Fly ash (FA), a major solid waste from coal-fired industries, represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure, holding significant strategic importance. In recent years, extensive research has been conducted on the mechanisms, optimization, and applications of FA-based road engineering materials. This review focuses on FA-based road engineering material systems, synthesizing previous studies from three perspectives: cement concrete pavement materials, asphalt mixture pavement materials, and stabilized soil road materials. The findings reveal that FA significantly enhances road material performance through its pozzolanic activity, micro-nano filling effects, and interfacial strengthening. In cement concrete systems, the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification. Integrating particle size optimization, nano-modification, and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems. For asphalt mixtures, leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion, while alkali activation further extends its application scope. In stabilized soil systems, FA enhances soil integrity by forming cementitious networks, with structural reinforcement achievable through alkali activation and composite stabilization. However, current research still faces unresolved challenges. These include elemental imbalances and performance limitations in single-FA-based road engineering materials, insufficient high-value applications of FA carbon sequestration technology in road materials, lack of systematic frameworks for environmental risk assessments of FA-based road systems, and constrained application scenarios for FA in road engineering. Future research should focus on innovating activation technologies to enhance the reactivity of FA, co-utilizing multi-source solid wastes, researching carbon sequestration technologies for FA-based road engineering materials, establishing environmental monitoring and evaluation systems, and promoting the application of FA in subgrade filling. The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction, supporting sustainable, low-carbon, and high-quality development in road engineering.
Highway engineering. Roads and pavements, Engineering (General). Civil engineering (General)
IntroductionGlass fibers with polyester resin structural composites are highly sought after in many sectors such as transportation industries, thanks to their low density and fairly good mechanical properties. However, their end-of-life management is not yet satisfactory. Composites mostly end in energy recovery in the best-case scenario or, worse, in landfills. Transformation into shreds and powders for reuse as a new source of raw material for the construction sector (concrete) is an economically and environmentally attractive recovery solution. The present study investigates the development of a concrete filled with glass/polyester composite shreds.MethodsTo this end, rheological (cone spread) and physico-mechanical (density and mechanical strength in flexion and compression) characterization tests were carried out. Several mix designs were tested in order to understand the impact of introducing composite shreds as a substitute for sand. Composite shreds were introduced in the following ratios by volume: 0, 1, 1.5, 2, 2.5, 3, and 7% with water and cement ratio equal to 0.5, 0.6, and 0.7.Results and discussionThe results obtained indicate that workability decreases with the substitution of sand by shreds. For a substitution of sand by shreds of 2%, it is relatively small, and the pouring of the mortar is still feasible. The decrease can be attributed to the water absorption of the composite shreds. Concerning mechanical results, for formulations with a substitution percentage of composite shreds lower than 3%, the mechanical strength (both compression test and flexure test) is slightly higher than that of the reference sample. The increase in compressive strength that can be observed is at its maximum, equal to 10%, compared to that of the reference sample. These results are in line with density results, which are also slightly higher than that of the reference sample. This effect can be attributed to water absorption of composite shreds and the filling effect of the powders. For a percentage of substitution equal to 7%, the mechanical strength is lower than that of the reference sample (30% decrease), with a compressive strength equal to 33 MPa (47 MPa for the reference sample). For this percentage of substitution equal to 7%, a decrease in density is also observed (6% decrease) and can be explained by the porosity created by the incorporation of the composite shreds into the mortar.
Tarek Uddin Mohammed, Md. Aktaruzzaman Rony, Mohammad Zunaied Bin Harun
et al.
To address SDG12 (ensure sustainable consumption and production patterns), and to provide technical evidence for alternative concrete constituents to traditional natural river sand, stone fine aggregate (SFA), brick fine aggregate (BFA), ladle-refined furnace slag aggregate (LFS), recycled brick fine aggregate (RBFA), and washed waste fine aggregate (WWF), ready-mix concrete plants were investigated. Concrete and mortar specimens were made with different variables, such as replacement volume of natural sand with different alternative fine aggregates, water-to-cement ratio (W/C), and sand-to-aggregate volume ratio (s/a). The concrete and mortar specimens were tested for workability, compressive strength, tensile strength, and Young’s modulus (for concrete) at 7, 28, and 90 days. The experimental results show that the compressive strength of concrete increases when natural sand is replaced with BFA, SFA, and LFS. The optimum replacement amounts are 30%, 30%, and 20% for BFA, SFA, and LFS, respectively. For RBFA, the compressive strength of concrete is increased even at 100% replacement of natural sand by RBFA. For WWF, the compressive strength of concrete increases up to a replacement of 20%. Utilizing these alternative fine aggregates can be utilized to ensure a circular economy in construction industries and reduce the consumption of around 30% of natural river sand.
<p>Extracting raw materials and processing them into products used in industry constitute a substantial source of CO<span class="inline-formula"><sub>2</sub></span> emissions, which are currently lacking process detail in many integrated assessment models (IAMs). To broaden the space of climate change mitigation options to include material-oriented strategies such as the circular-economy and material efficiency measures in IAM scenario analysis, we develop the MESSAGEix-Materials module, representing material flows and stocks within the MESSAGEix-GLOBIOM IAM framework. We provide a fully open-source model that can assess different industry decarbonization options under various climate targets for the most energy- and emissions-intensive industries: aluminum, iron and steel, cement, and petrochemicals. We illustrate the model's operation with a baseline and mitigation 2-degrees (2 °C) scenario setup and validate base year results for 2020 against historical datasets. We also discuss the industry decarbonization pathways and material stocks of the electricity generation technologies resulting from the new model features. The next steps are to extend the model to other sectors, end uses and materials, as well as the combined modeling of various supply- and demand-side measures.</p>
Micheal G. Wolde, Dilip Khatiwada, Getachew Bekele
et al.
Cement production is a major consumer of energy and the largest source of industrial CO2 emissions. This study aims to perform an environmental life cycle assessment of clinker and cement production in Ethiopia, using ReCiPe impact assessment method. Inventory data (material, energy, and transportation) is collected from seven major Ethiopian cement industries. The midpoint analysis identified nine hotspot environmental concerns: global warming, ozone formation (human health and terrestrial ecosystem), particulate matter formation, terrestrial (acidification and ecotoxicity), freshwater eutrophication, human carcinogenic toxicity, and fossil resource scarcity. Human health emerged as the most significantly affected endpoint damage category by the midpoint impacts. Among the process stages included in clinker system boundary, clinker production phase (kiln emissions) is a significant contributor to the total score of the hotspot impacts, ranging from 60.7% to 91.8%. The clinker system is responsible for over 81.03% of the overall environmental burden of cement. The sensitivity analysis reveals that a 5% change in kiln energy consumption and transportation burden could lead to a reduction in hotspot impacts ranging from 1.8% to 5%. To foster reliability of this study, uncertainty analysis is also conducted. Overall, the findings indicate the need to enhance environmental sustainability in Ethiopian cement production.
Abstract The development of alternative binders to Portland Cement has become a critical factor in decreasing the Portland cement industry’s carbon footprint, which nowadays represents about 7% of CO2 emissions worldwide. Thereby the seek for the development of alternatives binders led to a recent and growing interest in carbonate-based binders due to their ability to capture and store CO2 into their cementitious matrix and, consequently, leading to the rise of the research related to the scope of this work, Carbonated Reactive Magnesia Cement, which has as the main property the capability to adsorb CO2 into its cementitious matrix when subject to favourable carbonation curing conditions. Thus, this paper describes the Magnesia carbonation mechanism to subsequently review and enumerate the influencing factors over the carbonation curing of Carbonated Reactive Magnesia Cement-based materials. Afterwards, it summarizes recent works on this binding technology that don’t use Portland cement in their composition. Besides that, the carbonation curing conditions used in these studies are highlighted along with this work. Therefore, the main goal of this review is to bring a starting point of the carbonation curing influencing factors of Carbonated Reactive Magnesia Cement-based materials. Thereby, this review may help future research on this field and some issues to be overcome by this material group.
R. Gopalakrishnan, V. Sounthararajan, A. Mohan
et al.
Abstract This research work has been investigate on the foam concrete, which is an novel and very useful materials in construction industry , basically a cement mortar slurry with a maximum of 10% volume of foam. One of the main disadvantage of foam concrete is the large usage of river sand as a filler material, which leads to eco-friendly concrete. An experimental investigation has been done to effect of fly ash by partially replacing in cement from 0 to 50% and replacing river sand by quarry dust (0-50%) for various mixes. This research paper produce the compressive strength, split tensile strength and durability properties such as water absorption and permeability. From the investigation it have been concluded that the replacing partially 30% of fine sand b and quarry dust combination produced better quality results in par with the conventional foam concrete.
Abstract The energy intensive industry (EII) is responsible for two-thirds of industrial carbon dioxide emissions in the EU. It has been recognised by both public and private stakeholders that a far-reaching transformation of these industries is required to comply with the overall emission reduction goals stated by the European Union for 2050. Contrasting innovations discussed in pathway and roadmap publications for the different industries, it can be concluded that there is little consensus on how deep decarbonisation of the EII will be achieved. In this paper, a review of pathway and roadmap publications and scientific literature is presented. This permits to identify key areas for emission abatement across all subsectors. Results show significant discrepancies in the literature regarding the expected emission reductions achievable, but permit us to identify areas that are key for the transition towards a low-emission EII: the decarbonisation of low temperature heat by cross-sector technologies, use of membranes in the (petro)-chemical industry, carbon neutral steelmaking, alternative feedstock for the cement production and carbon capture & storage (CCS).
The huge demand for concrete is predicted to upsurge due to rapid construction developments. Environmental worries regarding the large amounts of carbon dioxide emanations from cement production have resulted in new ideas to develop supplemental cementing materials, aiming to decrease the cement volume required for making concrete. Palm-oil-fuel-ash (POFA) is an industrial byproduct derived from palm oil waste’s incineration in power plants’ electricity generation. POFA has high pozzolanic characteristics. It is highly reactive and exhibits satisfactory micro-filling ability and unique properties. POFA is commonly used as a partially-alternated binder to Portland cement materials to make POFA-based eco-efficient concrete to build building using a green material. This paper presents a review of the material source, chemical composition, clean production and short-term properties of POFA. A review of related literature provides comprehensive insights into the potential application of POFA-based eco-efficient concrete in the construction industry today.
S. K. Tripathy, Jayalaxmi Dasu, Y. R. Murthy
et al.
Abstract Efficient utilisation and recycling of industrial waste along with minimum exploitation of natural resources are major challenge towards the circular economy and sustainability of the planet. Blast furnace slag is a by-product of the iron-making process while producing pig iron. The present research provides an understanding of the two different types of slags of water quenched granulated slag and air-cooled slag that are generated from iron making process through the blast furnace route. The chemical, mineralogical, physical, thermal and morphological properties of four different slags generated under different cooling condition are evaluated for recycling to cement and aggregate application. Results indicated that the cooling pattern of the slag significantly affects the particle morphology and phase formation, which determines their usage and utilisation. Air-cooled slag contains substantial quantity of crystalline phases (>50%) which prevents the slag to exhibit cementitious properties whereas water-quenched slag mainly contains amorphous phases (>90%). In addition, the applicability in cement and aggregate application of both mentioned types of slags were studied. It is concluded that water quenched slag is closely matching with the properties required to be utilised in Portland slag cement manufacturing process. On the other hand, air-cooled slag is suitable as an aggregate for application in the construction industry.
Abstract This paper reviews the potential use of electric furnace ferronickel slag (FNS) as a fine aggregate and binder in Portland cement and geopolymer concretes. It has been reported that the use of FNS as a fine aggregate can improve the strength and durability properties of concrete. Use of some FNS aggregates containing reactive silica may potentially cause alkali-silica reaction (ASR) in Portland cement concrete. However, the inclusion of supplementary cementitious materials (SCM) such as fly ash and blast furnace slag as partial cement replacement can effectively mitigate the ASR expansion. When finely ground FNS is used with cement, it shows pozzolanic reaction, which is similar to that of other common SCMs such as fly ash. Furthermore, 20% FNS powder blended geopolymer showed greater strength and durability properties as compared to 100% fly ash based geopolymers. The utilization of raw FNS in pavement construction is reported as a useful alternative to natural aggregate. Therefore, the use of by-product FNS in the construction industry will be a valuable step to help conservation of natural resources and add sustainability to infrastructures development. This paper presents a comprehensive review of the available results on the effects of FNS in concrete as aggregate and binder, and provides some recommendations for future research in this field.
Abstract 3D printing for cement-based material is recently supposed to be the rapidly and innovative forming technology in the building industry. This paper is concentrated on the rheological and mechanical properties of hydroxypropyl methyl cellulose (HPMC), water-reducing agent (WRA) and lithium carbonate (Li2CO3) modified 3D printing sulphoaluminate cementitious materials based on the extrusion system of 3D printing. Experimental results show that HPMC notably increases the stress and viscosity of cement paste and the plastic viscosity need to reach 1.650 ∼ 2.538 Pa·s for the build-up of 3D structures. While the cement paste with WRA and Li2CO3 present low shear stress and apparent viscosity. Furthermore, the setting time and rheological properties of 3D printing cement paste with hybrid admixtures are investigated using response surface methodology (RSM). The optimal hybrid additions of admixtures enable the 3D printing paste to achieve a favorable deformation rate and higher compressive strength. In conclusion, utilization of admixtures has a great potential to develop 3D printing sulphoaluminate cementitious materials used in buildings, which can effectively control the printable properties and rheological behaviors.
Hamid Reza Vaezian, Reza Akbarian, Rohollah Shahnazi
et al.
In this research, the impact of the impact of the international sanctions index on the performance indices of the Tehran Stock Exchange by industries, including mass production indices, banks, insurance, automobiles, investments, basic metals, rubber, cement, chemical, industry, petroleum products, pharmaceuticals, transportation, sugar And thanks, we have checked for the time period from 2010 to 2020. For this purpose, we have used the weekly data of the above variables and using the Multivariate Generalized Autoregressive Conditional Heteroskedasticity (MGARCH), Dynamic Conditional Correlation Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model. Based on the results of the research, the influence of the sanctions index with different intervals (1 to 29) on the performance indicators of Tehran Stock Exchange with different ARCH and GARCH intervals (1 to 20) was proved by obtaining significant coefficients of -0.098417 to 0.137398.
In this work, Cold Water Extraction (CWE) was performed on blended cement pastes to extract the pore solution and determine the free alkali metal content. To better understand CWE results, the reactivity of cementitious materials was also investigated, complemented by TGA and quantitative XRD analysis. The study aimed at being generic to assess the suitability of the methods, and included 9 SCMs with various compositions: limestone, coal fly ash, two calcined clays, two biomass ashes, sewage sludge ash, crushed brick and glass beads.The study highlighted the importance of assessing the reactivity of SCMs in parallel to performing CWE, as this contributes to a more certain interpretation of the results. In general, results obtained with CWE were consistent with the existing literature about the effect of binder composition on the free alkali metal content. From a practical view, CWE and SCM reactivity tests could be performed with basic laboratory equipment and appeared to be applicable to both traditional and alternative SCMs.
Essossinam Beguedou, Satyanarayana Narra, Ekua Afrakoma Armoo
et al.
The conventional energy source in cement industries is fossil fuels, mainly coal, which has a high environmental footprint. On average, energy expenditures account for 40% of the overall production costs per ton of cement. Reducing both the environmental impact and economic expenditure involves incorporating alternative energy sources (fuels) such as biomass, solid-derived fuel (SDF), refuse-derived fuel (RDF) etc. However, within cement plants, the substitution of conventional fossil fuels with alternative fuels poses several challenges due to the difficulty in incorporating additional fuel-saving techniques. Typically, an additional 3000 MJ of electricity per ton of clinker is required. One of the most effective solutions to this is thermal optimization through co-processing and pre-processing, which makes it possible to implement additional fossil-fuel-saving techniques. In developing nations such as Togo, waste-management systems rely on co-processing in cement factories through a waste-to-energy relationship. Also, there are some old cement plants with low-efficiency, multi-stage preheaters without pre-calciners, reciprocating huge coolers, low-efficiency motors etc., which still operate and need to be made environmentally sustainable. However, compared to modern kilns which can have up to 95% of energy recovery from waste, an old suspension preheater kiln can recover only up to 60% of its heat energy depending on the cooler type, and due to the lack of a bypass and combustion chamber (pre-calciner). This research paper evaluated the performance of a cement plant incorporating AF and presents the procedures and recommendations to optimize AF substitution in cement plants. To achieve this, a comparative performance study was carried out by assessing the alternative fuel characteristics and the equipment performance before and after the incorporation of the alternative fuel. Data were collected on the optimum substitution ratio, pre-processing and co-processing performance, raw-meal design and economic analysis. Results indicated that the cost to be covered per ton of waste input is €10.9 for solid-derived fuel (SDF), €15 for refuse-derived fuel (RDF), and that the co-processing cost optimization for the cement plant could have a cost saving of up to 7.81€/GJ. In conclusion, it is recommended that appropriate kiln and alternative-fuel models be created for forecasting production based on various AF.