scholarly journals Cement-Stabilized Waste Sand as Sustainable Construction Materials for Foundations and Highway Roads

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 600 ◽  
Author(s):  
Faisal Shalabi ◽  
Javed Mazher ◽  
Kaffayatullah Khan ◽  
Mohammed Alsuliman ◽  
Ibrahim Almustafa ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Laser Scanning ◽  
Cement Content ◽  
Construction Material ◽  
Laser Scanning Microscopy ◽  
Tangent Modulus ◽  
Sustainable Construction ◽  
Dry Density ◽  
X Ray ◽  
Initial Tangent Modulus

In this study, cement-treated waste sand as a by-product material produced from Al-Ahsa quarries (Saudi Arabia) was experimentally tested and investigated as a base course material for the foundation of structures and roads. The study aimed to use the waste sand as a construction material by improving its strength, bearing capacity, and stiffness. The waste sand was mixed with different percentages of Portland cement content (0, 2, 4, 6, and 8%) at the maximum dry density and optimum water content of the standard Proctor compaction conditions of a non-treated sample. Unconfined compressive strength and California Bearing Ratio (CBR) tests for different curing times were conducted. X-ray diffraction (XRD), laser-scanning microscopy (LSM), and X-ray spectroscopy (XPS) were used to explore the microstructure and composition of the treated sand. The results showed that the compressive strength, initial tangent modulus, and CBR of the treated sand increase with the increase in cement content and curing time. Furthermore, good correlations were established among the strength, initial tangent modulus, and CBR. Based on the obtained results, cement-stabilized waste sand is a potential material for use in construction. This is expected to save the environment and reduce the cost of road construction.

scholarly journals Investigation of Spin Coating Cerium-Doped Hydroxyapatite Thin Films with Antifungal Properties

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 464
Author(s):  
Simona Liliana Iconaru ◽  
Mihai Valentin Predoi ◽  
Patrick Chapon ◽  
Sofia Gaiaschi ◽  
Krzysztof Rokosz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Spin Coating ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
X Ray ◽  
Antifungal Properties ◽  
Scanning Electron

In this study, the cerium-doped hydroxyapatite (Ca10−xCex(PO4)6(OH)2 with xCe = 0.1, 10Ce-HAp) coatings obtained by the spin coating method were presented for the first time. The stability of the 10Ce-HAp suspension particles used in the preparation of coatings was evaluated by ultrasonic studies, transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The surface morphology of the 10Ce-HAp coating was studied by SEM and atomic force microscopy (AFM) techniques. The obtained 10Ce-HAp coatings were uniform and without cracks or unevenness. Glow discharge optical emission spectroscopy (GDOES) and X-ray photoelectron spectroscopy (XPS) were used for the investigation of fine chemical depth profiling. The antifungal properties of the HAp and 10Ce-HAp suspensions and coatings were assessed using Candida albicans ATCC 10231 (C. albicans) fungal strain. The quantitative antifungal assays demonstrated that both 10Ce-HAp suspensions and coatings exhibited strong antifungal properties and that they successfully inhibited the development and adherence of C. albicans fungal cells for all the tested time intervals. The scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) visualization of the C. albicans fungal cells adherence to the 10Ce-HAp surface also demonstrated their strong inhibitory effects. In addition, the qualitative assays also suggested that the 10Ce-HAp coatings successfully stopped the biofilm formation.

scholarly journals Influence of Salt Support Structures on Material Jetted Aluminum Parts

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4072
Author(s):  
Benedikt Kirchebner ◽  
Maximilian Ploetz ◽  
Christoph Rehekampff ◽  
Philipp Lechner ◽  
Wolfram Volk
Keyword(s):  
Molten Salts ◽  
Laser Scanning ◽  
Water Soluble ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Support Structures ◽  
Micro Hardness ◽  
X Ray ◽  
Melting Temperatures ◽  
Economic Support

Like most additive manufacturing processes for metals, material jetting processes require support structures in order to attain full 3D capability. The support structures have to be removed in subsequent operations, which increases costs and slows down the manufacturing process. One approach to this issue is the use of water-soluble support structures made from salts that allow a fast and economic support removal. In this paper, we analyze the influence of salt support structures on material jetted aluminum parts. The salt is applied in its molten state, and because molten salts are typically corrosive substances, it is important to investigate the interaction between support and build material. Other characteristic properties of salts are high melting temperatures and low thermal conductivity, which could potentially lead to remelting of already printed structures and might influence the microstructure of aluminum that is printed on top of the salt due to low cooling rates. Three different sample geometries have been examined using optical microscopy, confocal laser scanning microscopy, energy-dispersive X-ray spectroscopy and micro-hardness testing. The results indicate that there is no distinct influence on the process with respect to remelting, micro-hardness and chemical reactions. However, a larger dendrite arm spacing is observed in aluminum that is printed on salt.

scholarly journals Utilization of Sugarcane Bagasse Ash from Power Co-generation Boilers as a Supplementary Cementitious Material

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Safiki Ainomugisha ◽  
Bisaso Edwin ◽  
Bazairwe Annet
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Sugarcane Bagasse ◽  
Low Income ◽  
Ordinary Portland Cement ◽  
Construction Material ◽  
Sustainable Construction ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Sugarcane Bagasse Ash

Concrete has been the world’s most consumed construction material, with over 10 billion tons of concrete annually. This is mainly due to its excellent mechanical and durability properties plus high mouldability. However, one of its major constituents; Ordinary Portland Cement is reported to be expensive and unaffordable by most low-income earners. Its production contributes about 5%–8% of global CO2 greenhouse emissions. This is most likely to increase exponentially with the demand of Ordinary Portland Cement estimated to rise by 200%, reaching 6000 million tons/year by 2050.  Therefore, different countries are aiming at finding alternative sustainable construction materials that are more affordable and offer greener options reducing reliance on non-renewable sources. Therefore, this study aimed at assessing the possibility of utilizing sugarcane bagasse ash from co-generation in sugar factories as supplementary material in concrete. Physical and chemical properties of this sugarcane bagasse ash were obtained plus physical and mechanical properties of fresh and hardened concrete made with partial replacement of Ordinary Portland Cement. Cost-benefit analysis of concrete was also assessed. The study was carried using 63 concrete cubes of size 150cm3 with water absorption studied as per BS 1881-122; slump test to BS 1881-102; and compressive strength and density of concrete according to BS 1881-116. The cement binder was replaced with sugarcane bagasse ash 0%, 5%, 10%, 15%, 20%, 25% and 30% by proportion of weight. Results showed the bulk density of sugarcane bagasse ash at 474.33kg/m3, the specific gravity of 1.81, and 65% of bagasse ash has a particle size of less than 0.28mm. Chemically, sugarcane bagasse ash contained SiO2, Fe2O3, and Al2O3 at 63.59%, 3.39%, and 5.66% respectively. A 10% replacement of cement gave optimum compressive strength of 26.17MPa. This 10% replacement demonstrated a cost saving of 5.65% compared with conventional concrete. 

scholarly journals ANALYSIS INFLUENCE OF CEMENT OF THE ASPHALT PAVEMENT DEMOLITION MATERIAL ON ROADS SEMARANG-DEMAK-INDONESIA

2017 ◽  
pp. 73-78
Author(s):  
P. Pratikso ◽  
A. Purwanto ◽  
S. Sudarno
Keyword(s):  
Compressive Strength ◽  
Technology Development ◽  
Cement Content ◽  
Asphalt Pavement ◽  
Construction Material ◽  
Road Construction ◽  
Dry Weight ◽  
Natural Material ◽  
Road Infrastructure ◽  
Asphalt Cement

Natural resources such as natural material such as stone, sand, asphalt which has long been used by humans for road construction because of the limited experience any material taken will collide with the preservation of the environment so that the construction work of road infrastructure obstacles and ultimately can lead to the work stalled road infrastructure. To overcome these problems it is necessary to the implementation of the technology development of road infrastructure by using recycled (recycling). The purpose of this study is to determine levels of cement that can be used for the top layer foundation (base course) with recycled materials mixed asphalt cement / Cement Treated Recycling Base (CTRB) on road rehabilitation Semarang - Demak and to determine the uncondifined compressive strength that occurs so that the material can be reused as construction material pavement layer. This study uses an experimental method in the laboratory with a cylindrical specimen diameter of 7 cm height of 14 cm made of asphalt pavement scratching Semarang-Demak roads with cement content variation 0%, 1.5%, 3%, 4.5%, 6% and 7.5% is used for testing the uncondifined compressive strength / (UCS) at the age of 7 days, 21 days, 14 days and 28 days. The results show that the addition of cement content will increase the value of the dry weight insignificantly, but will rise UCS value significantly and utilization of scratching asphalt cement with added material from these laboratory experiments can increase the carrying capacity CTRB construction. Levels of cement that meets the requirements of Unconfined Compressive Strength (UCS) for the construction of Cement Treated Recycling Base (CTRB) is between 6% to 7.5%. According to the results of research it is economically to used cement content at average of 6.75% for road rehabilitation works Semarang - Demak has met the required UCS test.

Microcontact Printed Protein Micropatterns on Titanium Surface Characterized by Confocal Laser Scanning Microscopy

2012 ◽  
Vol 487 ◽  
pp. 730-734 ◽  
Author(s):  
Chang Jiang Pan ◽  
Yu Dong Nie ◽  
Yun Xiao Dong
Keyword(s):  
Laser Scanning ◽  
Photoelectron Spectrum ◽  
Titanium Surface ◽  
Microcontact Printing ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Water Contact ◽  
X Ray ◽  
Replication Errors ◽  
Titanium Surfaces

In this paper, two kinds of stamps (squares (a×a)) separated by spacing b, the values of a and b were varied from 2.5 µm to 50 µm), i.e. positive and negative stamps, were prepared. The stamps inked with the rhodamine-labeled bovine serum albumin (BSA) were then microcontacted with the aldehyde-functionalized titanium surfaces. Water contact angle and X-ray photoelectron spectrum (XPS) indicated that BSA can be covalently immobilized on aldehyde modified titanium surface by microcontact printing. The experimental results of CLSM showed that the patterns with resolution from 2.5 µm to 50 µm were obtained successfully. Both positive stamp and negative stamp were deformed when the value of a was less than or equal to 5 µm, which resulted in replication errors. Furthermore, the larger spacing (50 µm) resulted in stamp collapse when the value a of the positive stamp was less than or equal to 10 µm, leading to whole fluorescence on substrates.

Experimental Study on the Axial Compressive Strength and Elastic Modulus of GHPFRCC

2013 ◽  
Vol 357-360 ◽  
pp. 1138-1141 ◽  
Author(s):  
Xiu Ling Li ◽  
Wang Juan
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
High Performance ◽  
Construction Material ◽  
Structure Design ◽  
Sustainable Construction ◽  
High Performance Fiber ◽  
Maintenance Decisions ◽  
Axial Compressive Strength ◽  
Pva Fiber

The sustainability of the construction material is increasingly coming to the forefront of the structure design and maintenance decisions. To address this, development of a new class of more sustainable construction material is needed, especially in China. This paper reports on the development of the green high-performance fiber-reinforced cementitious composites (GHPFRCC) with high volumes of fly ash and PVA fiber, and emphasizes the axial compressive strength and elastic modulus of GHPFRCC. Experimental results show that the prism axial compressive strength of GHPFRCC ranges from 15MPa to 40MPa. The elastic modulus of GHPFRCC is around 16-35GPa, typically lower than concrete.

scholarly journals Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms

2003 ◽  
Vol 69 (9) ◽  
pp. 5543-5554 ◽  
Author(s):  
J. R. Lawrence ◽  
G. D. W. Swerhone ◽  
G. G. Leppard ◽  
T. Araki ◽  
X. Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Laser Scanning ◽  
Heterotrophic Bacteria ◽  
Molecular Probes ◽  
Laser Scanning Microscopy ◽  
Biochemical Basis ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

ABSTRACT Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provided the highest-resolution structural imaging, CLSM provided detailed compositional information when used in conjunction with molecular probes, and STXM provided compositional mapping of macromolecule distributions without the addition of probes. By examining exactly the same region of a sample with combinations of these techniques (STXM with CLSM and STXM with TEM), we demonstrate that this combination of multimicroscopy analysis can be used to create a detailed correlative map of biofilm structure and composition. We are using these correlative techniques to improve our understanding of the biochemical basis for biofilm organization and to assist studies intended to investigate and optimize biofilms for environmental remediation applications.

scholarly journals The Time Effect and Micromechanism of the Unconfined Compressive Strength of Cement Modified Slurries

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Ping Jiang ◽  
Yewen Chen ◽  
Lin Zhou ◽  
Tianhao Mao ◽  
Wei Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Cement Content ◽  
Raw Materials ◽  
Time Effect ◽  
Test Results ◽  
X Ray ◽  
Strength Change ◽  
Effect Model ◽  
Curing Age

This study investigated the unconfined compressive strength change law of cement modified slurries (CMS) under different curing ages. We conducted unconfined compressive strength tests using slurry and cement as raw materials. The cement contents were 5%, 10%, 15%, 20%, and 25%. The curing ages were 7, 14, 28, 56, 90, 120, 150, and 180 d. A time effect model of CMS strength was established based on the measured UCS strength-curing age and the strength-cement content curves. The test results proved that the UCS of the CMS increased significantly with an increase in the curing age, and after 90 days, the UCS gradually increased to a fixed value. The time effect model better characterized the relationship between the UCS of the CMS and the curing age and the cement content, as the predicted value had a high correlation with the measured value. We conducted scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) tests to analyze the microstructure and chemical composition of the CMS. The microscopic test results demonstrated that the increase of cement content and curing age increased the amount of gelling substances in the CMS and made the overall structure more compact, thereby increasing its macro strength.

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