scholarly journals The influence of different fly ash-cement replacement ratios on the pressure drop of a horizontal backfilling pipe

2021 ◽  
Vol 942 (1) ◽  
pp. 012006
Author(s):  
D Wang ◽  
J Zhao ◽  
J Garcia-del-Real ◽  
H Mischo
Keyword(s):  
Fly Ash ◽  
Pressure Drop ◽  
Flow Velocity ◽  
Thermal Power ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
Pseudoplastic Fluid ◽  
Materials Used ◽  
Physical And Chemical ◽  
Flow Particle

Abstract Fly ash (FA) is a kind of harmful by-product in thermal power generation plants, and finding a way to enhance the utility of fly ash has been widely discussed among civil engineering and mining sectors. To investigate the possible optimal ratios of replacing usually used bind agent namely Portland cement (PC) with fly ash, this paper designed different test groups with varying PC-FA replacement ratio. To identify the physical and chemical characteristics of mixing materials used to produce the backfilling slurries, a rheological experiment and X-ray diffraction test have been conducted. Rheological tests show all these three replacement ratio groups (60%, 65%, 70% respectively) are yield pseudoplastic fluid. Computational fluid dynamics as an efficient and money-saving method also has been introduced in the present research to duplicate the flow behaviors and calculate the pressure drop (PD) in the backfilling pipe circuits. The simulation results suggested that all these three RR categories experience an increasing tendency in pressure drop with increasing flow velocity, but in the velocity range of 2 m/s - 2.4 m/s, the increasing tendency is gentle until flow velocity reaches 2.6 m/s, the PD increase evidently. Furthermore, when the RR = 65%, the pressure drop is significantly lower than that of RR = 60% or RR = 70% at all the corresponding investigated flow particle sizes have significant impact on the pressure drop across a pipe and is dependent on solid fraction and flow rate and velocities. Therefore, we can conclude that a proper dosage of FA in mixing backfilling slurries can reduce pressure drop obviously and thereby decrease the expenses in bind agent. Given the FA’s significant effect on pressure drop, and comprehensive considering the backfilling capacity and backfilling cost, the combination of RR = 65% and velocity = 2.6 m/s is optimum.

Pressure drop calculation for fly ash slurry using rheological model

2019 ◽  
Vol 16 (6) ◽  
pp. 751-767
Author(s):  
Kanwar Pal Singh ◽  
Arvind Kumar ◽  
Deo Raj Kaushal
Keyword(s):  
Fly Ash ◽  
Pressure Drop ◽  
Flow Velocity ◽  
Rheological Model ◽  
Flow Behavior ◽  
Thermal Power ◽  
Solid Concentration ◽  
High Concentration ◽  
Content Type ◽  
Flow Parameters

Purpose This paper aims to the transportation of high concentration slurry through pipelines that will require thorough understanding of physical and rheological properties of slurry, as well as its hydraulic flow behavior. In spite of several contributions by the previous researchers, there is still a need to enrich the current understanding of hydraulic conveying through pipeline at various flow parameters. The pilot plant loop tests, particularly at high concentrations, are tedious, time-consuming and complex in nature. Therefore, in the current research the prediction methodology for slurry pipeline design based on rheological model of the slurry is used for calculation of pressure drop and other design parameters. Design/methodology/approach It has been established that slurry rheology plays important role in the prediction of pressure drop for laminar and turbulent flow of commercial slurries through pipeline. In the current research fly ash slurry at high concentration is chosen for rheological analysis. The effect of particle size and solid concentration is experimentally tested over the rheological behavior of slurry and based on the rheological data a correlation is developed for calculation of pressure drop in slurry pipeline. Findings The present study strongly supports the analytical approach of pressure drop prediction based on the rheological parameters obtained from the bench scale tests. The rheological properties are strongly influenced by particle size distribution (PSD), shear rate and solid mass concentration of the slurry samples. Pressure drop along the pipeline is highly influenced by flow velocity and solid concentration. The presence of coarser particles in the slurry samples also leads to high pressure drop along the pipeline. As the concentration of solid increase the shear stress and shear viscosity increase cause higher pressure drop. Research limitations/implications The transportation of slurry in the pipeline is very complex as there are lot of factors that affect the flow behavior of slurry in pipelines. From the vast study of literature it is found that flow behavior of slurry changes with the change in parameters such as solids concentration, flow velocity, PSD, chemical additives and so on. Therefore, the accurate prediction of hydraulic parameter is very difficult. Different slurry samples behave differently depending upon their physical and rheological characteristics. So it is required to study each slurry samples individually that is time-consuming and costly. Practical implications Nowadays in the world, long distance slurry pipelines are used for the transportation of highly concentration slurries. Many researchers have carried out an experiment in the design aspects of hydraulic transportation system. Rheological characteristics of slurry also play crucial role in determining important parameters of hydraulic conveying such as head loss in commercial slurry pipeline. The current research is useful for the prediction of pressure drop based on rheological behavior of fly ash slurry at various solid concentrations. The current research is helpful for finding the effect of solid concentration and flow velocity on the flow behavior of slurry. Social implications Slurry pipeline transportation has advantages over rail and road transportation because of low energy consumption, economical, less maintenance and eco-friendly nature. Presently majority of the thermal power plants in India and other parts of the world dispose of coal ash at low concentration (20 per cent by weight) to ash ponds using the slurry pipeline. Transporting solids in slurry pipelines at higher concentrations will require a thorough knowledge of pressure drop. In the current research a rheological model is proposed for prediction of pressure drop in the slurry pipeline, which is useful for optimization of flow parameters. Originality/value All the experimental work is done on fly ash slurry samples collect from the Jharli thermal power plant from Haryana State of India. Bench scale tests are performed in the water resource laboratory of IIT Delhi for physical and rheological analysis of slurry. It has been shown in the results that up to solid concentration of 50 per cent by mass all the samples behave as non-Newtonian and follows a Herschel–Bulkley model with shear thickening behavior. In the present research all the result outcomes are unique and original and does not copied from anywhere.

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

scholarly journals Microwave absorption and mechanical properties of double-layer cement-based composites containing different replacement levels of fly ash

2018 ◽  
Vol 25 (4) ◽  
pp. 707-714 ◽  
Author(s):  
Yuefang Zhang ◽  
Shunhua Liu ◽  
wanJun Hao
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Double Layer ◽  
Impedance Matching ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
Matching Layer ◽  
Optimal Replacement ◽  
Zn Ferrite ◽  
Absorbing Layer

Abstract Double-layer absorbing cement-based composites with the thickness of 10 mm were prepared, including different replacement levels of fly ash (FA) in the absorbing layer as well as the matching layer for impedance matching. Waste polyethylene terephthalate bottle fragment was introduced as electromagnetic transparent reinforcement aggregate. Carbon black was used to be original absorbent in the absorbing layer. The microstructure and electromagnetic parameters of FA were closely looked at through scanning electron microscope, X-ray diffraction, and analyzer of vector network. The absorption and mechanical properties of cement-based composites were tested. It turned out that when the optimal replacement ratio of FA in the absorbing layer and matching layer gets to 50%:30%, the minimum value of reflection loss achieves −22.3 dB at 13.2 GHz; also, the value of absorption bandwidth that is effective (<−8 dB) is 6.4 GHz. Ni-Zn ferrite proves to be a feasible absorbent that is additional for the matching layer compared to what is added to the absorbing layer. The compressive strength of all the mixtures decreased, while the flexural strength decreased first and then increased with the rise of the FA replacement level.

scholarly journals Analysis of the Physicochemical and Mineralogical Properties of the Materials Used in the Preparation of Recoblocks

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3626
Author(s):  
María Neftalí Rojas-Valencia ◽  
José Alberto Lopez-López ◽  
Denise Yeazul Fernández-Rojas ◽  
José Manuel Gómez-Soberón ◽  
Mabel Vaca-Mier
Keyword(s):  
Field Tests ◽  
Construction Sector ◽  
X Ray Diffraction ◽  
Construction Waste ◽  
Mineralogical Properties ◽  
Bending Resistance ◽  
Resistance To Stress ◽  
Materials Used ◽  
Physical And Chemical ◽  
Properties Of Soil

The construction sector generates 14,000 t/d of construction waste in Mexico City, these materials do not have real applications and end up accumulating in landfills. This work, the objective of which was to analyze the physicochemical and mineralogical properties of soil and construction waste used in the manufacture of Recoblocks, is divided in five stages. First, the excavation material was submitted to field tests. Physical and chemical tests were then carried out on construction waste. Subsequently, the optimal mixture for making Recoblocks was determined. Next, Recoblocks were evaluated and compared with blocks made with water only, without mucilage of Opuntia ficus, and finally a feasibility study was performed. The X-ray diffraction study showed the presence of plagioclase, minerals that improve bending resistance, hardness, durability, as well as resistance to stress in a material. Compared to blocks manufactured without mucilage, the use of Opuntia ficus mucilage increased the compressive strength of the material by 59%, as well as the erodibility. Recoblocks are an environmentally friendly option because they are based on recycled materials, dried under the sun, which eliminates the use of brick oven. The production cost per unit is just USD 0.19, so it is a viable option as a building material.

scholarly journals Reactivity of fly ashes milled in different milling devices

2019 ◽  
Vol 58 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Yong-Sik Chu ◽  
Batmunkh Davaabal ◽  
Dae-Sung Kim ◽  
Sung-Kwan Seo ◽  
Yoo Kim ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Surface Area ◽  
Thermal Power ◽  
Chemical Properties ◽  
Particle Size Reduction ◽  
Attrition Mill ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Physical And Chemical

Abstract The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

scholarly journals Stabilization of B.C. Soil by Using Chemicals and Fly Ash

2021 ◽  
Vol 9 (VIII) ◽  
pp. 570-585
Author(s):  
Dhananjay B. Bawaskar
Keyword(s):  
Fly Ash ◽  
Calcium Carbonate ◽  
Zinc Chloride ◽  
Power Plants ◽  
Thermal Power ◽  
Calcium Sulphate ◽  
Black Cotton Soil ◽  
Experimental Program ◽  
Black Cotton Soils ◽  
Physical And Chemical

Black cotton soils are very susceptible to detrimental volumetric changes with changes in moisture. This behaviour of soil is attributed to the presence of mineral montmorillonite which has an expanding lattice. Black cotton soils because of their specific physical and chemical make are subjected to volume changes. In many countries including India, these soils are so extensive that alteration of highway routes to avoid the material is virtually impossible. Various remedial measures like soil replacement, prewetting, moisture control, lime stabilization etc. have been practiced with varied degrees of success. Extensive research is going on to find the solutions to Black cotton soils. Recent investigations on chemical stabilisation revealed that electrolytes like Calcium Sulphate, Calcium Carbonate, Zinc Chloride can be used in place of conventionally used lime, due to their ability to supply adequate cations. Fly ash is a waste by product from thermal power plants consuming thousands hectors of precious land for its disposal and also causing severe health and environmental hazards. This work presents the results of an experimental program undertaken to investigate the effect of Calcium Sulphate, Calcium Carbonate, Zinc Chloride and fly ash at different percentages on properties of black cotton soil. Atterbergs Limit of subgrade soil effect of addition of Fly Ash and Chemicals on CBR ,MDD ,OMC, From the results it is observed that 2% of Zinc Chloride and 12% of Fly ash improves the properties of black cotton soil as compared to Calcium sulphate & Calcium Carbonate. The conclusion drawn from this investigation is that a combination of 2% of chemicals and 12% of fly ash is more effective in improving the properties of black cotton soil.

scholarly journals Geosynthetics Stabilizers and Fly Ash for Soil Subgrade Improvement – A State of the Art Review

2021 ◽  
Vol 10 (2) ◽  
pp. 97-104
Author(s):  
Prateek Malik ◽  
Sudipta K Mishra
Keyword(s):  
Fly Ash ◽  
Soil Stabilization ◽  
Soft Soil ◽  
Thermal Power ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Compaction Behavior ◽  
Engineering Problems ◽  
Materials Used ◽  
Properties Of Soil

Soft soil having a low bearing capacity is found in many parts of the world and construction on soft soil is a challenge. To overcome the situation, the soil needs to be stabilized with some external material like geosynthetic, fly ash and rice husk. Geosynthetics materials are tremendous materials used to solve many civil engineering problems. Fly ash is a byproduct produced by burning of coal and is available in various thermal power plant as a waste material. Disposal of fly ash is also a problem but in one area where it can be used is soil stabilization. A comprehensive review of published literature on the use of geosynthetic and fly ash to stabilize and enhance the strength of soil was carried out. The effect of using geosynthetic material and fly ash was investigated on the properties of soil like Optimum Moisture Content, Maximum Dry Density, California bearing ratio, unconfined compressive strength and compaction behavior of the soft soil.

Characterization of Coal Fly Ash for Use in Synthesis of Zeolites

2018 ◽  
Vol 930 ◽  
pp. 578-583
Author(s):  
Augusto César Cavalcanti Gomes ◽  
Andrea de Vasconcelos Ferraz ◽  
Lucimar Pacheco Gomes da Rocha
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Coal Ash ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inorganic Oxides ◽  
Chemical Treatments ◽  
Xrf Scanning ◽  
The Matrix ◽  
Physical And Chemical

Due to the large quantity of fly ash produced during the combustion of coal, it has become necessary to give greater applicability to this residue of low commercial value. The residue contains inorganic oxides which can act on the crystalline structure of zeolites, namely silicon and aluminum oxide. The coal ash was submitted to physical and chemical treatments with the aim of potentiating the silicon and aluminum extraction from the residue. The pure ash and the treated ashes were characterized by: X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR). By means of the carried out characterizations it was observed that the treatments were effective for the extraction of aluminosilicates from the matrix. The treatments did not affect the morphology, the crystalline phases and neither the chemical composition of the ashes. Seeing this, the coal ash and its treatments showed to be a precursor for the synthesis of zeolites.

Analysis of Technical Suitability of Using Wood Ash in Cement Based Materials

2016 ◽  
Vol 881 ◽  
pp. 341-345
Author(s):  
Valeria Bennack ◽  
L.V.O. Dalla Valentina ◽  
Marilena Valadares Folgueras
Keyword(s):  
Natural Resources ◽  
Combustion Process ◽  
Chemical Properties ◽  
Wood Ash ◽  
Wood Product ◽  
X Ray Diffraction ◽  
Waste Wood ◽  
Cement Based Materials ◽  
Materials Used ◽  
Physical And Chemical

Economic and environmental issues are directly related to industrial processes which, not only employ natural resources but also generate by-products that may impact the environment. In order to achieve sustainable development, reducing the use of natural resources and lowering cost through adequate destination of waste becomes a crucial issue. The aim of this paper is to analyze the suitability of reusing waste (wood ash) resulting from the combustion process at wood product industries for manufacturing cement based materials used in civil engineering. The material assessed is ash from the combustion process of a wood product industry. In this study, physical and chemical properties such as grain size, mineral and chemical composition of this by-product were characterized. Thermal analysis and X-ray diffraction techniques were used for this purpose. Preliminary results show the suitability of using the waste (wood ash) for manufacturing cement based materials

Impact assessment of fly ash on ground water quality: An experimental study using batch leaching tests

2018 ◽  
Vol 36 (7) ◽  
pp. 624-634 ◽  
Author(s):  
Rahul Dandautiya ◽  
Ajit Pratap Singh ◽  
Sanghamitra Kundu
Keyword(s):  
Fly Ash ◽  
Thermal Power ◽  
X Ray Diffraction ◽  
Leaching Potential ◽  
Solid Ratio ◽  
Efficient Management ◽  
Iron Nickel ◽  
Copper Zinc ◽  
Contamination Levels ◽  
Titanium Vanadium

The fly ash, generated at the coal-based thermal power plant, is always a cause of concern to environmentalists owing to its adverse impact on air, water and land. There exists a high environmental risk when it is disposed to the environment. Thus, two different type of fly ash samples (FA-1 and FA-2) have been considered in this study to examine the leaching potential of the elements magnesium, aluminium, silicon, calcium, titanium, vanadium, chromium, manganese, iron, nickel, cobalt, copper, zinc, arsenic, selenium, strontium, cadmium, barium and lead for different types of leachant. Toxicity characteristics leaching procedure and ASTM tests have been performed in the laboratory to simulate different natural leaching scenarios. Characterisation of samples have been done through X-ray diffraction and field emission gun scanning electron microscope. The effect of different liquid to solid ratios (i.e. 5, 10, 20 and 50) on the mobilisation of elements has been analysed. The results indicated that the maximum leaching of all elements occurred at a liquid to solid ratio of 5 except for arsenic, barium and silicon. The groundwater analysis has also been done to understand the actual effects of leachate. The elements presenting the highest leachability in the two fly ash samples under all tested conditions were magnesium, aluminium, silicon and calcium. It has been observed that calcium exhibits greater leaching effects than all other constituents. The study presented here has been found very useful for assessing contamination levels in groundwater owing to leaching effects of fly ash under different scenarios, which can be helpful to prevent spreading of the contaminants by efficient management of fly ash.

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