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Facility maintenance management (FMM) is essential for ensuring long-term values and to sustain project goals throughout the life cycle delivery process. However, in underdeveloped nations such as Ethiopia, facility maintenance management is an immature and underutilised process that requires a holistic intervention for practical improvement. The main aim of this study was to identify and prioritise critical factors that affect the effectiveness of FMM, with a focus on public universities in Ethiopia. Initially, a total of thirty-three (33) crucial variables were identified with a systematic literature review and desk study. To collect primary data, a survey research design approach was utilised using questionnaires and informant interviews. A total of seventy-five (75) data sets were obtained from 180 online surveys for conducting exploratory factor analysis (EFA). The outcome of the study revealed thirteen (13) critical attributes grouped into four factors that affect the effectiveness of facility maintenance management practises. The final four-factor model includes F1, internal processes and organisation; F2, community culture, learning, and growth; F3, impacts of design and construction quality; and F4, facility maintenance approach and management. This study indicated that facility maintenance management practises in public universities in Ethiopia are immature and require extensive enhancement. The identified influencing factors highlight the need for a comprehensive intervention to promote improved facility maintenance management practises and applications in Ethiopia. Further research is needed to analyse a wider range of attributes and data using confirmatory factor analysis. [ABSTRACT FROM AUTHOR]

The toxicity, persistence, and propensity for accumulation of metals in aquatic environments have raised significant concerns globally. Expansion of urbanization with the growth of industrial and agricultural sectors in Miri City results in a high concentration of pollutants that flow directly into the Miri River. Hence, this study provides a comprehensive analysis of the Miri River water quality, focusing on spatial and temporal variations. River water samples were collected in two different time periods and analysed for physico-chemical parameters includes major ions, nutrients, metals and isotopes. Particularly, the metals were analysed in different size fractions (particulate and colloid) of the suspended solids. Geochemical plots, pollution index, geochemical modelling and factor analysis were used for the data analysis. Interpretation of data reveals that the mean concentration of metals in river water were increased from downstream to the upstream of the river irrespective of the seasons. Major ions were mostly derived from the chemical weathering of source rocks, which was supported by the Gibbs plot. Piper plot indicates the seasonal shifting of water types from Ca-Mg to Na-Cl. Isotopic signatures reveal direct atmospheric precipitation and evaporation were the major origins of river water. Fe was the dominant metal concentration in river water irrespective of the seasons (mean concentration 1.05 mg/L). Fe and Zn were the dominant metal concentration observed in all the 3 size fractions of suspended solids. Industrial activities and seawater influx dominate in the downstream, whereas weathering and agricultural inputs are significant in the upstream of the river. Particulate and colloidal fractions are the major contributors for the metal transport in the midstream and downstream of the river. The outcome of this study offer a thorough understanding of the seasonal elemental distribution at different size fractions, geochemical behaviour and the pollution status of the Miri River. With this knowledge, sustainable management strategies can be developed for this crucial water resource to the benefit of Miri community. [ABSTRACT FROM AUTHOR]

This research investigated the utilization of palm oil waste as a source material for developing an alkali activated binder with alumina-silicate properties. The geopolymer synthesis involved a combination of palm oil fuel ash (POFA) and fly ash (FA), as well as sodium silicate and sodium hydroxide as alkali activator solutions. The study assessed the physical, mechanical, water-transport and thermal performances of the binder, including the influence of oxide ratios on its strength-gain characteristic. The highest strength achieved was 54.7 MPa for a blend of POFA-FA in a ratio of 20:50 with a molarity of NaOH at 12M. The experimental results revealed good water-transport performance due to the dense nature of the binder that restricted water movement. However, the material's insulation performance did not produce significant results with the lowest thermal conductivity value of 0.59 W/mK. Overall, the developed binder has potential industrial applications, as it performed well in the technical aspects studied. [ABSTRACT FROM AUTHOR]

Cellular lightweight concrete (CLC), also known as foamed concrete, has been extensively used in construction for decades. Foamed concrete's properties include low density, excellent thermal conductivity, great workability, and selfcompaction; these features enable foamed concrete to be utilized in various contexts. However, the excessive use of conventional materials in concrete production harms the environment. Therefore, using agro-waste as a material to construct ecologically sustainable structures has numerous practical and financial benefits. Palm oil clinker (POC) is a waste product resulting from solid waste combustion during palm oil extraction. This research focused on the properties of foamed concrete with POC at 0%, 25%, 50%, 75%, and 100% as the fine aggregate replacement to develop lightweight foamed concrete (LFC) with a density of 1300 kg/m3. Besides, the potential of POC powder (POCP) and thermally activated POCP (TPOCP) at 0%, 10%, 20%, and 30% as cement replacements was examined. The development of compressive strength during a 90-day curing period was investigated. In addition, tensile and flexural strengths were assessed and reported, and the elastic modulus of the LFC was discussed. The transport properties of water absorption, porosity, and sorptivity were also investigated. The durability of concrete derivatives can exhibit the product's resistance to chemical attacks and environmental conditions. After 75 days of immersion in hydrochloric acid and magnesium sulfate, the chemical resistivity of the produced LFC was determined by measuring the loss in weight and compressive strength. In addition, the effects of elevated temperatures on the LFC were determined by analyzing the mass loss and compressive strength degradation of specimens exposed to temperatures ranging from 200 to 800 °C. The test results demonstrated that the complete replacement of sand with POC enhanced the compressive strength of LFC by more than 50%. Similarly, POC-based LFC had higher flexural and tensile strengths than normal LFC. Besides, substituting 20% of cement with TPOCP could improve the strength of LFC by 23% during the initial curing days. Utilizing the optimal proportions of POC and POCP could enhance the residual strengths of LFC. Therefore, POC has the potential to be utilized as a fine aggregate and cementitious material to produce sustainable concrete. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction With the emergence of new automation and mechanized technologies in the production and processing of agricultural products in Iran, which aim to accelerate the food supply process, adopting appropriate management models in the field of maintenance becomes inevitable. This is crucial to maintain and enhance the operational reliability of agricultural machinery, tools, and equipment. Furthermore, proper management of various physical assets in the agricultural industry, including operation and maintenance, is one of the most important requirements. This is due to their crucial role in ensuring readiness and high availability during the seasons of planting, cultivating, and harvesting agricultural products. These needs differ from that of other continuous production processes. Materials and Methods To achieve an efficient model in the field of maintenance, the following steps have been investigated: a) Reviewing and identifying the most important criteria and sub-criteria driving the maintenance management. This is based on the previous literature and the experts' opinion. b) Evaluating and prioritizing the main criteria and the interactions between their sub-criteria using the Best-Worst Method (BWM). c) Providing improved solutions for maintenance management of Iranian agro-industries. We decided to employ BWM because, compared to similar methods, it (i) provides more reliable pairwise comparisons, (ii) reduces the possible anchoring bias that may occur during the weighting process by respondents, (iii) is the most data-efficient method, and (iv) provides multiple optimal solutions which increase flexibility when accessing the best weight point. The process of weighting by BWM is summarized in five steps: 1) Determine a set of evaluation criteria identified by the experts or decision-makers. 2) Identify the most important (Best) and the least important (Worst) criteria according to the experts or decision-makers, each of which may have their own Best and Worst. 3) Determine the preference of the Best criterion over all the other criteria using a number from 1 to 9 (where 1 represents equal importance and 9 represents extremely more important). 4) Determine the preference of all the decision criteria over the Worst criterion. 5) Compute optimal weights. Results and Discussion According to the preliminary surveys, the most important criteria in the excellence maintenance model were identified as "organizational management", "human-related factors", and "organizational aspects", respectively. The results of the BWM revealed that sub-criteria such as "top management support," "fund allocation and inventory resource management," and "appropriate maintenance strategies" had the greatest impact on maintenance management in agro-industries, with global weights of 0.108, 0.075, and 0.067, respectively. Additionally, these findings were compared to previous research conducted in the field of agricultural and production system maintenance models. Conclusion The findings of this study could assist managers in revising and developing maintenance management models in the agro-industries. Future studies could consider calculating the interactions among the criteria that were omitted in this study to simplify the evaluation process which might improve the accuracy of weighing criteria. This can be achieved through the combination of the Decision Making Trial and Evaluation Laboratory (DEMATEL) and structural equation modeling. [ABSTRACT FROM AUTHOR]

In recent years, natural pozzolans have been proposed as a way to improve the mechanical and biocompatible properties of concrete. This study investigated the effects of different amounts of nanoparticles, coal slag pozzolan, and their combination on the mechanical properties and durability of concrete. For each mixed design, nine cubic samples of 10 × 10 × 10 cm and 30 × 15 cm were made and then cured in water for 28 days before being tested for compressive and tensile strength. According to the results, pozzolan at about 5% of cement weight increased the compressive strength of concrete compared to samples without pozzolan. Nanoparticles of FeNi3 greatly enhanced the compressive and tensile strength of concrete in most samples containing nanoparticles. The compressive and tensile strength of 28-day concrete increased by 27% and 18%, respectively. Pozzolan (10%) and 2% of FeNi3 (CP10F2) in concrete also reduced the water absorption of the samples, which can improve the durability parameters of concrete. In concrete exposed to sulfuric acid, sample CP0F2 (2% of FeNi3 nanoparticles) had a positive effect on compressive strength, and samples containing 2% of FeNi3 nanoparticles had higher compressive strength than those with pozzolan replacing cement. The simultaneous use of coal slag and FeNi3 nanoparticles has increased the mechanical properties and durability of concrete in addition to reducing cement consumption. [ABSTRACT FROM AUTHOR]

Adopting proper waste management technology in the place of the construction industry to the extent possible to lower the production of new materials and intern reduces the environmental impact pertaining to the industry. In this work, eggshell powder (ESP; waste from the poultry industry) and fly ash (FA; waste from combustion of coal) were utilized as precursors for producing geopolymer and to substitute conventional cement-based construction materials. Three different weight percentage ratios of precursors, namely, 90FA:10ESP, 80FA:20ESP, and 70FA:30ESP were reinforced with two different weight percentages, namely, 15 and 30 wt% of paddy straw in the presence of suitable combinations of sodium silicate and sodium hydroxide to obtain lightweight geopolymer panels. Results received from different analytical tests, namely, density, water absorption, compressive strength, and flexural strength infer that the incorporation of ESP enhances the performance of the geopolymer products to a considerable extent. The specimen sample made using 70FA:30ESP in the absence of paddy straw reinforcement possesses a compressive strength value of 15.64 MPa, which is higher than that of paddy straw reinforced panels. It was observed that there was a reverse trend noticed in the case of flexural behavior on reinforcement of paddy straw, namely, 15 wt% possesses a higher value than that of the panel (70FA:30ESP) made using in the absence of reinforcement. The lowest thermal conductivity value was observed at 0.0633 W/m·K for the sample 90FA:10ESP reinforced with 30% paddy straw. Data from different studies infer that using ESP and paddy straw reinforcement influences strength properties and thermal conductivity. The present study indicates valid information related to the using biowastes for the production of insulation materials and environmental preservation and energy conservation. [ABSTRACT FROM AUTHOR]

Oil palm shell (OPS) in concrete is well studied as an alternative material of fine aggregate in concrete, as a way to use agricultural waste, and helps to contribute to environmental sustainability and economical construction cost. However, OPS addition will lead to lower properties of the concrete, and much research focuses on treating the OPS to overcome it. Many previous works focused on replacement without examining the effect of different particle sizes of OPS. Hence, this study focuses on the performance of concrete with different particle sizes of OPS as sand replacers in concrete at 25% and 50%. The physical and permeability properties of concrete prepared with OPS particle sizes in the ranges between 600µm to 4.75mm (L), 300µm to 1.18mm (M), and of less than 600µm (S) and two different percentages of 25% and 50% by weight as sand replacement are examined. More than 200 cubes, cylinders, and prisms were tested to determine their physical, mechanical, and permeability properties. The workability was measured by the slump height, the mechanical properties by the compressive strength test, flexural strength test, splitting tensile test, ultrasonic pulse velocity (UPV) test, and rebound hammer test. While the permeability properties by the water penetration test, sorptivity test, and rapid chloride permeability test. The findings showed that increasing the particle sizes of OPS would reduce concrete's physical and permeability properties. The optimum OPS particle size for structural concrete grade 30 is less than 600µm. With OPS particles of 600um, green concrete using OPS can be made for medium to low-strength applications in the construction industry. [ABSTRACT FROM AUTHOR]

A lack of adequate building maintenance is a significant obstacle faced by governmental hospitals. This paper evaluates factors that negatively impact building-maintenance practices in Iraq. A literature review was conducted to identify factors affecting maintenance. A list of 42 factors affecting hospital-buildings was collected from previous studies and tested using a structured questionnaire distributed to hospital-maintenance experts. During the data analysis, 76 valid questionnaires were used. Based on the respondents' ratings, the relative-importance index (RII) was used to determine the level of importance of each factor. From the results, it was concluded that twelve factors affect maintenance practices in hospital buildings: faulty design (0.889), lack of funding (0.874), inadequate training (0.871), misuse of building facilities (0.866), construction errors (0.863), lack of work experience (0.858), building age (0.826), individual modifications carried out by the hospital staff (0.826), shortage of maintenance staff (0.824), administrative corruption (0.821), selection of unqualified maintenance contractors (0.816) and unavailability of skilled appointed maintenance personnel (0.808). Understanding these factors' effects is essential for maintenance-department managers to develop strategies for maintaining hospital buildings in Iraq by controlling them, as well as identifying problems and finding appropriate solutions to avoid them. [ABSTRACT FROM AUTHOR]

Artificial neural networks offer a viable route in assessing and understanding the presence and concentration of heavy metals that can cause dangerous complications in the wider context of water quality prediction for the sustainability of the ecosystem. In order to estimate the heavy metal concentrations in Iznik Lake, which is an important water source for the surrounding communities, characterization data were taken from five different water sources flowing into the lake between 2015 and 2021. These characterization results were evaluated with IBM SPSS Statistics 23 software, with the addition of the lake water quality system. For this purpose, seven distinct physicochemical parameters were measured and monitored in Karasu, Kırandere, Olukdere and Sölöz water sources flowing into the lake, to serve as input data. Concentration levels of 15 distinct heavy metals in Karsak Stream originating from the lake were as the output. Specifically, Sn for Karasu (0.999), Sb for Kırandere (1.000), Cr for Olukdere (1.000) and Pb and Se for Sölöz (0.995) indicate parameter estimation R 2 coefficients close to 1.000. Sn stands out as the common heavy metal parameter with best estimation prospects. Given the importance of the independent variable in estimating heavy metal pollution, conductivity, COD, COD and temperature stood out as the most effective parameters for Karasu, Olukdere, Kırandere and Sölöz, respectively. The ANN model emerges as a good prediction tool that can be used effectively in determining the heavy metal pollution in the lake as part of the efforts to protect the water budget of Lake Iznik and to eliminate the existing pollution., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The growth of Malaysia has caused many industries to grow rapidly, especially construction industries due to the demand for more homes, buildings, and infrastructure. The production of concrete and mortar is highly requested. Therefore, the demand for fine aggregate becomes higher because fine aggregate is one of the main elements in concrete and mortar production. The high demand for fine aggregates will create a worrying situation where the fine aggregate crisis will worsen. An alternative was introduced to replace the fine aggregate known as palm oil fuel ash (POFA) in order to reduce the use of natural resources such as fine aggregates and lead to the reduction of fine aggregate mining activity. POFA produced from palm oil fibre, palm oil shell, and mesocarp at high temperature has no benefits in the commercial return. Thus, POFA that has accumulated in landfill has the ability to create environmental pollution. Due to the pozzolanic behaviour of POFA, it could be relevant when POFA is used in the production of mortar as a partially fine aggregate replacement. There is a limited study on the effects of POFA as a partially fine aggregate replacement in the production of mortar. The aim of this research is to study the effects of POFA on the workability of fresh mortar, and for the hardened mortar, compressive strength and microstructural analysis will be analysed. A total of 45 cubes with dimensions of 100 mm × 100 mm × 100 mm were cast at different percentages of POFA at 0%, 2.5%, 5%, 7.5%, and 10% by the weight of fine aggregates. Slump and flow table tests were conducted during the casting process to determine the workability. All the specimens were water cured at days 3, 7, and 28 before being tested with a compression test and scanning electron microscope (SEM) on the hardened mortar. It was discovered that 0% POFA recorded the highest workability. Furthermore, the laboratory results showed that the 2.5% POFA in the mortar recorded the highest compressive strength compared to other specimens. Moreover, the microstructure of the mortar specimen was observed to be denser, and the pores were refined with the presence of POFA, compared to the control specimen. Based on the findings, this research enables us to give an understanding of the effect of POFA incorporated in mortar as a partially fine aggregate replacement in terms of workability, compressive strength, and microstructural analysis. Based on the results from this research, the advantage of POFA can be fully utilized and can help reduce the environmental problems. [ABSTRACT FROM AUTHOR]

Preventive conservation of cultural heritage can avoid or minimize future damage, deterioration, loss and consequently, any invasive intervention. Recently, Machine Learning methods were proposed to support preventive conservation and maintenance plans, based on their ability to predict the future state of the built heritage by collected data. Several data sources were used, such as structural data and images depicting the evolution of the deterioration state, but till now textual information, exchanged by people living or working in historical buildings to require maintenance interventions, was not used to support conservation programmes. This work proposes a method to support preventive conservation programs based on the analysis of data collected into CMMS (computer maintenance management software). In a Cultural Heritage building in Italy, hosting a University Campus, data about end-user's maintenance requests collected for 34 months were analysed, and LSTM neural networks were trained to predict the category of each request. Results show a prediction accuracy of 96.6%, thus demonstrating the potentialities of this approach in dynamically adapting the maintenance program to emerging issues. [ABSTRACT FROM AUTHOR]

The deterioration of fiber properties during recycling processes, especially the loss of tensile strength, raises concerns that paper products made from recycled fibers might not satisfy quality requirements. The purpose of this paper is to estimate the deterioration of tensile strength and the damage in paper sheets made of recycled fibers using the theory of damage mechanics and machine learning methods. Experiments were carried out to recycle wood fibers and nonwood fibers four times, and the physicochemical properties of the handsheets made from these fibers were measured after each recycling. Water retention value and relative bonded area were selected as the features to estimate and predict tensile strength during recycling because they had strong correlations with tensile strength. This paper proposed a damage index to quantitatively express the severity of the damage in paper sheets based on the experimental investigation and the theory of damage mechanics. Thus, the deterioration of tensile strength could be estimated and predicted. To determine the damage index, a curve fitting model based on the hyperbolic theory of pulp properties was developed. The proposed quantitative expression of the damage index is: D = (Ds - h)²/a2 - (Dh - k)²/b2, where the coefficients were determined through the curve fitting model. This paper also developed a long short-term memory recurrent neural network model to determine the damage index according to the sequence of recycling. Both models were trained with the experimental data of water retention value and relative bonded area. The estimation and prediction by the curve fitting model were more accurate than those of the neural network model. The root mean square errors by the curve fitting model were 0.0278 for estimation, 0.1667 for prediction; and by the neural network model were 0.2445 for estimation, 0.2206 for prediction, respectively. After the damage index was determined, the deterioration of tensile strength then could be calculated as T = T0 (1-D). [ABSTRACT FROM AUTHOR]

In recent years, research work on the use of coal bottom ash (CBA) as a partial alternative for aggregate in concrete is on the rise. This research is aimed at examining the characteristics of lightweight foamed concrete with CBA as fine aggregate to produce environmentally sustainable product. With the volume replacement technique, CBA was used as 25%, 50%, 75%, and 100% replacement for conventional mining sand with different sieve sizes of smaller than 4.75, 2.36, and 0.6 mm in concrete. Water absorption, porosity as well as mechanical characteristics tests, including compressive strength, splitting tensile strength, and modulus of elasticity (MOE) were conducted and analyzed. X-ray diffraction and scanning electron microscopy microstructural investigations were also performed to correlate test results. The quality of concrete was investigated using a non-destructive ultrasonic pulse velocity test. According to the findings, the highest replacement level of CBA with a sieve size smaller than 0.6 mm had an impact in reducing workability. The effect of CBA particles on water absorption, MOE, compressive strength, and tensile strength depends on the size of the fine aggregate, the replacement ratio and the density. In general, substituting mining sand with CBA aggregate improved the mechanical performance of concrete, notably for the aggregate size of less than 0.6 mm. Moreover, the SEM images indicate that the addition of CBA particles decreased the size and quantity of voids in the foamed concrete. [ABSTRACT FROM AUTHOR]

Several studies have synthesized silica from waste. The silica synthesis method from agricultural waste aims to produce high purity silica with low contaminants at an affordable cost. This study synthesized silica from oil palm boiler ash (OPBA) by means of various methods, such as ball milling, coprecipitation, and modification with methyl trichlorosilane (MTCS). XRD characterization results showed that the OPBA synthesized with ballmill and coprecipitation method has the smallest particle size of 14.90 nm. Morphology showed the OPBA obtained by using the ballmill method, the OPBA synthesized with ballmill and coprecipitation method, as well as the OPBA synthesized with ballmill, coprecipitation, and modified with methyl trichlorosilane as spherical particles. At the same time, the FTIR results show an absorption peak which is a characteristic of silica confirmed by the XRF results, where silica content is dominant. [ABSTRACT FROM AUTHOR]

Foamed concrete is a controlled low-density concrete, and due to its excellent thermal insulating and acoustic absorption properties, its application has been on a steady rise. Palm Oil Fuel Ash (POFA), an agricultural waste generated by the Palm Oil industry and Eggshells, causes many environmental problems. The pozzolanic nature of POFA and the high calcium oxide content in Eggshell Powder (ESP) are the components that contribute to their suitability as a partial cement replacement in concrete. This experimental work studied the flexural behavior, as well as the compressive strength of lightweight ternary binder foamed concrete incorporating 20% - 25% POFA and 5% - 10% ESP by weight of the total binder, as partial cement replacement. The test results were analyzed and compared with conventional foamed concrete without POFA and ESP. It was observed that POFA is a class C pozzolanic material. The combined utilization of POFA and ESP increased the compressive and flexural compared with control concrete. Furthermore, most of the cracks of the prisms were nearer to the middle of the samples and between two locations of loads applied due to the same load value applied at both locations. It was also observed the air voids were blocked due to increased pozzolanic activity and development of C-S-H gels and thus increase in strength. The utilization of POFA and ESP in concrete can be beneficial in reducing the overall cost. The cost to produce 1 m3 of concrete incorporating POFA and ESP was reduced ranging from was reduced by 12.59% (with 20% POFA and 5% ESP) to 17.53% (with 25% POFA and 10% ESP). It can be concluded that the M4 concrete mix is the optimum and cost-effective, as the maximum cement content is replaced (35%), as well as the compressive and flexural strengths are significantly higher than the control concrete M0. [ABSTRACT FROM AUTHOR]

The release of carbon dioxide (CO2) from the cement industry into the atmosphere and the increasing amount of oil palm waste from industrial plants lead to the problem of the greenhouse effect and environmental pollution. Studies on palm fuel ash (POFA) and metakaolin (MK) as a semi-substitute for cement can reduce the problem of the greenhouse effect and environmental pollution, as well as increase and improve the level of strength of concrete. Using mechanical and transport test methods as well as assisted by comparative X-ray Diffraction (XRD) analysis can prove the use of pozzolanic material as a catalyst to the compressive strength of concrete. In this study, slump test, compressive strength test, and water absorption test were conducted on samples containing total cement substitution up to 40% of POFA and MK as cement substitutes. The partial replacement of cement with MK and POFA reduced the workability of the concrete. However, binary and ternary blended concrete containing MK and POFA provide better compressive strength compared to OPC concrete up to 9.5% after 28 days age. Moreover, it was found that, the compressive strength of concrete containing POFA was better than the concrete containing MK up to 4%. [ABSTRACT FROM AUTHOR]

Concrete is the most extensively utilized construction material globally and is increasingly used due to industrialization and urbanization. Currently, most scientists worldwide are concentrating their attention on effective strategies to adopt materials from large amounts of waste resources as a partial substitute for cement in concrete production due to scarcity of resources and continuous environmental pollution. In this study, an experimental investigation was conducted on the properties of concrete made from the partial replacement of cement by hybrid coffee husk ash (CHA) and sugarcane bagasse ash (SCBA). The study considered different percentages (0%, 5%, 10%, and 15%) of hybrid ash to assess the engineering properties of fresh and hardened concrete of C-20/25. A slump and compaction factor test was conducted to study the workability of fresh concrete. The study showed that, as the percentage of replacement increased from 0% to 15%, the workability of the concrete decreased up to 15.15%. In addition, compression, split tensile, and flexural tests were done on the 7th, 14th, and 28th days to investigate the properties of hardened concrete. Based on the test result, 10% of hybrid ash was the maximum percentage of replacement that showed a compressive and tensile strength greater than the target strength. Therefore, the study concludes that up to 10% replacement of cement by hybrid ash may be employed in concrete production, which in turn is used to minimize the cost of construction and environmental pollution by recycling waste coffee husk and sugarcane bagasse. [ABSTRACT FROM AUTHOR]

The increase in building activity as a result of population expansion has resulted in an overexploitation of aggregate, with disastrous environmental consequences. Simultaneously, the disposal of spent garnet by the shipbuilding industry and palm oil clinker by palm oil mills harms the environment and needs a greater amount of landfill space. Therefore, the purpose of this study was to determine the influence of spent garnet as a fine aggregate substitute on the fresh, mechanical, and durability properties of palm oil clinker concrete. Concrete mixes were created using various percentages of spent garnet as a fine aggregate substitute, including 0%, 10%, 20%, 30%, and 40%. The workability, compressive strength, flexural strength, splitting tensile strength, modulus of elasticity, water absorption, and acid resistance of the water cured concrete were all determined. It was determined that using 20% spent garnet increased the compressive strength of lightweight concrete. The positive filler effect of spent garnet resulted in a densely packed internal structure of concrete, allowing it to have the lowest percentage of water absorption. The same mixtures exhibited the least mass change and strength reduction when exposed to acid solution. The results established that ecologically friendly concrete may be manufactured by including considerable volumes of waste from the shipbuilding and palm oil sectors. [ABSTRACT FROM AUTHOR]

The proper maintenance strategy is significant in extending assets and equipment, thus saving maintenance within an organization. Currently, there are three types of maintenance strategies implemented in the Royal Malaysian Air Force (RMAF), namely Reactive Maintenance (RM), Preventive Maintenance (PM), and Condition Based Maintenance (CBM). Due to the constraints in terms of maintenance costs by RMAF, choosing the right maintenance strategy is important to ensure that the maintenance provision can be optimized. In this research study, the Fuzzy Delphi Method has been used as a tool in determining the most effective maintenance strategies to be adopted by the RMAF. The output of agreement and opinion from experts in the related field has been used to select the appropriate maintenance strategy. In choosing this maintenance strategy, goals are set first in line with RMAF maintenance's objectives. The specified maintenance goals are as follows; low maintenance cost, reducing the chance of a breakdown, safety, feasibility on the acceptance by labor, and response time starting from failure. Later, the result showed that the fuzzy score for RM, PM, and CBM was 0.747, 0.789, and 0.767, respectively. The highest fuzzy score showed the most accepted method chosen by the expert. Based on the result and maintenance goals that have been outlined, experts have agreed to choose PM as a maintenance method that should be given priority to be implemented in RMAF compared to other maintenance methods due to the highest fuzzy score. [ABSTRACT FROM AUTHOR]

Improving the durability of building materials saves maintenance costs, construction time and energy. In this study, titanium dioxide-coated conventional and non-conventional composites were produced, and the effects of titanium dioxide coatings were investigated. Conventional composites were produced using river sand and Portland cement, whereas non-conventional composites were produced by partially replacing river sand and Portland cement with quarry dust and rice husk ash. Water absorption and thickness swelling tests were conducted on the produced coated and non-coated block samples. A reduction in water absorption was observed in the coated composite samples when compared to the non-coated composite samples and this is an indication of the improved durability of the samples coated with titanium dioxide. However, there was an increase in the thickness swelling of coatings on the coated block samples, but this increase has a slight influence on the compressive strength of the coated samples. The outcome of this study indicates that coating composite building blocks with titanium dioxide will improve their durability. Also, the site exposure experiments revealed the selfcleansing properties of TiO2-coated composite block samples, while the Rhodamine B discolouration test confirmed the photocatalytic features of TiO2-coated composite block samples. [ABSTRACT FROM AUTHOR]

In this paper, the effect on utilization of ultrafine palm oil fuel ash (UfPOFA) on the properties of interlocking compressed earth bricks (ICEB) were investigated. The materials used to produce Interlocking Compressed Earth Brick (ICEB) includes clay soil, sand, Ordinary Portland cement (OPC), and water. OPC were replaced at 0%, 10%, 20%, 30% and 40% by mass percentage with UfPOFA. The ICEB specimens were cured at 7 and 28 days to study the bulk density, compressive strength and water absorption of the ICEB. The experimental results found that the incorporation of UfPOFA reduced the bulk density and compressive strength at both ages of the specimens as compared to the control mix. However, it was observed that their compressive strength improved with age. The compressive strength of ICEB specimen with 10% of UfPOFA showed the highest strength at 28 days amongst all mixtures containing UfPOFA with 6.53MPa, which was higher than the strength value required for loadbearing earth bricks in Malaysian Standard (MS) 76:1972. In addition, the lowest rate of water absorption was found to be 15.44% for 28-day old ICEB specimen with 10% UfPOFA, which was just slightly higher than 15% in compliance with MS 76:1972 on the rate of water absorption for earth bricks. The results thus showed UfPOFA as a potential material to be used as an OPC replacement to produce a sustainable ICEB. [ABSTRACT FROM AUTHOR]

Increased usage of concrete contributes to urban thermal discomfort due to the Urban Heat Island effect. At the same time, the corresponding increased consumption of cement also causes a significant rise in carbon dioxide (CO2) gas emissions. This experimental work aims at evaluating the thermal and mechanical performance of 1800 kg/m3 dry density green sustainable foamed concrete (GFC) incorporating agroindustrial waste such as Palm Oil Fuel Ash (POFA) and Eggshell Powder (ESP) as supplementary cementitious materials (SCMs). The POFA content varied from 15 to 35%, with increments of 5%, while being supplemented with 5% ESP. To evaluate the performance of the developed GFC, the flowability, mechanical strengths (compressive and splitting tensile strengths), and thermal performances (thermal conductivity and surface temperature) were investigated. Incorporation of 15-25% of POFA supplemented with 5% ESP as partial cement replacement materials resulted in enhanced mechanical strengths. Although usage of POFA can reduce the thermal conductivity, the POFA content must be limited to 15–25% to prevent excessive heat absorption by the exterior surface of the concrete. Overall, the optimum use of 15% POFA in a combination of 5% ESP is desirable to produce an eco-friendly sustainable foamed concrete. [ABSTRACT FROM AUTHOR]

Pulp and paper industries emit various odorous gases during the pulp production and paper-making phase, which are unpleasant and have harmful effects on the human body. The working staffs are continuously exposed to these gases and develop various health issues. Hence, regular monitoring and analysis of such gases are necessary to avoid any sudden high concentration exposure and to prevent adverse health effects on the staff. An electronic nose (EN) has an array of gas sensors with an alert system for early detection of gases. Various ENs have been developed for varying applications till date. The detailed knowledge of the sensors used, their sensitivity and technology is helpful in development of any EN. The objective of this study is to comprehensively review various developed ENs with respect to their gas sensing and pattern recognition (PR) technologies. The information on gases released from pulp and paper industries is also compiled. The evolution of EN technology, its various applications, challenges in developing EN and its utility in safeguarding the industrial workers' life have been described. Further, gap analysis among previously developed EN, contemporary EN and wireless sensor network (WSN) is elaborated. It will facilitate future researchers for better selection of sensors and PR technologies while developing EN. The commonly used sensing technologies are described with their advantages, disadvantages and working principles. Metal oxide semiconductor (MOS) gas sensor and ANN algorithm show better result and hence recommended in the development of EN, whereas ZigBee protocol has been widely used for WSN., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Li, W.; Jiang, R.; Zhao, Y.; Xie, J.; Zhu, J., and Cao, R., 2019. Water ecological environment protection under changing environment: A systematic review and bibliometric analysis. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 9–15. Coconut Creek (Florida), ISSN 0749-0208. Systematic review is usually used to reveal the change characteristics of the quantity and law of the citations focus on one research theme. The paper investigated the research status, development trend and hotspots of water ecological environment protection using bibliometric analysis. Based on bibliometric, mathematics and statistics, articles related to the water ecological environment protection in Web of Science for the period of 2008-2019 were selected. CiteSpace software was used to conduct the annual frequency analysis of papers, countries and research institutions analysis, co-occurring keywords analysis, clustering analysis and research frontier. Results show that: (1) The number of published papers and cited papers have increased for the past 12 years. Especially, the number of published papers has increased sharply since 2015, indicating that the research on water ecological environment protection has been transferred from the exploration stage to rapid development stage, which needs to be analyzed from the aspects of national policy. (2) China has more publications than other countries. The research institutions are mainly concentrated on universities, the cooperation among them is not close. It shows the characteristics of small distribution and large concentration. Keywords such as "model" and "water quality" are research hotspots. (3) The results of clustering analysis show that water ecological environment quality assessment, water and soil conservation, ecosystem services and aquatic ecosystem are four main research directions of water ecological environment protection. (4) Using method of burst detection, nine keywords are obtained, which indicate that water ecological environment protection has rich research perspectives. The burst strength of land use is high, it will become the research hotspot of water ecological environment protection in future. The results should be beneficial to systematically understand research progress and future trends of water ecologic environment under changing environment, and therefore it promotes ecological civilization construction. [ABSTRACT FROM AUTHOR]

In this study, the rheology, fluidity, stability, and time-varying properties of cement paste with different substitute contents of silica fume (SF) were investigated. The result showed that the effects of SF on macro-fluidity and micro-rheological properties were different under different water–cement ratios. The addition of SF increased the yield stress and plastic viscosity in the range of 2.61–18.44% and 6.66–24.66%, respectively, and reduced the flow expansion in the range of 4.15–18.91%. The effect of SF on cement paste gradually lost its regularity as the w/c ratio increased. The SF can effectively improve the stability of cement paste, and the reduction range of bleeding rate was 0.25–4.3% under different water–cement ratios. The mathematical models of rheological parameters, flow expansion, and time followed the following equations: τ(t) = τ0 + k0t, η(t) = η0eat, and L(t) = L0 − k1t, L(t) = L0 − k1t − a1t2. The SF slowly increased the rheological parameters in the initial time period and reduced the degree of fluidity attenuation, but the effect was significantly enhanced after entering the accelerated hydration period. The mechanism of the above results was that SF mainly affected the fluidity and rheology of the paste through the effect of water film thickness. The small density of SF particles resulted in a low sedimentation rate in the initial suspended paste, which effectively alleviated the internal particle agglomeration effect and enhanced stability. The SF had a dilution effect and nucleation effect during hydration acceleration, and the increase of hydration products effectively increased the plastic viscosity. [ABSTRACT FROM AUTHOR]

Green economy is a major them of sustainable development. The application of biological waste in engineering is conducive to green development. This study reveals the effect of recycled eggshell waste on the physical and chemical properties as well as nano-microstructure characteristics of asphalt. The hardness, thermal stability and ductility of asphalt were explored by the penetration, softening point and ductility tests. The distribution and relative content of protons in asphalt were revealed by nuclear magnetic resonance hydrogen spectrum (1H-NMR). The microscopic characteristics of the particle morphology and surface structure of the eggshell powder were explored by scanning electron microscopy (SEM). An atomic force microscope (AFM) was used to analyze the evolution laws of asphalt nano-microstructures. The experiment results indicate that (1) the eggshell waste increases the hardness, thermal stability and reduces the ductility of asphalt; (2) the chemical environment in which the protons of the eggshell waste asphalt are located and the H index have no obvious changes; (3) the eggshell powder is characterized by a rough, wrinkled, porous and loosened structure; (4) the nano-microstructure of eggshell waste asphalt exhibits "bee-like structures", and the different proportion of eggshell waste changes the maturity, size and quantity of the "bee-like structures" and roughness, which can be attributed to the interaction of the asphaltene-waxiness system. [ABSTRACT FROM AUTHOR]

Palm oil clinker (POC) aggregates is a viable alternative to the naturally occurring sand and gravel in the manufacturing of concrete. The usage of POC aggregates assists in the reduction of solid waste and preserves the consumption of natural resources. Although researchers investigated the mechanical response of POC-containing concrete, limited research is available for its torsional behavior. In general, the torsional strength depends on the tensile strength of concrete. This research investigates the compressive, tensile, and torsional response of concrete with various ratios of POC-aggregates. Five batches of concrete were casted with POC-aggregate replacing granite at ratios of 0, 20, 40, 60, and 100%. The selection for the mixture proportions for the various batches was based on the design of experiments (DOE) methodology. The hard density, compressive strength, splitting tensile strength, and flexural strength of concrete with a 100% replacement of granite with POC-aggregates reduced by 8.80, 37.25, 30.94, and 14.31%, respectively. Furthermore, a reduction in initial and ultimate torque was observed. While cracks increased with the increase in POC-aggregates. Finally, the cracking of concrete subjected to torsional loads was monitored and characterized by acoustic emissions (AE). The results illustrate a sudden rise in AE activities during the initiation of cracks and as the ultimate cracks were developed. This was accompanied by a sudden drop in the torque/twist curve. [ABSTRACT FROM AUTHOR]