scholarly journals Explosive Spalling Behavior of Single-Sided Heated Concrete According to Compressive Strength and Heating Rate

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6023
Author(s):  
Euichul Hwang ◽  
Gyuyong Kim ◽  
Gyeongcheol Choe ◽  
Minho Yoon ◽  
Minjae Son ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Vapor Pressure ◽  
Heating Rate ◽  
Heated Surface ◽  
Concrete Surface ◽  
Slow Heating ◽  
Explosive Spalling ◽  
Fast Heating ◽  
Moisture Migration ◽  
Heated Concrete

In this study, the effects of heating rate and compressive strength on the spalling behavior of single-sided heated ring-restrained concrete with compressive strengths of 60 and 100 MPa were investigated. The vapor pressure and restrained stress inside the concrete were evaluated under fast- and slow-heating conditions. Regardless of the heating rate, the concrete vapor pressure and restrained stress increased as the temperature increased, and it was confirmed that spalling occurred in the 100-MPa concrete. Specifically, it was found that moisture migration and restrained stress inside the concrete varied depending on the heating rate. Under fast heating, moisture clogging and restrained stress occurred across the concrete surface, causing continuous surface spalling for the 100-MPa concrete. Under slow heating, moisture clogging occurred, and restrained stress continuously increased in the deep area of the concrete cross-section owing to the small internal temperature difference, resulting in explosive spalling for the 100-MPa concrete with a dense internal structure. Additionally, while the tensile strength of concrete is reduced by heating, stress in the heated surface direction is generated by restrained stress. The combination of stress in the heated concrete surface and the internal vapor pressure generates spalling. The experimental results confirm that heating rate has a significant influence on moisture migration and restrained stress occurrence inside concrete, which are important factors that determine the type of spalling.

Physical and Mechanical Properties of Fired Clay Bricks Incorporated with Cigarette Butts: Comparison between Slow and Fast Heating Rates

2013 ◽  
Vol 421 ◽  
pp. 201-204
Author(s):  
Aeslina binti Abdul Kadir ◽  
Abbas Mohajerani
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
Initial Rate ◽  
Physical And Mechanical Properties ◽  
Slow Heating ◽  
Firing Process ◽  
Heating Rates ◽  
Fast Heating ◽  
Rate Of Absorption

In general, firing process in brick manufacturing could affect the properties, colours and appearance of the brick. The main purpose of this study was to evaluate the effect of different heating rates on physical and mechanical properties during the firing of standard bricks and bricks incorporated with cigarette butt (CB). In this investigation, two different heating rates were used: slow heating rate (2oC min-1) and fast heating rate (5oC min-1). Samples were fired in solid forms from room temperature to 1050oC. All bricks were tested for their physical and mechanical properties including compressive strength, initial rate of absorption and density. Higher heating rates decrease compressive strength value but slightly increase the initial rate of absorption and density properties respectively. In conclusion, higher heating rates are able to produce adequate physical and mechanical properties especially for CB Brick.

Effect of moisture migration and water vapor pressure build-up with the heating rate on concrete spalling type

2019 ◽  
Vol 116 ◽  
pp. 1-10 ◽  
Author(s):  
Gyeongcheol Choe ◽  
Gyuyong Kim ◽  
Minho Yoon ◽  
Euichul Hwang ◽  
Jeongsoo Nam ◽  
...  
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Heating Rate ◽  
Water Vapor Pressure ◽  
Moisture Migration ◽  
Effect Of Moisture

Steel Ring-Based Restraint of HSC Explosive Spalling in High Temperature Environments

2014 ◽  
Vol 5 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Toru Tanibe ◽  
Mitsuo Ozawa ◽  
Ryota Kamata ◽  
Keitetsu Rokugo
Keyword(s):  
Thermal Stress ◽  
Vapor Pressure ◽  
High Strength Concrete ◽  
Rapid Heating ◽  
Heated Surface ◽  
High Strength ◽  
Heating Time ◽  
Explosive Spalling ◽  
Heating Curve ◽  
Support Estimation

This paper reports on an experimental study regarding the behavior of restrained high-strength concrete in response to the type of extreme heating associated with fire. The study was intended to support estimation of thermal stress from the strain in a restraining steel ring and vapor pressure in restrained concrete under the conditions of a RABT 30 rapid heating curve. The size of the specimens was φ300 X 100 mm, and the results showed that explosive spalling occurred between 4 and 10 minutes in terms of heating time. It was also observed that the thermal stress was greater than the vapor pressure value of 0.1 MPa at a point 10 mm from the heated surface at 5 minutes. The maximum spalling depth was about 61 mm. It was inferred that spalling behavior caused by thermal stress may become predominant under restrained conditions.

scholarly journals Peach and Nectarine Quality Following Treatment with High-temperature Forced Air Combined with Controlled Atmosphere

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1425-1430 ◽  
Author(s):  
David Obenland ◽  
Paul Neipp ◽  
Bruce Mackey ◽  
Lisa Neven
Keyword(s):  
Heating Rate ◽  
Fruit Quality ◽  
Prunus Persica ◽  
Total Duration ◽  
Storage Period ◽  
Soluble Solids ◽  
Slow Heating ◽  
Controlled Atmosphere ◽  
Heating Rates ◽  
Fast Heating

Yellow- and white-fleshed peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica (L.) Batsch var. nectarina (Ait) Maxim.] cultivars of mid- and late-season maturity classes were subjected to combined controlled atmosphere–temperature treatment system (CATTS) using heating rates of either 12 °C/hour (slow rate) or 24 °C/hour (fast rate) with a final chamber temperature of 46 °C, while maintaining a controlled atmosphere (CA) of 1 kPa oxygen and 15 kPa carbon dioxide. Fruit seed surface temperatures generally reached 45 °C within 160 minutes and 135 minutes for the slow and fast heating rate, respectively. The total duration of the slow heating rate treatment was 3 hours, while 2.5 h was required for the fast heating rate treatment. Following treatment the fruit were stored at 1 °C for either 1, 2, or 3 weeks followed by a ripening period of 2 to 4 d at 23 °C and subsequent evaluation of fruit quality. Fruit quality was similar for both heating rate treatments. Compared with the untreated controls, CATTS fruit displayed higher amounts of surface injury, although increased injury was only an important factor to marketability in cultivars that had high amounts of surface injury before treatment. The percentage of free juice in the flesh was slightly less in CATTS fruit early in storage but was often greater in treated fruit toward the end of the storage period. Slower rates of softening during fruit ripening were apparent in CATTS fruit. Soluble solids, acidity, weight loss and color all were either not affected or changed to a very small degree as a result of CATTS. Members of a trained sensory panel preferred the taste of untreated fruit over fruit that had been CATTS but the ratings of treated and nontreated fruit were generally similar and it is unclear whether an average consumer could detect the difference. Although further work needs to be done regarding the influence of CATTS on taste, it otherwise appears that CATTS does not adversely affect the marketability of good quality fruit and therefore shows promise as a nonchemical quarantine treatment for peaches and nectarines.

scholarly journals Mobility of Radiogenic Helium in Amphibole

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Igor Tolstikhin ◽  
Sergei Tarakanov ◽  
Vitalii Kolobov ◽  
Maria Gannibal
Keyword(s):  
Thermal Expansion ◽  
Size Distribution ◽  
Heating Rate ◽  
Diffusion Flux ◽  
Domain Size ◽  
Sharp Peak ◽  
Crystalline Lattice ◽  
Slow Heating ◽  
Fast Heating ◽  
Tensile Stresses

Recently experiments on He extraction from an amphibole by the incremental heating unexpectedly revealed that the He release pattern depends on the heating rate. During slow heating (~4 K·min−1) of the amphibole grains, one smooth peak of the He flux from the mineral was observed; in contrast, during fast heating (~40 K·min−1) an additional sharp peak appeared at a temperature about 750 °C. In order to explain these observations, we developed a model of He diffusion from the amphibole, which allowed the calculated He fluxes from the mineral to be reconciled with those observed. From the modelling we derived: (i) the helium diffusion domain size distribution, and evolution of the distribution in the course of incremental heating; (ii) occurrence of the tensile stresses, operating under enhanced temperatures above 700 °C. The stresses are different in sites with the different local thermal expansion of the crystalline lattice and they increase the He diffusion flux. The model can be applied to other minerals (materials).

Deterioration of Mechanical Properties of High-Strength Pumpcrete after Exposure to High Temperatures

2010 ◽  
Vol 168-170 ◽  
pp. 564-569
Author(s):  
Guang Lin Yuan ◽  
Jing Wei Zhang ◽  
Jian Wen Chen ◽  
Dan Yu Zhu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
High Strength Concrete ◽  
Heating Temperature ◽  
High Strength ◽  
Air Cooling ◽  
Test Results ◽  
Strength Deterioration ◽  
Residual Compressive Strength

This paper makes an experimental study of mechanical properties of high-strength pumpcrete under fire, and the effects of heating rate, heating temperature and cooling mode on the residual compressive strength(RCS) of high-strength pumpcrete are investigated. The results show that under air cooling, the strength deterioration speed of high-strength concrete after high temperature increases with the increase of concrete strength grade. Also, the higher heating temperature is, the lower residual compressive strength value is. At the same heating rate (10°C/min), the residual compressive strength of C45 concrete after water cooling is a little higher than that after air cooling; but the test results are just the opposite for C55 and C65 concrete. The strength deterioration speed of high-strength concrete after high temperature increases with the increase of heating rate, but not in proportion. And when the heating temperature rises up between 200°C and 500°C, heating rate has the most remarkable effect on the residual compressive strength of concrete. These test results provide scientific proofs for further evaluation and analysis of mechanical properties of reinforced-concrete after exposure to high temperatures.

scholarly journals A Comparative Study on the Efficiency of CFRP and GFRP in the Improvement of Compressive Strength, Acoustic Impedance and Bracing of Filled and Hollow Concrete Columns in Different Layers and Ages

2016 ◽  
Vol 9 (5) ◽  
pp. 110 ◽  
Author(s):  
Mohammadreza Zarringol ◽  
Mohammadehsan Zarringol
Keyword(s):  
Compressive Strength ◽  
Comparative Study ◽  
Ultimate Strength ◽  
Acoustic Impedance ◽  
Concrete Columns ◽  
Concrete Surface ◽  
Ultrasonic Waves ◽  
Shear Strengthening ◽  
Surface Strength ◽  
Strengthening Method

<p>FRP technique is growing in popularity as a modern strengthening method. When it comes to FRP, concrete surface strength plays a determining role in the bond between FRP and concrete. This paper aims to compare the efficiency of CFRP and GFRP in the improvement of compressive strength, acoustic impedance and bracing of filled and hollow concrete columns in different layers and ages. In doing so, we carried out various tests on 18 samples in the ages of 3, 7, 14, 28, 42 and 90 days. According to the results, the strength of un-braced carbon and glass increased by 19-40% and 8-43% respectively and the strength of braced carbon and glass increased by 17-25% and 10-82% respectively. The compressive strength increased by 66% in one-layer CFRP hollow column, 96% in two-layer CFRP hollow column, 123% in three-layer CFRP hollow column, 36% in one-layer GFRP hollow column, 63% in two-layer GFRP hollow column, 105% in three-layer GFRP hollow column, 71% in one-layer CFRP filled column, 138% in two-layer CFRP filled column, 154% in three-layer CFRP filled column, 45% in one-layer GFRP filled column, 79% in two-layer GFRP filled column, and 144% in three-layer GFRP filled column. The ultimate strength of the beams with flexural-shear strengthening was higher than other beams. Also, the increased percentage of fiber resulted in the increased speed of ultrasonic waves. </p>

Study on the residual performance of RC beams exposed to processed temperatures and fire

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin Vijaya Kumar ◽  
N. Suresh
Keyword(s):  
Failure Modes ◽  
Elevated Temperatures ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Rc Beams ◽  
Heating Rates ◽  
Fast Heating ◽  
Content Type ◽  
Temperature Increment ◽  
Residual Performance

PurposeThe Reinforced Concrete(RC) elements are known to perform well during exposure to elevated temperatures. Hence, RC elements are widely used to resist the extreme heat developing from accidental fires and other industrial processes. In both of the scenarios, the RC element is exposed to elevated temperatures. However, the primary differences between the fire and processed temperatures are the rate of temperature increase, mode of exposure and exposure durations. In order to determine the effect of two heating modalities, RC beams were exposed to processed temperatures with slow heating rates and fire with fast heating rates.Design/methodology/approachIn the present study, RC beam specimens were exposed to 200 °C, to 800 °C temperature at 200 °C intervals for 2 h' duration by adopting two heating modes; Fire and processed temperatures. An electrical furnace with low-temperature increment and a fire furnace with standard time-temperature increment is adapted to expose the RC elements to elevated temperatures.FindingsIt is observed from test results that, the reduction in load-carrying capacity, first crack load, and thermal crack widths of RC beams exposed to 200 °C, and 600 °C temperature at fire is significantly high from the RC beams exposed to the processed temperature having the same maximum temperature. As the exposure temperature increases to 800 °C, the performance of RC beams at all heating modes becomes approximately equal.Originality/valueIn this work, residual performance, and failure modes of RC beams exposed to elevated temperatures were achieved through two different heating modes are presented.

scholarly journals Effect of Heating Rate on the Dynamic Compressive Properties of Granite

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ronghua Shu ◽  
Tubing Yin ◽  
Xibing Li
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Heating Rate ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Quadratic Function ◽  
Peak Strain ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Dynamic Compressive Strength

Variation in the heating rate due to different geothermal gradients is a cause of much concern in underground rock engineering such as deep sea and underground tunnels, nuclear waste disposal, and deep mining. By using a split Hopkinson pressure bar (SHPB) and variable-speed heating furnace, the dynamic compressive properties of granite were obtained after treatments at different heating rates and temperatures; these properties mainly included the dynamic compressive strength, peak strain, and dynamic elastic modulus. The mechanism of heating rate action on the granite was simultaneously analyzed, and the macroscopic physical properties were discussed. The microscopic morphological features were obtained by scanning electron microscopy (SEM), and the crack propagation was determined by high-speed video camera. The experimental results show that the dynamic compressive strength and elastic modulus both show an obvious trend of a decrease with the increasing heating rate and temperature; the opposite phenomenon is observed for the peak strain. The relationships among the dynamic compressive properties and temperature could be described by the quadratic function. The ductility of granite is enhanced, and the number and size of cracks increase gradually when the heating rate and temperature increase. The microstructure of rock is weakened by the increased thermal stress, which finally affects the dynamic compressive properties of rock.

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