scholarly journals Bond Behavior of Reinforcing Steel Bars in Thermal Insulation Concrete Exposed to Freeze-Thaw Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Jinsong Tu ◽  
Ming Zhou ◽  
Yuanzhen Liu ◽  
Y. Frank Chen
Keyword(s):  
Mechanical Properties ◽  
Thermal Insulation ◽  
Ct Scanning ◽  
Reinforcing Steel ◽  
Freezing And Thawing ◽  
Scanning Method ◽  
Bond Behavior ◽  
Freeze Thaw ◽  
Bond Performance ◽  
Steel Bars

An experimental study on the bond behavior of reinforcing steel bars in thermal insulation concrete (TIC) mixed with glazed hollow beads (GHBs) and exposed to freeze-thaw (F-T) cycles was carried out. In order to investigate the effects of GHBs on freezing and thawing, the experimental results were compared with those of normal concrete (NC). The comparison shows that, after 300 F-T cycles, both bond behavior and mechanical properties of the TIC specimens are better than those of the NC specimens. Furthermore, in order to investigate the mechanism of frost effect on TIC, the CT scanning method was used to investigate the evolution of the inner structure of a TIC specimen exposed to F-T cycles. The CT images show that the deterioration of bond performance and mechanical properties of the TIC specimen appears to be caused by the increase of micropores in the TIC.

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

scholarly journals Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Chen ◽  
Jinjin Zhang ◽  
Jin Yang ◽  
Feilong Ye
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strength Steel ◽  
High Strength ◽  
Tensile Tests ◽  
Reinforcing Steel ◽  
Test Results ◽  
Cross Sectional ◽  
Steel Bars

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

Determination of Some Mechanical Properties of Welded Reinforcing Steel with Self-Shielded Wires by Vibration Tests

2014 ◽  
Vol 1029 ◽  
pp. 206-211 ◽  
Author(s):  
Liviu Bereteu ◽  
Mircea Burcă ◽  
Raul Moisa ◽  
Dorin Simoiu ◽  
Gheorghe Drăgănescu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
Steel Reinforcement ◽  
Reinforcing Steel ◽  
Coated Electrode ◽  
Major Disadvantage ◽  
Steel Bars ◽  
Vibration Tests ◽  
The Cost

Reinforced concrete is a material formed by pouring concrete over reinforcement steel bars and wires and sometimes by a polymer that turns by drying in a hard and rigid composite. Welding of steel reinforcement concrete is a relatively difficult operation and with a large amount of work, given by the large number of welds that are needed and when this work is make in site conditions. The most common method of steel reinforcement welding is manual welding with coated electrode. The major disadvantage of this process is low productivity in welding effects on execution time, and the cost of welding. An alternative to manual welding with coated electrode for steel reinforcement welding on site is the welding process with self-shielded tubular wires.The aim of this paper is to determine the mechanical properties of welded reinforcing steel PC 52 with self-shielded wires, using a vibroacustic technique. To validate this method, the results obtained by vibroacoustic signal processing are compared with those determined by the tensile stresses of the same samples.

scholarly journals Essential Mechanical Properties of Structural Steels for Steel Reinforced Buildings in the Earthquake Sensitive Areas

2011 ◽  
Vol 4 (1) ◽  
pp. 51 ◽  
Author(s):  
M. A. Islam
Keyword(s):  
Mechanical Properties ◽  
Structural Steel ◽  
Fatigue Loading ◽  
Structural Steels ◽  
Reinforcing Steel ◽  
High Rise ◽  
Steel Bar ◽  
Steel Bars ◽  
Cyclic Type ◽  
Earthquake Effects

During earthquake, the ground along with its various natural and manmade structures experiences shaking of various intensities and frequencies depending on the nature of the earthquake. The loading activities caused by earthquakes on various structures are very much cyclic type, which is popularly known as fatigue loading. On the other hand, for modern high-rise buildings a large volume of steel bar is used to reinforce the concrete because of the pioneer role of steel bars embedded inside the concrete for safety of the buildings. In this study various mechanical properties of reinforcing steel bars that are essential to counter balance the earthquake effects have been identified first. At the same time these essential mechanical properties have been defined and studied for most commonly used reinforcing steel bars. For doing this, both the conventional and advanced structural steels were selected. The mechanical properties and fatigue behaviours of these steels have been presented and discussed in this paper.  Keywords: Earthquake; High-rise buildings; Reinforcing steel bars; Conventional structural steel; Advanced structural steel.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i1.7069 J. Sci. Res. 4 (1), 51-63 (2012)

scholarly journals Chemical and Mechanical Properties of Reinforcing Steel Bars from Local Steel Plants

2019 ◽  
Vol 19 (4) ◽  
pp. 1067-1076
Author(s):  
Jamiu Kolawole Odusote ◽  
Wasiu Shittu ◽  
Adekunle Akanni Adeleke ◽  
Peter Pelumi Ikubanni ◽  
Olumide Adeyemo
Keyword(s):  
Mechanical Properties ◽  
Reinforcing Steel ◽  
Steel Bars

Microstructure and mechanical behavior of asphalt mixture based on freeze-thaw cycle

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ning Wang ◽  
Haitao Zhang ◽  
Huizhong Xiong
Keyword(s):  
Mechanical Properties ◽  
External Force ◽  
Asphalt Mixture ◽  
Particle Sizes ◽  
Freezing And Thawing ◽  
Content Type ◽  
Freeze Thaw ◽  
Thawing Cycle ◽  
Before And After ◽  
Cold Area

PurposeIn order to unravel the evolution of microstructure characteristics and the change of mechanical properties of bituminous mixture in the freezing and thawing environment in cold region, this study starts from macroscopic experiments and analyzes the changes in mechanical properties of asphalt mixtures before and after freezing and thawing in detail. On this basis, the displacement of key particles in the structure of asphalt mixture under the action of external forces (before and after freezing and thawing) is simulated through the combination macroscopic and microscopic methods.Design/methodology/approachThe climate in China exhibits high complexity and diversity, divided into five zones based on the temperature difference from south to north. Considering that the significant effect of geography and natural climate on the design, construction and maintenance of asphalt pavement, the criterion for the road construction at different areas should be highly different.FindingsThe results show that the mechanical properties of asphalt mixture greatly decrease due to the influence of freeze-thaw, and the displacement of key particles in the structure of asphalt mixture (several representative particle sizes were selected through experiments) is obviously observed because of the action of external force. By analyzing the variation of several key particle sizes after freezing-thawing cycle, the gradation standard of asphalt mixture aggregate suitable for cold area was obtained. The research results have certain theoretical and practical value for the design and application of asphalt mixture in cold area.Originality/valueThe results show that the mechanical properties of asphalt mixture greatly decrease due to the influence of freeze-thaw, and the displacement of key particles in the structure of asphalt mixture (several representative particle sizes were selected through experiments) is obviously observed because of the action of external force. By analyzing the variation of several key particle sizes after freezing-thawing cycle, the gradation standard of asphalt mixture aggregate suitable for cold area was obtained. The research results have certain theoretical and practical value for the design and application of asphalt mixture in cold area.

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