Search Results (62)

Global cement manufacturing generated 1.6 billion metric tons of CO₂ in 2022 and relies heavily on non-renewable raw materials. Utilizing agro-industrial waste as supplementary cementitious material (SCM) can help mitigate the demand for these resources. SCMs have been integrated into cement production to deliver both technical and environmental benefits to mortars and concrete. This study examines mortar blends containing blast furnace slag (BFS), Brazilian calcined clay (BCC), and bamboo leaf ash (BLA). While BFS and BCC are already established in the cement industry, recent research has highlighted BLA as a promising pozzolanic material. The SCMs were characterized, and mortars were produced to assess their flexural and compressive strength, as well as durability indicators such as electrical resistivity, chloride diffusion, migration coefficient, and carbonation resistance. The findings reveal significant performance enhancements. Partial cement replacement (20% and 40%) maintained the strength of both binary and ternary mortars, demonstrating statistical equivalence to the reference mortar (p > 0.05). It also contributed to an improved pore structure, reducing the migration coefficient by up to four times in the 20BLA20BCC mix (which replaces 20% of cement with BLA and 20% with BCC) compared to the reference mix. Chemically, the SCMs enhanced the chloride-binding capacity of the cementitious matrix by up to seven times in the case of the 20BCC mortar, thereby improving its durability. Therefore, all tested compositions—binary and ternary—showed mechanical and durability advantages over the reference while also contributing to the reduction in environmental impacts associated with the cement industry. Full article

An alternative to conventional methods for mine tailings disposal is stabilization with alkali-activated binders (AABs), developed from agro-industrial waste. Despite increasing interest in this topic, there is still a lack of studies focusing on the stabilization of iron ore tailings (IOTs) using AABs, particularly those that combine the characterization of cementitious gels with an evaluation of leaching behavior. This study assessed the strength, mineralogy, and leaching performance of IOTs stabilized with AABs formulated from rice husk ash (RHA) and hydrated eggshell lime (HEL), using sodium hydroxide as the alkaline activator. Tests included unconfined compressive strength (UCS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and metal leaching analyses. The IOT–AAB mixture with the highest AAB content and dry unit weight achieved an average UCS of 2.14 MPa after 28 days of curing. UCS increased with AAB content, followed by dry unit weight and curing time, the latter showing a non-linear influence. The formation of C–S–H gel was confirmed after 28 days, while N–A–S–H gel was detected as early as 7 days of curing. The cemented IOT–AAB mixtures showed no metal toxicity and effectively encapsulated barium originating from the RHA. Full article

The use of agro-industrial waste, such as wood ash or biomass ash, has been adopted as an alternative to synthetic fertilizers for providing nutrients to plants. This study aimed to evaluate the levels of primary and secondary macronutrients in soil cultivated with chrysanthemum under different types of fertilization management: organic, organomineral, and mineral, with and without liming. The experiment was conducted in a greenhouse for 185 days, using a randomized blocks design in a 5 × 2 factorial scheme: five fertilization types (incubated and unincubated wood ash, organomineral fertilizer, mineral fertilizer, and control) and two levels of liming (without liming and 70% base saturation) with five replicates. The soil used was Oxisol. The phosphorus, potassium, calcium, magnesium, and sulfur contents in the soil after cultivation were analyzed. There was a 77% increase in potassium in treatments with ash compared to treatments without ash. The corrected soil presented 173.2 mg dm⁻³ of potassium, compared to 153.6 mg dm⁻³ in the uncorrected soil, an increase of 11.6%. The calcium levels increased by 60% with the application of ash (incubated or not) and organomineral fertilizer, compared to soils without ash. Liming increased calcium by 1.12 cmol_c dm⁻³. Fertilizers with ash associated with liming resulted in higher magnesium levels. The sulfur content varied according to the fertilizer, with non-incubated ash showing the highest value (69.11 mg dm⁻³) compared to the control (11.08 mg dm⁻³), a difference of 83.96%. Organomineral fertilizer is an alternative for increasing the availability of macronutrients in the soil, allowing a second cropping cycle without the need to manage soil fertility, contributing to sustainable agriculture, encouraging the reuse of waste, and reducing the use of mineral fertilizers. Full article

Biomass is an energy source with variable physico-chemical properties. Thermal treatments lower moisture and volatile matter contents. They also raise the high heating value (HHV). This is especially desirable for agro-wastes with low-energy potential, like maize cobs. To make pellets from biomass, it is important to keep the lignin intact. It is responsible for particle adhesion. This paper presents a study focused on high-temperature drying of maize cobs. The process temperatures were selected from a range between 60 and 220 °C. The upper temperature limit prevents significant lignin breakdown. We also do not exceed the self-ignition temperature of the raw material. The study analyzed changes in basic technical parameters. These include moisture content, ash content, volatile matter, and HHV. We tested the grinding and densification process. We measured the raw material’s particle size distribution (PSD), specific density, and the mechanical durability (DU) of the agglomerates. The study showed a positive effect of high-temperature drying on the technical parameters. We found that the drying of corn cobs at a temperature of 180 °C gives the best results. Both PSD and DU values indicate that it is possible to create quality compacted biofuels from this material. Full article

This study evaluates pistachio shell ash (PSA) as a sustainable cement substitute and investigates its effect on setting time, strength and microstructure. In this study, pistachio shell ash (PSA) obtained from the kiln flue gas filter of pistachio shells burnt at 300–350 °C in an industrial kiln was used. PSA was substituted for ordinary Portland cement (OPC) at 5, 10, 15, 20, 25 and 30%. PSA increased the SO₃ value in the cement mortars, so 5% PSA substitution delayed the cement setting time by up to 174%. However, it increased the water requirement of the cement mortar by about 2%. While it increased the early strength (22% on day 1, 15% on day 2, and 5% on day 7), the 28-day strength decreased slightly (about 4.5%) due to low pozzolanic activity. Microstructural analyses such as SEM-EDX and XRD showed that the calcite and gypsum phases of PSA provided early strength gains, but there were long-term losses. With a 5% replacement rate, PSA provides significant environmental benefits by reducing CO₂ emissions while maintaining optimum mechanical performance and supports the circular economy through the efficient use of agricultural waste. Full article

Achieving net-zero carbon emissions, this study introduces a sustainable pathway for reducing strontium sulfate (SrSO₄) and celestite ore to strontium sulfide (SrS) using biofuels (biomethane, bioethanol) derived from agro-industrial waste and green hydrogen. Traditional SrSO₄ reduction methods, which rely on fossil-derived reductants like coal and operate at energy-intensive temperatures (1100–1200 °C), generate significant greenhouse gases and toxic byproducts, highlighting the need for eco-friendly alternatives. Experimental results demonstrate that bioethanol outperformed other reductants, achieving 97% conversion of synthetic SrSO₄ at 950 °C within 24 min and 74% conversion of natural celestite ore over 6 h. Remarkably, this bioethanol-driven process matches the energy efficiency of the conventional black ash method while enabling carbon neutrality through renewable feedstock utilization, reducing CO₂ emissions by 30–50%. By valorizing agro-industrial waste streams, this strategy advances circular economy principles and aligns with Mexico’s national agenda for sustainable industrial practices, including its commitment to decarbonizing heavy industries. This study contributes to sustainable development goals and offers a scalable solution for decarbonizing strontium compound production in the chemical industry. Full article

The utilization of agricultural wastes in composite fabrication leads to attaining sustainability in manufacturing. This study investigates the use of plantain peel ash (PPA) as a reinforcement to fabricate Al/Mg/PPA composites using ball milling and spark plasma sintering (SPS) technology. The impact of PPA weight fraction and SPS parameters on Al/Mg/PPA composites’ densification and hardness were analyzed. Microstructural characterization revealed that the PPA reinforcement was uniformly distributed in the aluminum matrix with no considerable microstructural defects. The relative densities of the composites were higher at elevated sintering temperatures, with composites displaying reduced porosity as the sintering temperature rose. The composites also exhibited the highest micro-hardness of 77 HV, improving 86.89% over the sintered aluminum matrix (base material). The Analysis of Variance (ANOVA) results revealed that the sintering temperature and reinforcement material significantly influenced the relative density (RD) of the sintered composites, while the reinforcement material significantly influenced the micro-hardness. Conclusively, the composite samples made using agricultural waste derivatives possess good mechanical properties and are suitable for various industrial applications. Full article

Agro-industrial activities generate significant amounts of organic waste and a variety of effluents thus posing environmental challenges. Viticulture in Argentina, which covered 204,847 ha in 2023, faces water scarcity as a limiting factor conditioning its production. This industry produces large volumes of grape marc, sediments, and stalks, which can be valorised into products like alcohol, tartaric acid, and compost. However, these valorisation processes generate effluents with high organic load and salinity, further stressing water resources. This study explores the potential of utilising these effluents to cultivate plant biomass in arid regions (sorghum or perennial pasture), which could serve as bioenergy, animal feed, or composting co-substrates, contributing to circular bioeconomy principles. The combined use of effluent as a water resource and the sowing of sorghum and pasture increased soil organic matter content and led to a slight reduction in pH (depth: 0.30–0.60 m) compared to the control treatment. The sorghum plots showed better establishment and higher dry biomass yield (32.6 Tn/ha) compared to the pasture plots (6.5 Tn/ha). Sorghum demonstrated better tolerance to saline soils and high salinity effluents, aligning with previous studies. Although pasture had a lower biomass yield, it was more efficient in nutrient uptake, concentrating more NPK, ash, and soluble salts. Sorghum’s higher yield compensated for its lower nutrient concentration. For biomass production, sorghum is preferable, but if nutrient capture from effluents is prioritised, summer polyphytic pastures are more suitable. These results suggest that the final selection between plant biomass alternatives highly depends on whether the goal is biomass generation or nutrient capture. Full article

The present investigation explores the potential of two synthesized zeolites, derived from coal fly ash (CFA; thermoelectric waste) and sugarcane bagasse ash (SCBA; agro-industrial waste), for the selective adsorption of cesium in wastewater. The synthesized zeolites (ZCFA and ZSCBA) were characterized and compared with a commercial zeolite to evaluate their physicochemical properties and effectiveness in removing cesium ions (Cs⁺) from simulated radioactive wastewater. The results obtained from X-ray diffraction, scanning electron microscopy, and elemental analysis confirmed the successful synthesis of high-purity zeolite from both solid wastes. The impurities present in the ashes impacted the Si/Al ratio and consequently influenced the exchange capacity. After adsorption experiments, neutron activation analysis (NAA) revealed that ZSCBA adsorbed 33.4% of Cs₂O by weight, outperforming both ZCFA (26.0%) and commercial zeolite (27.9%). The superior performance of ZSCBA is attributed to its distinct Si/Al ratio and lower levels of impurities, highlighting the impact of these factors on adsorption selectivity. The findings in this study demonstrate the feasibility of valorizing agro-industrial waste for synthesizing zeolites, offering a sustainable approach for managing these residues while producing valuable materials for environmental remediation. Full article

This research presents a proposal for alkali-activated permeable concrete composites with the use of industrial by-products, including ground granulated blast-furnace slag (GGBS) and waste-foundry sand, as well as agro-desecrate product, i.e., sugarcane bagasse ash (SBA). GGBS and SBA served as binders, with crushed granite as coarse aggregate and waste-foundry sand as fine aggregate. The novelty of this proposal is in examining the influence of SBA, in combination with slag, on the fresh- and hardened-state properties of the proposed permeable concretes. Experiments were conducted to optimize the SBA percentage based on hydraulic conductivity and compressive and tensile strength after 28 days of air curing. The hardened density, compaction factor (workability), and saturated water absorption were also measured for all the mixes. Furthermore, the control and optimal mixes were subjected to evaluate the microstructure analysis (EDX, XRD, and FESEM) after 28 days of air curing. The mix containing 100% GGBS and 0% SBA served as the reference, with the optimal 10% SBA mix (with 90% GGBS) used for comparative analysis to understand its effect on the properties of permeable composites. The results showed positive or acceptable mechanical performance at a mix ratio of 10% SBA to 90% GGBS as binders. This study aims to enhance the understanding of the engineering behavior of alkali-activated permeable composites, facilitating the rational design of permeable pavement systems through the effective use of agro-industrial waste products, thereby conserving ecosystems while meeting engineering requirements. Full article

This article presents the results of a systematic review investigating the potential of agricultural wastes as sustainable and low-carbon alternatives in reinforced concrete (RC) production. Background: The depletion of natural resources and the environmental burden of conventional construction materials necessitate innovative solutions to reduce the carbon footprint of construction. Agricultural wastes, including coconut shells (CSs), rice husk ash (RHA), and palm oil (PO) fuel ash, emerge as promising materials due to their abundance and mechanical benefits. Objective: This review evaluates the potential of agricultural wastes to improve sustainability and enhance the mechanical properties of RC structural elements while reducing carbon emissions. Design: Studies were systematically analyzed to explore the sources, classification, and material properties of agro-wastes (AWs), with a particular focus on their environmental benefits and performance in concrete. Results: Key findings demonstrate that AWs enhance compressive strength, tensile strength, and modulus of elasticity while reducing the carbon footprint of construction. However, challenges such as variability in material properties, limited long-term durability data, and lack of standardized guidelines hinder their broader adoption. Conclusions: AWs hold significant potential as sustainable additives for RC elements, aligning with global sustainability goals. Future research should address material optimization, lifecycle assessments, and regulatory integration to facilitate their mainstream adoption in construction. Full article

Biomass ash is currently attracting the attention of science and industry as an inexhaustible eco-friendly alternative to pozzolans traditionally used in commercial cement manufacture (fly ash, silica fume, natural/calcined pozzolan). This paper explores a new line of research into Marabou weed ash (MA), an alternative to better-known conventional agro-industry waste materials (rice husk, bagasse cane, bamboo, forest waste, etc.) produced in Cuba from an invasive plant harvested as biomass for bioenergy production. The study entailed full characterization of MA using a variety of instrumental techniques, analysis of pozzolanic reactivity in the pozzolan/lime system, and, finally its influence on the physical and mechanical properties of binary pastes and mortars containing 10% and 20% MA replacement content. The results indicate that MA has a very low acid oxide content and a high loss on ignition (30%) and K₂O content (6.9%), which produces medium–low pozzolanic activity. Despite an observed increase in the blended mortars’ total and capillary water absorption capacity and electrical resistivity and a loss in mechanical strength approximately equivalent to the replacement percentage, the 10% and 20% MA blended cements meet the regulatory chemical, physical, and mechanical requirements specified. Marabou weed ash is therefore a viable future supplementary cementitious material. Full article

In recent years, the demand for natural and synthetic zeolites has surged due to their distinctive properties and myriad industrial applications. This research aims to synthesise crystalline zeolites by co-recycling two industrial wastes: salt slag (SS) and rice husk ash (RHA). Salt slag, a problematic by-product of secondary aluminium smelting, is classified as hazardous waste due to its reactive and leachable nature, though it is rich in aluminium. Conversely, RHA, an abundant and cost-effective by-product of the agro-food sector, boasts a high silicon content. These wastes were utilised as aluminium and silicon sources for synthesising various zeolites. This study examined the effects of temperature, ageing time, and sodium concentration on the formation of different zeolite phases and their crystallinity. Results indicated that increased Na⁺ concentration favoured sodalite (SOD) zeolite formation, whereas Linde type–A (LTA) zeolite formation was promoted at higher temperatures and extended ageing times. The formation range of the different zeolites was defined and supported by crystallographic, microstructural, and morphological analyses. Additionally, the thermal behaviour of the zeolites was investigated. This work underscores the potential to transform industrial waste, including hazardous materials like salt slag, into sustainable, high-value materials, fostering efficient waste co-recycling and promoting clean, sustainable industrial production through cross-sectoral industrial symbiosis. Full article

Hydrothermal carbonization (HTC) is a promising method for the conversion of agricultural and agro-industrial residues into valuable products. HTC processes biomass through chemical reactions that produce hydrochar, a carbon-rich solid similar to lignite. Unlike other thermochemical processes, HTC can handle high-moisture biomass without pre-drying. This article evaluates the efficiency of HTC on wood chips, wheat straw, and grape pomace, examining their chemical and structural characteristics and critical operational parameters such as the temperature, pressure, biomass/water ratio, and reaction time. The obtained results highlight that the two key process parameters are the temperature and the ratio between the solid biomass and liquid phase. Increasing the first parameter increases the energy content by 20% and increases the carbon concentration by up to 50%, while reducing the oxygen content by 30% in the hydrochar. Varying the second parameter leads to the alternating reduction of the ash content but simultaneously reduces the energy content. The reaction time seems to have a limited influence on the quality parameters of the biochar produced. Lastly, HTC appears to successfully enhance the overall quality of widely available agricultural wastes, such as grape pomace. Full article

Climate change is characterized by shifts in temperature and climate patterns. Constructing new high-rise environments using materials that incorporate agro-industrial waste can help mitigate this impact without compromising technological properties. This study produced vitreous foams intended to replace natural aggregates in lightweight concrete partially. These foams were sintered in a microwave oven at temperatures of 750 °C, 800 °C, and 850 °C, utilizing glass powder and sugarcane bagasse ash as raw materials. The homogenization and preparation of these materials were conducted through a mechanical pelletization process, employing a constant rotation engine at approximately 40 rpm. The efficacy of microwave sintering was assessed by comparing the outcomes with those from sintering in a conventional electric muffle furnace under identical conditions. The results indicated that the microwave-sintered vitreous foams exhibited the following values for apparent density (≤0.30 g/cm³), porosity (86% to 94%), and compressive strength (0.48 MPa to 0.58 MPa), which align with the global standards for commercial vitreous foams. The microwave sintering route proved to be economically feasible by reducing sintering time and, consequently, energy costs, without sacrificing technological properties. The materials produced in this study offer a promising solution to minimize the environmental impact associated with constructing new buildings, particularly tall structures. Additionally, they support the circular economy by converting waste into valuable by-products. Full article