Production Of Construction Materials Research Articles

Development of a Drying and Grinding Plant for a Mixture of Milled Peat and Water Treatment Sediments for the Production of Construction and Ceramic Materials

Development of a Drying and Grinding Plant for a Mixture of Milled Peat and Water Treatment Sediments for the Production of Construction and Ceramic Materials

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.

Potential of Pressmud Waste from Sugar Industry in Brick Manufacturing for Green Business and Sustainability

The construction industry in Malaysia is currently witnessing sustained expansion, as seen by the rising demand for residential properties, commercial structures, and other infrastructures throughout our country. Therefore, the present study seeks to identify suitable materials and proportions for manufacturing lightweight bricks utilizing industrial waste materials. This study investigates the feasibility of using pressmud, a sugarcane refinery waste, as a fine bio-aggregate for the production of construction materials. Binary blended cement-pressmud bricks were formed by mixing Ordinary Portland cement with pressmud at various weights percentages (50%, 40%, 30%, 20%, and 10%). Various experiments were undertaken to investigate and compare the characteristics of pressmud bricks and commercial sand bricks. The experiments focused on density determination and compression tests (standard brick). The compression tests demonstrated that cement-pressmud bricks with a weight ratio of up to 20% exhibited a compatible strength to standard brick, with values ranging from 17.16 MPa to 23.01 MPa. The pressmud bricks exhibited reduced weight, with 10% and 20% variants weighing 17-23% less than the standard brick. Thus, it can be concluded that pressmud possesses significant potential as a bio-aggregate for producing lightweight and cost-effective construction materials when used in appropriate proportions.

Microstructural characterization and the influence of the chemical composition of the raw material mix on the physicochemical characteristics of waste-derived ceramic aggregates

This work presents the possibility of using a mixture of different mining and industrial wastes (fly ash, waste rock, glass cullet and waste solution as a binder) for ceramic aggregate production with the application of microwave radiation. The effect of the chemical composition of the raw material mix reflected by F/SA ratio (flux oxides/SiO2 + Al2O3) on the mechanical and microstructural properties of the aggregates was evaluated using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray nanotomography (nCT). A higher proportion of fly ash relative to waste rock in the mixture composition led to an increase in the F/SA ratio. The greater the F/SA, the higher the values of particle density and compressive strength, ranging from 1.72 to 1.87 g/cm3 and 6.31–7.31 MPa, respectively. Moreover, higher F/SA led to lower water absorption and porosity, which oscillated between 2.12 - 3.44% and 3.22–5.00%, respectively. X-ray nanotomography studies revealed an increasing contribution of larger pores with a radius of and an overall increase in porosity as the F/SA ratio rose. This finding was further confirmed by SEM investigations. TG-QMS analysis showed that organic matter could act as a pore-forming agent. The basic physical and mechanical paramaters of the obtained ceramic aggregates indicate the suitability of the studied wastes for the production of valuable construction materials.

Thermal decomposition mechanism and characterization of phosphogypsum in suspension under multifactor coupling effect

Phosphogypsum (PG) is solid waste generated by the phosphate fertilizer industry. However, by high-temperature thermal treatment, it can be effectively decomposed into byproducts like SO2 and CaO, which are valuable raw materials for the production of sulfuric acid and construction materials, respectively. In this study, we investigated the thermal decomposition properties of suspended PG, as well as the factors governing the PG decomposition procedure. The results show that the PG decomposition rate was influenced by several parameters, with temperature being the most significant, followed by time, atmosphere, and charcoal powder dosing. Similarly, the desulfurization rate was primarily influenced by time, followed by temperature, atmosphere, and charcoal powder dosing. The PG exhibited maximum decomposition and desulfurization rates of 97.73% and 97.2%, respectively, at a calcination temperature of 1180 °C, a calcination period of 15 min, a carbon powder dosage of 4%, and a CO concentration of 6%. Kinetic studies revealed that the activation energy of the PG decomposition reaction decreased from 303.45 to 254.28 kJ/mol as the CO concentration increased from 4% to 6% upon addition of charcoal powder as a reducing agent. Furthermore, higher CO concentrations had a more pronounced effect on lowering the activation energy of PG pyrolysis. When the contents of SiO2 and Al2O3 impurities in the PG content were higher, they reacted with CaO in the decomposition products to produce silicate and aluminate minerals, respectively, decreasing both the CaO content in the product and the PG decomposition rate.

Oyster shells’ incorporation into mortar to achieve blue circular economy – LCA case study in Portugal

Currently, society's great challenge is to face climate change and mitigate environmental impacts. This study aims to identify the environmental impacts of recovering traditional construction techniques in coastal regions by incorporating oyster shells into mortar to achieve the objectives of the blue circular economy. The possible environmental impacts are measured using Life Cycle Assessment. Oyster shell is considered as a powder or an aggregate in construction, and comparison is made between mortars produced with percentages of substitutions of traditional materials by oyster shell incorporation. The case study was carried out in the Algarve region, in the south of Portugal. Consequently, the potential of circularity for a biomaterial derived from the aquaculture industry and its inclusion in different particle size in the construction industry is discussed. This work is part of the activities to be carried out within the scope of the EEA granted Shellter Project, which aims to explore the potential of incorporation of oyster shells in the production of construction materials within a circular economy model.

Carbon emission scenarios of China's construction industry using a system dynamics methodology – Based on life cycle thinking

China is currently one of the world's major energy consumers and CO2 emitters. To save energy, and reduce consumption and carbon emissions, China proposed (at the 2020 United Nations General Assembly and Climate Summit) the introduction of stronger policies and measures for CO2 emissions to peak in 2030 and to achieve carbon neutrality by 2060. The construction industry is a major contributor to China's carbon emissions, thus research on energy saving and carbon reduction in this industry is essential. The construction industry is characterized by complex upstream and downstream industrial chains, with different energy consumption at each stage, and a long overall life cycle. We used life-cycle thinking (LCT) to analyze the carbon emissions of the whole life cycle of the construction industry and built a model by using a system dynamics method, which analyzes the carbon emission process of the construction industry at different stages. Combined with the planning and policies implemented by the construction-related departments, we identified the main indicators of policy regulation and control. We used sensitivity analysis to examine the impacts of factors of regulation and control. We also adjusted key indicators and set up different scenarios to simulate the carbon emissions based on the effort to achieve “peak carbon.” The results show that the carbon emissions of the construction industry will be reduced by 2060, achieving the goals of “peak carbon” and “carbon neutrality.” Although the construction and operation stages individually can achieve peak carbon by 2030, the whole process of the construction industry will reach peak carbon by 2045, 2038, or 2036, depending on specific aspects of the scenario considered. However, the indicators, such as the green building ratio can realize carbon emission reduction at building operation stage for 4%∼6%, but cause greater carbon emission for 5%∼7% at construction material production and transportation stage—a phenomenon called “policy island.” Therefore, the coupling of policies should be a key concern in policy formulation and implementation.

Detection of movement resistance and friction coefficient in the transport of building materials and construction materials

In the production of building materials and construction materials, continuously operating conveying equipment is commonly used, including roller conveyors. Roller conveyors are devices designed for horizontal, slightly ascending or descending transport of piece products moving on a system of rotating rollers of different shapes (cylindrical, conical, disc, pulley or according to the profile of the conveyed object). The rotating rollers are placed in the track frame (supporting structure), which can be either stable, relocatable or adjustable (height and length adjustable, so-called scissor conveyors). An analogue of the roller conveyor is the pulley conveyor, where instead of rollers, discs - pulleys are mounted on a non-rotating axis. Several discs are installed on the axis with gaps. The pulleys on adjacent axes overlap so that there is no continuous gap. The track is used for handling flat building parts and objects such as metal sheets, glass panes, furniture parts, etc. When transporting item building materials or bulk building materials placed in storage boxes which are transported on a powered roller track on pallets, a driving force is required depending on the angle of inclination of the roller track, the weight of the load, the number of rollers on which the load rests and the coefficient of shear friction during movement. The paper presents a laboratory device that has been designed to detect the adhesion force during the transport of piece loads by a roller conveyor. On the implemented device, it is possible to determine in laboratory conditions the amount of resistance to the movement of the load on the driven roller conveyor depending on the weight of the load. The paper presents measured values of the shear friction coefficient during the movement of a steel storage box on a driven roller track. In this paper, a driven roller track is used for laboratory tests, where the drive of the rollers is implemented by so-called short chains. In addition to horizontal tracks, this chain drive allows you to drive rising tracks with variable gradients or even rising curved tracks.

Research Results of Municipal Sewage Sludge Applied for Building Material Production

The study presents the experimental results on the use of ash obtained as a result of incineration of municipal sewage sludge from the water utility of Izhevsk, Udmurt Republic, for construction material production. Research methods are given and the results of strength tests of building material samples are given. The impact of the manufactured samples of construction materials on the ecology of the surrounding space and human health is assessed. To achieve the set objectives of the research laboratory experiment and determination of indicators of investigated values of sludge, ash and water extracts with the use of devices and measuring instruments are used. On the basis of the research laboratories of Kalashnikov Izhevsk State Technical University and MUE “IzhVodokanal” of the Udmurt Republic experimental studies on incineration of sewage sludge and the use of the resulting ash as a substituting or modifying component of the construction mixture in the manufacture of experimental samples of ceramics, cement-sand mortar and concrete were carried out. Methodology of manufacturing and algorithm of ceramic (fired) and cement-based (nonfired) testing specimens are presented. Measuring means for determination of gamma-radiation intensity indices of ash, cement and their influence on human health are used. The algorithm of experimental research, applied energy-efficient techniques used in the experiment and analysis of the obtained experimental results are presented. The analysis of experimental research results of ceramic and cement-based products, as well as the analysis of radiation safety, migration of heavy metals is presented. The energy-efficient methodology of sewage sludge utilization and further ways of applying ash as an environmental and resource-saving component used in manufacturing of experimental building materials are considered.

Comparative Environmental Evaluation of Sewage Sludge Treatment and Aggregate Production Process by Life Cycle Assessment

This study evaluated the environmental impact of landfill, incineration, and lightweight aggregate production for sewage sludge management techniques and compared the utilization of sewage-produced lightweight aggregates with natural aggregates in terms of building material production. Two scenarios were established for the life cycle assessment (LCA) of the sludge and associated product that was carried out after sludge generation. Sludge incineration and landfill deposition includes emissions from the drying, transportation, incineration of sludge, and landfill, and the production of lightweight aggregates and natural aggregates includes transportation to manufacturing facilities, the manufacturing processes themselves, and transportation of the produced aggregates to construction sites. We calculated the amount of pollutant emissions for each process in each scenario and analyzed the environmental impact index considering the environmental impact of each pollutant using the Open LCA program. The parameters used for the environmental impact index analysis for sludge management are potential acidification, climate change, eutrophication potential, human toxicity, photochemical oxidation, and stratospheric ozone depletion. The environmental impact values of lightweight aggregates (LWA) are GWP 100 441 kg CO2_Eq, AP 2.73 × 10−2 kg SO2_Eq, EP 4.46 × 10−3 kg PO4−_Eq, HTP 4.15 × 10−2 kg, 1,4-DCB_Eq, POCP 1.64 × 10−3 kg CH4_Eq, and ODP 3.41 × 10−7 kg CFC-11_Eq. We found that these values were low compared to landfill and incineration as a sewage sludge disposal method and compared to natural aggregate as a construction material production method. The environmental impact index analysis during LCA of lightweight aggregates produced from the sludge verified its positive environmental impact compared to the other potential methods of sludge management.

Study on reinforcing mechanism of carbon nanotubes on tensile behavior of gangue cemented rockfill

Gangue cemented rockfill (GCR) plays a key role in underground reinforcement projects and construction waste recycling. However, the tensile performance restricted by cementitious materials limits its wider application. Hence, in this study, carbon nanotubes (CNTs) was adopted to reinforce the tensile behavior of GCR samples, since CNTs own excellent mechanical properties and promising microstructure modification in cement-based materials. The test results demonstrate that only 0.007 wt% CNTs could significantly improve tensile strength up to 47.7% and ductility failure property. Through the characterization of acoustic emission (AE), digital image correlation (DIC) and SEM techniques, we found that the microscopic improvement of CNTs could reduce the intensity of failure events, promote the distribution of strain field, and weaken the stress concentration. AE counts of single failure events dropped over 80% and cumulative energy decreased up to 76.4%. Besides, the fractal dimension of macro strain field rose by 7.45∼15.5%, which further indicates the more complex strain distribution. The established CNTs pull-out model, based on above results, further revealed that bridging CNTs provided resistance, consumed fatal work during the pull-out process and slowed down the development of microcracks. This research broadens our understanding of the improvement mechanism of CNTs on the failure mode of GCR materials, which is of great significance for CNTs application and the production of eco-friendly construction materials.

Development of a drying and grinding plant for a mixture of milling peat with water treatment sediments for the production of construction and ceramic materials

The strategy of sustainable development assumes proper management of man-made waste, capable of ensuring their reuse and reducing the associated environmental burden on the environment. A promising direction for the utilization of water treatment sediments is the possibility of their use in a mixture with peat as a potential raw material for the production of construction and ceramic materials. An installation has been developed for the selection of milling peat, its mixing with water treatment sediments, drying of the resulting mixture and grinding for subsequent use in the production of construction and ceramic materials.