of masonry units, referred to as wood geopolymer masonry units (WGMUs), which were evaluated against established standards and compared with conventional masonry units (CMUs). The innovative WGMUs demonstrated improved ductility and reduced density compared to CMUs, making them easier to handle and lighter in construction. They also have a distinctive, rustic texture and consistent dimensions that meet Australian standards. Although WGMUs exhibited higher water absorption and drying contraction due to their wood content, these characteristics generally remain within acceptable limits, supporting their potential as eco-friendly construction materials.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI

Buildings have a large urban footprint, are one of the greatest consumers of resources and raw materialsMaterials, and are responsible for 40

As the environmental impact of modern society continues to escalate, the construction industry actively pursues environmentally friendly materials to revolutionize its practices. Recycling, especially repurposing end-of-service materials and industrial wastes, emerges as a pivotal strategy offering a promising path towards sustainable construction. This study focuses on the innovative reuse of end-of-service wood, crumb rubber, and cenosphere with geopolymer binder to produce sustainable alternatives to masonry units. The study was conducted in two stages. In the first stage, cube samples were produced and tested to establish an optimal mix design. Results indicated that as the relative volume of waste increased, the compressive strength decreased. The compressive strength of the wood geopolymer composite decreased from 25 MPa to 4 MPa as the wood-to-binder ratio increased from 0.1 to 0.5. An increasing trend was observed for density with the increase of the rubber-to-wood ratio. The compressive strength also increased with the increase of the rubber-to-wood ratio for most of the investigated ranges. As fly ash is gradually replaced by cenospheres, a significant decrease in compressive strength was noted, about 70% and 80% for wood-to-binder (ratios of 0.2 and 0.3, respectively). In the second stage, three distinct types of masonry units were produced and tested based on the optimized mix design. The compressive strength results indicated promising performance, with wood-geopolymer masonry units exhibiting a strength of 8.39 MPa, wood-rubber-geopolymer masonry units achieving 8.32 MPa, and wood-cenosphere-geopolymer masonry units resulting in 7.33 MPa. While these values fell below the target 10 MPa, it is noteworthy that wood-geopolymer masonry units and wood-rubber-geopolymer masonry units met the minimum compressive strength requirements of some standards and demonstrated significantly better ductility compared to traditional masonry units. The results showcase significant promise in the viability and performance of these innovative masonry units.

The impact of building construction on the environment is significant. Occupying large land areas (urban footprint), buildings are one of the most important consumers of resources and raw materials. They are responsible for 38% of greenhouse gas (GHG) emissions in both developed and developing countries. Therefore, incorporating sustainability and resilience into all aspects of urban infrastructure has become necessary. To curb emissions, part of the answer lies in the use of construction and building materials made from recycled materials. Bio-sourced materials, like wood chips, combined with a cementitious matrix, offer an alternative to conventional materials. They are sustainable, lightweight, and have good thermal insulation. However, because of their inferior mechanical strength, they have limited use as load-bearing structural parts. Furthermore, the use of Portland cement as a binder still poses some challenges due to its high carbon footprint. This study investigates the potential of wood-geopolymer composites for better mechanical performance and environmental sustainability. A 6x2x2x2 fractional factorial-based experimental design was used to simultaneously study the effect of slag content, wood binder ratio, and alkaline on the compressive strength of the wood-geopolymer composite. The experiments showed encouraging results for developing ambient cured wood geopolymer composites.

Addressing critical societal challenges, such as climate change, resource depletion, and environmental protection, requires sustainable management of resources. This study reports on the results of an experimental program using waste wood, including chromium copper arsenic (CCA) treated wood, to produce ambiently cured geopolymer cement bonded wood composites (WGC), and the results are very encouraging. The composite exhibited a reasonable compressive strength, which ranged between 7 and 27 MPa inversely corresponding to the amount of wood per binder ratio ranging between 0.1 and 0.4, conferring it the possibility of being used as a building material. The compressive strength of the composite with 40% wood chips showed the lowest compressive strength with values of 9.79, 7.29, and 7.92 MPa for decontaminated, CCA-treated, and non-CCA-treated wood chips, respectively. The results indicated that for all the wood per binder ratios, the use of decontaminated wood chips significantly improves the compressive, flexural, and specific strength of the composites, as well as their ductility, compared to non-decontaminated CCA-treated and non-CCA-treated wood chips. This paves the way for using wood waste in sustainability oriented product development and manufacturing.

This work explores how various superplasticisers (SPs), including a lignosulfonate-based (LS), a polynaphthalene-based (PNS) and two polycarboxylate-based (PCE-1 and PCE-2) ones, affected the reaction of a class F fly ash-based geopolymer (FABG) at 60celcius within five days. Setting time, reaction heat, pore solution elemental concentration, and product evolution were investigated. By linking to steps of dissolution, speciation equilibrium, gelation, reorganisation, and polymerisation, it is found that the SPs accelerated the dissolution, advancing the subsequent speciation equilibrium, gelation, and reorganisation, but hindered the polymerisation. More dissolved species can raise paste viscosity, potentially limiting SPs' dispersing effect and reducing initial setting time. PCE-1 and PCE-2 led to a faster dissolution than LS and PNS, while due to the quicker pace of Ca hydration than geopolymer formation, the Ca-based LS and PNS further shortened the initial setting. Hydrogen bonds and cation-bridge attractions between SPs and Si/Al species reduce intermediate products' reactivity, retarding polymerisation and post-hardening stage reaction, disadvantaging FABGs' strength development. Comb-like PCE-2 induced more steric hindrance, causing the most significant retardation. Semi-crystalline products were detected when a linear SP (PNS or decomposed PCE-1) was used, with an unclear impact on FABGs' fresh workability and strength, suggesting further exploration in relevant areas.

Chromated copper arsenate (CCA) is one of the most commonly used waterborne preservatives to protect wood from environmental damage in various outdoor applications. However, the leaching of arsenic and chromium into the environment has been confirmed in recent years. As a result, CCA-treated woods are classified as hazardous waste and must be disposed of in sanitary landfills. In this study, a sustainable reuse option for the spent CCA-treated wood, with a focus on the environmental and economic benefits of the process, is investigated. The pilot-scale decontamination of CCA-treated wood chips is performed with 0.05 M oxalic acid at 45 °C for 4 hours with a solid: liquid ratio of 50 g/L. To increase copper removal, the pH of the leachate is increased by adding sodium hydroxide towards the end of the reaction. Under the optimum operational condition, over 60% of arsenic, 55% of chromium, and 40% of copper ions are removed from the wood chips. These results compared well with the laboratory-scale experiments under the same operating conditions. The decontaminated wood chips were used to make geopolymer cement (GPC) wood composites. Similar blocks were made with CCA-treated wood chips that were not decontamination. To ensure that the GPC-wood blocks are environmentally safe, three basic tests, namely the synthetic precipitation leaching procedure (SPLP), the toxicity characteristics leaching procedure (TCLP), and the accelerated evaluation of preservative leaching (AEPL) test, were performed on both types of blocks. In all tests, the CCA leached from decontaminated GPC-wood blocks was less than 5 mg/L. However, arsenic leached from the contaminated blocks exceeded the environmental limit of 5 mg/L. These results confirmed the environmental safety of GPC-wood blocks made with decontaminated CCA wood, which can be an economical and safe solution for the disposal of CCA waste wood.

Over the last two decades, extensive research has been dedicated to the crisis stemming from fossil fuel usage and its environmental repercussions. This pressing concern has garnered substantial attention due to its potential to disrupt ecological equilibrium and sustainability. Pursuing more efficient and sustainable solutions in the heat exchangers realm has catalyzed the development and optimization of innovative designs, notably pillow-plate heat exchangers (PPHEs). These next-generation heat exchangers offer improved compactness and reduced material requirements, effectively tackling mounting concerns related to energy and resource consumption. Integrating such advancements can mitigate the adverse environmental impact, fostering a greener and more sustainable future. This paper presents an exhaustive review of recent progress in PPHE design and optimization, emphasizing their potential for widespread application across diverse industries. These innovative heat exchangers feature sleek, pillow-like channels, offering exceptional heat transfer capabilities and minimal pressure drops. These attributes position PPHEs as a compelling and eco-conscious alternative to traditional heat exchangers. Nevertheless, the intricate geometries of PPHEs pose challenges for comprehensive research, and existing studies underscore the limited number and scope of their industrial applications. This manuscript thoroughly examines the critical facets of the literature related to various aspects of PPHEs, encompassing manufacturing processes, thermohydraulic channel characteristics, design algorithms, and cost assessments. By meticulously identifying and emphasizing critical research gaps, this work not only underscores the need for further investigation but also sets the stage for future studies to enhance the reliability and performance of PPHEs as a heat transfer equipment solution.

Direct UV-Visible spectrophotometric measurement of copper ions (Cu(II)) in the presence of ferric ions (Fe(III)) using sodium diethyldithiocarbamate (NaDDC) dissolved in absolute ethanol as the colorimetric reagent, was shown to be a rapid and sensitive quantitative test. The copper complex showed a maximum absorption at λ max =435 nm, and Beer’s law was obeyed in the range between 0.5 and 10 ppm, comparable with the analysis with the carbon tetrachloride (CCl 4 ) extraction method. Experiments performed at room temperature optimized the pH and reagent concentration at 6 and 0.2 (w/w%), respectively. The effect of various interfering ions was studied and no colorimetric interference was observed except in the presence of Fe(II) and Co(II) ions. Furthermore, Fe(III) could be masked with citric acid and ammonium hydroxide or phosphoric acid for Fe(III)/Cu(II)<10 (w/w) while a large range of cations was masked with NaEDTA. The validity and accuracy of this method were determined by adding interfering metal ions and comparing the results with inductively coupled plasma optical emission spectroscopy measurements. The method was applied for determining Cu(II) concentration in copper chrome arsenic-treated wood leachate. This method has the potential to replace the CCl 4 extraction method as a safe alternative.

To explain the incompatibility of some superplasticisers with class F fly ash, the effectiveness and mechanisms of superplasticisers based on lignosulfonate (LS), polynaphthalene (PNS) and polycarboxylates (PCE-1 and PCE-2) in dispersing the fly ash pastes were studied. The most effective superplasticisers, PCEs (PCE-1 and PCE-2), produced almost no additional electrostatic repulsion, are adsorbed in low amounts, and exhibited negligible adsorbed layer thickness. It is suggested that the excellent dispersing abilities of PCEs rely on the molecules remaining in the liquid phases of the pastes. For the inefficacy of LS and PNS, the absorption of molecules and bridging flocculation are the most likely causes. Superplasticiser molecules that entered the fly ash through the pores on the fly ash surface lost their dispersing abilities. The highly negatively charged LS and PNS can attract several fly ash particles to form the bridging flocculation, which reduced the dispersion of the fly ash pastes.