scholarly journals Permeability Tests and Multi-Factor Analysis of Sand-Based Cemented Backfill Five-Component Samples With Different Mix Ratios

2021 ◽  
Author(s):  
Nan Zhou ◽  
Yinan Yao ◽  
Jixiong Zhang ◽  
Hao Yan ◽  
Cunli Zhu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Pore Size ◽  
Surface Structure ◽  
Univariate Analysis ◽  
Confining Pressure ◽  
Reducing Agent ◽  
Aeolian Sand ◽  
Cemented Backfill ◽  
Four Levels ◽  
Set Up

Abstract Extensive coal mining involves the challenge of liberating coal resources under buildings, railways, and water bodies. Sand-based cemented backfill (SCB) mining is considered an effective method to solve this problem while utilizing solid wastes in large quantities. Since the groundwater seeping into SCB pores in a complex mining environment deteriorates the SCB strength and stability, the permeability optimization of SCB samples under multi-factor conditions by adjusting their mix ratios is very topical. Therefore, in this study, a large number of SCB samples were prepared using aeolian sand as aggregates, cement and fly ash as cementing materials, and quicklime and water reducing agent as additives. The mass of the aeolian sand was a fixed value, while other ingredients' content ratios were expressed as a percentage of aeolian sand mass. With all other factors being constant, the level of one factor was changed at a time for univariate analysis. Four levels were set up for each of the four factors, and 16 tests were performed for a total of 13 mix ratios with an axial pressure of 1 MPa and confining pressure of 3 MPa. The effects of mix ratios, pore size, porosity, and surface structure on SCB's permeability were analyzed in detail. Experimental results show variations of quicklime and fly ash contents significantly changed the SCB's permeability, and variations of cement and water reducing agent contents had a minor impact on SCB's permeability. SCB's permeability positively correlated with porosity, primary pore size, and compactness of surface structure. These findings are considered instrumental in improving the SCB waterproof performance.

scholarly journals Coal Fly Ash Derived Silica Nanomaterial for MMMs—Application in CO2/CH4 Separation

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 78
Author(s):  
Marius Gheorghe Miricioiu ◽  
Violeta-Carolina Niculescu ◽  
Constantin Filote ◽  
Maria Simona Raboaca ◽  
Gheorghe Nechifor
Keyword(s):  
Fly Ash ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Coal Fly Ash ◽  
High Surface ◽  
Industrial Applications ◽  
Mixed Matrix Membranes ◽  
Co2 Removal ◽  
Mcm 41

In order to obtained high selective membrane for industrial applications (such as natural gas purification), mixed matrix membranes (MMMs) were developed based on polysulfone as matrix and MCM-41-type silica material (obtained from coal fly ash) as filler. As a consequence, various quantities of filler were used to determine the membranes efficiency on CO2/CH4 separation. The coal fly ash derived silica nanomaterial and the membranes were characterized in terms of thermal stability, homogeneity, and pore size distribution. There were observed similar properties of the obtained nanomaterial with a typical MCM-41 (obtained from commercial silicates), such as high surface area and pore size distribution. The permeability tests highlighted that the synthesized membranes can be applicable for CO2 removal from CH4, due to unnoticeable differences between real and ideal selectivity. Additionally, the membranes showed high resistance to CO2 plasticization, due to permeability decrease even at high feed pressure, up to 16 bar.

scholarly journals Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2653
Author(s):  
Tova Jarnerud ◽  
Andrey V. Karasev ◽  
Pär G. Jönsson
Keyword(s):  
Fly Ash ◽  
Pulp And Paper ◽  
Waste Materials ◽  
Paper Mills ◽  
Steel Mills ◽  
Lime Mud ◽  
Set Up ◽  
Pulp And Paper Industries ◽  
The Given ◽  
Acidic Wastewater

In this study, CaO-containing wastes from pulp and paper industries such as fly ash (FA) and calcined lime mud (LM) were utilized to neutralize and purify acidic wastewaters from the pickling processes in steel mills. The investigations were conducted by laboratory scale trials using four different batches of wastewaters and additions of two types of CaO-containing waste materials. Primary lime (PL), which is usually used for the neutralization, was also tested in the same experimental set up in the sake of comparison. The results show that these secondary lime sources can effectively increase the pH of the acidic wastewaters as good as the commonly used primary lime. Therefore, these secondary lime sources could be potential candidates for application in neutralization processes of industrial acidic wastewater treatment. Moreover, concentrations of metals (such as Cr, Fe, Ni, Mo and Zn) can decrease dramatically after neutralization by using secondary lime. The LM has a purification effect from the given metals, similar to the PL. Application of fly ash and calcined lime mud as neutralizing agents can reduce the amount of waste from pulp and paper mills sent to landfill and decrease the need for nature lime materials in the steel industry.

Effect of Fly Ash on the Mechanical Properties of Cemented Backfill Made with Brine

2018 ◽  
Vol 37 (2) ◽  
pp. 691-705 ◽  
Author(s):  
Bing-qian Yan ◽  
Kouame-Joseph-Arthur Kouame ◽  
Dwayne Tannant ◽  
Wen-sheng Lv ◽  
Mei-feng Cai
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Cemented Backfill

Microstructure of Cement Blends Including Fly Ash, Silica Fume, Slag and Fillers

1986 ◽  
Vol 86 ◽  
Author(s):  
Micheline Regourd
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Silica Fume ◽  
Blended Cement ◽  
Cement Clinker ◽  
Microstructural Development ◽  
Limestone Filler ◽  
Portland Cement Clinker

ABSTRACTThe hydration of a blended cement through hydraulic or pozzolanic reactions results in heterogeneous polyphase materials. Because portland cement clinker is the major component in most cement blends, the microstructural development of portland cement hydrates, including C-S-H and pore structures, is first discussed. Slag, fly ash, silica fume and limestone filler cements are then compared to portland cement with regards to C-S-H morphology and composition, aluminate crystallization, cement paste interfaces and pore size distribution.

scholarly journals Strength Characteristics of High Strength Concrete (HSC) with and without Coarse Aggregate

2019 ◽  
Vol 9 (2) ◽  
pp. 4701-4704
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Mechanical Characteristics ◽  
Coarse Aggregate ◽  
High Strength ◽  
Set Up

This paper aimed to investigate the mechanical characteristics of HSC of M60 concrete adding 25% of fly ash to cement and sand and percentage variations of silica fumes 0%,5% and 10% to cement with varying sizes of 10mm,6mm,2mm and powder of granite aggregate with w/c of 0.32. Specimens are tested for compressive strength using 10cm X 10cmX10cm cubes for 7,14,28 days flexural strength was determined by using 10cmX10cmX50cm beam specimens at 28 days and 15cm diameter and 30cm height cylinder specimens at 28 days using super plasticizers of conplast 430 as a water reducing agent. In this paper the experimental set up is made to study the mechanical properties of HSC with and without coarse aggregate with varying sizes as 10mm, 6mm, 2mm and powder. Similarly, the effect of silica fume on HSC by varying its percentages as 0%, 5% and 10% in the mix studied. For all mixes 25% extra fly ash has been added for cement and sand.

Interaction of external head impact parameters on region and volume of strain for collisions in sport

2018 ◽  
Vol 233 (2) ◽  
pp. 258-267 ◽  
Author(s):  
R Anna Oeur ◽  
Michael D Gilchrist ◽  
Thomas Blaine Hoshizaki
Keyword(s):  
Brain Injuries ◽  
Element Model ◽  
Brain Regions ◽  
Peak Strain ◽  
Centre Of Gravity ◽  
Impact Parameters ◽  
Four Levels ◽  
Set Up ◽  
The Impact ◽  
Strain Responses

Collisions with the head are the primary cause of concussion in contact sports. Head impacts can be further characterized by velocity, striking mass, compliance, and location (direction). The purpose of this study was to describe the interaction effects of these parameters on peak strain in four brain regions and the volume of strain for collision impacts. A pendulum test set-up was used to deliver impacts to an adult Hybrid III headform according to four levels of mass (3, 9, 15, and 21 kg), four velocities (1.5, 3.0, 4.5, and 6.0 m/s), two impact locations (through the centre of gravity and a non-centre of gravity), and three levels of compliance simulating unprotected, helmeted, and well-padded conditions in sport. Headform accelerations were input into a brain finite element model to obtain peak strain in the frontal, temporal, parietal, and occipital lobes and the volume of the brain experiencing 0.10, 0.15, 0.20, and 0.25 strains. Centre-of-gravity impacts created the highest strains (peak and volume) under low compliance and non-centre-of-gravity impacts produced greater strain responses under medium and high compliance conditions. The temporal lobe was the region that consistently displayed the highest peak strains, which may be due to the proximity of the impact locations to this region. Interactions between mass and velocity displayed effects where the 9-kg mass had higher peak and volumes of strain than the 15-kg mass at velocities of 3.0 and 4.5 m/s. This study demonstrates the important role of interacting impact parameters on increasing strain responses that are relevant to the spectrum of diffuse brain injuries, including concussion.

scholarly journals Influential Factors in Transportation and Mechanical Properties of Aeolian Sand-Based Cemented Filling Material

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 116 ◽  
Author(s):  
Nan Zhou ◽  
Haobin Ma ◽  
Shenyang Ouyang ◽  
Deon Germain ◽  
Tao Hou
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Cement Content ◽  
Ash Content ◽  
Influential Factors ◽  
Filling Material ◽  
Aeolian Sand ◽  
Early Hydration ◽  
Filling Materials ◽  
Slag Content

Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed in this study. We used laboratory tests to study how the fly ash (FA) content, cement content, lime–slag (LS) content, and concentration influence the transportation and mechanical properties of aeolian-sand-based cemented filling material. The internal microstructures and distributions of the elements in filled objects for curing times of 3 and 7 days are analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The experimental results show that: (i) the bleeding rate and slump of the filling-material slurry decrease gradually as the fly ash content, cement content, lime–slag content, and concentration increase, (ii) while the mechanical properties of the filled object increase. The optimal proportions for the aeolian sand-based cemented filling material include a concentration of 76%, a fly ash content of 47.5%, a cement content of 12.5%, a lime–slag content of 5%, and an aeolian sand content of 35%. The SEM observations show that the needle/rod-like ettringite (AFt) and amorphous and flocculent tobermorite (C-S-H) gel are the main early hydration products of a filled object with the above specific proportions. After increasing the curing time from 3 to 7 days, the AFt content decreases gradually, while the C-S-H content and the compactness increase.

5 Pottery

1959 ◽  
Vol 16 ◽  
pp. 117-161
Author(s):  
Clarence H. Webb
Keyword(s):  
Original Formulation ◽  
Four Levels ◽  
Set Up ◽  
State Area

The pottery from this site was described and classified in 1941 (Webb and Dodd 1941), on the basis of the sherds found in the four levels of Mound B (Houses 1 to 4), the floors of the adjoining Houses 5 and 6, and the fills between these levels, in addition to whole vessels from the associated Burials 1 through 19 and several of the house floors. This was the first attempt to set up pottery types from an excavated Caddoan site and was necessarily tentative. The classification has been subjected to continuing study and modification on the basis of reports from subsequent excavations and surface surveys in the four-state area.Much of this reclassification has resulted from correspondence and conversations with Alex Krieger as he developed the Texas materials, from the two Caddoan Conferences held at Norman, Oklahoma, in 1946 and 1952, and from several informal conferences with Krieger, Howard, Stephenson, Cotter, Haag, Baerreis, and others interested in the area. James B. Griffin and James A. Ford gave valuable assistance in the original formulation of Belcher types in 1941 and critical suggestions since that time.

Formation of Anodic Oxide Nanotubes in H2O2 - Fluoride Ethylene Glycol Electrolyte as Template for Electrodeposition of α-Fe2O3

2013 ◽  
Vol 832 ◽  
pp. 333-337 ◽  
Author(s):  
Zainovia Lockman ◽  
Dede Miftahul Anwar ◽  
Monna Rozana ◽  
Syahriza Ismail ◽  
Ehsan Ahmadi ◽  
...  
Keyword(s):  
Oxide Film ◽  
Ethylene Glycol ◽  
Pore Size ◽  
Surface Structure ◽  
Anodic Oxidation ◽  
Chloride Solution ◽  
Anodic Oxide ◽  
Nanoporous Structure ◽  
20 Nm

Anodic oxidation of titanium (Ti), zirconium (Zr) and niobium (Nb) foils in fluoride ethylene glycol (EG) added to it 1 H2O2 as oxidant was done to produce oxide film with nanostructures at 40 V. Whilst arrays of aligned nanotubes were successfully formed on the surface of Ti and Zr respectively, anodic Nb2O5 was found to consist of nanoporous structure with pore size of ~ 20 nm. Despite long nanotubes were formed on both Ti (2 μm) and Zr (3 μm), the surface of the nanotubes suffered from severe dissolution, thinning the wall and collapsing them. Well defined, ordered surface structure of the nanotubes is required as they will be used as template for subsequent deposition of nanoparticles. This was achieved when Ti anodised in 5 ml H2O2 fluoride EG. With excess H2O2 etching at the surface occur more uniformly forming homogenous surface structure. α-Fe2O3 were then electrodeposited on this surface at-3 V from chloride solution and the mode of formation is believed to be due to electrogeneration of base at the surface of the TiO2.

Preparation of FGD Gypsum-Fly Ash Plaster Material

2013 ◽  
Vol 327 ◽  
pp. 28-31
Author(s):  
Jiang Zhu ◽  
Guo Zhong Li ◽  
Chuan Wei Du
Keyword(s):  
Fly Ash ◽  
Citric Acid ◽  
Material Properties ◽  
Reducing Agent ◽  
Mass Ratio ◽  
Sodium Metaphosphate ◽  
Fgd Gypsum ◽  
Mix Proportion ◽  
Gypsum Plaster ◽  
Bone Glue

FGD gypsum-fly ash plaster material was prepared by desulfurization gypsum plaster and fly ash as main materials, compound retarder A (composed of citric acid, sodium metaphosphate and borax), methylcellulose (MC) as super absorbent polymers (SAP) and water reducing agent of lignosulfonate. Mix proportion was determined through studying effects of the experimental factors, including fly ash mixing amount, retarders of citric acid, bone glue and compound retarder A, and SAP of MC and dextrin, on plaster material properties. Final mix proportion was followed as: FGD gypsum to fly ash mass ratio of 4.0, compound retarder of 0.2%, methylcellulose of 0.2% and lignosulfonate of 0.1%.

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