Production Of Construction Materials Research Articles

Study of Mechanical Properties Using Carbonized Rice Husk and Eggshell to Prepare Sustainable Concrete and its Viability in Civil Construction

Sustainability has become an increasingly present concern in the construction industry, which has led to a search for more ecological and sustainable alternatives in the production of construction materials. In this context, research references have shown promising results in the use of carbonized rice husk and eggshell. The use of rice husk as a partial substitute for cement in concrete has proven to be effective in reducing environmental impact, since this residue has pozzolanic characteristics, providing greater resistance to the concrete. Eggshell, in turn, has been used as an additive in the production of mortars, providing improvements in the mechanical and thermal properties of these materials. These sustainable solutions in civil construction are aligned with the ESG agenda of companies, which are increasingly seeking minimize the environmental impact of its activities. The study verified through axial compression resistance tests that the composites prepared with 1.5 % (w/w) had superior compressive strength by around 20% compared to the composites prepared with 2 % (w/w). In other words, with a lower concentration it achieved a satisfactory reinforcement effect, better preserving the structure. From the analysis of the diametral compression resistance results, the concentration of 1.5% (w/w) showed a specific reinforcing effect, both with the use of crushed eggshells and with the use of carbonized rice husks dispersed in concrete. The concentration of 1.5% (w/w) showed a specific reinforcing effect, both with the use of crushed eggshells and with the use of carbonized rice husks dispersed in concrete. The lowest content of 1% (w/w) was not enough to reinforce the material, presenting the lowest yield strength values of 2.98 and 3.54 MPa for egg and rice, respectively. The values for 1.5% (w/w) reached values of 4.22 and 4.68 MPa, for egg and rice. Around 20% of the compounds prepared with the highest filler levels, both with crushed eggshell and carbonized rice husk.

Mechanical Characterization of Sustainable Mortars with Recycled Aggregates from Construction and Demolition Wastes: An Experimental Investigation

The use of recycled aggregates in the production of concrete and mortar represents a sustainable way to reintroduce these constituents—which are typically treated as waste and disposed of—in the production chain, providing new value to potentially polluting materials. The effect of recycled aggregates has been widely studied in the production of concrete due to the directions of National Standards in Italy; however, their role in the manufacturing of mortar must be investigated further due to the high variability that can be observed in the literature. In particular, the aim of this paper is the mechanical characterization of sustainable mortars defined by different mix designs and different binders, in which the aggregates are gradually replaced by a recycled sand obtained from the grinding of construction and demolition wastes, which could include old concrete, clay bricks, and minimal amounts of other kinds of residual materials. This investigation is carried out through experimentation, taking into account four different mortar compositions defined by an increasing percentage of recycled constituents. Virgin aggregates are also studied for the sake of comparison. The results, accomplished through a three-point bending test and an unconfined compression test, show that it is still possible to maintain acceptable mechanical properties by using these wastes as aggregates in spite of a decrease in the analyzed values. In general, the mean reductions with respect to the use of natural aggregates are about 30–40% and 35–55%, respectively, for compressive and flexural strengths. It should be highlighted that some experimental sets provide a maximum reduction of 70–80%, but the results are still within the limitations of the standards. This aspect can be considered to be a good compromise since the production of this sustainable construction material can represent a solution that is able to reduce the extreme exploitation of natural resources, the pressure on landfills, and the consumption of energy, which are related to the construction industry.

Assessment of the Carbon Footprint of Production of Construction Materials Used in Hydrogen Energy

The results of the analysis of production of construction materials used for manufacturing hydrogen life cycle equipment are presented. The aspects of the life cycle of the main construction materials (steel, aluminum, nickel, copper, titanium, platinum, carbon plastics) used in hydrogen power engineering are identified. The results of the carbon footprint assessment for the production of these materials are presented depending on the production technologies, the energy source used and the secondary raw materials. It is established that in the development of a hydrogen gas turbine unit (GTU) the main contribution to carbon footprint is made by titanium (50,9 %) and nickel (37,6 %) alloys, in spite of the fact that more than 50 % of GTU consists of steel. It has been determined that in the production of solid-polymer fuel cells the main contribution to the carbon footprint is made by the smallest construction materials — platinum (78,1 %) and carbon plastics (15,7 %) due to the fact that they have the largest carbon footprint per kg of produced material.

A Review of the Utilization of Recycled Powder from Concrete Waste as a Cement Partial Replacement in Cement-Based Materials: Fundamental Properties and Activation Methods

Recycled powder (RP) is the primary by-product generated during the reclamation process of construction and demolition waste (CDW). There is existing literature on the use of RP as supplemental cementitious materials (SCMs) in cement-based materials, but a comprehensive evaluation on the characteristics of RP generated from concrete waste has been missing until now. This paper critically reviews the use of RP from concrete waste in cement-based materials, as concrete waste makes up a significant amount of CDW and other components have designated recycling methods. In this sense, this study conducted a critical analysis on the use of RP as an SCM, using detailed literature research. The technology used for producing RP is detailed along with its chemical, mineralogy, and microstructural characteristics. Fresh-state properties in cementitious matrices with RP are introduced with the view of mechanical grinding, thermal activation, carbonation, chemical treatment, biomineralization, mineral addition, nano activation, and carbonation. The review highlights the significant potential of utilizing RP in cement-based materials. Specifically, RP can be advantageously utilized in the production of value-added construction materials.

Sustainable enhancement of fly ash-based geopolymers: Impact of Alkali thermal activation and particle size on green production

Addressing the challenges posed by the slow reactivity of fly ash (FA) with alkali at ambient temperatures, this study delves into the enhancement of FA-based geopolymers through alkali thermal activation (ATA). The ATA process, conducted at 550°C for 1 h, significantly increases the availability of reactive silica and alumina, which are essential for geopolymerization. A critical focus of the research is the influence of FA particle size on ATA’s efficacy and the resultant mechanical properties of the geopolymers. Findings reveal that the ATA process facilitates the rapid dissolution of the vitreous phase in FA. This leads to a sequential release of silica and alumina, which is pivotal for the geopolymer’s matrix development. Notably, geopolymers synthesized from finely milled FA, post-ATA, demonstrate a marked increase in compressive strength, escalating from 30.51 MPa to an impressive 38.46 MPa. The study meticulously delineates geopolymerization into four distinct stages—initial dissolution, depolymerization, geopolycondensation and gelation, and final diffusion, with the initial dissolution and final diffusion stages being paramount in defining the reaction kinetics and the ultimate strength of the geopolymer. This enhanced understanding paves the way for optimizing FA utilization in geopolymers, promising a more sustainable and efficient pathway for producing construction materials with superior mechanical properties.

Low-NOx thermal plasma torches: A renewable heat source for the electrified process industry

Industrial thermal plasma torches can heat a gas up to 5000–20,000 K, i.e., well above the temperature needed to replace the heat generated from the combustion of traditional fossil fuels (e.g., coal, oil, and natural gas) in large-scale process industry furnaces producing construction materials (e.g., iron, steel, lime, and cement). However, there is a risk for significant NOx emissions when air or N2 are used as plasma-forming gas since the temperature somewhere in the furnace always will be higher compared to the threshold NOx formation temperature of ∼1800 K. Torch NOx forms inside the high temperature region of the plasma torch (>5000 K) when air is used as gas. Process NOx forms instead when the hot gas (when air or nitrogen is used as plasma forming gas) from the plasma torch mixes with process air downstream the torch. By analysing the complex chemistry of both the torch- and process NOx formation with thermodynamic equilibrium and one-dimensional chemical kinetic calculations it was shown that adding H2 to the plasma-forming N2 gas significantly reduces the NOx emissions with more than 90 %. Verifying experiments with air, pure N2, and mixtures of H2 and N2 as plasma-forming gas were performed in a laboratory scale insulated laboratory furnace with different pre-heating temperatures of process air (293, 673, and 1073 K) which the plasma gas mixes with downstream the torch. Depending on the pre-heating temperature the NOx emissions were between 12,000–14,000 mg NO2/MJfuel when air was used as plasma forming gas. Substantial NOx emission reduction occurs both when N2 replaces air, where the NOx emissions was in the span of 8000–11,500 mg NO2/MJfuel and furthermore when H2 was mixed into the N2 gas stream. For the highest degree of H2 mixing (28.6 vol-%), the NOx emissions were between 450–1700 mg NO2/MJfuel depending on the pre-heat temperature of the process air, i.e., a reduction of 88–96 % and 85–94 %, respectively when air or N2 was used as plasma forming gas. The measured NOx emissions are then of the same order of magnitude as would be expected from the combustion of traditional fuels (coal, oil, biomass and pure H2). Finally, by analysing the aerodynamics in an axisymmetric furnace with an experimentally validated computational fluid dynamics (CFD) model using reduced chemistry for the NOx formation (19 species and 70 reactions), further guidelines into the process of NOx reduction from thermal plasma torches are given.

Recycling of magnesium oxychloride cement: Application of crushed MOC waste as a filler in the next-generation MOC composites

This study deals with magnesium oxychloride- (MOC-) based construction composites in which, a filler formed from end-of-life MOC-based composite recyclate is used as a partial or full replacement of standard quartz sand filler. The developed composites pose as a highly environmentally sustainable alternative to Portland cement (PC), which has dominated the global construction sector, largely due to its unique properties and adaptability to various conditions. As the PC industry is a major contributor to greenhouse gas emissions, it is ultimately necessary to find a suitable alternative. In our study, we demonstrated that the proposed composite, even with a very high content of the MOC-based recyclate performs well concerning its mechanical parameters evidenced by compressive strength exceeding 64 MPa. The developed composites also yield a low water absorption of about 3.3 wt% and even when exposed to the harsh environment of 95 % RH for 7 days, their softening coefficient reaches values higher than 85 %. The acquired material parameters of the prepared composites make them suitable for application in the production of construction materials with high mechanical strength and acceptable resistance to the action of moisture. The approach which was taken, where MOC-based construction waste can be fully reutilized in the next generation of MOC composites as a filler represents a very promising route for the development of waste-free and CO2-neutral technology.

Систематизация рабочих органов машин глубокого фрезерования

Currently, ensuring energy security is a key priority for the country. Peat resources account for one-third of the country's total energy potential. Apart from energy production, peat finds extensive use in agriculture, chemical industry, construction, and the production of construction materials. Presently, milled peat constitutes the main volume of production in the country. The technology of its extraction involves preparing areas and removing undergrowth, stumps, and wood debris during preparation of the deposit by trenching or deep milling. However, due to the imperfections of the equipment, peat contamination and loss of its quality occur. This article analyzes means for carrying out preparatory operations to condition the surface of the deposit. It discusses the designs of end effectors for deep milling machines, their cutting structures, and the specific features of the tools used, i.e. blades, cutters, mills, chains. Classification of end effectors for peat machines as well as tools for deep milling of the deposit surface is proposed. This systematization involves identifying classification features by the type of machines, impact on the wood debris, movement of the end effector, its arrangement and design, as well as by parameters and types of the end effector’s cutting structures. The article may be useful for engineers, researchers, graduate students, and organizations involved in designing and studying processes of peat deposits conditioning.

Green Building and Energy-Efficient Design

In the modern era, the rapid expansion of infrastructure is a crucial indicator of a country's development. However, this growth must be balanced with environmental conservation to ensure the well-being of humans and other living organisms. The construction industry, a significant development driver, is also a primary source of environmental pollution, contributing to approximately 40% of air pollution. The production and transportation of construction materials, particularly cement and steel, are primary culprits. These processes release substantial amounts of CO2, a greenhouse gas that deteriorates the ozone layer and exacerbates global warming. Cement production accounts for 8-10% of global anthropogenic CO2 emissions, while steel manufacturing contributes about 5-10%. These emissions harm the environment and adversely affect human living conditions. Although it is challenging to eliminate CO2 and other greenhouse gas emissions, adopting sustainable living practices, such as the construction of green buildings, offers a viable path toward mitigation. Green or sustainable buildings are designed, constructed, operated, and maintained to minimize adverse environmental impacts and promote occupant health and well being. These structures aim to reduce resource consumption, increase energy efficiency, improve indoor air quality, and decrease the overall environmental footprint compared to traditional buildings. By prioritizing Sustainability, green buildings present an effective strategy to address the ecological challenges the construction industry poses, paving the way for a more sustainable and harmonious relationship between development and the natural world.

Geopolymer composites reinforced with silverskin fibers from the coffee industry waste

This paper aims to develop sustainable geopolymer composites reinforced with silverskin fibers derived from coffee industry waste. Geopolymer and geopolymer composites were synthesized from blast furnace slags (BFS) with a solid/liquid (alkaline solution) ratio of 1.4. A sodium metasilicate/sodium hydroxide (Na2SiO3/NaOH) mixture at a mass ratio of 2.5 served as the alkaline activator in the geopolymerization process. The composites were evaluated by incorporating 2%, 3%, and 5% by weight of silverskin fibers, which were used in their natural form (SGCn), after treatment with sodium hydroxide (SGCNaOH), and after treatment with sodium hydroxide followed by a steam explosion process (SGCSE).Characterizations of the geopolymer composites included X-ray fluorescence analysis (XRF) for elemental oxide identification, Fourier transform infrared spectroscopy (FTIR) for functional group detection, and thermogravimetric analysis (TGA) for thermal stability assessment. The influence of fibers on the hardness of the geopolymer materials was evaluated using hardness scale measurements. Morphologies, microstructures, and elemental compositions were analyzed through field emission gun scanning electron microscopy with energy dispersive X-ray spectroscopy (FEG-SEM/EDS).The results demonstrate that the incorporation of silverskin fibers, especially those treated with NaOH and subjected to steam explosion, significantly enhances the thermal stability of geopolymer composites. The 5% NaOH-treated fiber composite exhibited the highest Tmax and Tend, indicating superior thermal stability. Additionally, the 5% SGCNaOH composite showed the highest residual mass, further supporting the enhanced thermal stability of these composites.Unlike other fibers, which showed a decrease in hardness, the addition of SGCSE fibers maintains a relatively high hardness in the geopolymer composites. The 2% SGCSE composite exhibited an average hardness equal to that of the pure geopolymer at 66 Shore D.These findings underscore the potential of using treated silverskin fibers to develop more thermally stable, cost-effective, and sustainable geopolymer materials. By utilizing industrial residues and waste, these advanced materials can be applied in the production of construction and building materials, contributing to both environmental sustainability and economic efficiency.

Assessment of the opportunities of demolition waste using as a building material of the future in Ukraine

The object of research is the potential of secondary use of waste from the destruction of buildings and structures, which were formed as a result of the military aggression of the Russian Federation on the territory of Ukraine. For Ukraine, the issue of demolition waste is critical at the level of environmental safety and ensuring the demand for building materials for the reclamation of Ukraine according to the principles of the circular economy. To date, there are no official methods that would allow to determine the exact amount of destruction and the quality of the material formed, which complicates the development of mechanisms for its utilization in production. The key industry considered during the research for disposal of demolition waste is the industry of construction materials production. In the course of research, it was determined that most of the generated waste is waste from the destruction of buildings and structures made of precast concrete, however, considering that these wastes are generated by the action of explosions from shells. It is very difficult to ensure their compliance with the requirements of current standards due to the inclusion that such waste can contain. Therefore, the problem considered by this study is the determination of the nature of waste from the destruction of buildings and structures, their physical, mechanical and chemical characteristics, in the context of the final applications of products based on them. The results of the study showed that when reproducing the concrete mix for tared concrete for civil purposes, which do not have high requirements for stability in aggressive operating conditions, when replacing natural aggregate crushed to a fraction of 5 to 20 mm, the requirements for concrete strength are achieved in the level of C40/50 strength class. But the rheological characteristics deteriorate due to the high absorption of water from the concrete mixture by the studied material. Research has shown that for further use in the production of ready-mixed concrete and precast concrete products, it is necessary to prepare demolition waste with a wide particle size distribution and low dust content. This can ensure a high level of recycling and meet the demand for concrete in the reconstruction of Ukraine. The fine aggregate from the demolition waste crushing process can be considered as secondary cementitious material for cement production.

Ecological modernization at construction industry enterprises as an innovative production and management technology

The article delves into the pivotal role of ecological modernization, specifically the environmentalization of production at enterprises in the building materials sector. A comprehensive study was conducted on the product range of Ivano-Frankivskcement PJSC, one of the largest enterprises in the Western region. This case study serves as a tangible example, demonstrating that the adoption of environmentally friendly production necessitates both the environmentalization of production processes and management. The implementation of a comprehensive environmentalization strategy involves the incorporation of ecologically oriented measures in both the internal and external environments of the production system, while the environmentalization of the management system entails a restructuring of organizational forms and management methods to align with ecological principles. It was established that an essential part of ecological modernization is the introduction of environmental management systems. This includes requirements for waste and its processing, control over the use of water resources, and implementation of environmental certification and standards. Ecological modernization at enterprises in the construction industry helps to reduce the sector's ecological impact on the environment, contributes to the preservation of natural resources, and improves people's quality of life. It is proposed that enterprises producing building materials switch to the use of a dry method of production - an innovative technology that will contribute to the reduction of morbidity in the population and will protect the natural environment from harmful impurities and combustion products. The main advantage of this is energy-saving and highly efficient cement production technologies. It is emphasized that when carrying out production activities, enterprises in the field of production of construction materials should also apply management technologies of controlling, outsourcing, foresight, etc., with the help of which adverse environmental and economic problems can be detected promptly, and suggestions for their elimination can be made. Keywords: ecological modernization, "green" technologies, enterprise, business entity, management, production, ecological situation.

Experiments Using Different Types of Waste to Manufacture Ceramic Materials: Examples on a Laboratory Scale

Reusing waste as raw materials to produce other materials can entail a decrease in production costs and in the abusive use of natural resources. Furthermore, it can even improve the properties of the end product or material. In this sense, a review of the most relevant literature published in recent decades shows that numerous solutions have been proposed or implemented, such as its use to produce construction materials, catalysts, pigments, pozzolana, refractory materials, glass-ceramic products, etc. Our research group has verified the viability of using different types of waste as secondary raw materials to obtain several types of ceramic, glassy and glassceramic materials, as well as frits. This article highlights several types of industrial waste that have both non-toxic (Li, Ca and Mn) and highly toxic (Cr VI) differentiating elements that can be used in sintering and vitrification industrial processes to immobilise them or render them inert. We studied the compositions and characterised the various materials obtained, conducting toxicity and leaching tests on waste/materials designed with high amounts of chromium. A suggestion for future lines of research has been proposed.

Improvements in Hydrolytic Stability of Alkali-Activated Mine Tailings via Addition of Sodium Silicate Activator.

Over 14 billion tons of mine tailings are produced throughout the world each year, and this type of waste is generally stored onsite indefinitely. Alkali activation is a promising strategy for the reuse of mine tailings to produce construction materials, converting this waste stream into a value-added product. One major problem with alkali-activated mine tailings is their low durability in water (i.e., low hydrolytic stability). In this article, the influence of a mixed sodium hydroxide/sodium silicate alkali activator on the compressive strength, hydrolytic stability, and microstructure of alkali-activated materials (AAMs) were systematically investigated. XRD, FTIR, NMR, and NAD were used to investigate microstructural changes, and a water immersion test was used to show improvements in hydrolytic stability. For gold mine tailings activated with pure sodium hydroxide, the compressive strength was 15 MPa and a seven-day water immersion test caused a strength loss of 70%. With an addition of 1 M sodium silicate in the activator, the AAMs achieved a compressive strength of over 30 MPa and strength loss of only 45%. This paper proposes a mechanism explaining why the strength and hydrolytic stability of AAMs are dependent on the dosage of soluble silicate. A high dosage of sodium silicate inhibits the depolymerization of the source material, which results in a sample with less amorphous aluminosilicate gel and, therefore, lower hydrolytic stability.

Carbon-captured sodium hydroxide solution for sustainable alkali-activated slag

The escalating impact of climate change, primarily driven by greenhouse gas emissions, has prompted global efforts to achieve carbon neutrality. Ordinary Portland cement production contributes approximately 7% to global carbon dioxide (CO2) emissions, necessitating innovative approaches for its sustainable production. A novel method is introduced that utilizes a sodium hydroxide (NaOH) solution captured with CO2 as an alkali activator for ground granulated blast furnace slag (GGBFS); it can substitute for the cement in producing construction materials. The method integrates CO2-dissolved alkaline solutions into the activation process of GGBFS, which results in the production of sustainable alkali-activated slag materials. Various concentrations of dissolved CO2 in the NaOH-based activator were used to evaluate their impact on compressive strength, setting time, and changes in phase composition. The results demonstrate that higher CO2 concentrations lead to increased compressive strength, but an excess hinders early-age strength development. X-ray diffraction and thermogravimetry analyses explain the phase changes during carbonation, emphasizing the role of CO2 in forming calcite and enhancing C-S-H production. Additionally, the study quantifies CO2 uptake, revealing a linear relationship with dissolved CO2 concentrations.

A wonder adhesive for replacing the scarce metal

Introduction. Based on archival materials, the article follows a little-known fact of the Great Patriotic War 1941–1945, namely, the scientific discovery by the specialists of the Central Research Institute (TsNIPS), related to the creation of the formulation for the TsNIPS-2 construction adhesive. With its help, in a difficult period for the country, the industrial production of new construction materials was established and Red Army gunsmiths, located on the front line, quickly restored small arms that went out of action in battles with the enemy.Aim. To introduce into a scientific discourse the materials of archival sources on the history of creating a TsNIPS-2 new construction material, as well as on the individual research results of its inventor – a senior researcher, Cand. Sci. (Engineering) Maria N. Plungyanskaya, who worked for a long period in the TsNIPS Laboratory of Timber Structures.Materials and methods. Archival materials on the current topic were used in the preparation of the publication. Due to them, as well as with the help of retrospective, historical-typological and comparative research methods, the author traced certain aspects of the complex path of creating a new adhesive by clarifying its composition, order of preparation and industrial application.Results. The article studies and shows the individual stages of creating the TsNIPS adhesive formula, which ensured (due to cold-dry setting) the large-volume industrial production of high quality construction plywood of various thicknesses for the construction industry, as well as other timber structures that replaced the scarce metal. The procedure and rules for the practical use of the TsNIPS-2 adhesive by gunsmiths beyond the limits of stationary conditions (“in a trench”) for the successful restoration of wooden parts in rifles and assault rifles (butt, forearm, etc.), as well as the prompt return of thousands of weapons to the units are described.Conclusions. The content of the article will serve as a vivid illustration in the scientific and educational context about the traditions and activities of scientific schools, presented by the institutes of JSC Research Center of Construction, their contribution to the research field on the creation of new construction materials for increasing the power of the country. The research work of the Institute’s scientists was of a great practical importance, offering the construction industry new types of light industrial collapsible structures with a high transportability, their numerous achievements were effectively used at the front to achieve the Great Victory. In the period of 1930–1940, the construction, widely developed in the country, required, on the one hand, high-quality design solutions and, on the other hand, the simplicity and economy of their implementation. In these conditions, adhesive and laminated plywood structures were of a particular importance, ensuring the industrialization of the wooden construction part production and the cost-effectiveness of using timber in construction. The important properties of the TsNIPs-2 adhesive, obtained by the researcher M.N. Plungyanskaya, including water resistance and durability, as well as simplicity and ease of its handling, made it possible to use the material in industry for assembling the hulls of wooden ships, producing laminated structures, parts of cars, and oil pipelines, made of veneer or thin plywood, as well as in combat conditions for the manufacture and repair of small arms, etc., thereby bringing a significant economic effect and expanding the possibilities of its use in the domestic industry.

Formulating Eco-Friendly Foamed Mortar by Incorporating Sawdust Ash as a Partial Cement Replacement

Utilizing sawdust efficiently to produce construction materials can help safeguard the environment and decrease costs by minimizing the need for traditional resources and reducing carbon dioxide (CO2) emissions. Additionally, recycling sawdust plays an essential role in creating a sustainable ecosystem. Hence, this study aimed to examine the potential use of sawdust ash (SDA) as a partial cement replacement on foamed mortar (FM) properties, including its fresh, mechanical, transport, thermal, and microstructural properties. A variety of FM mixtures were tested for workability, density, consistency, intrinsic air permeability, porosity, split tensile strength, compressive strength, flexural strength, and thermal conductivity by replacing cement with SDA at varying percentages of 0%, 10%, 20%, 30%, 40%, and 50%. The results revealed that FM’s workability was reduced by the introduction of SDA with a higher percentage cement replacement, while the density of the FM mixtures was reduced due to SDA’s specific gravity being lower than that of cement. A linear improvement was observed in the air permeability, sorptivity, and porosity of FM–SDA composites with an increased SDA percentage to 20%. It is notable that these properties started to deteriorate once the cement replacement by SDA surpassed 30%. A noticeable improvement of mechanical strength properties of the FM was found at 20% of SDA content, but they deteriorated when the SDA content was more than 30%. FM blends with higher SDA contents exhibited larger and more apparent voids, according to SEM analysis. In conclusion, incorporating sawdust into formulations emerges as a viable method for FM production. This approach not only mitigates the environmental impact of sawdust disposal but also reduces the need for extracting natural resources in construction material manufacturing.

Environmental performance of unfired bricks produced from co-disposal of mine tailings and municipal solid waste incineration fly ash based on comprehensive leaching tests

The potential leaching of heavy metals is a crucial concern for construction materials produced from solidification/stabilization (S/S) treatment of wastes. This study comprehensively evaluated the leaching characteristics of heavy metals from the unfired bricks produced from co-disposal of Pb–Zn mine tailings and municipal solid waste incineration fly ash using batch, sequential, and semi-dynamic leaching tests. The results show that S/S treatment drastically reduced the leachability of heavy metals from the unfired bricks through lowering their distribution in the acid-soluble fraction. The effective diffusion coefficients of heavy metals within unfired bricks were all below 1.55 × 10−13 cm2/s, which is indicative of low mobility in the environment. The release of heavy metals from the unfired bricks was primarily governed by diffusion and dissolution. Slaking treatment of fly ash significantly reduced the leaching of heavy metals from the unfired bricks due to their improved structural integrity and compactness, which minimizes the surface area in the solid matrix accessible by the leaching medium. The leachability indices of heavy metals within the unfired bricks ranged from 13.12 to 18.10, suggesting that they are suitable for “controlled utilization” in specific scenarios. Compared to untreated mine tailings, converting them into unfired bricks could reduce the releases of heavy metals by several to hundreds of folds. These findings demonstrate that S/S can be an effective and sustainable strategy for co-disposal of mining tailings and incineration fly ash to produce construction materials with sound long-term environmental performance.

Ranking of Technologies for Intralogistic Bulk Material Handling Processes Using Fuzzy Step-Wise Weight Assessment Ratio Analysis and Axial-Distance-Based Aggregated Measurement Methods

The logistics network is considered the provider of logistics activities in supply chains. The fluctuating requirements of customers and the logistics network’s complex structure are only a few of the factors that cause challenges to its management. Industrial facilities are particularly vulnerable to challenges because material handling operations dominate in addition to manufacturing activities. Disruptions at industrial plants are disseminated through the logistics network, affecting all supply chain participants. As a result, reducing material handling time and costs to decrease material losses, pollution, and productivity is vital to their business. Due to their distinctive properties and significant share in finished goods, bulk materials are particularly vulnerable to issues during manufacturing. Accordingly, this study aims to rank and select technologies for handling bulk materials in an industrial plant where the production of construction materials is performed. This paper proposes four alternative solutions for the observed case study, and nine criteria were selected for the evaluation. A new hybrid multi-criteria decision-making model is proposed. The model combines Fuzzy Step-Wise Weight Assessment Ratio Analysis (SWARA), used to determine the weight of criteria, and the Axial-Distance-Based Aggregated Measurement (ADAM) method, used to rank alternative solutions. The model results indicate that the pneumatic conveyor is the best ranked alternative that significantly increases productivity, reduces losses, and improves working conditions. The key contributions of this study are its analysis of the efficiency of the technologies proposed for bulk material handling and the development and implementation of a model framework for the ranking of these technologies.

Investigation of the Compressive Strength of Sand-Filled Polyethylene Terephthalate Bottles as a Material for Wall Construction

The disposal of plastic wastes in the environment has negatively impacted the environment as plastics are non-biodegradable and contain chemicals that are harmful to humans, animals, plants, and the environment at large. The increased demand for infrastructure across the globe has also resulted in a rapid depletion of natural resources used for the production of construction materials. The need therefore arises for research to proffer solutions that would lead to the better management of plastic wastes, and provide sustainable construction materials. This study evaluated the compressive strength of sand-filled PET bottles (with varying moisture content, 0-15%) and clay bricks incorporating sand-filled PET bottles for wall construction. Cement was used to stabilize the clay at 0%, 10%, and 15% by weight. The compressive strength of the bricks produced was compared with that of control bricks (without sand-filled PET bottles). The results obtained reveal that the compressive strengths of the PET bricks were less than those of the control bricks. An optimum of 2% moisture content of sand is recommended for filling the PET bottles while 15% stabilization of clay with cement is recommended for the production of sand-filled PET bricks. The sand-filled PET bricks can be used for non-load-bearing wall construction as their compressive strengths fall below the minimum requirements of the Nigeria Building and Road Research Institute and the Standards Organization of Nigeria for load-bearing walls.