scholarly journals High Temperature Degradation Mechanism of Concrete with Plastering Layer

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 398
Author(s):  
Chihao Liu ◽  
Jiajian Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Thermal Decomposition ◽  
Electron Microscope ◽  
High Temperature ◽  
Thermogravimetric Analysis ◽  
Degradation Mechanism ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Scanning Electron

At present, the research on the high temperature degradation of concrete usually focuses on only the degradation of concrete itself without considering the effect of the plastering layer. It is necessary to take into account the influence of the plastering layer on the high temperature degradation of concrete. With an increase in the water/cement ratio, the explosion of concrete disappeared. Although increasing the water/cement ratio can alleviate the cracking of concrete due to lower pressure, it leads to a decrease in the mechanical properties of concrete after heating. It is proved that besides the water/cement ratio, the apparent phenomena and mechanical properties of concrete at high temperature can be affected by the plastering layer. The plastering layer can relieve the high temperature cracking of concrete, and even inhibit the high temperature explosion of concrete with 0.30 water/cement ratio. By means of an XRD test, scanning electron microscope test and thermogravimetric analysis, it is found that the plastering layer can promote the rehydration of unhydrated cement particles of 0.30 water/cement ratio concrete at high temperature and then promote the mechanical properties of concrete at 400 °C. However, the plastering layer accelerated the thermal decomposition of C-S-H gel of concrete with a water/cement ratio of 0.40 at high temperature, and finally accelerate the decline of mechanical property of concrete. To conclude, the low water/cement ratio and plastering layer can delay the deterioration of concrete at high temperature.

scholarly journals Mechanical Properties of Concrete with Various Water-Cement Ratio After High Temperature Exposure

2019 ◽  
Vol 2 (2) ◽  
pp. 126-136
Author(s):  
M.I Retno Susilorini ◽  
Budi Eko Afrianto ◽  
Ary Suryo Wibowo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Modulus Of Elasticity ◽  
Building Materials ◽  
Heating Process ◽  
High Temperature Exposure ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Temperature Exposure

Concrete building safety of fire is better than other building materials such as wood, plastic, and steel,because it is incombustible and emitting no toxic fumes during high temperature exposure. However,the deterioration of concrete because of high temperature exposure will reduce the concrete strength.Mechanical properties such as compressive strength and modulus of elasticity are absolutely corruptedduring and after the heating process. This paper aims to investigate mechanical properties of concrete(especially compressive strength and modulus of elasticity) with various water-cement ratio afterconcrete suffered by high temperature exposure of 500oC.This research conducted experimental method and analytical method. The experimental methodproduced concrete specimens with specifications: (1) specimen’s dimension is 150 mm x 300 mmconcrete cylinder; (2) compressive strength design, f’c = 22.5 MPa; (3) water-cement ratio variation =0.4, 0.5, and 0.6. All specimens are cured in water for 28 days. Some specimens were heated for 1hour with high temperature of 500oC in huge furnace, and the others that become specimen-controlwere unheated. All specimens, heated and unheated, were evaluated by compressive test.Experimental data was analyzed to get compressive strength and modulus of elasticity values. Theanalytical method aims to calculate modulus of elasticity of concrete from some codes and to verifythe experimental results. The modulus elasticity of concrete is calculated by 3 expressions: (1) SNI03-2847-1992 (which is the same as ACI 318-99 section 8.5.1), (2) ACI 318-95 section 8.5.1, and (3)CEB-FIP Model Code 1990 Section 2.1.4.2.The experimental and analytical results found that: (1) The unheated specimens with water-cementratio of 0.4 have the greatest value of compressive strength, while the unheated specimens with watercementratio of 0.5 gets the greatest value of modulus of elasticity. The greatest value of compressivestrength of heated specimens provided by specimens with water-cement ratio of 0.5, while the heatedspecimens with water-cement ratio of 0.4 gets the greatest value of modulus of elasticity, (2) Allheated specimens lose their strength at high temperature of 500oC, (3) The analytical result shows thatmodulus of elasticity calculated by expression III has greater values compares to expression I and II,but there is only little difference value among those expressions, and (4)The variation of water-cementratio of 0.5 becomes the optimum value.

Influence of SiC on the Properties of PcBN Cutting Tools Fabricated by High Pressure and High Temperature Sintering

2016 ◽  
Vol 697 ◽  
pp. 526-529 ◽  
Author(s):  
Shi Xun Zhang ◽  
Jian Li ◽  
Yao Ma ◽  
Hai Long Wang ◽  
Rui Zhang
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Electron Microscope ◽  
High Temperature ◽  
Scanning Electron Microscope ◽  
Cutting Tools ◽  
X Ray Diffraction ◽  
Micro Structure ◽  
X Ray ◽  
Scanning Electron

SiC-Al3BC3-cBN composites with different contents of cBN were fabricated by high pressure and high temperature sintering (HPHT) at 1450 °C for 3 min under a pressure of 5.0 GPa using SiC, Al, B4C and C as additives. The effect of SiC content on the density and mechanical properties of SiC-Al3BC3-cBN composites was investigated. X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to analyze phases and micro-structure of the sintered samples. The hardness of SiC-Al3BC3-cBN composites decreased with the increasing of SiC content, However, the fracture strength of SiC-Al3BC3-cBN composites increased with the increasing of SiC content.

scholarly journals Mechanical Degradation and Thermal Decomposition of Ethylene-Vinyl Acetate (EVA) Polymer-Modified Cement Mortar (PCM) Exposed to High-Temperature

2019 ◽  
Vol 11 (2) ◽  
pp. 500 ◽  
Author(s):  
Hyung-Jun Kim ◽  
Jae-Yeon Park ◽  
Heong-Won Suh ◽  
Beom-Yeon Cho ◽  
Won-Jun Park ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Decomposition ◽  
Compressive Strength ◽  
High Temperature ◽  
Vinyl Acetate ◽  
Cement Mortar ◽  
Ethylene Vinyl Acetate ◽  
Mechanical Degradation ◽  
Rc Structures ◽  
Cement Ratio

A polymer-modified cement mortar (PCM) is widely used as a repair material for reinforced concrete (RC) structures owing to its excellent strength and durability. However, considering the maintenance of the RC structures and the use period of the structures, the change in the physical properties of the PCM should be evaluated when exposed to various high-temperature environments, such as fires. In this study, the degradation of the mechanical properties (compressive strength and modulus of elasticity), thermal decomposition of the PCM in various high-temperature environments, and the change in the pore structure of the PCM after exposure to high temperatures were quantitatively investigated. A mechanical property evaluation of PCM was performed under three heating conditions: (i) heating in a compression tester, (ii) heating the specimen in an oven to a predetermined temperature and then moving it to a compression tester preheated to the same temperature, and (iii) cooling to room temperature after heating. In the experiment, a PCM specimen was prepared by changing the polymer–cement ratio (polymer content) of ethylene-vinyl acetate (EVA), the most commonly used polymer, to perform a high-temperature sectional test from 200 to 800 °C. In addition, to investigate the change in the PCM mechanical properties in the high-temperature region, in terms of the pyrolysis of EVA, the porosity change and mass change were examined using thermal analysis and mercury intrusion porosimetry. Before heating, the compressive strength of the PCM increased with the EVA content up to 10 % of the polymer–cement ratio. Under the cooling conditions after heating up to 200 °C, the mechanical performance of the PCM was restored, whereas the degradation of the mechanical properties of the PCM without cooling was more pronounced. Furthermore, the mass loss, heat flow, and the total porosity of the PCM increased as the EVA content increased, which is correlated with the degradation of the mechanical properties of the PCM.

Effect of Austenizing Temperature on Microstructures and Mechanical Properties of Cr-W-Ni-Alloy Steel

2012 ◽  
Vol 248 ◽  
pp. 26-30
Author(s):  
Xia Qu ◽  
Ying Chun Wang ◽  
Xing Wang Cheng ◽  
Shuang Zan Zhao ◽  
Shu Kui Li
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Tensile Properties ◽  
Alloy Steel ◽  
Martensitic Matrix ◽  
Ni Alloy ◽  
Strength And Ductility ◽  
Scanning Electron

An investigation was made to determine the effect of austenizing temperature on microstructure and tensile properties of Cr-W-Ni-alloy steel. Correlations of microstructure tensile properties and austenizing temperature parameters were established. Analysis of optical and scanning electron microscope show that there were a lot of coarse spherical undissolved carbides dispersed on the lath martensitic matrix in as-quenched specimens when austenized at 900°C while there were only very little nanometer carbides when austenized at 1000°C and 1100°C. The tensile properties show that austenizing temperature had large effect on the mechanical property of the Cr-W-Ni-alloy steel. Oil quenching after austenized at 1100°C for 26 minutes followed with tempering at 260°C for 3h, Cr-W-Ni-alloy steel obtained best strength and ductility match.

Effect of the Neodymium Content on Mechanical Properties of the Electro-Brush Plated Nano-Al2O3/Ni Composite Coating

2012 ◽  
Vol 525-526 ◽  
pp. 277-280
Author(s):  
Guo Jin ◽  
Xiu Fang Cui ◽  
Er Bao Liu ◽  
Qing Fen Li
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Composite Coating ◽  
Nanoindentation Test ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Cracks ◽  
Scanning Electron

The effect of the neodymium content on mechanical properties of the electro-brush plated nanoAl2O3/Ni composite coating was investigated in this paper. The microstructure and phase structure were studied with scanning electron microscope (SEM) and X-ray diffraction (XRD). The hardness and abrasion properties of several coatings with different neodymium content were studied by nanoindentation test and friction / wear experiment. Results show that the coatings are much finer and more compact when the neodymium was added, and the hardness and abrasion property of the coatings with neodymium were improved obviously. Besides, the small cracks conduced by the upgrowth stress in the coatings were ameliorated when the rare earth neodymium was added. The improvement mechanism was further discussed.

Influence of Aging Treatments on the Structural and Mechanical Properties of AGS Alloy Wire Cold Drawn

2018 ◽  
Vol 18 ◽  
pp. 73-78
Author(s):  
Mokhtar Bayarassou ◽  
Mosbah Zidani ◽  
Hichem Farh
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Electron Microscope ◽  
Artificial Ageing ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Alloy Wire ◽  
X Ray ◽  
Plastic Deformation Rate ◽  
Scanning Electron

The scope of this work is to study of microstructural changes and mechanical properties during natural and artificial ageing treatment of AGS Alloy wire cold drawn with different deformation at ENICAB in Biskra. And as well to know the phase formation during different deformation of aluminum alloys wires. as well as the combined influence of the plastic deformation rate and the aging temperature. Wire section reduction shows a change in microstructure and texture. The methods of characterization used in this work are: scanning electron microscope and X-ray diffraction, micro hardness (Hv).

Effect of Functionalized MWCNT on the Mechanical and Dielectric Properties of PMMA Nanocomposites

2018 ◽  
Vol 18 (06) ◽  
pp. 1850035
Author(s):  
Punyapriya Mishra ◽  
Narasingh Deep ◽  
Sagarika Pradhan ◽  
Vikram G. Kamble
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Tensile Strength ◽  
Electron Microscope ◽  
Dielectric Properties ◽  
Conductive Polymer ◽  
Mechanical Tests ◽  
Surface Structures ◽  
Scanning Electron

Carbon nanotubes (CNTs) are widely explained in fundamental blocks of nanotechnology. These CNTs exhibit much greater tensile strength than steel, even almost similar to copper, but they have higher ability to carry much higher currents, they seem to be a magical material with all these mentioned properties. In this paper, an attempt has been made to incorporate this wonder material, CNT, (with varying percentages) in polymeric matrix (Poly methyl methacrylate (PMMA)) to create a new conductive polymer composite. Various mechanical tests were carried out to evaluate its mechanical properties. The dielectric properties such as dielectric loss and dielectric constant were evaluated with the reference of temperature and frequency. The surface structures were analyzed by Scanning Electron Microscope (SEM).

Influence of Mn and Ni on Austenite Stabilization during a High Temperature Q&P Treatment

2021 ◽  
Vol 1016 ◽  
pp. 379-384
Author(s):  
Eider Del Molino ◽  
Teresa Gutierrez ◽  
Mónica Serna-Ruiz ◽  
Maribel Arribas ◽  
Artem Arlazarov
Keyword(s):  
Phase Transformation ◽  
Electron Microscope ◽  
High Temperature ◽  
Retained Austenite ◽  
Nickel Content ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
X Ray ◽  
Scanning Electron ◽  
P Cycle

The aim of this work was to study the influence of quenching and partitioning temperatures combined with various levels of Mn and Ni contents on the austenite stabilization along the quenching and partitioning (Q&P) cycle. Three steels with 2 wt.%, 4 wt.% and 6 wt.% manganese and one steel with 2 wt.% nickel content were investigated. Phase transformation temperatures and critical cooling rates were obtained experimentally using dilatometer for each alloy. Q&P cycles with different quenching and partitioning temperatures were also done in dilatometer, thus, allowing monitoring of the expansion/contraction during the whole Q&P cycle. Microstructure characterization was performed by means of a Scanning Electron Microscope and X-Ray Diffraction to measure retained austenite content. It was found that, strongly depending on the Q&P conditions, austenite stabilization or decomposition occurs during partitioning and final cooling. In case of high partitioning temperature cycles, austenite reverse transformation was observed. Certain cycles resulted in a very effective austenite stabilization and interesting microstructure.

Scanning Electron Microscope in Rocks and their Comparison with Physical-Mechanical Properties

2020 ◽  
Vol 841 ◽  
pp. 114-118
Author(s):  
Marco Antonio Navarrete Seras ◽  
Francisco Javier Domínguez Mota ◽  
Elia Mercedes Alonso Guzmán ◽  
Wilfrido Martínez Molina ◽  
Hugo Luis Chávez García ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Mechanical Tests ◽  
Structural Element ◽  
Concrete Mixtures ◽  
Hydraulic Concrete ◽  
Stone Materials ◽  
Historical Monuments ◽  
Scanning Electron

. Banks of stone materials from Michoacán, Mexico were characterized, since they are used in the construction of infrastructure in the area. With these materials are made hydraulic concrete mixtures or asphalt mixtures, foundations, paving stones and in restoration of historical monuments. The rocks analyzed and characterized, come from banks of volcanic stone materials and banks of crushed stone materials, which were subjected to mechanical tests such as uniaxial compression resistance (UCR), in addition was used scanning electron microscope (SEM), by means of which the characterization was carried out, obtaining morphological information of the material. The comparison of physical-mechanical properties with the elements they possess is important to estimate their behavior within ceramic matrices or as a structural element.

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