Life Cycle Assessment of Cement Production with Marble Waste Sludges

The construction industry has a considerable environmental impact in societies, which must be controlled to achieve adequate sustainability levels. In particular, cement production contributes 5–8% of CO2 emissions worldwide, mainly from the utilization of clinker. This study applied Life Cycle Assessment (LCA) methodology to investigate the environmental impact of cement production and explore environmental improvements obtained by adding marble waste sludges in the manufacture of Portland cement. It was considered that 6–35% of the limestone required for its production could be supplied by marble waste sludge (mainly calcite), meeting the EN 197-1:2011 norm. Energy consumption and greenhouse gas (GHG) emission data were obtained from the Ecovent database using commercial LCA software. All life cycle impact assessment indicators were lower for the proposed “eco-cement” than for conventional cement, attributable to changes in the utilization of limestone and clinker. The most favorable results were achieved when marble waste sludge completely replaced limestone and was added to clinker at 35%. In comparison to conventional Portland cement production, this process reduced GHG emissions by 34%, the use of turbine waters by 60%, and the emission of particles into the atmosphere by 50%. Application of LCA methodology allowed evaluation of the environmental impact and improvements obtained with the production of a type of functional eco-cement. This approach is indispensable for evaluating the environmental benefits of using marble waste sludges in the production of cement.Junta de Andalucía and Fondo Europeo de Desarrollo Regional (FEDER) Ref. P18-RT-419

Managing Marble Quarry Waste: Opportunities and Challenges for Circular Economy Implementation

Marble has been a prominent natural stone exploited since ancient times, commonly employed as a building material and ornamental stone. However, the disposal of waste generated from marble extraction, particularly fine sludge, poses significant environmental challenges for the dimensional stone industry. The difficulty in managing and recovering these materials, exacerbated by local regulations and the absence of suitable recovery protocols, often leads to landfilling. This issue is exemplified by the Carrara Marble Basin in the Apuan Alps (Tuscany, Italy), where more than half of the extracted marble remains as quarry waste or debris. Modern cutting technologies have intensified the production of finer materials and sawing residue, known as “marmettola”, ranging in size from fine sand to silt. The disposal of these materials, commonly through landfilling or abandonment, has profound environmental repercussions. This research primarily aimed to carry out a preliminary physical, mineralogical, and morphological characterization of the fine waste and sludges generated from Carrara Marble exploitation. The findings reveal the high granulometric uniformity of the materials, and a nearly pure carbonate composition, suggesting potential for reuse in various industrial sectors such as paper, plastics, and pharmaceuticals production

Performance-related characterization of fluidized thermal backfills containing recycled components

The investigation described in this paper focused on the performance-related characterization of cementitious Fluidized Thermal Backfills (FTBs) containing recycled components derived from pavement maintenance and aggregate or stone processing operations. In particular, the study was performed with the purpose of assessing the suitability of these peculiar mixes in situations which require the filling of cavities in the presence of several conduits with high-voltage transmission cables. FTBs were prepared in the laboratory by modifying their standard composition in order to include variable percentages of reclaimed asphalt pavement (RAP) and of three different types of mineral sludge. Components were subjected to preliminary physical characterization and the sludges were investigated in detail with the purpose of identifying their microstructure and chemical composition. In consideration of their intended end-use, FTBs were characterized in terms of their flowability, thermal conductivity and thermal stability. Furthermore, while considering a typical layout of high-voltage cables, an analysis was carried out in order to quantitatively assess the influence of FTB composition and characteristics on line ampacity. Results showed that FTBs may be successfully designed to include recycled components while still retaining satisfactory flow characteristics and thermal properties, although it should be considered that they are extremely sensitive to variations in composition. Furthermore, it was proven that the considered FTBs all led to a satisfactory line ampacity and that in fact their formulation may be adjusted to improve the durability of high-voltage cables

Waste recycling in ceramic tiles: a technological outlook

The ceramic industry is going to be deeply involved in the transition to a circular economy. However, the main obstacle to a widespread recourse to waste recycling is the lack of knowledge about its effect in ceramic tile manufacturing. The rationale behind this work is to look at recycling from the industrialist's point of view. The goal is overviewing the effects of different kinds of waste on technological behavior, technical performance, and environmental impact of ceramic tiles in the prospect of an industrial transfer. Technical constraints that waste recycling must comply to be transferable to ceramic tile manufacturing were examined in detail. Available information on the behavior of ceramic tile bodies containing wastes from various sources was critically reviewed for every manufacturing stage. The main outcome is an outlook about feasibility (expressed in terms of Technology Readiness Level) and recommended recyclable amount. In addition, hindrances to scale up and matters of concern (e.g., hazardous components and gaseous emissions) are pointed out and discussed. Examples and reasons of success/unsuccess are briefly illustrated, and prospect of waste recycling in ceramic tiles production from a circular economy perspective was appraised

Treatment and valorization plants in materials recovery supply chain

Aim of industrial symbiosis is to create synergies between industries in order to exchange resources (by-products, water and energy) through geographic proximity and collaboration [1]. By optimizing resource flows in a “whole-system approach”, a minimization of dangerous emissions and of supply needs can be achieved. Resources exchanges are established to facilitate recycling and re-use of industrial waste using a commercial vehicle. Several paths can be identified in order to establish an industrial symbiosis network (Figure 1, left), in relation (i) to the life cycle phase (raw material, component, product) and (ii) to the nature (material, water, energy) of the resource flows to be exchanged. Sometimes by-products and/or waste of an industrial process have to be treated and valorized in order to become the raw materials for others. In particular, two main treatment processes can be identified: refurbishment/upgrade for re-use (Figure 1, center) and recycling for material recovery (Figure 1, right). A brief overview of technological and economic aspects is given, together with their relevance to industrial symbiosis

INNOVATIVE SOLUTIONS FOR THE PRODUCTION OF BRICKS FROM WASTEWATER TREATMENT SLUDGE

Based on the need to recover various wastes such as waste from wastewater treatment plants, it is proposed to use sludge in the manufacture of various building materials as bricks. So far, bricks made of different materials and combinations of classical materials as burnt clay, cement, sand, but also of other unconventional materials, most of them coming from different wastes, are used in construction. In order to use the sludge for bricks fabrication, it is necessary to inert it and to obtain a moisture content below 80%. Also, the physico-chemical and ecological parameters must be suitable for sludge utilization and their values must be situated within the limits imposed by legislation. So, the sludge is centrifuged in order to reduce the moisture content from (90-95)% to a maximum of 80%, treated, then the sludge batches are characterised and finally the sludge is recovered by inert cement

A review: construction and demolition waste as a novel source for CO2 reduction in Portland cement production for concrete

There is an increasing global recognition of the need for environmental sustainability in mitigating the adverse impacts of cement production. Despite the implementation of various carbon dioxide (CO2) mitigation strategies in the cement industry, such as waste heat recovery, the use of alternative raw materials and alternative fuels, energy efficiency improvements, and carbon capture and storage, overall emissions have still increased due to the higher production levels. The resolution of this matter can be efficiently achieved by the substitution of traditional materials with an alternative material, such as calcined clay (CC), construction and demolition waste (CDW), which have a significant impact on various areas of sustainable development, including environmental, economic, and social considerations. The primary objectives of employing CDW in the Portland cement production are twofold: firstly, to mitigate the release of CO2 into the atmosphere, as it is a significant contributor to environmental pollution and climate change; and secondly, to optimize the utilization of waste materials, thereby addressing the challenges associated with their disposal. The purpose of this work is to present a thorough examination of the existing body of literature pertaining to the partial replacement of traditional raw materials by CDW and the partial replacement of Portland cement by CDW and to analyze the resulting impact on CO2 emissions.This work was supported by Fundação Para a Ciência e Tecnologia (FCT)/MCTES through national funds (PIDDAC) under the R&D Unit Centre for Territory, Environment and Construction (CTAC) under reference UIDB/04047/2020

Environmental effects of using clay bricks produced with sewage sludge: leachability and toxicity studies

Peer ReviewedPostprint (published version

Co-processing of Industrial Waste in Cement Kiln – A Robust System for Material and Energy Recovery

AbstractWaste management is a serious issue around the world. It is most prominent in the developing countries. Non–hazardous industrial waste is another aspect at 100 million tons/year with coal ash accounting for 70 million ton/year in India. It is the second highest waste stream ending up in landfill site. The quantity is projected to be increased at faster rate in coming years with increasing industrialization. This industrial waste has characteristics of municipal solid waste with percentage of non-biodegradable waste on the higher side. Co-processing of this waste for energy recovery and as an alternative raw material in cement kiln can be an effective management methodology for this waste stream. This is being practiced sustainably in number of countries but in India the process lacks proper implementation. The auxiliary technological requirement is less and the process is highly economical and effective. This study specifically shows the effectiveness of the co-processing in cement plants in India, as a way for an effective utilization of energy and recoverable raw materials locked in the industrial waste. The robustness of the co-processing of industrial waste has been analyzed based on three cases studies in India. The findings revealed that it can be one of the most effective industrial waste disposal techniques in India and in other developing countries considering other practices of waste disposal methodology in terms of zero ash generation, emission, less auxiliary technology requirements, less set up cost, etc. The robustness of the co-processing as a waste disposal technique was also revealed by the economic and environmental statistical analysis. The study shows the sustainability of co-processing as an energy and material recovery process and addresses the issues related to sustainable management of industrial wastes. Number of study is available in the literature but analysis based on multiple case studies specific to Indian scenario is scarce

Performance‐Related Assessment of the Potential Use of Sawing Sludge in Cementitious Fluidized Thermal Backfills

The management of sawing sludge originated from cutting operations of ornamental stones represents a challenging task as a consequence of its peculiar composition that includes non‐negligible amounts of heavy metals resulting from the wear and tear of cutting tools. The aim of the research work presented in this paper was to investigate the feasibility of using these by‐products as supplementary constituents of cementitious mixtures employed for the formation of Fluidized Thermal Backfills (FTB). These mixtures are designed and produced for filling operations in pavement subgrades in which high‐voltage electrical transmission cables are buried for protection purposes. Two different types of sawing sludge were thoroughly analyzed from a physical and chemical point of view and thereafter employed for the laboratory production of four FTB mixtures. Then, these were subjected to thermal, mechanical, and environmental tests in order to verify their suitability for their intended use. All investigated FTB mixtures exhibited a satisfactory and stable thermal conductivity, and they also displayed enhanced stiffness properties in comparison to standard subgrade and sub‐base materials. Controversial results were obtained with respect to environmental properties resulting from leaching tests, thus suggesting that further investigations are needed before any full‐scale application can take place