Comparative Analysis of Woody Biomass Fly Ash and Class F Fly Ash as Supplementary Cementitious Materials in Mortar.

Biomass fly ash is a sustainable, eco-friendly cement substitute with economic and performance benefits, being renewable compared to coal fly ash. This study examines using biomass fly ash (BFA) as a sustainable cement substitute, comparing it with Class F fly ash (CFA). With a water-binder ratio of 0.5 and replacement rates of 10%, 15%, 20%, 25%, and 30% (by mass), the research highlights BFA's promising applications. BFA and CFA were mixed into cement paste/mortar to analyze their reactivity and properties, with hydration products CH and C-S-H evaluated at 7, 28, and 91 days. Compressive strength, micro-pore structure, and drying shrinkage (assessed from 7 to 182 days) were tested. Results showed BFA had similar pozzolanic reactions to CFA at later stages. While compressive strength decreased with higher BFA replacement rates, early-stage performance matched CFA; growth was CFA-10 (18 MPa) and BFA-10 (17.6 MPa). BFA mortars exhibited slightly better deformation properties. BFA-30 cement had superior performance, with a lower drying shrinkage rate of 65.7% from 14 to 56 days compared to CFA-10's 73.4% and a more stable shrinkage growth rate decrease to 8.4% versus CFA-10's 6.4% after 56 days. This study concluded that BFA, usable without preprocessing, performed best at a 10-15% replacement rate.

Biomass fly ash as nanofiller to improve the dielectric properties of low-density polyethylene for possible high-voltage applications.

Flexible capacitive energy storage applications require polymer nanocomposites with high dielectric properties, which can be accomplished by addition of inorganic nanofillers to the polymer matrix. Low-density polyethylene (LDPE), known for its good dielectric characteristics and wide use in electrical insulation have been investigated for the desired applications. However, the improvement of its breakdown strength still continues with the use of various nanomaterials employed as nanofillers. In this study, a waste-derived material known as biomass fly ash (BFA) as a nanofiller to improve the dielectric properties of LDPE has been explored. BFA exhibits versatility in its composition with various metal oxides, making it an attractive choice as a nanofiller. The BFA-LDPE sheets were prepared using a conventional solvent mixing and subsequent hot-pressing process, incorporating BFA loadings ranging from 1 % to 4 wt%. The effects of different BFA loadings were carefully examined, and the synthesized nanocomposites were extensively characterized using various characterization methods, such as XRD, SEM, FTIR, TGA and dielectric constant measurements, to investigate the crystallographic properties, morphology, chemical composition, and thermal stability. Among all the nanocomposites, 4 wt%BFA-LDPE exhibited the highest dielectric constant, with a value of 11.58, compared to simple LDPE that had a dielectric constant of 8.33. This improvement is ascribed to the synergistic effects of different inorganic metal oxides (SiO2, MgO, and Fe2O3) present in BFA. The results showed a significant enhancement in dielectric properties, indicating that the waste-derived BFA can be purposefully applied as an effective nanofiller in the LDPE-based composites with even less than 4% loading for electrical insulating applications in future studies.

Experimental and numerical techniques to evaluate coal/biomass fly ash blend characteristics and potentials.

Fossil and renewable fuels are used by industrial units that produce energy-intensive products. Competitive fuel pricing encourages these fuel sources' usage globally, particularly in developing nations, which leads to large volumes of byproducts like fly ash among thermal power plant operators. The elements and compounds found in coal fly ash (CFA) and biomass fly ash (BFA) can be utilized through several engineering applications. This study aims to assess typical CFA and BFA samples quantitatively and qualitatively via techniques such as ultimate analysis (CH-S), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XRF) elemental analysis, and ash fusion temperature (AFT), to anticipate the ideal ratios of coal to biomass blends for combustion applications while adhering to environmental regulations. The optimal blend, consisting of 75 % CFA and 25 % BFA, exhibited improved carbon (C%) and hydrogen (H%) percentages, increasing from 2.5 % to 4.67 % and from 0 % to 0.12 %, respectively. These improvements were further confirmed by the observed functional groups in FTIR, indicating a rising trend in both carbon and hydroxyl groups from BFA to CFA. XRF and XRD also confirmed it and TGA also showed optimum mass loss (ML%) behavior of 14.55 % for 75CFA + 25BFA. According to slagging and fouling indices, the values of RB/A, Rs, and Fu indicate a reduction in slagging and fouling issues through the blending of CFA with BFA. Simultaneously, the fusion temperature increased from 1181 °C to 1207 °C. CFA was found to increase the AFT of the BFA from 1197 °C to 1247 °C, mitigating their propensity. This suggests that a blend of 75CFA + 25BFA results in lower to medium range of slagging and fouling. However, AFI and BAI indicate a slightly higher range. AFT analysis further validates the conclusions drawn from the indices. The ternary phase diagram shows that the ash's melting point increases in the optimum blend. This is attributed to a reduced content of K2O (<15 %) and increased proportions of >50 % CaO and SiO2, effectively inhibiting slagging, agglomeration, and deposition. Meanwhile, the blend maintains a medium level of acidity and susceptively to corrosion, as observed in the case of 75CFA + 25BFA. The identification of optimal blend ratios can be anticipated to offer essential solutions for future research, aiming to ensure smooth industrial operations and regulatory compliance in power plants.

Mechanical Properties and Microstructural Features of Biomass Fly Ash-Modified Self-Compacting Coal Gangue-Filled Backfill.

To achieve sustainable utilization of a large amount of mine solid waste, this study investigated the performance of self-compacting coal gangue-filled backfill (SCFB) containing biomass fly ash (BFA) generated from biomass power plants as a supplementary cementitious material (SCM). The correlations between the physical structure and compressive strength of SCFB samples were obtained by ultrasonic pulse velocity (UPV). The failure process of the SCFB samples was monitored by the digital image correlation (DIC) technique, and the stress-strain relationship and failure pattern were also analyzed. The micro-morphological structure and hydration products of SCFB samples were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and backscattered electron imaging (SEM-BSE). The results show that the usage of 30~40% BFA in SCFB improves the physical structure and strength of the samples. The compressive strength and UPV value of SCFB samples with different water-to-cement (w/c) ratios showed a similar trend of increasing and then gradually decreasing as the proportion of ordinary Portland cement (OPC) replaced by BFA increased. BFA exhibits better reactivity and filling effect in SCFB samples with a high w/c ratio. The peak stress of SCFB samples gradually decreases, and resistance to deformation gradually weakens with the increase in w/c ratios, while the DIC results further verify the mechanical experimental results. Microstructural analysis revealed that reducing the w/c ratio and incorporating specific ratios of BFA can reduce the thickness of the interface transition zone (ITZ) and porosity. The results of the study will provide theoretical guidance for the modification, stability monitoring, and strengthening of SCFB.

Modelling and optimization of sewage sludge composting using biomass ash via deep neural network and genetic algorithm.

In this study, the use of Deep Cascade Forward Neural Network (DCFNN) was investigated to model both linear and non-linear chaotic relationships in co-composting of dewatered sewage sludge and biomass fly ash (BFA). Model results were evaluated in comparison with RSM, Feed Forward Neural Network (FFNN) and Feed Back Neural Network (FBNN), and Cascade Forward Neural Network (CFNN). DCFNN produced predictive results with MAPE values less than 1% for all datasets in all experimental designs except one with 1.99%. Furthermore, the decision variables were optimized by Genetic Algorithm (GA). The desirability level obtained from the optimization results was found to be 100% in a few designs and above 95% in all other designs. The results showed that DCFNN is a reliable and consistent tool for modeling composting process parameters, also GA is a satisfactory tool for determining which outputs the input parameters will produce in an experimental setup.

Effects of Na2CO3/Na2SiO3 Ratio and Curing Temperature on the Structure Formation of Alkali-Activated High-Carbon Biomass Fly Ash Pastes.

This study explored unprocessed high-carbon biomass fly ash (BFA) in alkali-activated materials (AAM) with less alkaline Na2CO3 as the activator. In this paper, the effects of the Na2CO3/Na2SiO3 (C/S) ratio and curing temperature (40 °C and 20 °C) on the setting time, structure formation, product synthesis, and physical-mechanical properties of alkali-activated BFA pastes were systematically investigated. Regardless of curing temperature, increasing the C/S ratio increased the density and compressive strength of the sample while a decrease in water absorption. The higher the curing temperature, the faster the structure evolution during the BFA-based alkaline activation synthesis process and the higher the sample's compressive strength. According to XRD and TG/DTA analyses, the synthesis of gaylussite and C-S-H were observed in the sample with an increasing C/S ratio. The formation of the mentioned minerals contributes to the compressive strength growth of alkali-activated BFA pastes with higher C/S ratios. The findings of this study contribute to the applicability of difficult-to-recycle waste materials such as BFA and the development of sustainable BFA-based AAM.

Valorization of Kraft Pulp and Paper Mill Slaker Grits and Biomass Fly Ash as Fillers in a Commercial Screed Mortar Formulation.

Slaker grits (SG) and biomass fly ash (BFA), two waste streams generated in the pulp and paper industry, are commonly disposed of in landfills, a practice with a high economic and environmental burden. In this work, their individual valorization as fillers in a commercial screed mortar formulation was evaluated in order to achieve a more sustainable management practice. The waste streams were characterized in terms of true density, particle size and morphology, and chemical and mineralogical composition. The influence of their incorporation amount (5.0, 7.5, and 10.0 wt.% of the total solids) and pre-treatment (sieving and grinding) on the fresh (workability) and hardened state (density, water absorption by capillarity, and flexural and compressive strength) properties of the mortars were assessed. The results show that the addition of 10.0 wt.% of the SG after milling and sieving (<75 µm) and 7.5 wt.% of BFA in the as-received condition, or up to 10.0 wt.% after grinding and sieving (<63 µm), allowed for the production of mortar samples with properties within the recommended specifications and that were resistant to 25 consecutive freeze-thaw cycles. This waste valorization route could represent an economic benefit of up to 8.85 €/tmortar and 2.87 €/tmortar for mortar, and pulp and paper companies, respectively.

Development and Characterization of a Novel Soil Amendment Based on Biomass Fly Ash Encapsulated in Calcium Alginate Microspheres.

Biomass fly ash (BFA) from a biomass cogeneration plant was encapsulated into calcium alginate microspheres (ALG/Ca) and characterized. An FTIR analysis indicated that BFA loading weakened molecular interactions between ALG/Ca constituents (mainly hydrogen bonding and electrostatic interactions), thus changing the crosslinking density. SEM and AFM analyses revealed a wrinkled and rough surface with elongated and distorted granules. The in vitro release of BFA's main components (K, Ca, and Mg) was controlled by diffusion through the gel-like matrix, but the kinetics and released amounts differed significantly. The smaller released amounts and slower release rates of Ca and Mg compared to K resulted from the differences in the solubility of their minerals as well as from the interactions of divalent cations with alginate chains. The physicochemical properties of the novel microsphere formulation reveal significant potential for the prolonged delivery of nutrients to crops in a safe manner.

The Influence of Cement Substitution by Biomass Fly Ash on the Polymer-Cement Composites Properties.

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer-cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer-cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer-cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.

Production of biosilica nanoparticles from biomass power plant fly ash.

When it comes to the combustion of biomass, per ton of solid biofuel will generate 70 kg ash on average. Additionally, these ashes have a high specific surface area, especially fly ash, which may adsorb harmful substances and damage to human health. This work was aimed to reutilize biomass power plant fly ash to produce silica material, to reduce the hazard of ash landfill for environment. The ash underwent acid leaching with 1.5 M HCl after proper heating pre-treatment. Then, 2 M NaOH was direct to react with residue to obtain sodium silicate. Finally, acid titration of solution was used to precipitate silica. The results showed that the amorphous silica has been produced from fly ash successfully with the purity from 44.41% to 93.63% and yield of 20.45%, and the optimal calcination conditions for amorphous transformation of silica in fly ash were temperature of 611 °C with time of 5 h and the minimum crystallinity was 17.41%, modeled with response surface methodology. Spectroscopy analysis revealed that the three-dimensional network silica was hydroxylated to form the linear structure. Thermal analysis indicated that the decomposition of silanol groups tend to be stable at 400 °C, but the ash was decomposing up to 1000 °C. Morphological analysis demonstrated that BET surface area ranged from 24 m2/g to 115 m2/g, agglomerate particle size from 380.9 nm to 178.8 nm, when the ash was conversion to spherical silica. Consequently, it is possible to turn blend biomass fly ash into amorphous silica nanoparticles.

Recycling of biomass and coal fly ash as cement replacement material and its effect on hydration and carbonation of concrete.

The construction sector has been using supplementary materials in concrete production worldwide, such as coal fly ash. Nowadays, several sub/products or wastes have been studied to be incorporated in construction materials, and one of those wastes is biomass fly ash. However, using high volumes of these materials has some drawbacks, one of them being carbonation. In order to understand phenomena such as this, it is important to study the interaction between the additions and hydration of cement. This paper focuses on the study of hydration and carbonation of cementitious pastes containing biomass fly ash and/or coal fly ash by using thermogravimetric analysis and X-ray diffraction analysis and by accelerated carbonation tests. BFA present different chemical and mineralogical composition than CFA. The results show that incorporating biomass fly ash into construction materials has a similar carbonation behaviour to coal fly ash. Biomass fly ash seems to give some extra alkalinity to the mixtures, and this may present benefits to the construction materials and for the ash management.

Innovative application for bauxite residue: Red mud-based inorganic polymer spheres as pH regulators.

In this study, and for the first time, red mud (RM)-based geopolymer spheres were synthesised, with varying porosity and RM content, and then their use as pH regulators was evaluated. The aluminosilicate sources of these inorganic polymers were 100% waste-based, consisting of a mixture of RM and fly ash wastes. Geopolymer spheres containing up to 60 wt.% RM were successfully produced, while higher RM contents distorted the specimens' spherical shape. Results showed that alkalis leaching from the spheres over time can be controlled by their porosity, while the RM content induces only minor changes to leaching. The RM-based spheres leached up to 0.0237 mol/dm3g of OH- ions from their structure, this being among the highest values ever reported for geopolymers. This allowed a continuous and prolonged pH buffer capacity with narrow pH decay over the 28 days (2.4 pH units), suggesting the use of the RM-based spheres as pH buffering materials in wastewater treatment and anaerobic digestion systems.

Fractionation of Heavy Metals in Fly Ash from Wood Biomass Using the BCR Sequential Extraction Procedure.

The aim of this study was to extract the wood biomass fly ash fractions by a three-stage sequential extraction method for acetic acid and ion exchangeable (BCR 1), hydroxylamine hydrochloride reduction (BCR 2), and hydrogen peroxide oxidation (BCR 3) fractions in order to access the leaching behavior of this residue. The fly ash was collected as a by-product from the processing of mixed wood biomass in Udbina combustion facility, Croatia. Concentrations of several elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in all extracts were determined by inductively coupled plasma atomic emission spectrometry. The acidic exchangeable form of the metals was used to evaluate the potential ecological risk of biomass fly ash. According to calculated potential ecological risk index, it is confirmed that mobility of Ni and As has major environmental impact. However the results of potential ecological risk show that biomass fly ash had a low risk.

Novel porous fly-ash containing geopolymer monoliths for lead adsorption from wastewaters.

In this study novel porous biomass fly ash-containing geopolymer monoliths were produced using a simple and flexible procedure. Geopolymers exhibiting distinct total porosities (ranging from 41.0 to 78.4%) and low apparent density (between 1.21 and 0.44g/cm(3)) were fabricated. Afterwards, the possibility of using these innovative materials as lead adsorbents under distinct conditions was evaluated. Results demonstrate that the geopolymers' porosity and the pH of the ion solution strongly affect the lead adsorption capacity. Lead adsorption by the geopolymer monoliths ranged between 0.95 and 6.34mglead/ggeopolymer. More porous geopolymers presented better lead removal efficiency, while higher pH in the solution reduced their removal ability, since metal precipitation is enhanced. These novel geopolymeric monoliths can be used in packed beds that are easily collected when exhausted, which is a major advantage in comparison with the use of powdered adsorbents. Furthermore, their production encompasses the reuse of biomass fly-ash, mitigating the environmental impact associated with this waste disposal, while decreasing the adsorbents production costs.

Contaminated biomass fly ashes--Characterization and treatment optimization for reuse as building materials.

The incineration of treated waste wood generates more contaminated fly ashes than when forestry or agricultural waste is used as fuel. The characteristics of these biomass fly ashes depend on the type of waste wood and incineration process parameters, and their reuse is restricted by their physical, chemical and environmental properties. In this study, four different fly ash types produced by two different incineration plants were analysed and compared to Dutch and European standards on building materials. A combined treatment was designed for lowering the leaching of contaminants and the effect of each treatment step was quantified. A pilot test was performed in order to scale up the treatment. It was found that chlorides (which are the main contaminant in all studied cases) are partly related to the amount of unburnt carbon and can be successfully removed. Other contaminants (such as sulphates and chromium) could be lowered to non-hazardous levels. Other properties (such as particle size, LOI, oxide and mineralogical compositions) are also quantified before and after treatment.

Preparation of clinker from paper pulp industry wastes.

The production of paper pulp by the Kraft method generates considerable amounts of wastes. Namely, lime mud generated in the recovery circuit of chemical reagents, biological sludge from the wastewater treatment of wood digestion process and fly ash collected in the fluidized bed combustor used to generate electricity from biomass burning. The final destination of such wastes is an important concern, since environmental regulations are becoming stricter regarding their landfill. Driven by this fact, industries are looking for more sustainable solutions, such as the recycling in distinct products. This work tested these wastes as secondary raw materials to produce clinker/cement that was then experienced in mortar formulations. The first step involved the residues detailed characterization and a generated amounts survey. Then, specific but simple steps were suggested, aiming to facilitate transport and manipulation. Distinct blends were prepared and fired in order to get belitic and Portland clinkers. The Portland clinkers were processed at lower temperatures than the normally used in the industry due to the presence of mineralizing impurities in some wastes. Belite-based cements were used to produce mortars that developed satisfactory mechanical strength and did not reveal signs of deterioration or durability weaknesses.