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.

Influence of High-Temperature Curing on the Properties of the Concrete Containing Ground Iron and Steel Slag

2014 ◽  
Vol 507 ◽  
pp. 337-342
Author(s):  
Meng Yuan Li ◽  
Jin Hu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Steel Slag ◽  
Curing Temperature ◽  
Early Age ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Iron And Steel ◽  
Negative Effect ◽  
Curing Condition

The influence of high-temperature curing on the compressive strength and chloride permeability of the concrete containing ground iron and steel slag (GISS) was investigated. Under standard curing condition (20°C), the early-age compressive strength of the concrete with GISS is much lower than that of the pure cement concrete. The activity of GISS is more sensitive to the increase of curing temperature than that of cement. The increase amplitude of early-age strength of the concrete with GISS is much greater than that of the pure cement concrete by increasing curing temperature. Increasing curing temperature tends to decease the late-age strength and enhance the late-age permeability of concrete. The negative effect of increasing curing temperature on the late-age properties of the concrete with GISS is smaller than that of the pure cement concrete.

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.

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.

Mechanical Behavior and Recovery of FRC after High Temperature Exposure

2016 ◽  
Vol 711 ◽  
pp. 457-464 ◽  
Author(s):  
Abdullah Huzeyfe Akca ◽  
Nilüfer Özyurt
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Melting Point ◽  
Modulus Of Elasticity ◽  
Morphological Changes ◽  
Heated Surface ◽  
Fiber Reinforced Concrete ◽  
Partial Recovery ◽  
High Temperature Exposure ◽  
Temperature Exposure

During fire, one or two faces of structural members experience higher temperatures than other faces and the deterioration on these faces may continue after fire. High temperature exposure above 400 °C causes deterioration in strength, modulus of elasticity and durability of concrete. Inclusion of fibers and air entraining agents in concrete mixes may reduce the destructive effects of high temperatures on concrete. Therefore, 8 groups of 0.45 w/c ratio of concrete were designed by using polypropylene fibers as low melting point fibers and hooked end steel fibers as high melting point fibers and air entraining admixture as a chemical additive. 15 cm cubic concrete specimens were produced and the five sides of the cubes were insulated with gypsum boards to maintain one face heating. An electrical furnace was used to heat concrete to 1000 °C and K-type thermocouples were placed in specimens to monitor temperature distribution in concrete. Moreover, two different re-curing methods, air and water, were applied after heating to see the change in mechanical properties and crack occurrences on the heated surface of concrete specimens. SEM and XRD investigations were conducted on the samples taken from the heated surfaces and the inner parts of the concrete in order to understand the morphological changes due to heating and re-curing. Results showed that deterioration on the surfaces due to high temperature exposure continued during air re-curing process and compressive strength and modulus of elasticity values of these specimens also diminished. On the other hand, compressive strength of water re-cured concrete stayed constant after heating and partial recovery of modulus of elasticity were obtained and the positive effect of water re-curing were observed on polypropylene fiber reinforced concrete prominently.

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 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 Image analysis on disintegrated concrete at the post-heating stage

2020 ◽  
Vol 10 (2) ◽  
pp. 219-229
Author(s):  
A. H. Akca ◽  
N. Özyurt
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
High Temperature ◽  
Crack Growth ◽  
High Temperature Exposure ◽  
Single Lens ◽  
Temperature Exposure ◽  
Extent Of Damage ◽  
Damage In Concrete ◽  
Non Destructive

The relation between crack growth and reduction in the compressive strength after high temperature exposure and after air re-curing was investigated in this study. Concrete specimens were heated to 1000 ºC and they were subjected to air re-curing for 28 days. During re-curing period, their heated surfaces were monitored by using a digital single-lens reflex camera and the images were analyzed by using image analysis software. After cooling, the maximum reduction in the compressive strength of concrete was 49.5% and that of air re-cured concrete was 66.8%. Image analyses showed high correlations between crack growth and reduction in the compressive strength. This non-destructive method has the potential to represent the extent of damage in concrete after high temperature exposure.

Performance of Concrete at Sustained High Temperature in Material Applications

2012 ◽  
Vol 578 ◽  
pp. 150-153
Author(s):  
Hong Zhu Quan
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
High Temperature ◽  
Portland Cement ◽  
Test Results ◽  
Test Procedures ◽  
High Temperature Exposure ◽  
Concrete Properties ◽  
Early Strength ◽  
Temperature Exposure

The effects of sustained high temperature on concrete properties are discussed in this paper. In this experiment, concrete with 6 types of cement were tested after high temperature exposure. Although, test procedures were the same as past literature, test results showed different tendency. The temperature of 50°C at which compressive strength was minimal were found for concrete with high-early strength and medium-heat portland cement, which concrete with other cements showed no change up to 110°C. Relationship between weight loss and compressive strength differed from past literature.

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