Use of marble sludge waste in the manufacture of eco-friendly materials: applying the principles of the Circular Economy

Recycling of sewage sludge in clay-free thermal insulation brick: assessment of microstructure, performance, and environment impact

Recycling municipal sewage sludge in fired bricks not only contributes to environmental protection, but is also an alternative to natural clay resource. The complex compositions of sludge have a great influence on the brick property. This work presents a systematical investigation on fired bricks made only with sludge and shale. The physicochemical properties of the raw mixtures, macroscopic performance, microstructure, and its evolution were quantitatively determined. The coordination between shale and sludge enables the blend of raw materials to achieve the desired gradation and plasticity. Although a reduction in compressive strength was observed, the open porosity was increased to 31.6% and thermal conductivity was reduced to 0.51 W·(m·K)^-1, indicating the benefit to the performance of lightweight thermal insulation bricks. The fitting results confirm the pore-forming effect induced by the organic matter in the sludge. The obtained bricks possess good performance, especially in thermal insulation properties, and environmental and economic benefits.

Production of high value-added filler from harmful dust of marble industry using N-sodium lauroyl sarcosinate surfactant as a new flotation collector

In the stone industry, about 73% of the total production is generated as solid waste. In the processing phase, only 20% is produced as harmful ultra-fine sawdust sludge. In the Turah area, Cairo, Egypt, an estimated 448,000 tons are produced annually. About 60% of the total production of dimension stones is carbonate stones. The objective of this study is to properly dispose of the ultrafine pollutants and produce value-added products. The ultrafine marble waste was characterized by different methods such as XRD, XRF, FTIR, particle size analysis and zeta potential. Calcite and dolomite minerals were the main constituents of this waste (91%). The average particle size was 6.656 µm. The fine fraction with a particle size of less than 25 µm contains 97.6% calcite with 81% weight. Sodium N-lauroyl sarcosinate (SNLS) was used as a selective flotation collector for calcite as a calcium mineral. A flotation concentrate with a purity of 99.6% and an overall yield of 80% was obtained at a pH of 9. The bleached product meets ASTM standard specifications for paint and paper applications.

Recycling of marble cutting waste additives in fired clay brick structure: a statistical approach to process parameters

Within the scope of the present study, the marble cutting waste, which is an industrial waste of different sizes (< 75 µm and < 150 µm), was incorporated into the clay structure at various rates and a total of 36 series bricks were produced. The brick mixtures were prepared by the semi-dry molding method and the brick specimens were sintered for three temperatures (850 °C, 950 °C, and 1050 °C). The fired bricks containing marble cutting waste with a lower particle size (75 µm) have higher compressive strength. However, all samples produced can meet the relevant standard requirements in terms of compressive strength. Thermal conductivity decreased from 1.008 to 0.775 W/mK with the incorporation of marble cutting waste, a decrease of approximately 23.11%. The effects of grain size, firing temperature, and marble cutting waste concentration on the quadratic model were statistically determined by variance analysis (ANOVA). According to statistical findings, the order of importance of design factors for brick properties (except for compressive strength) is marble cutting waste > firing temperature > particle size. For compressive strength, the most dominant factor is amount of marble cutting waste, followed by particle size and firing temperature, respectively. Consequently, the results suggest that marble cutting waste does not need to be reduced to smaller particle sizes to improve the fired clay brick properties.

A multifunctional plant for a sustainable reuse of marble waste toward circular economy

The marble processing cycle involves the production of large quantities of wastes whose disposal represents an economic and environmental concern for marble companies due to the difficulty of identifying suitable landfills and the high transfer costs. In this context, the design of a sustainable industrial plant that allows the reuse of the calcium carbonate (CaCO₃) contained in the marble waste is extremely challenging. With this recognition, the main industrial applications of CaCO₃ are firstly analyzed in the present work to identify the physical-chemical properties required to CaCO₃ in these contexts. Later, different plant solutions are suggested to recover CaCO₃ from marble sludge in order to allow its use in industrial applications. The designed industrial plant includes an energy efficient drying phase, which exploits the thermal waste of the exhaust gases produced in a cogeneration section, and a subsequent milling phase. Since marble wastes currently constitute an economic burden for companies and an environmental emergency for the Public Administration, the performed technical-economic analysis shows that its recovery may represent an opportunity of sustainable development for the marble sector.

A Triple-Helix Intervention Approach to Direct the Marble Industry towards Sustainable Business in Mexico

The marble industry in Mexico, similarly to the international market, is going through some problems which are characterized by low productivity performance, inconsistency in management and administrative organization, high raw material waste, and negative social and environmental impact. The methodology used in this paper is based on a systematic review of the strategies and solutions used to address these problems reported between 2014 and 2021, including the results of the application of in situ surveys to three marble companies in the Mixteca Poblana region. These surveys are collected in this article alongside industry experience to propose, in a structured way, a three-pronged management approach with the aim of directing the marble industry towards a sustainable industry model. The structure of this approach, based on forms of capital and sustainability dimensions, engages governments, companies, schools and society to guide this industrial sector to become a sustainable business, integrating knowledge and experience of the marble industry processes. We recommend adding performance metrics to this approach to assess the value chain of the marble industry.

Applying rail transit construction waste to make building materials: using the theory of sustainable development

With the rapid development of the rail industry, a large amount of construction waste will be generated during the construction phase, posing a significant risk of environmental pollution and exacerbating the plight of global resource shortages. This study establishes a green disposal system for rail transportation based on the theory of sustainable development. Shield slag, shield weathered sand, shale, and engineering slag are used as raw materials, and sintered bricks are adopted as their innovative disposal method. The heavy metals in the four types of construction waste and recycled products were tested by X-ray fluorescence analysis technique to analyze the actual environmental pollution risk and explore the influence of the firing stage on the performance of the recycled products through the enrichment factor evaluation method. The results of the physical and chemical property tests of the fired samples showed that the environmental pollution risk of the four recycled products after firing was at a low-risk level (EF < 2), the strength test results showed that the best specimens had a strength rating of 20 MPa and the other performance indicators (frosting degree, lime bursting test) measured also met the requirements of the recycled bricks. This study achieves the harmless treatment of construction waste, provides a disposal system for the green recycling of construction waste from rail transport, and provides a theoretical basis for subsequent studies on the effects of different external conditions on such recycled products.

Marble waste site suitability assessment using the GIS-based AHP model

Site suitability with regards to environmental protection, public concerns, and the legitimate prerequisite is a basic issue that has been tended to in this study. By and large, marble waste is being unloaded on accessible open spaces or released in water to the close by waterways in the territory, Mohmand marble zone (Shabqadar), Khyber Pakhtunkhwa, Pakistan. Suitability assessment for marble waste collection and disposal was carried out through the integrated approach of analytical hierarchy process (AHP) and geographic information system (GIS) to limit the ecological dangers, public, and government concerns related to marble waste. The available land use was ordered into three main land use classes followed by six sub-classes including water bodies and agriculture (environmental), settlement and social site (social), and marble units and roads (economic). These sub-classes in the investigation region were organized through pairwise correlation and weighted sum analysis, AHP procedure. The AHP results were interpreted through GIS tools of digitization, buffering, and overlay in ArcMap, ArcGIS. The integrated AHP and GIS outcomes were consolidated to get the optimum results of the study, marble waste collection, and disposal options. It was concluded that priority should be given to water bodies followed by agricultural land while protecting the available land use classes from marble waste hazards. The percent priority values calculated are 32.33%, 30.50%, 12.16%, 10.66%, 8.50%, and 6% for water bodies, agricultural land, settlements, marble processing units, roads, and cultural sites respectively. The sequence of priority of the land use values are waterbodies > agriculture > settlement > marble industries > road > cultural site. The proposed integrated model is helpful in site suitability for waste management by the authorities and decision-makers associated with waste management.

Recycling of Mining Waste in the Production of Masonry Units

Masonry units made of clay or Autoclaved Aerated Concrete (AAC) are widely used in constructions from Romania and other countries. Masonry units with superior mechanical and thermal characteristics can improve the energy efficiency of buildings, especially when they are used as the main solutions for building envelope construction. Their production in recent years has increased vertiginously to meet the increased demand. Manufactured with diversified geometries, different mechanical and/or thermal characteristics have a high volume in the mass of the building and a major influence in their carbon footprint. Starting from the current context regarding the target imposed by the long-term strategy of built environment decarbonization, the aim of the paper is to analyze the potential of reusing mining waste in the production of masonry units. Mining waste represents the highest share of waste generated at national level and may represent a valuable resource for the construction industry, facilitating the creation of new jobs and support for economic development. This review presents the interest in integrating mining wastes in masonry unit production and the technical characteristics of the masonry units in which they have been used as raw materials in different percentages. Critical assessment framework using SWOT analysis highlights the key sustainability aspects (technical, environmental, social, economic) providing a comprehensive and systematic analysis of the advantages and disadvantages regarding the integration of mining waste as secondary raw materials into masonry units production.

Production of Greener High-Strength Concrete Using Russian Quartz Sandstone Mine Waste Aggregates

Quartz sandstone (QS) is a mine waste; therefore, its use in construction allows for both reducing the cost of the concrete and contributing to the utilization of waste. The scientific originality of this study is the identification of models of the effect of QS aggregate on the physicomechanical, durability characteristics, and eco-safety of greener high-strength concrete. The study used an energy-efficient method of non-thermal effects of electromagnetic pulses on the destruction mechanisms of quartz-containing raw materials. The characteristics of quartzite sandstone aggregates, including the natural activity of radionuclides, were comprehensively studied. The features of concrete hardening, including the formation of an interfacial transition zone between the aggregate and the cement matrix, were studied, taking into account the chemical and morphological features of quartzite sandstone. In addition, the microstructural and morphological properties of concrete were determined after a 28 day curing. In this study, the behaviors of the concrete with QS aggregate were investigated, bearing in mind the provisions of geomimetics science on the affinity of structures. The results obtained showed that the QS aggregate had the activity of natural radionuclides 3-4 times lower compared to traditional aggregates. Efficient greener concrete with a 46.3 MPa compressive strength, water permeability grade W14, and freeze-thaw resistance of 300 cycles were also obtained, demonstrating that the performance of this greener concrete was comparable to that of traditional concrete with more expensive granite or gabbro diabase aggregates.

Assessing enablers of e-waste management in circular economy using DEMATEL method: An Indian perspective

With increasing population, excessive use of electrical and electronic products and extreme demand of resources have compelled the linear economy to transform into Circular Economy (CE). In the current scenario, e-waste management has become the top priority of all the developed and developing nations especially those in the transition phase. The generation of e-waste has increased proportionally across the world and created an intense pressure on the firms to implement sustainable practices to redesign and recycle the products. The current status of the developing countries like India confronts number of challenges to manage e-waste produced, and the only possible solution is to minimize the waste generation and practicing recycling processes. For transforming into CEs, there is a need to identify the most influencing key enablers through which an effective and robust e-waste management (e-WM) system can be developed. An extensive literature review and expert judgments are expended to identify the most influencing key enablers of e-WM in circular economies, and, being the highest producer of e-waste, Mumbai (Maharashtra) has been chosen as the case location. To explore the strength of causal and effect enablers, the DEMATEL method is applied. This study has shown that 'Environmental management system' (EMS) is the most significant and important driving enabler to influence all the other existing enablers. This study has also highlighted that e-WM can be efficient if it focuses on producing eco-friendly products, developing strict legislations, building green image and supporting the producers to implement CE practices. This study helps stakeholders and policy makers to reduce the burden from the environment and focus on developing an efficient e-WM system on the basis of identified key enablers like EMS and collaboration with environmental partners to contribute towards CE transition.