Ash Size Research Articles

Effect of particle size of rice husk ash on aluminium/graphene composites

Aluminium/graphene (Al/G) composite has gained wider engineering applications because of its unique properties such as lightweight, excellent corrosion resistant, improved strength and enhanced thermal conductivity. However, difficulty in dispersing graphene in molten aluminium remains one of the major optimization challenges. This study developed, by stir casting technique, composites of aluminium alloy from recycled aluminium can, 0.4 wt. % graphene (G) and 1.6 wt.% rice husk ash (RHA) with particle sizes of 150, 300 and 600 μm. The tensile, hardness, impact and fatigue properties were analyzed using Instron Extensometer, Vickers hardness tester, Charpy Impact machine and rotating fatigue machine respectively. Furthermore, the cast samples were characterized using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The morphology of the microstructure of all composites showed the retention and uniform distribution of G and RHA particles in the Al matrix devoid of presence of harmful aluminium carbide with improved mechanical properties. The study established a new approach of dispersing graphene in molten aluminium through a stir cast method with 150 μm particle size of RHA given the best mechanical and morphological properties.

RATIONALE OF TECHNOLOGY FOR THE COMMON AND HULLED WHEAT PROCESSING INTO WHOLE GRAIN FLOUR

The article is devoted to rationale the need of expand the range of flour products and increase its nutritional and biological value by the whole wheat flour production. The article shows the main tasks and problems facing the modern grain processing industry: increasing the utilization rate of grain; reducing the energy intensity of grain processing technological process; and to expand the range of end-products with increased nutritional and biological value. The production of whole grain flour (WGF) will allow expanding the range and increasing the nutritional value of the finished products. Ukraine's state standards for WGF are absent today. DSTU 46.004-99 named «Wheat flour. Specifications» applies only to high-grade flour and dark flour. The studying of Ukrainian WGF quality indicators showed that some manufacturers are guided by DSTU 46.004-99 in the WGF production, other manufacturers control the quality of flour with their own local specifications. Depending on such indicators as ash and particle size, some of WGF manufacturers adhere to the principle of almost 100% entry of all anatomical grain components into end-products. Despite of this, the particle size may vary by the level of the particle size of the dark flour or significantly differ from it. It depends either on the type of grinding machines (millstones or roller mill) or also on the usage of additional bran grinding in the technological scheme. Other manufacturers, in forming WGF to improve its baking properties, adhere to the principle of eliminating a certain amount of shell particles (in bran form). Such flour has an ash content much lesser comparing to the grain, but also its size depends on different structure and modes of grinding process. The purpose of the work is to substantiate the structure of the technological scheme and optimal modes while making WGF. During the research, a number of laboratory grindings of common wheat and spelta wheat into whole-grain flour were conducted. It is established that for the production of WGF it is most expedient to use combined technological schemes with the use of roller machines as grinding equipment on the main systems of technological process and millstones on the last stage systems for the final grinding of intermediate products. Due to the research, it is possible to recommend a scheme consisting of 3-4 roller mill systems and 1-2 millstone systems. The requirements determined for the wheat WGF particle size: top on sieve No. 067 – less than 2.0% and passage through sieve No. 38 – more than 50%.

Effect of Particle Size Variation of Bagasse Ash on Mechanical Properties of Aluminium Hybrid Metal Matrix Composites

Abstract Aluminium hybrid metal matrix composites are best suitable materials as per today’s requirement in automobile and aerospace industries. These are good replica of traditional ceramic composite materials. The fabrication and experimental analysis of hybrid metal matrix composite using base alloy Al-6061, alumina as primary reinforcement and bagasse ash as secondary reinforcement through stir casting route has been reported in this paper. Three different particle sizes of bagasse ash (37µm, 53µm and 75µm) were used and the mechanical properties (tensile strength, impact strength and micro hardness) were studied. These were compared with cast samples of base alloy Al-6061 and composite of Al-6061 and alumina. It was found that tensile strength; micro hardness and impact strength were decreased as the particle size of bagasse ash increased; however, the values were more than base alloy Al-6061. Microstructural images show the fair uniform distribution of reinforcement of different particle size in the metal matrix region

Application of Fly Ash and Slag Generated by Incineration of Municipal Solid Waste in Concrete

As landfill space for the disposal of products of municipal solid waste incineration (MSWI) such as fly ash and slag becomes increasingly scarce, a reduction of disposed material is urgently required. The method of using incineration products in concrete production is explored in this paper through a feasibility study of utilizing fly ash and slag to replace cement and coarse aggregate in appropriate proportions. Results show that C30 concrete optimum replacement rates of fly ash and slag are 30% and 20%, which can meet the minimum strength requirement. The leaching concentrations of Cu, Zn, Pb, Cr, and Cd in MSWI concrete samples are determined to be less than the identification value of solid waste leaching toxicity. Based on scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analyses, MSWI fly ash has certain dispersion. The particle size of MSWI fly ash is determined to be close to that of the coal fly ash, and the surface morphology is irregular. The main components include SiO2, CaCO3, and Ca2SiO4, and they are similar to those present in the coal fly ash. The slag structure is loose as well as irregular, and its main component is SiO2. The SiO2 and Al2O3 in fly ash and slag participate in the hydration reaction of cement and can increase concrete strength. It is thus confirmed that fly ash and slag generated by waste incineration can be used to replace cement and coarse aggregate in appropriate proportions, and it is an effective method to solve the problem of scarcity of solid waste landfill space.

Study of Panchashirishadi Agad on the basis of physicochemical and phytochemical analysis

Background: Many antidotes are mentioned in the classical text for the management of animal poisoning. Panchashirishadi Agad is one of the formulations indicated for Kita Visha (insect bite). Aim: To assess the physicochemical and phytochemical properties of Panchashirishadi Agad.Setting and Design: This was an original analytical study. Materials and Methods: Five parts of Shirish (Albizia lebbeck) were collected from local area of Wardha (Sewagram) and Panchashirishadi Agad was formulated as per the reference of classical text. Result: After the analytical study, the physicochemical properties that include loss on drying at 105°C, total ash value, acid-insoluble ash, water-soluble extractive, alcohol-soluble extractive, pH, and particle size were analyzed and the obtained values were 12.0%, 10.0%, 1.0%, 11.0%, 13.0%, 5.45%, and 100 mesh, respectively. In the similar way, the herbal formulation is devoid of microbial contamination. Phytochemical analysis includes the presence of 48% polyphenols. Conclusion: As the formulation contains more percentage of polyphenols, it can be anticipated that it can act as antiallergic agent.

Comparative analysis of milling time on the particle sizes of coal fly ash and wood fly ash using Otsu Method for thresholding

South Africa remains one of the countries with an abundance of coal fly ash (CFA) emerging from her abundant coal deposit. Despite the hazardous and environmental unfriendliness of fly ash, so many benefits can be derived therein. With new policies of waste-to-wealth, the country seeks ways by which this resource could be of value addition. However, CFA in its raw form often requires further milling operation to enhance suitability for the intended use. This study investigated the effect of milling time on the particle size of CFA and wood fly ash (WFA) using image segmentation. Both CFA and WFA received at micro-sized particles were washed with distilled water to remove impurities and dried in the oven at 80°C for 48 hours then sieved using 75µm size. Microstructural images of both CFA and WFA milled at varying times (t = 0, 20, 40, 60 minutes) were morphologically and physiochemically analysed using scanning electron microscope (SEM), X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), and X-Ray Fluorescence (XRF). SEM images of CFA and WFA were segmented using Otsu thresholding technique and average particle sizes were estimated. CFA contains a higher composition of Al2O3 (30.93%) and SiO2 (51.43%) compared to WFA, which has 10.70% and 46.31% respectively. However, WFA contains more of Fe2O3 (17.28%) than CFA (2.29%). The number of particle size increased with increases in milling time while the particle area decreased with an increase in milling time. At a 95% confidence interval, there exists a significant difference between results obtained at different milling time. Also, a significant difference exists between the mean particle diameters of the two ash sources.

Effect of particle size, porous structure and content of rice husk ash on the hydration process and compressive strength evolution of concrete

Compressive strength evolution of high strength concrete with rice husk ash (RHA) was evaluated as a function of RHA particle size, porous structure and replacement content. RHA porous structure was investigated by N2 absorption isotherm and its effect on hydration evaluated using isothermal calorimetry and thermogravimetry. Results indicated that RHA particle size influenced compressive strength until 28 days, whereas at 91 days replacement content became the significant factor. Preserved porous structure of RHA particles besides improving hydration kinetics enabled its action as internal curing agent improving compressive strength at late age.

The sintering kinetics and properties of sintered glass-ceramics from coal fly ash of different particle size

Coal fly ash, a solid waste from powder plant, was fully used to produce sintered glass-ceramics by direct sintering in air after dry pressing at 10 MPa. The influence of particle size on the sinterability and properties of sintered glass-ceramics had been systematically discussed. Compared with CFA (d50 = 12.6 μm), sintered glass-ceramics issued from 20CFA (d50 = 7.5 μm) and 40CFA (d50 = 4.9 μm) had higher bulk density, higher linear shrinkage and lower porosity. The sintering activation energy of the sintered glass-ceramics obtained from the three sizes of coal fly ash (CFA, 20CFA and 40CFA) were estimated by bulk density and linear shrinkage, which were 127, 102, 81 kJ/mol and 124, 106, 83 kJ/mol respectively, meaning the smaller the particle size, the easier the sintering. According to the XRD analysis, anorthite was formed by the reaction of portion dissolved quartz with the amorphous metastable glassy phase in coal fly ash. The smaller the particle size of coal fly ash is, the easier the formation of anorthite. Moreover, the properties (water absorption, flexural strength and chemical resistance) of the sintered glass-ceramics were enhanced with the decrease of the particle size and reached the standards of architectural decoration materials.

Geochemistry of the Zeolite-rich Miocene Pyroclastic Rocks from the Gördes, Demirci and Şaphane Regions, West Anatolia, Turkey

The western Anatolian Miocene volcano-sedimentary basins in the Gordes, Demirci and Şaphane regions host abundant heulandite/clinoptilolite (hul/cpt) bearing widespread zeolitized pyroclastic rocks. Lithostratigraphy of these zeolitic pyroclastic levels show comparable association. Petrography and geochemistry of all the samples show mainly rhyolithic and rhyodacitic character and ash size vitric tuffs. Polarized microscopy and X-ray diffraction determinations of the samples show composition of 55–95 wt % hul/cpt and accessory of smectite, illite/mica, opal–CT, quartz, K–feldspar, plagioclase and opaque minerals. Geochemical results obtained from the studied samples represent hul/cpt–rich facieses formed under the moderate alkaline conditions in these pyroclastic units. Correlation of geochemical results and concentration of hul/cpt in these pyroclastic rocks gives some chemical data on zeolitization process and on adsorption and ion-exchange character of hul/cpt type of zeolites. Depleted and enriched elements by zeolitization have similar ionic radii in general. Ca and H2O clearly increased, Si, Na and Si/Al ratio decreased in hul/cpt bearing Lower-Middle Miocene pyroclastic rocks of western Anatolia. Additionally, Sr, Nb, Th, Ni, Hf, Cs, Pb and Ta increased, and Zr, Co, W and most of the rare earth elements (REE) decreased in highly hul/cpt–rich pyroclastics.

Effects of different size of fly ash as cement replacement on self-compacting concrete properties

This paper aims to investigate experimentally the influence of replacing cement with different fineness of fly ash based on flowability, passing ability, compressive strength, tensile strength (splitting). Concretes with 15% fly ash (passed a number 100 sieve) and fine fly ash (passed a number 200 sieve) as cement replacement were cast and tested at 7, 14, 28 days after water curing. A superplasticizer in the form of viscocrete 3115 N was constantly used for each concrete mixtures as much as 1% by weight of cement. The results show that the use of fly ash does not significantly increased the compressive strength and tensile strength of SCC mixtures. However, concrete with 15% fine fly ash its self and combined 7.5% fly ash with 7.5% fine fly ash show better flowability and passing ability when compared to concrete with cement only indicating the performance of using smaller particle sizes of fly ash could lead better properties of SCC that can be potentially used for building construction application.

An Experimental Modeling for Dense Phase Pneumatic Conveying Capability using Multiple Hole Orifice in Air Supply Line for Dry Ash

Optimization of dry ash flow is an important aspect in the field of dry ash conveying system in power plant. Material pickup and conveying to desired distance at desired rate with minimum conveying medium (air) is a primarily requirement of any pneumatic conveying dry ash system. Though it looks simple task to determine parameters of conveying medium i.e. air flow but significant challenges poses while designing air parameters at Material pickup point and to maintain to convey desired throughput to conveying distance. In today’s prevalent designs / technology for pneumatic dry ash conveying system, it uses valve as controlling device in air supply system. But such system of using valve as controlling device has certain drawbacks like a) Malfunctioning of valve due to moisture & ash accumulation leading to system failure. b) Unstable operation due to high vibration and temperature Compressed air is used for instruments control purpose as well as a conveying medium. Air is a compressible gas which makes controlling difficult when specific parameters needed at certain location depending on the ash collection rate & accordingly distribution piping layout. At such locations, we need a device i.e orifice in place of valve for the same in order to achieve the desired result. In general most of system designed for two stages 1) Air storage to maintain desired air parameters passing through system. 2) In 2nd phase of pneumatic conveying air supply lines, we require fine controlling of air parameters for air supply to multiple points / ash hoppers (108 Nos). Air required in system operation is controlled by valves in prevalent designs but due to drawbacks of valve (malfunction, high initial cost and high maintenance cost of valves), orifice is one of the most commonly used element in flow regulation because of its simple structure, construction, easy installation and reliable performance (as no moving part) the orifice is increasingly adopted in air supply lines of dry ash pneumatic conveying system. The work present experimental investigation of dry ash pneumatic conveying system using multiple hole orifice in conveying air supply line to enhance flow uniformity and mass distribution downstream of manifolds or at pickup point of material as a distributors at Koradi Thermal Power Plant and result where compare with previous data and the study is extended for different parameters like conveying pressure and fluidizing pressure mean in particle size of dry ash, orifice numbers, thickness of orifice and place of orifice mounting along with corresponding loading ratio. A new approach of modeling on similar pipe line configuration since scaling is not required, it has provided better accuracy and approximation when the result was compared with experimental data. This method of online experimentation is aimed to address the partial filling of pipe's cross section by the dune of dry ash which requires high volume conveying air, or sometimes chocking of section occurs due to large volume of dry fly ash. To handle these problems, online experimentation has proved to be a better method than test conducted on test rig setup for representation of the optimum flow conditions, especially such complex mode of dense-phase pneumatic conveying of fine powders like dry fly ash materials.

Analisis Kelayakan Produksi Silikon dari Abu Ampas Tebu

It is estimated that the increase of sugarcane production will also increase the amount of bagasse. Sugar mills utilize dried bagasse as boiler fuel and the burning results a bagasse ash.Unrefined bagasse is estimated to contribute to the impact of the environment, including health problems when inhaled by humans. When covers the leaves, it will block the process of photosynthesis in plant. This are due to the size of ash and the contents of silica dioxide compound inside the bagasse. Besides providing impact, silica dioxide compounds are compounds that have high economic value as it can be used as silicon. The purposes of the utilization of bagasse ashes into silicon are to reduce the impact on the environment, to increase the economic value of bagasse ash and to empower community. The results of the feasibility analysis of silicon production from bagasse ash arethe planned production capacity of 10,000 tons/year, breakeven point (BEP) that is 3,400 tons/year or 34% of production capacity, Return of Investment (ROI) that is 28%, Payout Time (POT) of 3,6 years and 28,25% of Internal Rate of Return (IRR).Therefore, the plan to utilize the bagasse ash from silicon can be considered to be done.

The Influence of Natural Pozzolans Structure on Marl Soil Stabilization

Marl as a calcareous soil has heterogeneous nature in terms of structure and properties. Any change in the water content of marl can cause significant strength loss; therefore, prior stabilization while constructing civil infrastructures is necessary. A fundamental element in soil stabilization is the relationship between soil structure and stabilizers, but this important factor has been ignored in the available literature, especially in the case of marl soil. Lately, alternative environmentally friendly additives (natural pozzolans) as well as traditional chemical stabilizers (cement and lime) have been successfully used for stabilization of marl soil. This paper presents the results of an experimental study which investigates the influence of natural pozzolans structure on marl soil stabilization. Transmission electron microscopy (TEM), X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR) tests were used for size and structure analysis of marl soil and two types of natural pozzolans called Qizkorpi and Mamaloo of Iran which have been successfully used for marl soil stabilization by the authors, recently. Based on the obtained results by TEM, FTIR, and XRF tests, due to the similarity of the structure and size of Gizkorpi volcanic ash and marl soil when compared to that of Mamaloo volcanic ash, it can be concluded that the electrostatic and magnetic interactions in marl and Gizkorpi volcanic ash lead to a better stabilization and strengthen of the marl, while these interactions are less in Mamaloo volcanic ash when mixed with the marl soil.

Effect of recoating slurry with different particle size on the properties of reticulated porous mullite ceramics

Mullite reticulated porous ceramics (RPCs) were fabricated with fly ash, alumina, and andalusite by polymer sponge replica technique, followed by the process of vacuum infiltration with recoating slurry included. And the effect of different recoating slurry with different particle size fly ash on the properties of mullite RPCs was studied. The matrix slurry and recoating slurry were investigated and optimized. And then, the microstructure, composition of phases, and mechanical properties of mullite RPCs were examined by SEM (scanning electron micrograph), XRD (X-ray diffraction), and hydraulic universal testing machine. Moreover, the influence of particle size of fly ash on the thermal shock stability was analyzed by calculating residual stress model and grey relational model. The result indicated that the specimens that were recoated by the slurry with the smaller particle size of fly ash might have more excellent properties.

Catalytic effects of shale ash with different particle sizes on characteristics of gas evolution from retorting oil shale

Huadian oil shale samples were pyrolyzed in a small retort at 520 °C in the absence and presence of shale ashes with different particle sizes of 0–0.20 mm, 0–0.60 mm and 0–1.25 mm under argon atmosphere to evaluate the catalytic effects of shale ash on the products yield and non-condensable gases evolution characteristics. The shale ash samples were recorded as 0.20 mm, 0.60 mm and 1.25 mm shale ashes. The results indicate that the shale ash samples with good adsorption capacity and certain catalytic performance significantly affect the reactivity of oil shale pyrolysis. There are a slight decrease in the shale char yield and an increase in the total yield of volatile products with the particle size of shale ash decreasing from 1.25 to 0.20 mm. The shale oil yield increases after adding 0.20 mm and 0.60 mm shale ashes, especially 0.20 mm, but decreases after adding 1.25 mm shale ash compared with that obtained without adding shale ash, while the non-condensable gases yield decreases after adding shale ashes with three particle sizes, especially 0.60 mm. In addition, the gas products contain higher-volume content of CO2, CH4 and H2, and lower-volume content of CO and C2–C4 hydrocarbons. Adding the shale ash makes the peak concentrations of all gases shift to the lower temperatures and increases the maximum peak concentrations of C4H8 and H2, especially H2, but decreases those of other gases. The non-condensable gases mainly contain CO2 and CH4, and smaller amounts of other gases in terms of their mass distribution. The addition of shale ashes reduces the yields of several gases except CO2, H2, C2H6 and C4H8 compared with those obtained without adding shale ash. Adding three shale ash samples increase the H2 content, but cause different effects on the contents of CO2, C2H6 and C4H8. Among three shale ash samples, adding 1.25 mm shale ash produces the largest amount of CO2 and CO, as well as the lowest total content of C2–C4 alkenes, while adding 0.60 mm shale ash produces the largest amount of H2 and largest total content of C1–C4 alkanes. Adding the shale ash decreases the ethene/ethane ratio and increases the other alkene/alkane ratios compared with those obtained without adding shale ash. Adding 0.2 mm shale ash among three shale ash samples produces the lowest ethene/ethane and propene/propane ratios, being possibly related to the most significant coking reactions. Adding shale ashes with smaller particle sizes are more conducive to obtain non-condensable gases of higher heating value. The addition of 0.20 mm shale ash is the optimal for improving the shale oil yield and the conversion rate of kerogen to volatile products.

Influence of the particle size of wheat straw ash on the microstructure of the interfacial transition zone

Wheat straw ash, a potential pozzolanic material, can contribute to the reduction of CO2 emissions by lowering the demand for Portland cement. The particle size of pozzolanic admixtures has a significant effect on the microstructure of the interfacial transition zone of concrete. In this study, concrete specimens were made with water-binder ratios of 0.35 and 0.55 and three sizes of wheat straw ash particles obtained by mechanical processing for various durations. The particle size of the wheat straw ash decreased as the processing duration increased. Specimens with an equivalent amount of silica fume were also made in order to make a comparison. The influence of the particle size of the ash and the water-binder ratio on the microstructure of the interfacial transition zone was investigated via compressive strength and microhardness tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that increasing water-binder ratio caused a reduction in microhardness values. This effect was minimized with the addition of fine size wheat straw ash and silica fume particles. Additionally, incorporating fine ash particles prominently enhanced the microstructure of the interfacial transition zone.

Rice Husk Ash Pozzolan as Valuable Supplement in Concrete for Industrial and Domestic Applications

Controlled burning of rice husks at<700°C produced rice husk ash (RHA) which is predominantly amorphous silica (SiO2). RHA was used as a substitute for laterite and cement in proportions of 5%, 10%, 15%, 20%, 25% and 30% of concrete. The concrete was cured for 7 days, 14 days, 21 days, and 28 days respectively. It was observed that 20% of RHA provides the optimum strength. The effects of different particle sizes of 75, 150, 212, 300, 425 and 600 microns (µm) were tested using a compression test machine. A graph of average strength against particle size indicates 2.9 Nm-2 as the optimum strength at 75 µm and 1.2 Nm-2 as the minimum at 150 µm. From the ash size distribution, the presence of grains of several different sizes was observed. The grains were weighed using a weighing machine and a graph of particle size against percentage plotted to determine the particle size distribution. This showed that rice husk ash (RHA) is coarse grain material.

Enhanced Desilication of High Alumina Fly Ash by Combining Physical and Chemical Activation

In this work, a physical–chemical activation desilication process was proposed to extract silica from high alumina fly ash (HAFA). The effects of fly ash size, hydrochloric acid concentration, acid activation time, and reaction temperature on the desilication efficiency were investigated comprehensively. The phase and morphology of the original fly ash and desilicated fly ash were analyzed by X-ray diffraction (XRD) and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS). Compared with the traditional desilication process, the physical–chemical activation desilication efficiency is further increased from 38.4% to 53.2% under the optimal conditions. Additionally, the kinetic rules and equations were confirmed by the experimental data fitting with shrinking core model of liquid–solid multiphase reaction. Kinetic studies show that the enhanced desilication process is divided into two processes, and both steps of the two-step reaction is controlled by chemical reaction, and the earlier stage activation energy is 52.05 kJ/mol and the later stage activation energy is 58.45 kJ/mol. The results of mechanism analysis show that physical activation breaks the link between the crystalline phase and the amorphous phase, and then a small amount of alkali-soluble alumina in the amorphous phase is removed by acid activation, thereby suppressing the generation of side reactions of the zeolite phase.

Effect of Particle Size on Physical and Mechanical Properties of Fly Ash Based Geopolymers

The particle size of fly ash has influenced the physical and mechanical properties of geopolymers. Fly ash completely was ground to different pre-decided sizes, sieve sizes 180 μm, 90 μm and 45 μm (80 mesh, 170 mesh, 325 mesh) for formulation of geopolymer paste, and two activators were used: 8(M) NaOH and 1:1 mixture of NaOH and Na2SiO3. The heat evolution increased with increasing fineness of fly ash. The increase in ambient temperature enhanced the extent of geopolymerization. The maximum heat flow was obtained with the finest fly ash particle of size 45-μm (325 mesh). The microstructures of the various geopolymers revealed the compactness of the structure which had the finest 45-μm (325 mesh) particle size and silicate-activated geopolymers. Apparent porosity was found to decrease with increasing fineness and addition of sodium silicate. Mercury intrusion porosimetry (MIP) revealed the total porosity; median pore size and average pore diameter were found to decrease with increasing fineness. However, mesopores were seen to be more in 45-μm (325 mesh) fly ash geopolymers compared to 180-μm (80 mesh) fly ash geopolymers. Compressive strengths of geopolymer formed by 45-μm (325 mesh) particle size had greater compressive strength in comparison with the coarser one. Inclusion of sodium silicate in the activator solution was helped in enhancing the compressive strength.

Reaction kinetics of fly ash geopolymerization: Role of particle size controlled by using ball mill

Fly ash is milled for 0, 30 and 90 min and used to study the role of particle size on the kinetics of geopolymer formation. The increase in particle fineness is very prominent in the initial milling stage, and then slows down due to agglomeration effect of finer fraction. The fly ash geopolymerization kinetics and its mechanism is determined using heat of reaction data measured by isothermal conduction calorimeter. The improvement in reaction rate with milling is correlated with the median particle size of the fly ash. The apparent activation energy decreases with size reduction because finer fractions are more prone to alkali activation. Although the kinetics changes with particle fineness, but no alternation is detected in the reaction mechanism, governed by nucleation and growth. The apparent activation energy evaluated by rate method is showing three major steps of geopolymerization such as dissolution, gel formation and restructuring.