Fly Ash Materials Research Articles

Flowability and strength properties of high volume of fly ash material on self-compacting concrete

The detail complexity level of the building structure is getting more complicated. The use of a high volume of fly ash self-compacting concrete (HVFA-SCC) with better flowability properties is one alternative to address this problem. This research aims to investigate the strength properties and flowability of a high volume of fly ash self-compacting concrete (HVFA-SCC). The primary materials of HVFA-SCC were Ordinary Portland Cement (OPC), fly ash as OPC replacement material, fine and coarse aggregates. The ratio of OPC to fly ash was 0.500:0.500, 0.475:0.525, and 0.450:0.550. The strength properties were determined based on compressive strength and porosity in hard concrete conditions at 28 days. While the flow abilities were identified conforming slump test and slump flow in fresh concrete condition directly after a mixing process. The results show that the substitution of 0.500 fly ash as shown by the HVFA-SCC-2 specimen gives the best strength properties and flow abilities. The highest strength was achieved at 32.4 MPa with a porosity of 0.48 at 28 days-age. The slump and slump flow properties also demonstrate a good flow behavior under EFNARC standard with a slump of 26.1 cm and a slump flow of 656.9 mm. It can be concluded that the 50% substitution ratio of fly ash can replace the role of OPC in HVFA-SCC and improve its strength properties and flow behavior. The use of fly ash also able to overcome the global warming issue regarding OPC production.

The effect of TiO2 addition on thermal resistance of geopolymer mortar based low alumina fly ash

The utilization of fly ash with low alumina has been carried out. The addition of TiO2 to the base material of fly ash and fly ash added with 20% metakaolin mixed with an alkaline solution has been characterized by heat resistance, compressive strength and porosity. These results indicate that the addition of TiO2 to both fly ash and fly ash with an additional 20% metakaolin shows a reduction in porosity reduction, an increase in the compressive strength value, and an increase in the thermal resistance of the sample. Despite an increase in the compressive strength value, however, the minimum requirement for a fire brick has not been achieved.

Effect of partial replacement of cement with nano fly ash on permeable concrete: A strength study

Abstract In the recent times, the permeable concrete has grasped an attention of the civil engineering research community to address the drainage issues in the transportation sectors. Even though the surface nature appears to be rough and non-uniform, but it can effectively drain out the water through its interconnecting pore like structure in a large volume. The constituents of this concrete were as like conventional concrete but the difference is in the quantity of fine aggregate. It has been only little quantity and even some times there is no fine aggregate part also. In this paper, the work is planned to estimate the properties of compression and tension strength of permeable concrete which is prepared with cement and nano fly ash. In this work, the cement (C) to coarse aggregate (C.A) mix ratios were adopted was 1:4, 1:6 and 1:8 with respect to various water - binder ratios 0.32, 0.33 and 0.34. For each of these mixes, the cement was replaced from 0% to 50% with nano fly ash materials. The above mentioned strength tests were performed at 7th and 28th days of age of curing and it has compared with the permeable concrete with conventional cement. From the test results, it was found that 1:6 mix, 0.34 water - binder ratio, 40% replacement fraction of cement through nano fly ash was found be optimum among the other mixing compositions.

Coal Fly Ash Waste, a Low-Cost Adsorbent for the Removal of Mordant Orange Dye from Aqueous Media

In this study, a coal fly ash material generated in a Portuguese coal thermal powerplant was tested as a low-cost adsorbent to remove dye molecules. Pre-treatment of the coal fly ash samples was not performed in order to reduce end use cost. Physical and chemical characterization revealed their inert nature and low effects lixiviation in aqueous media. Preliminary adsorption studies include adsorbent quantity, and adsorption kinetics. The adsorption studies focused on Mordant Orange 1 (Mo1) dye, but two other molecules, Rhodamine B (RhB) and Methylene Blue (MeB) were also included for comparison reasons. The adsorption isotherms were tested with different models including Langmuir, Freundlich and modified Langmuir-Freundlich. The effect of temperature, pH and unburn carbon in the adsorption process were also studied. The results show that adsorption capacity of the coal fly ash occurs mainly due to electroestatic interactions between the adsorbent surface and the adsorbate, which depends on the pH of the aqueous media and the surface chemistry of the material, quantified by the point of zero charge, pHpzc. These joint effects are responsible for the higher retention of Mo1 that is about 16 times higher, when compared to the other two molecules tested.

Suitability Evaluation of Ash-And-Slag Waste from Coal Power Plants as Soil Components


 
 
 The chemical and fractional composition of ash-and-slag waste and fly ash materials of three large combined heat and power plants in Central Russia was compared in this study to assess their influence on the germination of oats as an indicator of the phytotoxic effect of these materials as soil components. It was found that these materials have an acceptable chemical composition from the viewpoint of their release into the environment, but there are factors such as fractional composition that significantly affect the growth and the development of plants when using these materials as soil components during soil reclamation.
 
 
 
 Keywords: Ash-And-Slag waste, coal fly ash, Chemical and fractional composition
 
 
 
 
 

Experimental Studies On Strength and Durability Characteristics of 8M GeoPolymer Mortar Based On Fly Ash and GGBS

Ordinary Portland cement (OPC) is one of the most misfortune cover measurable in the structure business. It is evaluated that the production of OPC, discharges the enormous measure of Carbon-di-oxide (CO2) gas which makes the 65% of a global warming which leads to global weather imbalance. For the manufacture of one ton of OPC transmits roughly 0.8 ton of CO2 in the worldwide gases, along these lines the cement industry produces 7% of all (CO2 ) ecological contaminating gases. The properties of the mortar have been calculated according to Indian and ASTM standard requirements, specific gravity, compressive and split tensile strength. The ratio of “Na2SiO3 to NaoH” is 2.5, and the ratio of “alkaline solvent to binder” is equal to 0.4, 0.45, 0.5, 0.55 in the cases of binder components are calculated with each ratio like in this research we calculated with each fluid/binder ratio with different mix proportions 1:15, 1:2, 1:2.5, 1:3 in this research using only two materials fly ash then GGBS, using the different ratios of fly residue and GGBS with identical molarity and IS specified normal sand sieve sizes. Once prepared with the “alkaline liquid to binder” ratio, it creates higher strength to the geopolymer mortar. It can be inferred that the results in terms of intensity by ambient curing are strong relative to outdated mortar.

Potential of using a new aluminosilicate amendment for the remediation of paddy soil co-contaminated with Cd and Pb.

Cadmium (Cd) and lead (Pb) are toxic heavy metals that impact human health and biodiversity. Removal of Cd/Pb from contaminated soils is a means for maintaining environmental sustainability and biodiversity. In this study, we applied a newly modified material fly ash (NA), zeolite (ZE), and fly ash (FA) to the paddy soils and evaluated the effects of Cd/Pb accumulation in rice via a one-year field experiment. The results showed that the application of NA and ZE enhanced the soil pH and nutrients to a large extent and reduced the availability of Cd/Pb in soil. The Cd and Pb concentrations in rice grains decreased by 32.8% and 62.9%, respectively, with the NA treatments. Similarly, the application of ZE reduced the Cd and Pb concentrations in rice grains by a factor of 27.9% and 63.5%, respectively, which indicates that the amendments can promote the transfer of Cd and Pb from acid-exchangeable fraction to oxidizable and residual fractions. The Cd/Pb showed a significant positive correlation to other metal ions and a negative correlation to the nutrients. Generally, the application of NA and ZE was effective in reducing Cd/Pb accumulation and improving rice yield. Moreover, the NA was more cost-effective than ZE. Hence, this study proves that NA may be a better amendment for remediation of Cd/Pb contaminated soils.

Effect of fly ash and slag on properties of normal and high strength concrete including fracture energy by wedge splitting test: Experimental and numerical investigations

The effect of supplementary cementitious material (fly ash and slag) on the properties of concrete was investigated at different ages starting from as early as 18 h in this paper. The tests covered concrete mix with a different amount of supplementary cementitious material (SCM). The effect of SCM on the properties of concrete (compressive strength, splitting tensile strength, modulus of elasticity, Poisson’s ratio and fracture energy) was investigated. Properties of concrete including fracture energy of concrete by wedge splitting test (WST) with different percentage of fly ash (FA) and slag were evaluated. For a mix with 50% slag, there was a decline in the values of compressive strength of concrete, splitting tensile strength, modulus of elasticity and fracture energy compared with a mix with 25% FA. The mix with 25% FA also had a higher fracture energy of concrete than the mix with 50% slag. The fracture energy decreased when FA and slag were added at all ages compared to the pure cement mix. A finite element (FE) model was developed and the results from the FE analysis were compared with the experimental work. A good agreement was achieved in terms of fracture energy and splitting load vs crack mouth opening displacement.

Resistance of fiber-reinforced fly ash-steel slag based geopolymer mortar to sulfate attack and drying-wetting cycles

Fly ash-steel slag based geopolymer mortar was studied for recycling solid wastes and developing a sustainable alternative to Ordinary Portland Cement (OPC). The fiber-reinforced geopolymer mortar was prepared from the main raw materials of fly ash, steel slag, and fibers. This paper studies the mechanical properties, mass loss rates and appearance of fiber-reinforced geopolymer under double-factor coupling, i.e. sulfate corrosion and drying-wetting cycle process on the geopolymer samples. The results show that the compressive strength and flexural strength of each sample gradually increase and tend to be stable under double-factor coupling. After 15 cycles, the compressive strength of the SF-4 (mixed with 0.4 vol% steel fiber) is still the highest, which is 67.9 MPa, and the compressive strength of the BF-3 (mixed with 0.3 vol% basalt fiber) increases the most, whose growth rate is 96.6%. Due to the evaporation of water and diffusion of sodium sulfate between samples and solution, the change of mass loss rate of samples was unstable. The white precipitate was observed on the surface of samples, and it was sodium sulfate by X-ray diffraction (XRD) analysis. Both stable and dense structures of samples and fiber-bridged matrix function make fiber-reinforced geopolymer mortar present excellent performance in resistance to double-factor coupling corrosion.

Investigation of Fly Ash Concrete by Slump Cone and Compaction Factor Test

The supplementary or alternative material to cement has been an emerging field in civil engineering. The concrete ingredients have become modern due to the need for reducing global warming and material scarcity problem. Fly ash is used to replace cement partially in concrete, therefore the concrete mix has changed their characteristics as obtained by normal concrete. The proper investigation always required for performance measurement and to measure the fresh concrete property, the slump cone test, and compaction factor test are the tool. The Slump Test has become the most frequently performed due to the practicality of the recommended equipment and the experiment protocol. The slump test involves the cone’s behavior under the action of gravitational forces. The slump check is a realistic way to gauge the workability. The concrete slump test and compaction factor test are used to determine the consistency of fresh concrete before it sets. This paper has focused on testing the 54 mixes having various water-cm ratios like 0.5, 0.55, 0.6, 0.45, and 0.4. Fly ash material possesses satisfactory workability properties due to their similar oxide compositions. Due to the fineness of fly ash, less bleeding observed than control concretes.

Recent progress in environmentally friendly geopolymers: A review

The manufacturing of cement demand burning of huge quantities of fuel as well as significant emissions of CO2 resulting from the decomposition of limestone that consequently resulted in severe environmental impact that is estimated by one ton of CO2 per ton of cement. Geopolymerization technology is an effective method for converting wastes (containing alumina and silica) into useful products. It can reduce CO2 emissions significantly from the cement industry. The geopolymerization process usually starts with source materials based on alumina/silicate in addition to alkaline liquids. The compressive strength, setting time, and workability of the final product depends mainly on the type and proportions of the precursors, the type and strength of the activator, the mixing and curing conditions. The structural performance of a geopolymer is similar to that of ordinary Portland cement (OPC). Therefore, geopolymer can replace OPC, and thus decreasing the energy consumption, reducing the cost of the building materials, and minimizing the environmental impacts of the cement industry. This review summaries the mechanism of geopolymerization, including the controlling parameters and different raw materials (fly ash, kaolinite and metakaolin, slag, red mud, silica waste, heavy metals waste, and others) with particular focus on recent studies and challenges in this area.

Hydration behavior of cements with reduced clinker factor in mixture with sulfoaluminate binder

CO2 regulation and raw material availability will strongly influence the future cement market and a wider use of composite cements containing limestone and pozzolan or slag is expected.In the present paper, the possibility to combine Portland cements (PCs) with reduced clinker factor with sulfoaluminate cement (CSA), is explored. Low Portland clinker cements are prepared in laboratory using different supplementary cementitious materials (limestone, slag, pozzolan and fly ash) and mixed with a sulfoaluminate cement: the hydration behavior of the resulting binders is investigated up to 90 days through a multi-technique approach involving X-ray diffraction, differential scanning calorimetry and nuclear magnetic resonance spectroscopy. Understanding the interaction mechanisms between SCMs and CSA/PC blends will support the development of innovative high performing binders based on CEM III or CEM V, or even on new standardized CEM II. Results highlight that slag is particularly suitable promoting late strength development.

Expansive behavior of an alkali-carbonate reactive dolostone from Argentina: Proposal of an osmotic theory-based model to explain the expansion caused by the alkali attack

The expansion mechanism of dolomitic rocks in alkaline environments is complex and a current topic of debate, since two different chemical reactions can coexist: one linked with silica attack (alkali-silica reaction, ASR) and the other with dolomite attack (alkali-carbonate reaction, ACR). In previous works, a potentially reactive, fine-grained argillaceous dolomitic rock was identified in Argentina, with similar expansive characteristics to the typical American reactive carbonates. When this rock is used as aggregate in mortars or concretes, the dolomite experiences a clearly expansive dedolomitization reaction, which cannot be controlled by the classical techniques that allow the inhibition of ASR: supplementary cementitious materials (SCMs) (fly ash, natural pozzolan, silica fume, etc.) or Li-based admixtures. Since none of the classical theories proposed by the literature adequately describe the expansive behavior of this rock, an expansion mechanism based on the osmotic phenomenon is proposed in the present work. This mechanism describes the behavior of the Argentine dolostone more appropriately and allows explaining the effect of the main factors involved in the concrete expansion (pH of the pore solution, nature of the alkali cation associated with the OH−, role of water in the expansion, temperature, aggregate particle size, effect of the SCMs, etc.). The basis of the osmotic model is presented, and its advantages are discussed compared with the classical ACR mechanisms proposed by the literature.

Thermomechanical behavior of bio-fiber composite thermal insulation panels

The thermomechanical properties of the bio-fiber composite, as material for the production of thermal insulation panels, were evaluated. The observed mixtures were composed of Miscanthus × giganteus bio-fibers, mineral binders (cement or lime), pozzolanic materials (zeolite and fly ash), and water. The favorable heat transfer behavior of composites based on Miscanthus × giganteus bio-fibers was already affirmed by literature data of similar natural bio-fiber materials, the author’s previous experimental results, and consideration of dynamic heat transfer processes in the insulated outer wall exposed to variable ambient conditions. The experimental assessment was focused on the bearing capacity (i.e. compressive and flexural strength), water absorption, and durability (i.e. resistance to freeze-thaw and carbonation), because there is scarce literature data regarding these properties, whose thorough understanding and systematization are highly important for a wider application of biomass-based thermal insulation materials. The obtained results were evaluated through the comparison to published data from similar bio-based thermal insulations, as well as from conventional thermo-insulation materials such as polystyrene and stone or glass wool.

Manufacturing and Mechanical Characterization of Fly-Ash-Reinforced Materials for Furnace Lining Applications

Fly ash is the major wastes generated during the combustion of coal in thermal power plants. More than 110 million tons of fly ash produced in India annually. It leads to a significant disposal problem. An attempt has been made by numerous researchers to integrate the fly ash in the industry sector. The key applications include the manufacturing of bricks, production of cement, soil amelioration, mine backfilling, etc. Nevertheless, the refractory bricks for furnace lining are mainly formed from iron and steel, which are imported and are very expensive. Hence, to tackle this issue, the current study is focused on the synthesis of fly-ash-rich brick for high-temperature applications. In this investigation, fly ash material combined with minor additives such as granite powder, alite cement, and black sand were manufactured. The pellets of these materials with a varying additive percentage from 5 to 30% were prepared using hydraulic pressure. The heat-treated pellets were physically and mechanically characterized to ensure the brick properties suitable for furnace lining applications. Surface morphology of raw materials and particle–particle interaction after palletization were evaluated using scanning electron microscopy. Energy Dispersive x-Ray Analysis and x-ray diffraction technique were conducted to detect elemental analysis and phase evaluation of raw materials and fly-ash-rich brick after heat treatment. Microhardness of the samples was determined using a Vickers hardness tester. It is found that the formation of various complex compounds with respect to constituent composition, and pellet formation temperature has a great influence on the variation in hardness.

A Low-Autogenous-Shrinkage Alkali-Activated Slag and Fly Ash Concrete

Alkali-activated slag and fly ash (AASF) materials are emerging as promising alternatives to conventional Portland cement. Despite the superior mechanical properties of AASF materials, they are known to show large autogenous shrinkage, which hinders the wide application of these eco-friendly materials in infrastructure. To mitigate the autogenous shrinkage of AASF, two innovative autogenous-shrinkage-mitigating admixtures, superabsorbent polymers (SAPs) and metakaolin (MK), are applied in this study. The results show that the incorporation of SAPs and MK significantly mitigates autogenous shrinkage and cracking potential of AASF paste and concrete. Moreover, the AASF concrete with SAPs and MK shows enhanced workability and tensile strength-to-compressive strength ratios. These results indicate that SAPs and MK are promising admixtures to make AASF concrete a high-performance alternative to Portland cement concrete in structural engineering.

Research on Mix Proportion Design Method of Cement Concrete for Road Mixed with Antifreeze Admixtures Sealed in Capsules

In order to explore the influence of a new mixed type antifreeze material on the flexural strength of concrete for road, the orthogonal design method was used to conduct experimental research on six factors including the water-binder ratio, the antifreeze material content, the fly ash content, the feeding process, the shape of the antifreeze material and the pre-absorption of antifreeze material. The influence degree of various factors on the flexural strength of concrete was studied, and the mixing ratio design method of concrete for road mixed with the antifreeze material was given. It was found that the water-binder ratio is the main factor affecting the strength of the concrete and that when the amount of antifreeze material is less than 15%, the effect on the strength is small. The influence of other factors on the strength is greatly influenced by the interaction of water-binder ratio. When it comes to the mix design, the content of gelling material is 500 kg/m3, and the water-binder ratio changes from 0.35 to 0.43 under different traffic levels. The recommended antifreeze material content and fly ash content is 10% and 15% respectively. It’s also suggested that the antifreeze material should be pre-absorbed, and the cement sand and stone be mixed before the antifreeze material is put into the mixing.

Prediction of mechanical properties of lightweight basalt fiber reinforced concrete containing silica fume and fly ash: Experimental and numerical assessment

As a building material, concrete has its own advantages and disadvantages. One of the weaknesses of concrete is its very low tensile strength and strain as well as brittleness under flexural or compressive loading, which results in sudden failure of the concrete structures during earthquakes. On the other hand, low strength of lightweight aggregates and their fragility lead to poor performance of the lightweight concrete against ductility. Therefore, this study investigated mechanical properties of the lightweight structural concrete containing expanded clay aggregate and different amounts of basalt fibers (0–0.5%). Hence, pozzolanic materials of silica fume and fly ash were used to modify some of the concrete properties in lightweight concrete mixtures as a substitute of part of the cement weight. In total, 21 mix designs were made and their fresh and hardened properties were tested at different ages of 7, 28, and 90 days. Results indicated that the presence of basalt fibers reduced slump and compressive strength by 37% and 13%, respectively. It was also found that all mixtures had a “good” level of water absorption quality and thus were placed in the category of “structural concrete”. Results also indicated that addition of fibers improved tensile, flexural strength, and shrinkage. In order to predict empirical results, an adaptive neuro-fuzzy inference system (ANFIS) was used as a reliable method for evaluating and estimating the results and numerical analysis outputs showed accurate estimation of the empirical results.

Evaluating Optimum Strength of Geopolymer Concrete using Quarry Rock Dust with Inclusion of Natural and Hybrid Fibers Under Ambient Curing

Conventionally used cement –a primary binder also a necessitate element in producing concrete rates first in the construction industry. Production of conventional cement requires a greater skill and is energy intensive. The usage of waste materials in the production of concrete and reduction in cement content was only the possible alternative in the past decade. Associated risks with the production of Ordinary Portland Cement are well known. A greener aided with a natural friendly claim can be made only with the usage of the waste materials and reduction in evolving respiration gas to the atmosphere. Almost all works are carried out using source material fly ash, with fine aggregate and coarse aggregate. Concrete plays a vital role in the construction industry and on the other hand, river sand; one of the essential material has become very expensive which is a scarce material. Depletion of sand is a hectic issue due to increased usage of sand in construction. No other replacement materials such as quarry rock dust is not concentrated in casting geopolymer specimens. Even though in some research papers the replacement materials are added only in partial replacement without aiming on 100% replacement. Many researches mainly focus towards test results of GPC specimens using steel fibers, glass fibers. But the study related to natural fibers and hybrid fibers are found scarce. The main part of this work aimed at characterizing the engineering strength properties of geopolymer concrete by 100% replacement of fine aggregate with quarry rock dust. Hence, combination of flyash and quarry rock dust in GPC have been considered for evaluating the mechanical properties of geopolymer concrete. Also, investigation focuses on incorporation of three different fibers namely polypropylene fibers(PF), coir fibers(CF) and hybrid fibers(HF) in different percentage of proportions such as 0.5%,1%,and 1.5% to determine the maximum strength properties of GPC.

Effect of SiC/Fly Ash Reinforcement on Surface Properties of Aluminum 7075 Hybrid Composites

Friction stir processing (FSP) has emerged as a valuable technique in the surface metal matrix composite fabrication field. In this process, solid-state processing mostly avoids the formation of detrimental phases inside composites. Despite having a high specific strength, further extensive Al alloy applications are limited due to their poor surface properties. A hybrid reinforcement approach can be used to improve surface properties. In this study, industrial waste fly ash material is mixed with hard SiC ceramic particles. The main focus of this research is to improve wear resistance under dry sliding conditions and microhardness of aluminum 7075-T651 by dispersion of silicon carbide-fly ash (SiC/fly ash) powder in a base alloy by FSP. The parameters used for this investigation are: tool rotation rpm (500, 1000 and 1500), the tool traverse mm/min (20, 30 and 40), the reinforcement’s hybrid ratio HR (60:40, 75:25 and 90:10) and the volume percentage vol.% (4%, 8% and 12%). The influence of these parameters on the resultant composite’s microstructure, dry sliding wear rate and micro-hardness was studied. By using response surface methodology (RSM), desirable ranges of process parameters for lower wear rate and higher microhardness were obtained. The interaction effect of SiC/fly ash volume percentage and hybrid ratio had the most influential effect on the wear rates, as well as microhardness of composites. Moreover, microhardness increased with an increase in the volume percentage of SiC/fly ash powders towards high SiC content in hybrid ratio. Interestingly, among stirring parameters, tool traverse speed was found to be more influential than tool rotational speed. The minimum wear rate was observed for the Run 20 sample (w: 1000 rpm, v: 40 mm/min, HR: 75:25, vol.%: 8). A maximum microhardness of 241.20 HV was achieved for Run 15 (w: 500 rpm, v: 40 mm/min, HR: 90:10, vol.%: 12) sample. Mainly, reinforcement distribution—in accordance with the stirring action generated by the tool—had a major role in controlling the surface properties of the resultant composites.