Residual Fracture Toughness of Concrete Subject to Elevated Temperatures

2011 ◽  
Vol 488-489 ◽  
pp. 743-746
Author(s):  
Jiang Tao Yu ◽  
Ke Quan Yu ◽  
Zhou Dao Lu
Keyword(s):  
Fracture Toughness ◽  
Experimental Investigation ◽  
Weight Loss ◽  
Elevated Temperature ◽  
Significant Influence ◽  
Elevated Temperatures ◽  
Uniform Size ◽  
Increasing Temperature ◽  
The Relationship ◽  
Wedge Splitting

This paper presents an experimental investigation on the variation of residual fracture toughness of concrete after being exposed to elevated temperatures. A total of 60 specimens, with a uniform size of 200x200x230mm and precast notches of 80mm in height, were heated to constant temperatures of 65°C, 120°C, 200°C, 300°C, 350°C, 400°C, 450°C, 500°C and 600°C respectively. After cooling, standard wedge splitting tests, according to the corresponding Chinese Specification, were employed. The results indicate that the elevated temperature has significant influence on the residual fracture toughness of concrete. The magnitude of fracture toughness decreases drastically with increasing temperature. Additionally the relationship between residual fracture toughness and weight loss of specimens with respect to temperatures is also investigated.

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.

Experimental Investigation on Relative Crack Length For Fracture Toughness of Concrete

2010 ◽  
Vol 146-147 ◽  
pp. 1524-1528 ◽  
Author(s):  
Xue Zhi Wang ◽  
Zong Chao Xu ◽  
Zhong Bi ◽  
Hao Wang
Keyword(s):  
Fracture Toughness ◽  
Experimental Investigation ◽  
Crack Length ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Toughness Test ◽  
Wedge Splitting Test ◽  
Splitting Test ◽  
Wedge Splitting

The wedge splitting test specimens with three series of different relative crack length were used to study the influences of relative crack length on the fracture toughness of common concrete. The suitable formulation for fracture toughness of concrete with different relative crack length was gotten on comparing between fracture toughness test results and computation results of the model developed from Hu formula.

The Room Temperature and Elevated Temperature Fracture Toughness Response of Alloy A-286

1978 ◽  
Vol 100 (2) ◽  
pp. 195-199 ◽  
Author(s):  
W. J. Mills
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Second Phase ◽  
Surface Micromorphology ◽  
Second Phase Particles ◽  
The Matrix ◽  
Temperature Fracture ◽  
Increasing Temperature ◽  
Base Superalloy

The elastic-plastic fracture toughness (JIc) response of precipitation strengthened Alloy A-286 has been evaluated by the multi-specimen R-curve technique at room temperature, 700 K (800°F) and 811 K (1000°F). The fracture toughness of this iron-base superalloy was found to decrease with increasing temperature. This phenomenon was attributed to a reduction in the materials’s strength and ductility at elevated temperatures. Electron fractographic examination revealed that the overall fracture surface micromorphology, a duplex dimple structure coupled with stringer troughs, was independent of test temperature. In addition, the fracture resistance of Alloy A-286 was found to be weakened by the presence of a nonuniform distribution of second phase particles throughout the matrix.

scholarly journals Effect of elevated temperature on the population dynamics of fall armyworm, Spodoptera frugiperda

2021 ◽  
Vol 42 (4(SI)) ◽  
pp. 1098-1105
Author(s):  
K. Ashok ◽  
◽  
V. Balasubramani ◽  
J.S. Kennedy ◽  
V. Geethalakshmi ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Life Table ◽  
Spodoptera Frugiperda ◽  
Elevated Temperatures ◽  
Fall Armyworm ◽  
Developmental Time ◽  
Fecundity Rate ◽  
Temperature Regimes ◽  
Custom Made ◽  
Increasing Temperature

Aim: The present study was conducted to determine the growth, survival, fecundity and mortality rate of Spodoptera frugiperda in maize at elevated temperature. Methodology: Biology and life table experiments were carried out in custom made Open Top Chambers (4m x 4m x 4m size) fitted with SCADA under increasing temperature regimes viz., 32˚C, 33˚C, 34˚C, 35˚C and 36˚C. Each stage of the insects was examined daily and the fertility and life-table parameters were calculated by using TWOSEX-MS chart. Results: The overall developmental time for egg, larva, pupa and adult stages (total lifespan) at different elevated temperatures were in the order of 32˚C > 33˚C > 34˚C > 35˚C > 36˚C. The fecundity rate of S. frugiperda at different elevated temperatures were in the order of 34˚C > 33˚C > 32˚C > 35˚C > 36˚C. Interpretation: The current study confirms that the elevated temperature regimes had a positive correlation with fecundity rate upto 34˚C and negative correlation with the survival rate of S. frugiperda.

Permittivity Study of a CuCl Residue at 13–450 °C and Elucidation of the Microwave Intensification Mechanism for Its Dechlorination

2019 ◽  
Vol 38 (2019) ◽  
pp. 135-142
Author(s):  
Guo Zhanyong ◽  
Li Fachaung ◽  
Su Guang ◽  
Zhai Demei ◽  
Cheng Fang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Microwave Irradiation ◽  
Loss Factor ◽  
Elevated Temperatures ◽  
Temperature Dependent ◽  
Positive Interaction ◽  
Increasing Temperature ◽  
Relationship Of ◽  
The Relationship ◽  
Metallurgy Process

AbstractPermittivity is a vitally important parameter for describing the absorbing and heating characteristics of a material under microwave irradiation, and it is also strongly dependent on temperature. However, the literature contains little information on this topic and even less particular permittivity data at elevated temperatures. In this paper, the permittivity of a CuCl residue at temperatures from 13 to 450 °C at 2.45 GHz was measured using the cavity perturbation method. The relationship of its real part (ε′) and imaginary part (ε″) with temperature (T) was deduced. In addition, the temperature-dependent tangent (tan δ) and the penetration depth (d) of microwaves into the material were calculated. The results of the permittivity study show that the dielectric constant (ε′) of the CuCl residue increased linearly with increasing temperature. In contrast, the dielectric loss factor (ε″) and loss tangent first maintained on a steady value between 13 and 300 °C and then substantially increased from 300 to 450 °C. The positive interaction of the dielectric property and temperature showed the reasonableness of our earlier metallurgy process, where the CuCl residue for dechlorination was roasted at 350–450 °C under microwave irradiation.

UAE Rhazya Stricta Decne extract as a corrosion inhibitor for mild steel in HCl solution

2014 ◽  
Vol 61 (4) ◽  
pp. 261-266 ◽  
Author(s):  
Ayssar Nahlé ◽  
Ibrahim Almaidoor ◽  
Ibrahim Abdel-Rahman
Keyword(s):  
Weight Loss ◽  
Mild Steel ◽  
Elevated Temperatures ◽  
Physical Adsorption ◽  
Inhibition Mechanism ◽  
Content Type ◽  
Highly Efficient ◽  
Rhazya Stricta ◽  
Increasing Temperature ◽  
Hcl Solution

Purpose – This study aims to study electrochemically and by weight-loss experiments the effect of UAE Rhazya Stricta Decne extract on the corrosion inhibition of mild steel in 1.0 M HCl solution, which will serve researchers in the field of corrosion. Design/methodology/approach – Weight loss measurements were carried out on mild steel specimens in 1.0 M HCl and in 1.0 M HCl containing various concentrations (ranging from 2.0 to 0.002 g/L.) of the UAE Rhazya Stricta Decne extract at temperatures ranging from 303 to 343 K. Findings – The aqueous Rhazya Stricta Decne leaves extract was found to be a highly efficient inhibitor for mild steel in 1.0 M HCl solution, reaching about 90 per cent at 2.0 g/L and 303 K, a concentration considered to be very moderate. Even with one-tenth of that concentration, 0.2 g/L, an inhibition of about 82 per cent was obtained at 303 K. The rate of corrosion of the mild steel in 1.0 M HCl is a function of the concentration of the Rhazya Stricta Decne extract. This rate increases as the concentration of the Rhazya Stricta Decne extract is increased. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature. Practical implications – This inhibitor could have application in industries, where HCl solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary. Originality/value – This paper is intended to be added to the family of green corrosion inhibitors which are highly efficient and can be used in the area of corrosion prevention and control.

Investigation of Elevated Temperature Mechanical Properties of Intermetallic Compounds in the Cu–Sn System Using Nanoindentation

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Zuozhu Yin ◽  
Fenglian Sun ◽  
Mengjiao Guo
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elevated Temperature ◽  
Intermetallic Compounds ◽  
Lattice Structure ◽  
Hexagonal Lattice ◽  
Parabolic Law ◽  
Dislocation Movement ◽  
Increasing Temperature ◽  
The Relationship

Abstract In electronic packaging, most researchers are mainly focused on the mechanical properties of Cu–Sn intermetallic compounds (IMCs) at room temperature; few studies have looked into the relationship between hardness, elastic modulus, and plasticity of IMCs and elevated temperature. The hardness, elastic modulus, and plasticity of Cu6Sn5 and Cu3Sn at 25–200 °C are investigated by the nanoindentation method. The results show that the hardnesses of Cu6Sn5 and Cu3Sn obey linear attenuation law with elevated temperature. The hardness of Cu6Sn5 is more sensitive to temperature than that of Cu3Sn. This is due to the fact that the melting point of Cu6Sn5 (415 °C) is lower than that of Cu3Sn (670 °C), Cu6Sn5 has a lower normalization temperature than that of Cu3Sn. The elastic modulus of Cu6Sn5 and Cu3Sn and temperature have a parabolic law at 25–200 °C. The elastic modulus of Cu6Sn5 is more sensitive to temperature. This is attributed to the fact that the lattice structure of Cu6Sn5 is changed from hexagonal lattice to monoclinic lattice, causing its volume to expand, thereby making it more sensitive to temperature. The plasticity factors of Cu6Sn5 and Cu3Sn meet the polynomial relationship with elevated temperature. The plasticity factors of Cu6Sn5 and Cu3Sn increase with increasing temperature, which will reduce the resistance to plastic deformation. This is attributed to the fact that the vacancy generated into the material is conducive to the dislocation movement, the dislocation movement will be more active so that the plasticity factors of Cu6Sn5 and Cu3Sn gradually increase.

Tribological Properties Improvement of Mo-Alloyed HfN Films With a High H/E Ratio at Elevated Temperatures

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Zhaoli Liu ◽  
Hang Li ◽  
Jianliang Li ◽  
Jiewen Huang ◽  
Jian Kong ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Tribological Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Structure Stability ◽  
Solid Solution Phase ◽  
High Structure ◽  
Worn Surface ◽  
The Relationship ◽  
Fcc Structure

Abstract In this study, the Mo-alloyed HfN films were prepared by DC-magnetron sputtering and studied their tribological properties at 25–600 °C under dry friction conditions. The relationship between H/E value and tribological properties at elevated temperature was illustrated. A single solid-solution phase was formed for all Hf-Mo-N films which with an FCC structure, and the H/E and H3/E2 values are increased. The film with x = 0.56 obtained a lower friction coefficient (0.4) and wear-rate (1.23 × 10−6 mm3/N m) at room temperature. At elevated temperature, this film maintained high structure stability, meanwhile, a dense and continuous oxide layer with lubrication was formed and tightly covered on the worn surface, that it obtained a lower coefficients of friction and better wear resistance.

scholarly journals Effect of Elevated Ambient Temperature on Simulator-Derived Oscillometric Blood Pressure Measurement

2020 ◽  
Author(s):  
Jennifer S Ringrose ◽  
Michael D Kennedy ◽  
Jalisa Kassam ◽  
Omar Mouhammed ◽  
Sangita Sridar ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Elevated Temperature ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Blood Pressure Measurement ◽  
Ambient Temperatures ◽  
Oscillometric Blood Pressure Measurement ◽  
Increasing Temperature ◽  
Relative Differences

Abstract BACKGROUND Oscillometric blood pressure (BP) devices are typically labeled for use up to 40 °C. Many geographic regions have ambient temperatures exceeding 40 °C. We assessed the effect of increased ambient temperature (40–55 °C) on simulator-derived oscillometric BP measurement. METHODS Three Omron BP769CAN devices, 3 A&D Medical UA-651BLE devices, and accompanying cuffs were used. A custom heat chamber heated each device to the specified temperature. A noninvasive BP simulator was used to take 3 measurements with each device at differing temperatures (22, 40, 45, 50, and 55 °C) and BP thresholds: 80/50, 100/60, 120/80, 140/90, 160/110, and 180/130 mm Hg. Using each device as its own control (22 °C), we determined the relative differences in mean BP for each device at each temperature and BP setting, assessed graphical trends with increasing temperature, and examined variability. RESULTS Graphical trends of mean simulator-subtracted BP differences from room temperature showed no discernable pattern, with differences clustered around zero. Overall mean difference in BP (combined elevated temperatures minus room temperature) was −0.8 ± 2.1 (systolic ± SD)/1.2 ± 3.5 (diastolic ± SD) mm Hg for the A&D device and 0.2 ± 0.4 (systolic ± SD)/−0.1 ± 0.1 (diastolic ± SD) mm Hg for the Omron. All individual elevated temperature differences (elevated temperature minus room temperature) except A&D diastolic BP at 50 °C were within 5 mm Hg. CONCLUSIONS In this simulator-based study assessing within-device differences, higher ambient temperatures resulted in oscillometric BP measurements that were comparable to those performed at room temperature.

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