scholarly journals Failure Mechanisms of Structural Bamboo Using Microstructural Analyses

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Mutaz K. Chahrour ◽  
Md. Akter Hosen ◽  
Yingxin Goh ◽  
Teong Yen Tong ◽  
Soon Poh Yap ◽  
...  
Keyword(s):  
Cell Walls ◽  
Structural Characteristics ◽  
Microstructural Analysis ◽  
Experimental Studies ◽  
Construction Materials ◽  
Parenchyma Cell ◽  
Tensile Modulus ◽  
Constructional Material ◽  
Positive Message ◽  
Direct Tensile

Bamboo is deemed an emerging constructional material with promising application projections due to the reliable natural properties and advantageous structural characteristics. However, there is a lack of systematic studies on the mechanical characteristics of the bamboo species from a microstructural scale. Hence, this paper investigated the primary mechanical properties of the bamboo specimens (Dendrocalamus asper) with further microstructural analysis on the bamboo failure. The direct tensile strength of bamboo specimens was about 226.45 MPa, while the final splitting tensile modulus was found to be 2.88 MPa. Microstructural characterisation of the failed tensile specimens indicates that fibre debonding is the main failure mechanism under tensile conditions. On the other hand, splitting and end bearing failure were found on compression test specimens. In addition, nanoindentation tests were carried out on different cell structures to articulate the hardness and Young’s modulus. The elastic modulus of the fibre cell walls is three times that of the parenchyma cell walls, yet the hardness values are comparable. This confirms that the specimen failure of previous macromechanical testing is due to crack propagation along the parenchyma cells, instead of the cell walls. Based on the experimental studies discussed in this paper, the conclusion can convey a positive message regarding the ability of bamboo as a primary sustainable substitute for conventional construction materials.

CREDO RADON UA – INFORMATION MODEL FOR CALCULATION OF ROAD CONSTRACTION

2019 ◽  
pp. 34-42
Author(s):  
Volodymyr Karedin ◽  
Nadiya Pavlenko
Keyword(s):  
Design Process ◽  
Static Loading ◽  
Computer Aided Design ◽  
Experimental Studies ◽  
Construction Materials ◽  
Residual Deformation ◽  
Road Construction ◽  
Information Support ◽  
Existing Structures ◽  
Road Pavement

CREDO RADON UA software provides an automated calculation of the strength of the pavement structures of non-rigid and rigid types, as well as the calculation of the strengthening of existing structures. In the article, one can see the main features and functionality of the CREDO RADON UA software, the main points in the calculations according to the new regulations. Information support of the design process includes necessary databases, informational and helping materials that make up the full support of the pavement design process. The concept of CREDO RADON UA 1.0 software is made on the use of elasticity theory methods in calculations of initial information models of pavements. Performing optimization calculations, the roadwear in CREDO RADON UA is designed in such a way that no unacceptable residual deformation occurs under the influence of short-term dynamic or static loading in the working layer of the earth bed and in the structural layers during the lifetime of the structure. The calculation algorithms were made in accordance with the current regulatory documents of Ukraine. CREDO RADON UA software allows user to create information bases on road construction materials and vehicles as part of the traffic flow for calculations. The presented system of automated modeling makes it easier for the customer to control the quality of design solutions, to reasonably assign designs to layers of reinforcement, to quickly make comparisons of calculations of different designs for the optimal use of allocated funds. Prospects for further improvement of the program should be the results of theoretical and experimental studies on filling the databases, which are used as information support for automated design of road structures. Keywords: CREDO RADON UA, road, computer-aided design, repair project, road pavement, strengthening, construction, rigid pavement, elasticity module, a transport stream, calculation method, information support, dynamic or static loading.

scholarly journals Waste-Based One-Part Alkali Activated Materials

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2911
Author(s):  
Margarida Gonçalves ◽  
Inês Silveirinha Vilarinho ◽  
Marinélia Capela ◽  
Ana Caetano ◽  
Rui Miguel Novais ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Sodium Metasilicate ◽  
High Compressive Strength ◽  
Hardened State ◽  
First Time ◽  
Furnace Slag ◽  
Alkali Activated

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

MICROSTRUCTURE ANALYSIS OF MOSO BAMBOO (Phyllostachys pubescens MAZEL) SURFACE AFTER UV RADIATION

2019 ◽  
Vol 27 (01) ◽  
pp. 1950090
Author(s):  
HAIXIA YU ◽  
XIN PAN ◽  
WEIMING YANG ◽  
WENFU ZHANG ◽  
XIAOWEI ZHUANG
Keyword(s):  
Uv Radiation ◽  
Cell Walls ◽  
Uv Light ◽  
Parenchyma Cell ◽  
Moso Bamboo ◽  
Thick Wall ◽  
Phyllostachys Pubescens ◽  
Thin Wall ◽  
Intercellular Spaces ◽  
Parenchyma Cell Walls

Bamboo material is widely used in outdoor applications. However, they are easily degraded when exposed to sunlight, their smooth surface will gradually turn to rough, and small cracks will appear and finally develop to large cracks. The paper presents a first-time investigation on the microstructure changes in the tangential section of Moso bamboo (Phyllostachys pubescens Mazel) radiated by artificial UV light. The results showed that the cracks mainly appeared at intercellular spaces of fibers where lignin content was high, the parenchyma cell walls and neighbor pits where the cell wall was very thin and more vulnerable than the other parts. In addition, the part of raised area and pit cavity tended to absorb more UV light radiation and showed more and larger cracks than the otherwhere. Cracks at the intercellular spaces of fibers were larger and bigger than those on the parenchyma cell walls. The cracks on the pits of the parenchyma cell walls normally appeared at one pit and then extended to the several surrounding pits. Bordered pits cavity showed more and larger cracks than the pits on the thin wall cells. The simple pits on the thick wall cells and the fiber cells were unaffected by UV radiation.

Extraction and analysis of polysaccharides from tissues of Retama monosperma branches

2020 ◽  
Vol 9 (5) ◽  
pp. 214-221
Author(s):  
H. Bokhari-Taieb Brahimi ◽  
D. E. Aizi ◽  
A. Bouhafsoun ◽  
K. Hachem ◽  
R. Mezemaze ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Biochemical Analysis ◽  
Colorimetric Assay ◽  
Structural Characteristics ◽  
Water Extract ◽  
Uronic Acids ◽  
Symbiotic Associations ◽  
Physical Chemical ◽  
Retama Monosperma

Retama monosperma is a fabaceous shrub that colonizes dune sands owing to its particularly important root system at depth and on the surface. It establishes symbiotic associations with rhizobia and thus plays a role in the bio -fertilization of soils. The stem fibers of R. monosperma are an interesting material for industry because of their useful biometric, physical, chemical and structural characteristics. The aim of this study was to complete these data with a biochemical analysis of the cell walls tissues of adult branches of R. monosperma. Cellulose, hemicelluloses and pectins were extracted from cell wall. The weight dosage indicated that cellulose remained the major component of the wall (56% from the crude cell wall and 52% from the delignified cell wall) ahead of hemicelluloses (16% from the crude cell wall and 14% from the delignified cell wall) and pectins (5.6% from the crude cell wall and 5% from the delignified cell wall for water extract pectins and 3% from the crude cell wall and 2.4% from the delignified cell wall for oxalate extract pectins). The colorimetric assay of pectins extracted from lignified cell wall of R. monosperma suggested presence of more uronic acids (14.95µg/mL) than pectins extracted from a delignified cell wall (12.37 µg/mL). Gas chromatographic analysis of hemicellulosic extracts showed the presence of xylose as the major ose (54.7% from the crude cell wall and 46.7% from the delignified cell wall). Pectins were represented by homogalacturonan chains and rhamnogalacturonans 1. Data generated in this study are helpful for valorization of this plant.

scholarly journals DEFORMATION MONITORING OF RETROFITTED SHORT CONCRETE COLUMNS WITH LASER SENSOR

2016 ◽  
Vol XLI-B5 ◽  
pp. 765-769
Author(s):  
E. Ö. Avsar ◽  
M. F. Celik ◽  
E. Binbir ◽  
A. E. Arslan ◽  
D. Çokkeçeci ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Reference Sample ◽  
Experimental Studies ◽  
Construction Materials ◽  
Mechanical Tests ◽  
Deformation Monitoring ◽  
Laser Sensor ◽  
Scanning Method ◽  
Compression Load ◽  
Short Columns

This paper presents one of the applications of monitoring mechanical tests carried out in Construction Materials Laboratory of Istanbul Technical University. In Turkey, as in many countries, large amount of existing buildings exposed to seismic hazard, therefore various analytical and experimental studies are being conducted to contribute to the solution of the problem. One of the new generation retrofitting techniques is to strength the structural members by using Fiber Reinforcing Polymer (FRP). This study summarize the results of monitoring of deformations short concrete column samples under the incremental compression load. In this study, result of two rectangular short columns are given. One of them was tested as a reference sample, the other sample were tested after strengthening by PET reinforced polymer composite materials. Besides conventional displacement and strain measurement systems, laser scanning method was used to get three dimensional deformed shape of sample at each selected steps.

Microstructural Analysis of Changes in the Morphology of Quartz Raw Materials of Different Genesis at Dry Milling

2021 ◽  
Vol 1017 ◽  
pp. 91-100
Author(s):  
Ekaterina V. Fomina ◽  
Natalia I. Kozhukhova ◽  
Evgeny A. Belovodsky ◽  
V.A. Klimenko ◽  
Marina I. Kozhukhova
Keyword(s):  
Materials Science ◽  
Fine Particles ◽  
Raw Materials ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Degree Of Crystallinity ◽  
Energy Potential ◽  
Natural Quartz ◽  
Defective Structure ◽  
Dry Grinding

The influence of the genesis of quartz-containing rocks on the strength of particles and changes in morphology during destruction from the standpoint of the mineralogical approach in the development of the scientific direction "geonics" ("geomimetics") has been investigated. The kinetics of dry grinding of raw materials in a laboratory ball roller mill was carried out. The features of the formation and development of cracks, particle size distribution, changes in the morphology and microstructure of fragments have been studied. It was found that in natural quartz cracks develop along the surface, where the highest concentration of impurities creates a defect structure with destruction into small particles. The purest structure of hydrothermal quartz is susceptible to brittle fracture into fragments similar in morphology to the base particle. Reducing the defectiveness of the structure increases the strength of the crystals. The internal energy potential of techno genic raw materials is determined by its defective structure, which undergoes the greatest deformations during grinding, allowing obtaining the maximum values of the specific surface area and reduce the grinding time. A difference in the degree of crystallinity of quartz, which composes the polymineral techno genic raw materials, makes it possible to obtain the optimal granulometry of fine particles. The conducted research is aimed at identifying the mechanisms of destruction of quartz rocks and can be used in solving engineering problems not only in construction materials science, but also in geotechnics.

scholarly journals Determination of Direct Tensile Strength Values of Rock Materials by a New Test Method of Drilled Disc Tension

2019 ◽  
Author(s):  
Eren Komurlu ◽  
Serhat Demir
Keyword(s):  
Tensile Strength ◽  
Experimental Studies ◽  
Test Method ◽  
Uniaxial Tensile ◽  
Direct Tension ◽  
Rock Materials ◽  
Uniaxial Tensile Stress ◽  
Direct Tensile ◽  
Drill Holes ◽  
Direct Tensile Strength

Use of drilled disc specimens was investigated with both numerical and experimental studies to determine direct tensile strengths of rock materials. A new loading apparatus with rods to insert into the drill holes of discs has been designed and manufactured to supply tension by using the compression test presses. In addition to the use of popular compressive presses for direct tension, elimination of the gluing in the standard direct tensile strength test method is a significant advantage to make possible both hard and soft rocks to be tested. The Brazilian test discs with the diameter of NX size and length to diameter ratio of 0.5 were used in tests. Different loading apparatus designs were analyzed and ideal angle of contact between rock and the loading rods was assessed to be 50° within various choices investigated in this study. The drilled discs were determined to fail due to the crack initiation under the condition of uniaxial tensile stress distribution at sidewalls of the hole. In addition to the drilled disc tension test, standard direct tensile strength tests were also carried out to take as reference and compare the results obtained from different methods. According to the results of both numerical and experimental studies, an equation was suggested to determine uniaxial tensile strengths of drilled disc specimens with 20 mm hole diameter and the contact angle of 50°.

Kinetics of Structural Changes in Strontium Hexa-Ferrite Powder during Milling in Beater Mill

2020 ◽  
Vol 989 ◽  
pp. 199-203
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Viktor P. Kryzhanovsky
Keyword(s):  
Particle Size ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Experimental Studies ◽  
Milling Process ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Relative Deformation ◽  
Ferrite Powder ◽  
Electromagnetic Effect

The paper presents the results of experimental studies of strontium hexa-ferrite average particle size and structural characteristics changes during milling process. Coarse strontium hexaferrite was milled in beater mill, without and with electromagnetic effect. Electromagnetic effect was produced by constant and alternating gradient magnetic fields with mutually perpendicular induction lines. Particle sizes were measured by microscopic methods, and structural characteristics were calculated by processing of X-ray diffractograms. Diffraction studies showed that during milling process, both with and without electromagnetic effect, the most intensive changes of coherent scattering region (CSR) sizes, dislocation densities and relative deformation of particulate material occur at earlier stage of milling. At this stage the speed of average particle size decrease is maximal. At later stage both average particle size and structural characteristic changes correlate and have asymptotic character.

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