scholarly journals Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 941
Author(s):  
Raad A. Al-Ameri ◽  
Sallal R. Abid ◽  
G. Murali ◽  
Sajjad H. Ali ◽  
Mustafa Özakça
Keyword(s):  
High Temperature ◽  
Impact Strength ◽  
Elevated Temperatures ◽  
Impact Resistance ◽  
Test Results ◽  
Repeated Impact ◽  
High Temperature Exposure ◽  
Compressive And Flexural Strengths ◽  
Temperature Exposure ◽  
The Impact

Portland cement concrete is known to have good fire resistance; however, its strength would be degraded after exposure to the temperatures of fire. Repeated low-velocity impacts are a type of probable accidental load in many types of structures. Although there is a rich body of literature on the residual mechanical properties of concrete after high temperature exposure, the residual repeated impact performance of concrete has still not been well explored. For this purpose, an experimental study was conducted in this work to evaluate the effect of high temperatures on the repeated impact strength of normal strength concrete. Seven identical concrete patches with six disc specimens each were cast and tested using the ACI 544-2R repeated impact setup at ambient temperature and after exposure to 100, 200, 300, 400, 500 and 500 °C. Similarly, six cubes and six prisms from each patch were used to evaluate the residual compressive and flexural strengths at the same conditions. Additionally, the scattering of the impact strength results was examined using three methods of the Weibull distribution, and the results are presented in terms of reliability. The test results show that the cracking and failure impact numbers of specimens heated to 100 °C reduced slightly by only 2.4 and 3.5%, respectively, while heating to higher temperatures deteriorated the impact resistance much faster than the compressive and flexural strengths. The percentage reduction in impact resistance at 600 °C was generally higher than 96%. It was also found that the deduction trend of the impact strength with temperature is more related to that of the flexural strength than the compressive strength. The test results also show that, within the limits of the adopted concrete type and conducted tests, the strength reduction after high temperature exposure is related to the percentage weight loss.

scholarly journals Residual Impact Performance of ECC Subjected to Sub-High Temperatures

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 454
Author(s):  
Raad A. Al-Ameri ◽  
Sallal Rashid Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Mustafa Özakça ◽  
...  
Keyword(s):  
High Temperatures ◽  
Reference Group ◽  
Impact Resistance ◽  
Impact Response ◽  
Repeated Impact ◽  
Impact Performance ◽  
Compressive And Flexural Strengths ◽  
Reference Specimens ◽  
Temperature Exposure ◽  
The Impact

Despite the fact that the mechanical properties of Engineered Cementitious Composites (ECC) after high-temperature exposure are well investigated in the literature, the repeated impact response of ECC is not yet explored. Aiming to evaluate the residual impact response of ECC subjected to sub-high temperatures under repeated drop weight blows, the ACI 544-2R repeated impact test was utilized in this study. Disk impact specimens (150 mm diameter and 64 mm thickness) were prepared from the M45 ECC mixture but using polypropylene fibers, while similar 100 mm cube specimens and 100 × 100 × 400 mm prism specimens were used to evaluate the compressive and flexural strengths. The specimens were all cast, cured, heated, cooled, and tested under the same conditions and at the same age. The specimens were subjected to three temperatures of 100, 200 and 300 °C, while a group of specimens was tested without heating as a reference group. The test results showed that heating to 100 and 200 °C did not affect the impact resistance noticeably, where the retained cracking and failure impact numbers and ductility were higher or slightly lower than those of unheated specimens. On the other hand, exposure to 300 °C led to a serious deterioration in the impact resistance and ductility. The retained failure impact numbers after exposure to 100, 200, and 300 °C were 313, 257, and 45, respectively, while that of the reference specimens was 259. The results also revealed that the impact resistance at this range of temperature showed a degree of dependency on the compressive strength behavior with temperature.

The effect of abrupt temperature increase on growth and phosphorus fractions of Pisum sativum

1969 ◽  
Vol 47 (7) ◽  
pp. 1199-1203 ◽  
Author(s):  
J. Rowell M. Potts ◽  
Douglas P. Ormrod
Keyword(s):  
High Temperature ◽  
Temperature Increase ◽  
Elevated Temperatures ◽  
Inorganic Phosphorus ◽  
Phosphorus Fractions ◽  
Internode Elongation ◽  
High Temperature Exposure ◽  
Controlled Environments ◽  
Temperature Exposure ◽  
Node Formation

Pea plants were grown in controlled environments at 25/15 C day/night temperatures and transferred abruptly to each of three higher temperatures, 32/22, 35/25, and 38/28 C, to determine the effects on growth and development and on phosphorus fractions. Samples were taken for analysis on a logarithmic high-temperature exposure time scale. Rate of node formation increased sharply during the first 24 hours of exposure to the elevated temperatures and then declined to a rate which was somewhat greater than that of 25/15 C plants. Rate of internode elongation was initially stimulated and then slowed slightly during continued high temperature exposure. Inorganic phosphorus declined slightly within 10 minutes of temperature increase but increased to about three times the original level by 6 days. Organic, lipid, and nucleic acid and protein phosphorus were not appreciably affected by the temperature change.

scholarly journals Microbiological evaluation of the impact of high temperature exposure on activity of antimicrobial drugs.

2019 ◽  
Vol 199 (1) ◽  
pp. 27-31
Author(s):  
B.Ye. Tuleubaev ◽  
◽  
D.A. Saginova ◽  
E.R. Tashmetov ◽  
A.A. Koshanova ◽  
...  
Keyword(s):  
High Temperature ◽  
Antimicrobial Drugs ◽  
High Temperature Exposure ◽  
Temperature Exposure ◽  
The Impact

scholarly journals Effect of Cement Type on the Mechanical Behavior and Permeability of Concrete Subjected to High Temperatures

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3021 ◽  
Author(s):  
Izabela Hager ◽  
Tomasz Tracz ◽  
Marta Choińska ◽  
Katarzyna Mróz
Keyword(s):  
High Temperature ◽  
Modulus Of Elasticity ◽  
Experimental Investigations ◽  
Test Results ◽  
Cement Type ◽  
High Temperature Exposure ◽  
Static Modulus ◽  
Granulated Blast Furnace Slag ◽  
Temperature Exposure ◽  
Static Modulus Of Elasticity

The paper presents experimental investigations concerning the influence of the cement type (CEMI 42.5 R Portland cement and CEMIII/A 42.5 N slag cement—with 53% granulated blast furnace slag) on the mechanical and transport properties of heated concretes. The evolution of properties due to high temperature exposure occurring during a fire was investigated. High temperature exposure produces changes in the transport and mechanical properties of concrete, but the effect of cement type has not been widely studied in the literature. In this paper, concretes were made with two cement types: CEMI and CEMIII, using basalt (B) and riverbed aggregates (RB). The compressive and tensile strength, as well as the static modulus of elasticity and Cembureau permeability, were tested after high temperature exposure to 200, 400, 600, 800, and 1000 °C. The evaluation of damage to the concrete and crack development due to high temperature effects was performed on the basis of the change in the static modulus of elasticity. The test results clearly demonstrated that permeability increases with damage, and it follows an exponential type formula for both types of cement.

scholarly journals Effect of the Curing Condition and High-Temperature Exposure on Ground-Granulated Blast-Furnace Slag Cement Concrete

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Eskinder Desta Shumuye ◽  
Jun Zhao ◽  
Zike Wang
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Curing Temperature ◽  
Stable Phase ◽  
Cement Concrete ◽  
Slag Cement ◽  
High Temperature Exposure ◽  
Curing Condition ◽  
Temperature Exposure

AbstractIn this study, the effect of curing temperature on the properties of slag cement concrete after high-temperature exposure was studied, and elevated curing temperature (45 ± 2 °C and 95% relative humidity (RH)) was selected to compare with the standard curing temperature (20 ± 2 °C and 95%RH). Four different concrete mixes with the same mix proportion, except for different slag replacement ratios, were used: 0% (reference), 30% (slag), 50% (slag), and 70% (slag). After high-temperature exposure at 200, 400, 600, and 800 °C, the effect of slag replacement, high temperature, and curing temperature on the compressive strength and mineralogical and microstructural properties of slag cement concrete were studied. Test results indicated that the compressive strength of concrete cured for 7 d at elevated temperatures increased by 28.2, 20.7, 28.8, and 14.7% compared with that cured at the standard curing condition at slag percentages of 0, 70, 50, and 30%, respectively. X-ray diffraction (XRD) and Scanning electron microscope (SEM) results revealed that concrete cured at elevated temperatures exhibited a more condensed phase and contained a higher percentage of hydrates than that cured for 7 d in the standard curing condition. However, after 56 d of curing, concrete in the standard curing condition exhibited a more stable phase and a higher concentration of hydrates.

scholarly journals Using the Plate-Creep test to determine the impact strength properties of concrete

2021 ◽  
Author(s):  
Murat Gökçe ◽  
Keyword(s):  
Impact Strength ◽  
Creep Test ◽  
Impact Test ◽  
Impact Resistance ◽  
Strength Properties ◽  
Test Results ◽  
Test Device ◽  
Concrete Mixtures ◽  
Repetitive Impact ◽  
The Impact

The paper aims to design a concrete against repetitive impact and abrasion resistance. Macro/micro steel fibers and two types of crushed stone based on limestone and corundum as aggregate were used in concrete mixtures. Impact test device has been modified, designed and used for impact strength testing of concrete. The usability of the plate creep test in determining the impact strength of concrete was also investigated. According to the test results, a high correlation was found between the abrasion, impact resistance tests and the creep test.

scholarly journals Effect of Exposure to High Temperature on the Mechanical Properties of SIFRCCs

2020 ◽  
Vol 10 (6) ◽  
pp. 2142
Author(s):  
Seungwon Kim ◽  
Topendra Oli ◽  
Cheolwoo Park
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Flexural Strength ◽  
Fire Resistance ◽  
Fiber Reinforced ◽  
High Temperature Exposure ◽  
Organic Fiber ◽  
Compressive And Flexural Strengths ◽  
Temperature Exposure ◽  
Concrete Model

Many researchers have studied explosion prevention and fire resistance of high-strength concrete mixed with organic fiber and steel fibers. The fire resistance of high-performance fiber reinforced cement composites is desirable in terms of physical and mechanical properties. However, the use of a polymer as an alternative to organic fiber has not been clearly studied. In this study, a slurry infiltration method was used to obtain slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs) specimens. Powder polymer was used instead of organic fibers during mixing of the slurry. The compressive and flexural strengths of the specimens after 1 hr of high temperature exposure according to the KS F 2257 (ISO 834) standard fire-temperature curve were measured. The addition of the polymer before and after high temperature (about 945 °C) exposure affected the strength of the SIFRCCs. The compressive and flexural strengths were decreased after exposure to high temperature in comparison with SIFRCCs without polymer because polymer create capillary pores due to melting and burning when exposure to high temperature. This minimizes the vapor pressure inside the concrete model and reduces the failure of the concrete model. The experimental results showed that the flexural strength at a high temperature for 1.0 % polymer content was the highest at 53.8 MPa. The flexural strength was reduced by 40~50% when compared to the flexural strength before high temperature exposure and comparing to SIFRCCs without polymer, the compressive strength in 1.5% polymer is lower, owing to voids that are created in the SIFRCCs after exposure to a high temperature.

Preparation and Test of Conventional Composite Abrasives Using Recycled Alumina Grains

2016 ◽  
Vol 874 ◽  
pp. 199-204 ◽  
Author(s):  
Alexandre Dutra Golanda ◽  
Sandro Galisteu Luiz ◽  
Katia C. Gandolpho Candioto ◽  
Carlos Yujiro Shigue
Keyword(s):  
Impact Strength ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Silica Content ◽  
Alumina Content ◽  
Test Results ◽  
Abrasive Tools ◽  
Penetration Tests ◽  
The Impact ◽  
Preparation And Evaluation

In this work we report the preparation and evaluation of the mechanical characteristics of resin-bond composite abrasives using virgin and recycled alumina grains. The composite abrasives were made with phenolic resin as binder and as-received virgin and recycled alumina grains. Three different recycled alumina grains were studied: i) alumina from wood firing resin-bond abrasive tools; ii) alumina from wood firing vitrified-matrix abrasive tools; and iii) ground alumina from vitrified-matrix abrasive tools. The virgin alumina grains were employed in order to compare the mechanical performance of the prepared composite abrasive. The composition of alumina grains, analyzed by X-ray fluorescence spectroscopy revealed the recycled alumina grains have lower alumina content and higher concentration of silica in vitrified-matrix abrasives samples. The sand blast penetration tests have shown lower penetration depth in the virgin and the ground vitrified-matrix grains composites. The impact strength test results revealed its dependence on the alumina and silica content: samples with higher alumina content present the higher impact resistance whereas samples with higher silica content present lower impact strength.

Novel protection solutions against environmental attack for light weight high temperature materials

2013 ◽  
Vol 1492 ◽  
pp. 155-160
Author(s):  
Alexander Donchev ◽  
Michael Schütze
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Oxidation Mechanism ◽  
Transport Systems ◽  
Surface Zone ◽  
Light Weight ◽  
Alumina Layer ◽  
High Temperature Exposure ◽  
Temperature Capability ◽  
Temperature Exposure

ABSTRACTThe use of light weight structural materials such as titanium in transport systems like aero planes leads to a significant reduction in fuel consumption. However, titanium and its alloys cannot be used at elevated temperatures above 500°C for several reasons. Today aero engine compressors are made of a mixture of light Ti- and heavy Ni-alloys. The improvement of Ti-alloys to withstand the conditions in the high pressure compressor i.e. temperatures above 500°C would enable the manufacturing of a compressor from titanium as a whole with all its associated benefits. Intermetallic TiAl-alloys are another class of light weight materials for several high temperature applications. The use of TiAl as low pressure turbine (LPT) blades in the last sections of a large jet engine could save up to 150 kg of weight. In the last sections of the LPT the temperature is quite moderate (max. 650°C). The improvement of the high temperature capability of TiAl would allow its use in hotter sections of the engine with additional weight reduction. Similarly, the response performance of TiAl-turbocharger rotors in automotive engines would be much faster compared to the heavy Ni-based alloys used today. Furthermore higher rotation speeds are possible. Due to the novel so called fluorine effect the oxidation mechanism of TiAl can be altered. Fluorine-treated TiAl-components are protected by an alumina layer formed during high temperature exposure in oxidizing environments. This effect can be transferred to Ti-base materials if they are enriched with aluminum in a thin surface zone. The concepts and the results of high temperature exposure experiments of treated Ti- and TiAl-specimens are presented in this paper. They are discussed in the view of a use for real components.

scholarly journals Mechanical and Impact Properties of Engineered Cementitious Composites Reinforced with PP Fibers at Elevated Temperatures

Fire ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 3
Author(s):  
Raad A. Al-Ameri ◽  
Sallal Rashid Abid ◽  
Mustafa Özakça
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Impact Resistance ◽  
Ductile Failure ◽  
Cementitious Composites ◽  
Repeated Impact ◽  
Normal Concrete ◽  
Engineered Cementitious Composites ◽  
Impact Performance ◽  
The Impact

The repeated impact performance of engineered cementitious composites (ECCs) is not well explored yet, especially after exposure to severe conditions, such as accidental fires. An experimental study was conducted to evaluate the degradation of strength and repeated impact capacity of ECCs reinforced with Polypropylene fibers after high temperature exposure. Compressive strength and flexural strength were tested using cube and beam specimens, while disk specimens were used to conduct repeated impact tests according to the ACI 544-2R procedure. Reference specimens were tested at room temperature, while three other groups were tested after heating to 200, 400 and 600 °C and naturally cooled to room temperature. The test results indicated that the reference ECC specimens exhibited a much higher failure impact resistance compared to normal concrete specimens, which was associated with a ductile failure showing a central surface fracture zone and fine surface multi-cracking under repeated impacts. This behavior was also recorded for specimens subjected to 200 °C, while the exposure to 400 and 600 °C significantly deteriorated the impact resistance and ductility of ECCs. The recorded failure impact numbers decreased from 259 before heating to 257, 24 and 10 after exposure to 200, 400 and 600 °C, respectively. However, after exposure to all temperature levels, the failure impact records of ECCs kept at least four times higher than their corresponding normal concrete ones.

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