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 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.

Repeatability and Reproducibility of the Static Elastic Modulus of Concrete Measurement

2018 ◽  
Vol 272 ◽  
pp. 214-219
Author(s):  
Petr Misák ◽  
Tomáš Vymazal ◽  
Dalibor Kocáb ◽  
Barbara Kucharczyková
Keyword(s):  
Elastic Modulus ◽  
Statistical Methods ◽  
Modulus Of Elasticity ◽  
Interlaboratory Comparison ◽  
Hardened Concrete ◽  
Test Results ◽  
Static Modulus ◽  
Repeatability And Reproducibility ◽  
Expected Values ◽  
Static Modulus Of Elasticity

In recent years, the static modulus of elasticity is one of the most discussed property of hardened concrete. The aim of this article is to show results of 6 performed experiments focused on test results precision. The measurements were made according to the standards ISO 6784 and ISO 1920-10. More than 20 participants (laboratories) from Europe took part in these experiments. Test results were compared using the statistical methods for interlaboratory comparison. Repeatability and reproducibility, which provide more detailed information about range of expected values of elastic modulus, are the most discussed characteristics in the article.

Experimental Assessment of the Influence of Multiple Cyclic Loading on Selected Properties of Lightweight Concrete

2019 ◽  
Vol 292 ◽  
pp. 45-49
Author(s):  
Petr Misák ◽  
Dalibor Kocáb ◽  
Martin Alexa ◽  
Barbara Kucharczyková ◽  
Petr Daněk ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Cyclic Loading ◽  
Modulus Of Elasticity ◽  
Test Specimen ◽  
Lightweight Concrete ◽  
Test Results ◽  
Static Modulus ◽  
Before And After ◽  
The Difference ◽  
Static Modulus Of Elasticity

The paper deals with results of the experiment when ordinary and lightweight concrete was subjected to cyclic loading. Each test specimen was loaded with the force equivalent to one third of the expected compressive strength value similarly to the static modulus of elasticity test with the difference that the total number of loading cycles was nearly 4500. Dynamic modulus of elasticity and compressive strength was measured before and after cyclic loading. The result of this experiment is statistical analysis of the test results and assessment of the influence of multiple cyclic loading.

scholarly journals Suppressing the oxygen ingress into Ti-alloys by a one-step Al- plus F-treatment

2020 ◽  
Vol 321 ◽  
pp. 06003
Author(s):  
Alexander Donchev ◽  
Mathias Galetz
Keyword(s):  
High Temperature ◽  
Alumina Scale ◽  
Experimental Investigations ◽  
Oxygen Solubility ◽  
Surface Zone ◽  
High Temperature Exposure ◽  
Ti Alloys ◽  
One Step ◽  
Oxygen Ingress ◽  
Temperature Exposure

Oxygen ingress into technical Ti-alloys during high temperature exposure in oxygen containing environments leads to an enriched surface zone due to the high oxygen solubility in titanium. This affected zone is known as alpha case and is embrittled compared to the substrate material. Therefore, the operating temperature of these alloys is limited. An enrichment of Al in the surface zone of Ti-alloys leads to an improvement by the formation of intermetallic TixAly-phases with decreased oxygen solubility. This one-step Al-enrichment plus a F-treatment is proposed for the formation of a continuous stable alumina scale which prevents oxygen inward diffusion. In this paper the results of high temperature exposure tests in air of technical Ti-alloys are presented without any treatment and treated with Al-enrichment including fluorination. Post experimental investigations such as SEM reveal the formation of thin alumina layers on treated samples. Hardness measurements confirm that no embrittlement was observed for the treated samples while untreated specimens show increased hardness values in the subsurface zone corresponding with the oxygen inward diffusion profile.

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.

scholarly journals Modulus elasticity of the graded concrete, a preliminary research

2018 ◽  
Vol 195 ◽  
pp. 01005 ◽  
Author(s):  
M. Mirza Abdillah Pratama ◽  
B. Sri Umniati ◽  
Bunga Arumsari Mutiara Wulandari ◽  
Ay Lie Han ◽  
Buntara Sthenly Gan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Modulus Of Elasticity ◽  
Concrete Strength ◽  
Test Results ◽  
Structural Element ◽  
Concrete Material ◽  
Static Modulus ◽  
Preliminary Research ◽  
Static Modulus Of Elasticity

The elastic modulus of materials plays a role in determining the stiffness of a structural element and its level of serviceability. Previous research indicates that the concrete modulus of elasticity could be improved by combining 2 (two) concrete mixes using a gradual compacting method. In this study, the effect of different concrete strength combinations to the resulting modulus of elasticity is examined. Three types of concrete mixes with a strength of 30 MPa, 40 MPa and 50 MPa are prepared. The graded concrete is moulded in cylindrical concrete casts (150 mm x 300 mm) with the following casting configurations: 30-40 MPa, 30-50 MPa, and 40-50 MPa. The static modulus of elasticity test is performed at an age of 28 days using compressometers in accordance with ASTM C469. The test results show that the modulus of elasticity of the graded concrete is proportionally influenced by the stiffness of the higher and the lower concrete material. Additionally, the resulting compressive strength of the graded concrete is determined by the lower concrete strength.

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.

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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