Types Of Ash Research Articles

Effect of Biomass Ash on the Properties and Microstructure of Magnesium Phosphate Cement-Based Materials

The disposal of biomass ash (BA) will be of great importance for environmental protection and sustainability, and the aim of this study is to analyze the feasibility of the resourceful use of biomass ash in civil engineering materials. The effects of the content and type of biomass ash on the flowability, setting time, compressive strength, flexural strength, bonding strength, and drying shrinkage of magnesium phosphate cement (MPC) mortar were investigated. In addition, the effects of BA on the hydration and microstructure of MPC were investigated by X-ray diffraction (XRD), thermogravimetry, mercury intrusion porosimetry (MIP), and scanning electron microscope (SEM). The results showed that BA significantly affects the flowability and setting time of MPC mortar. The compressive and flexural strength of MPC mortars decreases with increasing amounts of BA. The drying shrinkage of MPC mortar specimens increases exponentially with the increase of BA content. The incorporation of BA will reduce the bonding strength of the MPC mortar, which is associated with increased drying shrinkage. The incorporation of BA into MPC results in low hydration product generation and poor pore structure. The incorporation of BA into MPC has a significant effect on the microstructure morphology and the hollow columnar-like hydration product may be formed by the reaction of BA with MgO in the paste.

Durability of peat stabilized by RHA based geopolymer formed by adding pure alumina and bauxite powder

This study examines the effect of Nwd cycles on unconfined compressive strength (UCS), pH, electrical conductivity (EC), mass loss (ML) of treated sapric, fibric and hemic peat. The two types of rice husk ash (RHA) based geopolymers are formed by adding two different sources of extra aluminium as pure Al2O3, referred to as G1, and bauxite referred to as G2. For comparison, ordinary Portland cement was selected as a control sample. From the results, the UCS of geopolymer treated peats show more strength than cement treated peats because the hydrotalcite phases of geopolymer fill the voids more efficiently. However, the rate of decrement of UCS in both geopolymer treated peats is more than cement treated peats because the increased number of micropores in geopolymer treated peats. The field emission scanning electron microscope (FESEM) micrographs show dense and smooth cementitious products before Nwd cycles consistent with X-ray diffraction (XRD) results and show the existence of micropores after Nwd cycles for geopolymer treated peats. Fourier transform infrared spectroscopy (FTIR) confirms the results of XRD as it shows the adsorption bands of aluminosilicates, which form the basis of geopolymerization, and further confirms the existence of cavities and cracks in samples after Nwd cycles.

Effects of Ca-Compounds on the Gases Formation Behavior during Molten Salts Thermal Treatment of Bio-Waste

Bio-waste utilization is essential, and pyrolysis is a prominent way for its effective utilization. However, the gradual accumulation of ash compounds in the intermediate products probably affects the thermal conversion characteristics of bio-waste. In the present study, beech wood and disposable chopsticks were selected as bio-waste samples. The effects of typical ash components (Ca-compounds) on volatile formation behavior were investigated during the molten salts thermal treatment of bio-waste. Results demonstrated that about 80% mass of initial bio-waste was gasified into the volatiles at 300 °C. The introduction of Ca-compounds in the molten salts slightly decreased the total yield of gaseous products. More specifically, Ca2+ could improve the generation of CO2 and suppress the generation of other gases (CO, H2, and CH4), and this is accompanied by a reduction in the low heating value (LHV) of the gases. The possible reason is that Ca2+ might act on the -OH bonds, phenyl C-C bond, methoxy bond and carboxylic acid -COOH bonds of the bio-waste to promote CO2 release. In contrast, the introduction of CO32− and OH- tended to relieve the inhibition effect of Ca2+ on the generation of H-containing gases. Meanwhile, the introduction of Ca2+ can promote the conversion of bio-waste into liquid products as well as increase the saturation level of liquid products. Moreover, as a vital form of carbon storage, CO2 was found to be abundant in the pyrolysis gases from molten salts thermal treatment of bio-waste, and the concentration of CO2 was much higher than that of direct-combustion or co-combustion with coal. It’s a promising way for bio-waste energy conversion as well as synchronized CO2 capture by using molten salts thermal treatment, while the introduction of small amounts of Ca-compounds was found to have no significant effect on the change of CO2 concentration.

An exploratory study into ash mobilization using lysimeters

Abstract Wildfires burn vegetation and leave the resultant organic and inorganic ash into the soil surface. Depending on the temperatures and burn durations, the quantity and type of ash can vary widely. Ash mobilization following wildfire is a topic of major concern, since it may result in contamination of surface water bodies within and downstream of the burnt areas. The present study aims to analyse the influence of black and white ash on surface runoff, leachate and total erosion and erosion of organic matter by running a field experiment along 6 weeks, using three replicate lysimeters with control soil, soil with addition of black ash and soil with addition of white ash. There was some suggestion but no statistical evidence that black ash reduced overland flow generation during the initial rainfall events, while black ash was found to increase sediment and organic matter losses by overland flow in a statistically significant manner. This was not during the initial rainfall events and, therefore, not directly related to the presence of a homogenous cover of a well-defined ash layer on the soil surface.

Migration characteristics and ecological risk assessment of heavy metals in ash from sewage sludge co-combustion in coal-fired power plants

Co-combustion in coal-fired power plants is one of the main methods to dispose of municipal sewage sludge (MSS). The high heavy metals content of MSS increases the ecological risk of ash from the coal and MSS co-combustion. In response to this problem, the three types of fly ash or bottom ash from MSS co-combustion in the three coal-fired power plants were sampled. The properties of fly ash and bottom ash were analyzed in terms of ash composition, particle size distribution, heavy metals content and leaching characteristics. The potential ecological risks were evaluated using the ecological risk index assessment method. The results showed that the co-combustion of MSS had no significant effect on the ash composition order and heavy metals content order. However, the total content of Cu, Mn, Pb and Zn, Hg in the co-combustion ash was higher than that in the coal-fired ash without sludge blending but did not exceed the risk screening value for soil heavy metal contamination of residential land. Heavy metals showed significant enrichment in fly ash and dilution in bottom ash. The leaching concentrations of Cr and Ni were several times the limit value. The potential ecological risk levels of fly ash and bottom ash were moderate risk and high risk respectively. Cr and Hg were the main contributors to potential ecological risks. The contents of Cr, Hg and Ni need to be paid attention to in the subsequent utilization of coal ash mixed with co-combustion of sewage sludge.

The potential use of cold-bonded lightweight aggregate derived from various types of biomass fly ash for preparation of lightweight concrete

• Cold-bonded artificial lightweight aggregate was produced from biomass fly ash. • Strength of artificial aggregate was compared to expanded clay aggregate. • Artificial aggregates could be applied as reinforcement for lightweight concretes. This paper explores the potential use of various types of biomass fly ash (FA); palm oil (P-FA), wood chip (W-FA), bagasse (BA-FA), and rice husk (R-FA), as raw material for lightweight aggregate formed by cold-bonded pelletization (CBP) for the first time. The results suggest it is possible to form 756–881 kg/m 3 lightweight aggregate with 20.30–28.84% water absorption, using FA and 10% Portland cement type 1 (PC). Single pellet crushing strength of 4–8 mm BA-FA and W-FA aggregates were 272.97 N and 194.82 N, making it comparable in strength to a commercially available ECA. The high strength of CBP aggregates was attributed to the SAI values, SiO 2 and Al 2 O 3 content of the ashes. Compressive strength of lightweight concrete reinforced with CBP biomass ash aggregate was found to be as high as 19.65 MPa.

Mechanism of Different Mechanically Activated Procedures on the Pozzolanic Reactivity of Binary Supplementary Cementitious Materials

In this study, a type of fly ash and iron tailing powder were used as a binary supplementary cementitious material (SCM) and two different mechanically activated procedures, named coalescent activation and separated activation, were carried out to improve the pozzolanic reactivity. Then, three binary supplementary cementitious materials were used to replace 30 wt% of ordinary Portland cement to develop cemented mortars, and the compressive strength, hydration products, and micro-structure were studied. The experimental results indicated that the activated supplementary cementitious materials increased the compressive strengths of the mortars by 5.4% and 13.2%, negligibly changed the hydration product types, and impacted the quantity only. The application of SCMs also prolonged the setting time and decreased the hydration rate, profiting the application. Simultaneously, the micro-pore structure was ameliorated, and the porosity decreased. Therefore, comprehensively considering the improved mechanical behavior and inexpensive cost, the activated binary SCM can be considered an ecological and economical admixture, especially for the coalescent activation procedure.

Uncertainty-bounded estimates of ash cloud properties using the ORAC algorithm: application to the 2019 Raikoke eruption

Abstract. Uncertainty-bounded satellite retrievals of volcanic ash cloud properties such as ash cloud-top height, effective radius, optical depth and mass loading are needed for the robust quantitative assessment required to warn aviation of potential hazards. Moreover, there is an imperative to improve quantitative ash cloud estimation due to the planned move towards quantitative ash concentration forecasts by the Volcanic Ash Advisory Centers. Here we apply the Optimal Retrieval of Aerosol and Cloud (ORAC) algorithm to Advanced Himawari Imager (AHI) measurements of the ash clouds produced by the June 2019 Raikoke (Russia) eruption. The ORAC algorithm uses an optimal estimation technique to consolidate a priori information, satellite measurements and associated uncertainties into uncertainty-bounded estimates of the desired state variables. Using ORAC, we demonstrate several improvements in thermal infrared volcanic ash retrievals applied to broadband imagers. These include an improved treatment of measurement noise, accounting for multi-layer cloud scenarios, distinguishing between heights in the troposphere and stratosphere, and the retrieval of a wider range of effective radii sizes than existing techniques by exploiting information from the 10.4 µm channel. Our results indicate that 0.73 ± 0.40 Tg of very fine ash (radius ≤ 15 µm) was injected into the atmosphere during the main eruptive period from 21 June 18:00 UTC to 22 June 10:00 UTC. The total mass of very fine ash decreased from 0.73 to 0.10 Tg over ∼ 48 h, with an e-folding time of 20 h. We estimate a distal fine ash mass fraction of 0.73 % ± 0.62 % based on the total mass of very fine ash retrieved and the ORAC-derived height–time series. Several distinct ash layers were revealed by the ORAC height retrievals. Generally, ash in the troposphere was composed of larger particles than ash present in the stratosphere. We also find that median ash cloud concentrations fall below peak ash concentration safety limits (< 4 mg m−3) 11–16 h after the eruption begins, if typical ash cloud geometric thicknesses are assumed. The ORAC height retrievals for the near-source plume showed good agreement with GOES-17 side-view height data (R=0.84; bias = −0.75 km); however, a larger negative bias was found when comparing ORAC height retrievals for distal ash clouds against Cloud-Aerosol Lidar with Orthogonal Polarisation (CALIOP) measurements (R=0.67; bias = −2.67 km). The dataset generated here provides uncertainties at the pixel level for all retrieved variables and could potentially be used for dispersion model validation or be implemented in data assimilation schemes. Future work should focus on improving ash detection, improving height estimation in the stratosphere and exploring the added benefit of visible channels for retrieving effective radius and optical depth in opaque regions of nascent ash plumes.

Study on Mechanical and Rheological Properties of Solid Waste-Based ECC

As one of the main raw materials of engineered cementitious composite (ECC), fly ash exerts the “ball effect” and “pozzolanic effect” in concrete, which improves the working performance of concrete and enhances the strength of the concrete matrix. Polyvinyl alcohol (PVA) fiber has been widely used in the preparation of ECC, while ground fly ash can be used to enhance the performance of ECC as a kind of high-activity admixture. In this paper, the compressive strength, flexural strength and flexural toughness of ECC prepared from different types of fly ash (raw fly ash, sorted fly ash and ground fly ash) are compared, and the rheological properties of the ECC are analyzed by studying the two parameters of yield stress and plastic viscosity. The results show that the smaller the particle size of fly ash is, the more sufficient it reacts with Ca(OH)2 produced by cement hydration, and the more it can improve the compressive strength and flexural strength of the matrix. In addition, the smaller the particle size of fly ash, the higher the yield stress and plastic viscosity of ECC; therefore, the distribution of PVA fiber in ECC is more uniform, thereby improving the flexural toughness and ductility of ECC.

Implications of the Use of Biodiesel on the Longevity and Operation of Particle Filters

While biodiesel is one of many necessary steps forward in a cleaner transportation future, alkali metal residuals, including Na and K (in the form of oxides, sulfates, hydroxides, and carbonates) originating from fuel production catalysts were found to be detrimental to emissions control components. Na + K and Ca + Mg (also biodiesel production byproducts) are regulated by ASTM-D6751 standards (American Society for Testing and Materials) to be less than 5 ppm for B100; however, the literature gives examples of physical and chemical degradation of automotive emissions catalysts and their substrates with these Na and K residuals. The purpose of this study is to investigate the impacts of ash from Na-doped biodiesel fuel (B20) on a diesel particulate filter (DPF). Investigations found that the Na-ash accumulated in the DPF has several unique properties which help to fundamentally explain some of the interactions and impacts of biodiesel on the particle filter. The biodiesel-related Na-ash was found to (1) have a significantly lower melting temperature than typical ash from inorganic lubricant additives and Ultra Low Sulfur Diesel (ULSD) fuel resulting in ash particles sintered to the DPF catalyst/substrate, (2) have a primary particle size which is about an order of magnitude larger than typical ash, (3) produce a larger amount of ash resulting in significantly thick wall ash layers and (4) penetrate the DPF substrate about 3× deeper than typical ULSD and lubricant-related ash. This study utilizes numerous characterization techniques to investigate the interactions between biodiesel-related ash and a DPF, ranging from visualization to composition to thermal analysis methods. The findings suggest the need for tighter control of the thermal environment in the DPF when using biodiesel, additional/improved DPF cleaning efforts, and avoidance of unregulated biodiesel with high Na/K levels.

Potential of municipal woody biomass waste ash in the production of cold-bonded lightweight aggregates

Nowadays, increasing biomass wastes are incinerated and then transported to landfills for disposal, which occupies many land resources and causes health problems due to lack of any form of control. Therefore, a novel and green recycling method is urgently needed. In this study, a type of municipal woody biomass waste ash (MWBA) was granulated into a new type of artificial lightweight aggregates by the cold-bonded method. The effects of different water content (20–33%), rotation speed (30, 40, 50, 60 rpm) and rotation angle (30–60°) on the granulation efficiency and particle size fraction (4 mm–10 mm, 10 mm–16 mm, 16 mm–20 mm) of the municipal woody biomass waste ash aggregate (MWBAA) as well as the impact of varying cement content (5, 10, 15, 20%) and curing time (3, 7, 14, 28 days) on the performance of MWBAA were investigated. The MWBAA met the bulk density requirement of lightweight aggregate in EN13055 with bulk density between 841 and 1058 kg/m3. It was also found that 27–29% is the optimum water content for MWBAA manufacturing. The highest granulation efficiency (97.84%), as well as better gradation of MWBAA, could be achieved at a rotation angle of 55° and a rotation speed of 60 rpm. After 28 days of curing, the highest compressive strength of 2.6 MPa was achieved by the MWBAA with 20% cement content. Nevertheless, the porous and irregular shape of the unburned wood ash resulted in higher water absorption (25%), but had negligible effect on the bulk density and strength performance of MWBAA. This study thus provides an alternative solution to effectively recycle MWBA and potentially granulate MWBA into lightweight aggregate that can be utilized in concrete.

Assessing the effects of native and alien plant ash on mosquito abundance.

Plant invasions have been linked to displacement of native vegetation and altering of fire regimes and might influence vector mosquito populations by altering habitats or nutrient inputs. Whereas wildfire effects on terrestrial ecosystems are relatively well‐studied, ash depositions into aquatic ecosystems and effects on semi‐aquatic taxa such as mosquitoes have remained overlooked. Here, we investigated mosquito colonization in water treated with ash from native plants [quinine tree (Rauvolfia caffra), Transvaal milk plum (Englerophytum magalismontanum), apple leaf (Philenoptera violacea)] and invasive alien plants [i.e., lantana (Lantana camara), guava (Psidium guajava), red river gum (Eucalyptus camaldulensis)] in containers at two ash concentrations (i.e., 1, 2 g/L). Overall, there was no statistically clear difference in colonization between ash from native and alien species. We recorded colonization by two mosquito genera (Culex spp. and Anopheles spp.), with Culex generally much more abundant than Anopheles. Few differences were identified among the plants, with statistically clear effects of ash type and concentration on larval and pupal stages. High Culex egg and larval abundances were shown in lantana and apple leaf treatments compared to controls, and milkplum versus controls for pupae of both genera. Further research is required to elucidate the influence of nutrient inputs from different ash species on vector mosquito population dynamics.

OCCURRENCE OF POLYCYCLIC AROMATIC HYDROCARBONS IN BOTTOM ASH FROM INDIVIDUAL HEATING DEVICES

Combustion of solid fuels such as coal, biomass and, contrary to the applicable law, waste in individual heating devices still remains a serious problem in Poland. It causes the generation of large amounts of pollutants and harmful substances contained not only in fly ash released into the air with smoke but also in the bottom ash, which constitutes a serious environmental problem. This paper presents the results of a comparative study on the contents of 16 polycyclic aromatic hydrocarbons (PAHs) in bottom ash from the combustion of hard coal (HC), wood (W) and a mixture of different solid fuels including municipal waste (MW), their sums and profiles. For the bottom ash samples taken for these fuels, the share of carcinogenic congeners in the sum of PAHs, toxicity, mutagenicity and carcinogenicity equivalents have also been determined. The highest content of total PAHs, amounting to an average of 20.7 ppb, was recorded for bottom ash obtained from combustion of a mixture of solid fuels and waste. For such ash, the toxicity and carcinogenicity equivalents were approximately twice as high as for other types of ash. Bottom ash was found to be dominated by benzo[a]anthracene, and the tetracyclic congeners accounted for 60-68% of all PAHs (W<MW<HC). Regardless of the origin of the bottom ash, approximately 60% of the total PAHs were constituted by carcinogenic compounds.

The Mechanical Behavior of Sustainable Concrete Using Raw and Processed Sugarcane Bagasse Ash

Sugarcane Bagasse Ash (SCBA) is one of the most common types of agricultural waste. By its availability and pozzolanic properties, sugarcane bagasse ash can be utilized as a partial replacement for cement in the production of sustainable concrete. This study experimentally investigated the impact of employing two types of sugarcane bagasse ash as a partial substitute for cement up to 30% on the compressive strength, flexural strength, and Young’s modulus of the concrete mixture. The first type of bagasse ash used was raw SCBA, which was used as it arrived from the plant, with the same characteristics, considering that it was exposed to a temperature of 600 °C in the boilers to generate energy. The second type of bagasse ash utilized, called processed SCBA, was produced by regrinding raw SCBA for an hour and then burning it again for two hours at a temperature of 600 °C. This was done to improve the pozzolanic activity and consequently the mechanical properties of the concrete mixture. The findings indicated that employing raw sugarcane bagasse ash had a detrimental effect on the mechanical characteristics of the concrete mixture but using processed sugarcane bagasse ash at a proportion of no more than 10% had a considerable effect on improving the properties of the concrete mixture. The utilization of processed SCBA up to 10% into the concrete mixture resulted in a 12%, 8%, and 8% increase in compressive strength, flexural strength, and Young’s modulus, respectively, compared to the normal concrete specimen. On the contrary, the inclusion of raw SCBA with varying content into the concrete mixture decreased compressive strength, flexural strength, and Young’s modulus by up to 50%, 30%, and 29%, respectively, compared to the normal concrete specimen. The experimental findings were validated by comparison with ACI predictions. ACI overestimated the flexural strength of SCBA concrete specimens, with a mean coefficient of difference between the ACI equation and experimental results of 22%, however, ACI underestimated the Young’s modulus of SCBA concrete specimens, with a mean coefficient of difference between the ACI equation and experimental results of −6%.

Effects of Eucalypt ashes from moderate and high severity wildfires on the skin microbiome of the Iberian frog (Rana iberica)

Forest fires can threaten amphibians because ash-associated contaminants transported by post-fire runoff impact both terrestrial and aquatic ecosystems. Still, the effects of these contaminants on the skin microbiome of amphibians have been overlooked. Thus, the main objective of this study was to assess the effects of ash from different severity wildfires (moderate and high) on the skin microbiome of the Iberian frog (Rana iberica). Bacterial isolates sampled from R. iberica skin microbiome were tested for their antimicrobial activity against the pathogen Aeromonas salmonicida. The isolates with antimicrobial activity were identified and further exposed to several concentrations (0, 6.25, 12.5, 25, 50, 75, and 100%) of Eucalypt (Eucalyptus globulus) aqueous extracts (AAEs) of ash from both a moderate and a high severity wildfire. The results showed that 53% of the bacterial isolates presented antimicrobial activity, with Pseudomonas being the most common genus. Exposure to AAEs had diverse effects on bacterial growth since a decrease, an increase or no effects on growth were observed. For both ash types, increasing AAEs concentrations led to an increase in the number of bacteria whose growth was negatively affected. Ash from the high severity fire showed more adverse effects on bacterial growth than those from moderate severity, likely due to the higher metal concentrations of the former. This study revealed that bacteria living in Iberian frogs' skin could be impaired by ash-related contaminants, potentially weakening the individual's immune system. Given the foreseen increase in wildfires' frequency and severity under climate change, this work raises awareness of the risks faced by amphibian communities in fire-prone regions, emphasising the importance of a rapid implementation of post-fire emergency measures for the preservation and conservation of this group of animals.

Comparative Study on Selected Properties of Modified Polyurethane Foam with Fly Ash.

The aim of the article is to compare two types of fly ash (from the fluidized and pulverized coal combustion process) as a filler for rigid polyurethane foam. Pulverized fly ash (PFA) is widely used in building materials, while fluidized fly ash (FFA) is not currently recycled, but landfilled. The produced rigid polyurethane foams were reinforced with 5 and 10% by weight addition of fly ash from two different types of boilers. The foaming process, physical properties, morphologies and thermal degradation were subject to comparative analysis. The research indicated that fly ash intensifies the reactions of foam synthesis, most commonly, polyurethane (PU) foam with an addition of 10% PFA. What is interesting is that both ashes can be used in PU foam technology as they do not cause deterioration of the physical parameters. As shown, the addition of filler affects the morphology and impairs the brittleness. Additionally, the use of fly ash from coal combustion in the technology of polyurethane materials complies with the guidelines of the circular economy stated in the European Union legislation. Partial replacement of petrochemical components with waste filler also reduces the total energy consumption in the production of PU composites.

Utilization of fly ash as building material admixture: Basic properties and heavy metal leaching

The potential harm to the environment and human body caused by heavy metal elements such as Cd, Cr, Pb in fly ash cannot be ignored. In this study, microscopic analysis and heavy metal hazard analysis were performed on fly ash samples from four regions in China. XRF, XRD, FTIR and SEM/EDS test results showed that the main components of fly ash are Si, Ca, Al, O and other elements, and the main mineral components are mullite, quartz and amorphous aluminosilicate. The results showed that six heavy metal elements of As, Hg, Cd, Cr, Pb and Ni from the EDS test charts of these four types of fly ash. Based on the detection of the six heavy metal contents in fly ash, the results of the pollution evaluation of these four types of fly ash were consistent according to the single factor index, potential ecological risk index, and index of geo-accumulation. This indicated that Cd/Hg in FA 1, FA 2 and FA 3 has a high risk of environmental pollution. In the meantime, Cr and As in fly ash need to be controlled, because the human health risk assessment showed that they will bring carcinogenic risk to the human body through oral intake. The study on the migration law of characteristic heavy metals by taking FA 4 as an example showed that the leaching rate of Cr, Hg and Cd decreased with the increase of grinding particle size. Among the three characteristic heavy metals, mercury had the highest leaching rate. From the XPS detection results of FA 4, it was found that the valence states of these three heavy metals in FA 4 are Cr3+, Cr6+, Cd2+, Hg2+ respectively. These harmful heavy metal ions gradually enter the deep soil and groundwater through osmosis. Finally, based on the control model constructed in this study, the contents of these three heavy metals in fly ash in different application scenarios were limited.

Corrosive Effect of Wood Ash Produced by Biomass Combustion on Refractory Materials in a Binary Al-Si System.

In terms of its chemical composition, biomass is a very complex type of fuel. Its combustion leads to the formation of materials such as alkaline ash and gases, and there is evidence of the corrosive effect this process has on refractory linings, thus shortening the service life of the combustion unit. This frequently encountered process is known as “alkaline oxidative bursting”. Corrosion is very complex, and it has not been completely described yet. Alkaline corrosion is the most common cause of furnace-lining degradation in aggregates that burn biomass. This article deals with an experiment investigating the corrosion resistance of 2 types of refractory materials in the Al2O3-SiO2 binary system, for the following compositions: I. (53 wt.% SiO2/42 wt.% Al2O3) and II. (28 wt.% SiO2/46 wt.% Al2O3/12 wt.% SiC). These were exposed to seven types of ash obtained from one biomass combustion company in the Czech Republic. The chemical composition of the ash is a good indicator of the problematic nature of a type of biomass. The ashes were analyzed by X-ray diffraction and X-ray fluorescence. Analysis confirmed that ash composition varies. The experiment also included the calculation of the so-called “slagging/fouling index” (I/C, TA, Sr, B/A, Fu, etc.), which can be used to estimate the probability of slag formation in combustion units. The corrosive effect on refractory materials was evaluated according to the norm ČSN P CEN/TS 15418, and a static corrosion test was used to investigate sample corrosion.

Investigation of different paper mill ashes as potential supplementary cementitious materials

Integrating supplementary cementitious materials (SCMs) in cement-based construction materials is a key strategy for reducing environmental burdens and the greenhouse gas emissions related to cement production. Supplies of commonly applied SCMs such as fly ash and blast furnace slag are becoming limited, and therefore the search for alternative SCMs is of high significance. The present research investigates the viability of four paper mill ashes collected at different stages from the same incineration process as SCMs at different cement substitution rates (5–30 wt%). The ashes were first classified depending on their mineralogical and chemical composition, and their contribution to strength development of the prepared mortars is examined. Furthermore, the effects of the ashes on the hydration kinetics and the fresh and hardened properties of the prepared mortars were studied. The obtained results showed that a high level of SCM replacement accelerates the early hydration reactions and decreases the setting time. In addition, the incorporation of paper mill ashes increased the bound water depending on the ash type and resulted in strength development of the mortars at low replacement percentages (5–10 wt%). This study shows that the ashes belonging to type C medium acid based on bio ash classification could be incorporated as SCMs at a maximum level of 10 wt%, while those corresponding to type C low acid could be used up to 20–30 wt%. • Four paper mill ashes were characterized and classified based on the chemical and mineralogical composition then used as SCM. • Paper mill ashes corresponding to type C low acid based on bioash classification could be used as SCMs up to 20–30 wt%. • The addition rate of paper mill ashes controls the fresh properties and strength development of the mortars.

Physical and Mechanical Properties of Alkali Activated Mortars Produced Using Different Types of Fly Ash

Çimento üretimi sırasında atmosfere salınan karbondioksit (CO2), küresel ısınmaya neden olan önemli faktörlerden biridir. Bu nedenle, çimento tüketimini azaltmak amacıyla farklı malzemelerin kullanımı önem kazanmıştır. Bu amaçla alkalilerle aktive edilmiş malzemelerin (AAM) kullanımı oldukça yaygınlaşmaktadır. Bu çalışmada; yüksek fırın cürufu (YFC) ve 2 farklı tipte uçucu kül (UK) ile üretilen alkaliyle aktive edilmiş harçların fiziksel ve mekanik özellikleri araştırılmıştır. Harçlar; Tunçbilek Termik Santrali'nden temin edilen F sınıfı UK ile Çayırhan Termik Santrali'nden elde edilen C sınıfı UK, CEN referans kumu, YFC, sodyum hidroksit (NaOH), distile su ve kimyasal katkı maddesi kullanılarak üretilmiştir. Su/bağlayıcı ve kum/bağlayıcı oranı sırasıyla 0.5 ve 3 olarak alınmıştır. UK; YFC ile ağırlıkça %0, %10, %20, %30 ve %40 oranlarında yer değiştirilerek kullanılmıştır. Alkaliyle aktive edilmiş harç numunelerinin 1. serisine; 28 gün boyunca 21±1˚C’de sızdırmazlık kürü, 2. serisine ise 2 gün boyunca 105±5˚C’de ısıl kür ve 26 gün boyunca 21±1 ˚C’de sızdırmazlık kürü uygulanmıştır. Alkaliyle aktive edilmiş harç numunelerinin yayılma değeri, ağırlıkça su emme oranı, boşluk oranı, eğilme dayanımı ve basınç dayanımı belirlenmiştir. Çalışma sonucunda 1. ve 2. seride YFC100’e en yakın basınç dayanımı UKF10’da elde edilmiştir.