The Static Mechanical Property of Concrete at Elevated Temperature

2011 ◽  
Vol 261-263 ◽  
pp. 212-216
Author(s):  
Jun Lin Tao ◽  
Li Bo Qin ◽  
Kui Li ◽  
Bin Jia
Keyword(s):  
Mechanical Property ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Critical Strain ◽  
Plain Concrete ◽  
Constitutive Relationship ◽  
Heating Method ◽  
Experiment System ◽  
Wave Heating ◽  
Static Mechanical

Using micro-wave heating method, the previous disadvantages of heating slowly and non-uniform are broken through. And plain concrete high temperature loading experiment system is composed of the method and material experiment machine. Many experiments of self-made concrete are carried out from room temperature to 600°C by this system. The strength and critical strain of concrete with temperature are obtained, and through analysis of the compressive stress-strain curves under different temperature, the constitutive relationship is established. The result shows that this constitutive relationship is greatly agrees with experiment. Meanwhile, the phenomenon is analyzed and explained in the progress of experiment.

Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel

1981 ◽  
Vol 39 ◽  
pp. 314-315 ◽  
Author(s):  
M.T. Jahn ◽  
J.C. Yang ◽  
C.M. Wan
Keyword(s):  
Mechanical Property ◽  
Chemical Composition ◽  
Alloy Steel ◽  
Thermomechanical Treatment ◽  
Room Temperature ◽  
Good Combination ◽  
Thermal Treatments ◽  
Low Carbon ◽  
4340 Steel ◽  
Good Improvement

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Phase Relationship Studies of Silicon Nitride System—A Key to Materials Design

1992 ◽  
Vol 287 ◽  
Author(s):  
T.S. Yen ◽  
W.Y. Sun
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Phase Behavior ◽  
Phase Diagrams ◽  
Room Temperature ◽  
Phase Relationship ◽  
Materials Design ◽  
Basic Approach ◽  
System A

ABSTRACTAdditions and revisions to several of the most important phase diagrams and phase behavior diagrams in the silicon nitride field are reviewed in this work, with emphasis on the Y-Si-A1-O-N system. This information is further used to make observations on the promising silicon nitride systems containing either highly refractory grain boundary phases or compatible matrix phases of desirable properties. Examples are provided to illustrate the advantage of such a basic approach to materials design. Hardness, toughness, strength at room temperature and elevated temperature and even sinterability can all be improved by adopting such an approach.

Surface Structures of Phosphorus and Indium on Si(111)

1998 ◽  
Vol 05 (01) ◽  
pp. 69-76
Author(s):  
F. P. Netzer ◽  
L. Vitali ◽  
J. Kraft ◽  
M. G. Ramesy
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Diffusion Limited ◽  
Lower Terrace ◽  
Surface Reconstructions ◽  
Low Energy Electron ◽  
Stm Images

The interaction of vapor phase P2 with the [Formula: see text] monolayer surface at room temperature and elevated temperature has been monitored by scanning tunneling microscopy (STM) and spectroscopy (STS) in conjunction with Auger electron spectroscopy and low-energy electron diffraction (LEED). The surface rection can be readily followed by STM because of the very different contrast of the reacted areas in the STM images. The reaction develops around overlayer defects at room temperature and appears to be diffusion-limited, whereas at 300°C the reaction is initiated at the step edges, from which the reaction front progresses onto the lower terrace areas. At elevated temperature several ordered surface reconstructions, showing different STS fingerprints, are detected on the P–In/Si(111) surfaces, which are associated tentatively with P- and Si-terminated structures and an ordered InP phase.

Thermal Resistance of Fly Ash Geopolymers with Alumina as Additive

2018 ◽  
Vol 281 ◽  
pp. 182-188
Author(s):  
Yong Sing Ng ◽  
Yun Ming Liew ◽  
Cheng Yong Heah ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Thermal Resistance ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Strength Degradation ◽  
Alumina Addition ◽  
Higher Temperature ◽  
Temperature Exposure

The present work investigates the effect of alumina addition on the thermal resistance of fly ash geopolymers. Fly ash geopolymers were synthesised by mixing fly ash with activator solution (A mixture of 12M sodium hydroxide and sodium silicate) at fly ash/activator ratio of 2.5 and sodium silicate/sodium hydroxide ratio of 2.5. The alumina (0, 2 and 4 wt %) was added as an additive. The geopolymers were cured at room temperature for 24 hours and 60°C for another 24 hours. After 28 days, the geopolymers was heated to elevated temperature (200 - 1000°C). For unexposed geopolymers, the addition of 2 wt % of alumina increased the compressive strength of fly ash geopolymers while the strength decreased when the content increased to 4 wt.%. The temperature-exposed geopolymers showed enhancement of strength at 200°C regardless of the alumina content. The strength reduced at higher temperature exposure (> 200°C). Despite the strength degradation at elevated temperature, the strength attained was relatively high in the range of 13 - 45 MPa up to 1000°C which adequately for application as structural materials.

scholarly journals Characterization and Comparison of Geopolymer Synthesized Using Metakaolin Bangka and Metastar as Precursors

2018 ◽  
Vol 67 ◽  
pp. 03022
Author(s):  
Sotya Astutiningsih ◽  
Dicky Tambun ◽  
Ahmad Zakiyuddin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Mechanical Test ◽  
Strength Test ◽  
Thermal Activity ◽  
Metallurgical Properties ◽  
Metakaolin Geopolymer ◽  
Kaolin Deposit

Various aluminosilicate material have been used as precursor for geopolymer. Geopolymer gets its strength from the polycondensation of silicate and alumina. Metakaolin, calcinated kaolin, is pozzolan with the highest alumina and silicate purity. Indonesia, especially Bangka Island, has a large amount of kaolin deposit that being sold at low price. This price could be increased ten times when being sold as metakaolin. This study aimed to compare mechanical and metallurgical properties of commercial metakaolin and Bangka kaolin which calcinated at 700°C. Both metakaolins reacted with NaOH and waterglass as the activator followed by curing at room temperature for 7, 14 and 28 days and elevated temperature of 60°C for 4, 12 and 24 hours. Mechanical properties will be examined by compressive strength and flexural strength test, while the metallurgical properties will be evaluated with SEM, and TAM. The results of the mechanical test will be used to determine which geopolymer will perform well with the microstructure and thermal activity to support the finding. These attempts will be done in order to improve the properties of Bangka metakaolin geopolymer superior to commercial metakaolin.

scholarly journals Physical Stability and Viscoelastic Properties of Co-Amorphous Ezetimibe/Simvastatin System

2019 ◽  
Vol 12 (1) ◽  
pp. 40 ◽  
Author(s):  
Justyna Knapik-Kowalczuk ◽  
Krzysztof Chmiel ◽  
Karolina Jurkiewicz ◽  
Natália Correia ◽  
Wiesław Sawicki ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Viscoelastic Properties ◽  
Room Temperature ◽  
Physical Stability ◽  
Ternary Systems ◽  
Storage Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Conditions ◽  
First Time

The purpose of this paper is to examine the physical stability as well as viscoelastic properties of the binary amorphous ezetimibe–simvastatin system. According to our knowledge, this is the first time that such an amorphous composition is prepared and investigated. The tendency toward re-crystallization of the amorphous ezetimibe–simvastatin system, at both standard storage and elevated temperature conditions, have been studied by means of X-ray diffraction (XRD). Our investigations have revealed that simvastatin remarkably improves the physical stability of ezetimibe, despite the fact that it works as a plasticizer. Pure amorphous ezetimibe, when stored at room temperature, begins to re-crystallize after 14 days after amorphization. On the other hand, the ezetimibe-simvastatin binary mixture (at the same storage conditions) is physically stable for at least 1 year. However, the devitrification of the binary amorphous composition was observed at elevated temperature conditions (T = 373 K). Therefore, we used a third compound to hinder the re-crystallization. Finally, both the physical stability as well as viscoelastic properties of the ternary systems containing different concentrations of the latter component have been thoroughly investigated.

Sign in / Sign up

Export Citation Format

Share Document