scholarly journals Improvement of Pavement Subgrade by Adding Cement and Fly Ash to Natural Desert Sand

2021 ◽  
Vol 6 (11) ◽  
pp. 151
Author(s):  
Talal S. Amhadi ◽  
Gabriel J. Assaf
Keyword(s):  
Fly Ash ◽  
Shear Failure ◽  
Poor Quality ◽  
Fine Aggregate ◽  
Lateral Shear ◽  
X Ray ◽  
Pavement Distress ◽  
Manufactured Sand ◽  
Desert Sand

Soil characteristics are paramount to design pavements and to assess the economic viability of a road. In the desert, such as that found in southern Libya, the very poor quality of soils leads to important pavement distress such as cracks, rutting, potholes, and lateral shear failure on the edges. To improve the strength of desert sand, an innovative approach is proposed, consisting of adding manufactured sand, ordinary Portland cement (OPC), and fly ash (FA) as a binder. OPC and FA improve the characteristics of mixes of crushed fine aggregate (CFA) and natural desert sand (NDS). These results are based on a gradation of two sand sources to determine the particle distribution and X-ray fluorescence (XRF) to determine their chemical and physical properties, respectively. This research assesses the effect of cement and fly ash on the geotechnical behavior of two mixtures of fine desert and manufactured sands (30:70% and 50:50%). The mix composed of 26% of CFA, 62% of NDS, 5% of OPC, and 7% of FA shows optimal results in terms of strength, compaction, and bearing capacity characteristics.

scholarly journals Recycling and Application of Mine Tailings in Alkali-Activated Cements and Mortars—Strength Development and Environmental Assessment

2020 ◽  
Vol 10 (6) ◽  
pp. 2084 ◽  
Author(s):  
Nuno Cristelo ◽  
João Coelho ◽  
Mafalda Oliveira ◽  
Nilo Cesar Consoli ◽  
Ángel Palomo ◽  
...  
Keyword(s):  
Mine Tailings ◽  
Sodium Intake ◽  
Sodium Sulphate ◽  
Strength Development ◽  
Strength Increase ◽  
Fine Aggregate ◽  
Reaction Products ◽  
X Ray ◽  
Alkali Activated

Mine tailings (MT) could represent a step forward in terms of the quality of the aggregates usually used in civil engineering applications, mostly due to its high density. The Portuguese Neves Corvo copper mine, owned by the Lundin Mining Corporation, produces approximately 3 million tonnes per year. Nevertheless, it cannot be used in its original state, due to its high levels of sulphur and other metals (As, Cr, Cu, Pb, Zn). This paper focuses on the stabilisation/solidification of high-sulphur MT, without any previous thermal treatment, using alkali-activated fly ash (FA). The variables considered were the MT/FA ratio and the activator type and concentration. A fine aggregate was then added to the pastes to assess the quality of the resulting mortar. Maximum compressive strengths of 14 MPa and 24 MPa were obtained for the pastes and mortars, respectively, after curing for 24 h at 85 °C. Thermogravimetric analysis, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction, and infrared spectroscopy were used to characterize the reaction products, and two types of leaching tests were performed to assess the environmental performance. The results showed that the strength increase is related with the formation of a N-A-S-H gel, although sodium sulphate carbonate was also developed, suggesting that the total sodium intake could be optimized without strength loss. The solubility of the analysed metals in the paste with 78% MT and 22% FA was below the threshold for non-hazardous waste.

CONSTRUCTION PLACEMENT AND HARDENED PROPERTIES OF SHOTCRETE WITH HIGHLY FUNCTIONAL FLY ASH

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2472-2477
Author(s):  
KUNIHIRO YUNO ◽  
MITSUHIRO ISHII ◽  
CHIKANORI HASHIMOTO ◽  
HIROYUKI MIZUGUCHI
Keyword(s):  
Fly Ash ◽  
Construction Projects ◽  
Power Plants ◽  
Fine Particles ◽  
Coal Ash ◽  
Fine Aggregate ◽  
Road Tunnel ◽  
Engineering Structures ◽  
Hardened Properties

Shikoku Electric Power Co., Inc. has developed the technology to manufacture a brand name "Finash" about 12 years ago, by sorting and classifying coal ash generated in coal fired power plants. "Finash" is highly functional fly ash (HFA) is produced by removing irregular coarse particles. It is important for the production of HFA to minimize the variation in quality of coal ash with sophisticated classification technique and extracting good-quality spherical fine particles. It is now widely utilized as concrete admixture for general civil engineering structures and buildings in Japan. When highly functional fly ash (HFA) is used as shotcrete admixture to substitute for fine aggregate of 100kg/m3, the shotcrete has the advantages of decreasing the amount of dust and rebound during spraying operation, improving the hardened properties of concrete, etc. Therefore, it has been applied in many tunnel construction projects. This paper discusses about the various characteristics such as construction placement, strength, neutralization and dry shrinkage of shotcrete using highly functional fly ash (HFA), using the results that is obtained from spray test in an actual road tunnel.

scholarly journals Mechanical and Microstructural Properties of Copper Slag Based Blended Geopolymer Concrete

2021 ◽  
Author(s):  
Vijayasarathy RATHANASALAM ◽  
Jayabalan PERUMALSAMI ◽  
Karthikeyan JAYAKUMAR
Keyword(s):  
Fly Ash ◽  
Mechanical Characterization ◽  
Copper Slag ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulated Blast Furnace Slag ◽  
Mechanical And Microstructural Properties ◽  
Furnace Slag

This work presents a novel way to examine the characteristics of fly ash, copper slag (CPS) along with the addition of Ultrafine Ground Granulated Blast Furnace Slag (UFGGBFS) based Geopolymer Concrete (GPC) for various molarities (10M, 12M and 14M). In GPC, fly ash was replaced with UFGGBFS (5 %, 10 % and 15 %) and copper slag was used as fine aggregate. Mechanical Characterization such as split tensile, flexural strength, workability and water absorption were conducted . GPC characterization and microstructural behaviour was studied  by examining X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). From experimental results this study concludes that with a rise in molarity of GPC, along with incorporation of UFGGBFS, improved the performance, densification and strength of GPC.

scholarly journals Studies on manufactured sand effect on mechanical properties of geopolymer concrete as replacement of river sand in fine aggregate

2021 ◽  
Vol 309 ◽  
pp. 01114
Author(s):  
K. Veera Babu ◽  
T. Srinivas ◽  
Mahathi Tummala
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Material ◽  
Environmental Concerns ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Low Calcium

Concrete is the most adaptable, long-lasting, and dependable construction material on the planet. There are numerous environmental concerns associated with the production of OPC, and natural sand is becoming more expensive and scarce as a result of unlawful river sand dredging. The greatest replacement material for traditional concrete is geopolymer concrete with low calcium fly ash. The purpose of this paper is to investigate the mechanical properties of geopolymer concrete of grades G30 and G50, which are equivalent to M30 and M50, when river sand is substituted in various quantities with manufactured sand, such as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. When compared to the equivalent grades of controlled concrete, geopolymer concrete improves mechanical properties such as compressive, tensile, and flexural strengths.

Theoretical insight into the disordered structure of (Z)-2-[(E)-(4-methoxybenzylidene)hydrazinylidene]-1,2-diphenylethanone: the role of noncovalent interactions

2018 ◽  
Vol 74 (9) ◽  
pp. 1058-1067
Author(s):  
Xue-Jie Tan ◽  
Di Wang ◽  
Xu-Gang Lei ◽  
Jun-Peng Chen
Keyword(s):  
Room Temperature ◽  
Noncovalent Interactions ◽  
Poor Quality ◽  
X Ray ◽  
Disordered Structure ◽  
Theoretical Insight ◽  
Insight Into ◽  
Shed Light

A global glide disorder has been discovered during an X-ray investigation of the crystal structure of (Z)-2-[(E)-(4-methoxybenzylidene)hydrazinylidene]-1,2-diphenylethanone (MHDE, C22H18N2O2) at room temperature. In another crystal, however, such disorder disappears (still at room temperature). Even though the disorder may be partly due to the poor quality of the harvested crystal, the structure can shed light on the nature of disorder. With the help of quantum chemical calculations, it is found that the global disorder seems to be connected with the need for stabilization of the somewhat rigid but mobile and unstable molecular structure. The most relevant feature driving the packing of the disordered structure concerns the slight perturbations (such as glide) of two or more disorder components (fractional occupancies) distributed throughout the crystal.

scholarly journals Assessment of the Quality of Diesel Fuel from Some Selected Filling Stations in Tarkwa, Ghana

2020 ◽  
Vol 4 (4) ◽  
pp. 1-6
Author(s):  
Broni-Bediako E
Keyword(s):  
Diesel Fuel ◽  
Poor Quality ◽  
Sulphur Content ◽  
Fuel Quality ◽  
X Ray ◽  
American Standard ◽  
The Government ◽  
Fluorescence Spectrometer ◽  
Near Future

Automobile fuel quality is becoming a subject of concern across the world and particularly in Ghana because of potential problems associated with poor quality fuel. Poor quality fuel leads to health and environmental problems, reduced performance and lifetime of engine and other components of an automobile. This paper presents the assessment of the quality of diesel fuel from selected filling stations in Tarkwa. Fifteen fuel samples were collected from Reseller Outlets (Gao Gao), Local Oil Marketing Companies (LOMCs) and International Oil Marketing Companies (IOMCs). Density, flashpoint and sulphur content of the sampled fuels were examined in the laboratory using hydrometer, Cleveland closed cup flash point tester and energy dispersive x-ray fluorescence spectrometer respectively. All the tests were conducted based on the American Standard for Testing Materials (ASTM) and the results were compared with the requirements of Ghana Standards Authority (GSA). The results from the tests indicated variations in the fuel properties among all the oil marketing companies. All the samples tested were found to be within the required density limit set by GSA. Also, about 81% of the fuels had the flashpoint within the required limit. In general, all the diesel samples had high sulphur content above the GSA limit of 0.005 wt% (50 ppm). It is recommended that; the Government of Ghana should ensure that all oil marketing companies operate within the acceptable sulphur content limit in Ghana and should also consider reducing the acceptable sulphur content to meet international standard in the near future.

scholarly journals Matta’s criteria may be useful for evaluating and predicting the reduction quality of simultaneous acetabular and ipsilateral pelvic ring fractures

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yi-Hsun Yu ◽  
Chang-Heng Liu ◽  
Yung-Heng Hsu ◽  
Ying-Chao Chou ◽  
I-Jung Chen ◽  
...  
Keyword(s):  
Acetabular Fracture ◽  
Pelvic Ring ◽  
Univariate Analysis ◽  
Poor Quality ◽  
Fracture Reduction ◽  
Acetabular Fractures ◽  
X Rays ◽  
X Ray ◽  
Pelvic Ring Fractures

Abstract Background Although the incidence, types, and radiological outcomes of simultaneous ipsilateral pelvic ring and acetabular fractures have been reported, there have been no reports on factors that may affect the quality of acetabular fracture reduction. Here, we evaluate the radiological outcomes of patients treated for simultaneous ipsilateral pelvic and acetabular fractures and analyze the factors that affect the quality of acetabular fracture reduction. Methods We conducted a retrospective review of patients treated for simultaneous ipsilateral pelvic ring and acetabular fractures between 2016 and 2020. Factors that may predict inadequate reduction of the acetabular fracture were analyzed. Results Data from 27 hips of 26 patients were collected. AO B2.2 and anterior columnar fractures were the most common types of pelvic ring and acetabular fractures, respectively. Univariate analysis revealed that Matta’s criteria for pelvic ring fracture may be useful for predicting fair to poor quality of acetabular fracture reduction on X-rays. Furthermore, associated fractures identified by Letournel’s classification system on computed tomography may be predictive of greater step-offs. Conclusions Associated fractures identified via Letournel’s classification may contribute to inadequate reduction of acetabular fractures. Matta’s criteria for pelvic ring fractures may also be useful for predicting the risk of inadequate reduction of the acetabulum on X-ray scans. These findings may be assessed intraoperatively by fluoroscopy before beginning osteosynthesis for acetabular fractures.

Study on Application of Artificial Sand in Ready-Mixed Concrete

2013 ◽  
Vol 800 ◽  
pp. 40-43
Author(s):  
Jian Mei Zhou
Keyword(s):  
Fresh Concrete ◽  
Clay Content ◽  
Poor Quality ◽  
Fine Aggregate ◽  
Natural Sand ◽  
The Poor ◽  
Concrete Property ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

Artificial sand can be obtained by mixing washed sand formed from the the poor quality of natural sand with high clay content and stone powder formed from processing and screening production by appropriate ratio, Which be applied to C20~C35 ready-mixed concrete. By studying the effect the artificial sand on the properties of fresh concrete and concrete after hardening, the result showed that artificial sand substitute for natural sand as ready-mixed concrete fine aggregate is entirely feasible. Key words: Artificial sand, Ready-mixed concrete, Property

Design of Photon Beam Vibration Measurement System for the CLS HXMA Beamline

2010 ◽  
Author(s):  
J. W. Li ◽  
X. B. Chen ◽  
E. Matias ◽  
W. J. Zhang
Keyword(s):  
Measurement System ◽  
Vibration Isolation ◽  
Poor Quality ◽  
Vibration Measurement ◽  
Beam Size ◽  
Photon Beams ◽  
Detailed Design ◽  
Beam Vibration ◽  
X Ray

At synchrotron radiation facilities vibration is often a problem causing poor quality of photon beams. At the Canadian Light Source (CLS) Hard X-ray MicroAnalysis (HXMA) beamline, the MicroProbe endstation is particularly sensitive to vibrations since very small beam size (∼ 3μm × 5μm) is required. Thus, a measurement system is desired to investigate vibrations of the X-ray beam at HXMA beamline. This paper presents a design of such a X-ray beam vibration measurement system. The system consists of two sub-systems: (a) measurement system and (b) vibration-isolation platform. Mathematical models are developed and detailed design is conducted. The design is numerically investigated and it shows very promising results.

scholarly journals Full crystal structure, hydrogen bonding and spectroscopic, mechanical and thermodynamic properties of mineral uranopilite

RSC Advances ◽  
2020 ◽  
Vol 10 (53) ◽  
pp. 31947-31960 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Vicente Timón ◽  
Jiří Čejka
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Thermodynamic Properties ◽  
Poor Quality ◽  
X Ray Diffraction ◽  
Uranyl Sulfate ◽  
X Ray ◽  
The Poor

The determination of the full crystal structure of the uranyl sulfate mineral uranopilite, including the positions of the H atoms in the corresponding unit cell, has not been feasible to date due to the poor quality of its X-ray diffraction pattern.

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