Influence of the Maximum Aggregate Grain Size on the Modulus of Elasticity and on the Parameters of the Acoustic Emission of Concrete Exposed to High Temperatures

2018 ◽  
Vol 276 ◽  
pp. 134-139
Author(s):  
Libor Topolář ◽  
Dalibor Kocáb ◽  
Michaela Hoduláková ◽  
Romana Halamová
Keyword(s):  
Acoustic Emission ◽  
High Temperatures ◽  
Modulus Of Elasticity ◽  
Building Materials ◽  
Emission Method ◽  
High Rise ◽  
Grain Sizes ◽  
Static Modulus ◽  
Internal Structures ◽  
Static Modulus Of Elasticity

Several very large and tragic fires of buildings have occurred recently, drawing attention to the issues of fire resistance of buildings (especially high-rise buildings and tunnels) and of building materials. For cement-based composites, it is essential to comprehensively understand the behaviour of their internal structures when exposed to high temperatures. This paper deals with the changes of the physical properties of concrete with different aggregate grain sizes when exposed to high temperatures. The emphasis is placed on the changes of the static and dynamic modulus of elasticity as an important parameter in assessing the behaviour of structures or their parts. During the test of the static modulus of elasticity, the acoustic emission method was also used as its results may reveal the behaviour of the internal structure of the material during mechanical loading.

Experimental Analysis of the Development of Compressive Strength, Modulus of Elasticity and Acoustic Emission Parameters of Alkali-Activated Composites

2018 ◽  
Vol 760 ◽  
pp. 266-271
Author(s):  
Dalibor Kocáb ◽  
Libor Topolář ◽  
Vlastimil Bílek Jr. ◽  
Barbara Kucharczyková ◽  
Michaela Hoduláková ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Modulus Of Elasticity ◽  
Stress Test ◽  
Ultrasonic Pulse ◽  
Static Modulus ◽  
Activated Slag ◽  
Static Modulus Of Elasticity ◽  
Non Destructive ◽  
Alkali Activated

This paper describes an experiment focused on monitoring the development of the modulus of elasticity and the compressive strength of composites that are based on alkali‑activated slag (AAS) during the first 28 days of ageing. The test specimens were tested at the age of 3 and 28 days using two non-destructive methods (ultrasonic pulse and resonance methods) to determine the value of the dynamic modulus of elasticity. Subsequently, the same specimens were used to determine the static modulus of elasticity using compressive stress test, during which the behaviour of the composite was monitored by equipment for recording the acoustic emission in the material. The result of the experiment is the evaluation of the behaviour of the AAS composite in regard to the development of its modulus of elasticity and compressive strength, as well as in regard to the acoustic emission method during loading.

Nondestructive Evaluation of Red Oak and White Oak Species

2020 ◽  
Vol 70 (3) ◽  
pp. 370-377
Author(s):  
Cristian Grecca Turkot ◽  
Roy Daniel Seale ◽  
Edward D. Entsminger ◽  
Frederico José Nistal França ◽  
Rubin Shmulsky
Keyword(s):  
Modulus Of Elasticity ◽  
Longitudinal Vibration ◽  
Mechanical Tests ◽  
Modulus Of Rupture ◽  
Red Oak ◽  
Quercus Alba ◽  
White Oak ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
The Relationship

Abstract The objective of this article is to evaluate the relationship between the dynamic modulus of elasticity (MOEd), which was obtained with acoustic-based nondestructive testing (NDT) methods, and static bending properties of two domestic hardwood oak species. The mechanical properties were conducted using static modulus of elasticity (MOE) and modulus of rupture (MOR) in radial and tangential directions. Mechanical tests were performed according to ASTM D143 on small clear, defect-free specimens from the two tree species: red oak (Quercus rubra) and white oak (Quercus alba). The MOEd was determined by two NDT methods and three longitudinal vibration methods based on the fast Fourier transform. The destructive strength values obtained in this study were within the expected range for these species. The MOE was best predicted by NDT methods for both species but also had a strong capability to predict MOR.

scholarly journals Influence of Hybrid Fibers on Toughness Behavior of High Strength Flowing Concrete

2011 ◽  
Vol 57 (3) ◽  
pp. 249-260 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Mahyuddin Ramli
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Hybrid Composite ◽  
High Strength ◽  
Steel Fibers ◽  
Hybrid Fibers ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
Strength And Toughness

Abstract This study investigates the use of steel fibers and hybrid composite with a total fibers content of 2% on the high strength flowing concrete and determines the density, compressive strength, static modulus of elasticity, flexural strength and toughness indices for the mixes. The results show that the inclusion of more than 0.5% of palm fibers in hybrid fibers mixes reduces the compressive strength. The hybrid fibers can be considered as a promising concept and the replacement of a portion of steel fibers with palm fibers can significantly reduce the density, enhance the flexural strength and toughness. The results also indicates that the use of hybrid fibers (1.5 steel fibers + 0.5% palm fibers) in specimens increases significantly the toughness indices and thus the use of hybrid fibers combinations in reinforced concrete would enhance their flexural toughness & rigidity and enhance their overall performances

The Assessment of High-Temperature Degraded Concrete Specimens of Different Mixtures by Acoustic Emission Method during Three-Point Bending Test and Pulse Velocity Method in Comparison with Destructive Tests

2017 ◽  
Vol 908 ◽  
pp. 88-93 ◽  
Author(s):  
Libor Topolář ◽  
Richard Dvořák ◽  
Luboš Pazdera
Keyword(s):  
Acoustic Emission ◽  
Building Materials ◽  
Pulse Velocity ◽  
Bending Test ◽  
Structural Components ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Three Point Bending ◽  
Live Loads ◽  
Non Destructive

One of the advantages of concrete over other building materials is its inherent fire-resistive properties. The concrete structural components still must be able to withstand dead and live loads without collapse even though the rise in temperature causes a decrease in the strength and modulus of elasticity for concrete and steel reinforcement. In addition, fully developed fires cause expansion of structural components and the resulting stresses and strains must be resisted. This paper reports the results of measurements by Acoustic Emission method during three-point bending test on concrete specimens. The Acoustic emission method is a non-destructive technique used widely for structural health monitoring purposes of structures. The sensors are mounted by beeswax on the surface of the material or structure to record the motion of the surface under the elastic excitation of the cracking sources. The concrete specimens were heated in a programmable laboratory furnace at a heating rate of 5 °C/min. The specimens were loaded at six temperatures, 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, and 1200 °C maintained for 60 minutes. The results are obtained in the laboratory.

Modeling temperature effect on dynamic modulus of elasticity of red pine (Pinus resinosa) in frozen and non-frozen states

Holzforschung ◽  
2015 ◽  
Vol 69 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Shan Gao ◽  
Xiping Wang ◽  
Lihai Wang
Keyword(s):  
Temperature Effect ◽  
Modulus Of Elasticity ◽  
Freezing Point ◽  
Red Pine ◽  
Analytical Models ◽  
Clear Wood ◽  
Green Wood ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
Increasing Temperature

Abstract The response of dynamic and static modulus of elasticity (MOEdyn and MOEsta) of red pine small clear wood (25.4×25.4×407 mm3) within the temperature range -40 to 40°C has been investigated. The moisture content (MC) of the specimens ranged from 0 to 118%. The MOEdyn was calculated based on measured ultrasonic velocity (V) and wood density. The MOEsta was measured by static bending tests in a climate chamber between -40 and 40°C. The results indicate that both MOEdyn and MOEsta were affected by temperature and the MC. Above freezing point, MOE decreased linearly at a slow rate with increasing temperature. Below freezing point, MOE increased at a rapid rate with decreasing temperature. The MC-level had a significant effect on the MOE-temperature relationships. Temperature effect was much more significant in green wood than in dry wood. Analytical models were developed to predict the change of MOEdyn relative to that at 20°C in the case of acoustic measurements under different temperature conditions.

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