scholarly journals Steel Reinforcing Bar and Steel Fibers Content Effect on Tensile and Electrical Behaviors of Strain-Hardening Cement Composite (SHCC) with MWCNTs in Direct Tension

2021 ◽  
Vol 11 (5) ◽  
pp. 2446
Author(s):  
Dong-Hui Kim ◽  
Wan-Shin Park ◽  
Sun-Woo Kim ◽  
Moon-Sung Lee ◽  
Soo-Yeon Seo ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Tensile Strain ◽  
Cement Composite ◽  
Initial Crack ◽  
Steel Fibers ◽  
Cement Composites ◽  
Electrical Behavior ◽  
Direct Tension ◽  
Reinforcing Bar ◽  
Steel Bar

This research examines the influence of an embedded steel reinforcing bar and micro steel fibers on the tensile and electrical properties of polyethylene (PE) fibers reinforced cement composite dumbbell-shaped specimens with multi-walled carbon nanotubes (MWCNTs) in direct tension. The cement composites are reinforced with 0.75 vol.% PE fibers to achieve a strain-hardening performance in direct tension and 1.0 wt % MWCNTs are incorporated to give the electrical conductivity into the cement composites. To investigate the steel bar and steel fibers effect on the electrical behavior of synthetic PE fiber reinforced strain-hardening cement composites (PE-SHCCs), a round bar with a diameter of 4 or 7 mm is placed at the center of specimen’s cross-section. Additionally, steel fibers’ content of 0, 0.5 and 1.0 vol.% are added into the PE-SHCC mixtures. The test result indicates that the addition of steel fibers improves the tensile strength and electrical behavior of synthetic PE fiber reinforced SHCC. The self-sensing ability of PE-SHCC with 1.0% steel fibers is improved by the presence of the embedded steel bar before an initial crack while the reinforced PE-SHCC specimens were less sensitive as the tensile strain increased after the initial crack. The optimal linear regressions between fractional changes in resistivity (FCR) and tensile strain were achieved for PE-SHCC containing 1.0% steel fibers.

Tensile and Cracking Behaviors of Strain-Hardening Cement Composite (SHCC) with Fluosilicate Based Shrinkage-Reducing Agent (SRA)

2014 ◽  
Vol 525 ◽  
pp. 473-477 ◽  
Author(s):  
Seung Ju Han ◽  
Seok Joon Jang ◽  
Zhong Jie Yu ◽  
Hyun Do Yun
Keyword(s):  
Strain Hardening ◽  
Volume Fraction ◽  
Cement Composite ◽  
Tensile Tests ◽  
Reducing Agent ◽  
Direct Tension ◽  
Direct Tension Test ◽  
Rich Mixture ◽  
Direct Tensile ◽  
Shrinkage Reducing Agent

This paper provides the results of direct tensile tests for strain-hardening cement composite (SHCC) to investigate the influence of fluosilicate based shrinkage-reducing agent (SRA) on the tensile and cracking behaviors of SHCC material under direct tension. The specified compressive strength of the SHCC material is 50MPa. The adding ratio of fluosilicate based SRA for SHCC material is 2.5 and 5.0%. Two mixitures of SHCC with 2.2% polyvinyl alcohol (PVA) fibers at the volume fraction were mixed; two mixtures with SRA and one mixture of conventional SHCC material. To evaluate the tensile and cracking behaviors of SHCC materials, two dumbbell-shaped tensile specimens for each mixture were manufactured and tested in direct tension. Test results show that the addition of fluosilicate based SRA improved direct tensile and cracking behaviors of SHCC materials with rich mixture. This phenomenon is noticeable for SHCC with higher volume of SRA.

EFFECT OF RECYCLED MATERIALS ON THE TENSILE BEHAVIOR OF STEEL FIBER-REINFORCED CEMENT COMPOSITE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Sun-Woo Kim ◽  
Wan-Shin Park ◽  
Young-Il Jang ◽  
Yi-Hyun Nam ◽  
Sun-Woong Kim ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Steel Fiber ◽  
Cement Composite ◽  
Fine Aggregate ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Direct Tension ◽  
Recycled Materials ◽  
Reinforced Cement

Conventional cement composite is generally produced with ordinary Portland cement (OPC) as a binder. However, during manufacturing the cement composite, large amount of carbon dioxide (CO2) are emitted. Therefore, fly ash is proposed to be replaced to OPC in order to reduce CO2 emission of cement composites. For reinforcing fibers, micro steel fibers were used. For investigating mechanical properties of steel fiber-reinforced cement composites (SFRCCs), direct tension tests were conducted. The test results showed that fly ash improves tensile strength and ductility of SFRCCs. However, tensile strength of the SFRCC decreased as replacement ratio of recycled fine aggregate increased. The use of recycled materials in FRCC helps to save natural resources and promote sustainability in civil engineering materials.

Effects of Shrinkage Reducing Admixture (SRA) on the Tensile Behavior of Strain-Hardening Cement Composite (SHCC)

2013 ◽  
Vol 372 ◽  
pp. 203-206
Author(s):  
Seung Ju Han ◽  
Hye Ran Kim ◽  
Hyun Do Yun
Keyword(s):  
Strain Hardening ◽  
Volume Fraction ◽  
Cement Composite ◽  
Tensile Behavior ◽  
Direct Tension ◽  
Air Content ◽  
Shrinkage Reducing Admixture ◽  
Cracking Characteristics ◽  
Shrinkage Reducing Admixtures ◽  
Change Material

This research investigates the influence of shrinkage reducing admixture (SRA) on the tensile behavior of strain-hardening cement composite (SHCC). SHCC materials with specified compressive strength of 50MPa were mixed and tested. All SHCC mixes with different dosage of shrinkage reducing admixtures were reinforced with 2.2 % polyvinyl alcohol (PVA) fibers at the volume fraction. A special SRA, i.e. strontium (Sr)-based SRA, used in this study was based on a phase change material (PCM) that has the ability to absorb or release the hydration heat of cement composite. This paper focuses on the tensile behavior and cracking characteristics of SHCC materials under direct tension. The effect of a special SRA on the fresh properties, such as flow and air content, and hardened properties of SHCC materials was investigated. Test results showed that SRA reduces the air content of SHCC material. The SRA can also improve the tensile strength of SHCC material.

Strain-hardening and cracking behavior of fiber-reinforced sustainable cement composites under direct tension

2015 ◽  
Vol 8 ◽  
pp. 757-764
Author(s):  
Seok-Joon Jang ◽  
Dae-Hyun Kang ◽  
Kyung-Lim Ahn ◽  
Hyun-Do Yun ◽  
Sun-Woo Kim ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Direct Tension ◽  
Cracking Behavior

Tension Stiffening and Cracking Behavior of Ultra High Strength Strain-Hardening Cement Composite (UHS-SHCC) Ties in Monotonic and Cyclic Tension

2012 ◽  
Vol 204-208 ◽  
pp. 3982-3985
Author(s):  
Young Jae Song ◽  
Hyun Do Yun
Keyword(s):  
Strain Hardening ◽  
High Strength ◽  
High Volume ◽  
Cement Composite ◽  
Initial Crack ◽  
Conventional Concrete ◽  
Tension Stiffening ◽  
Cracking Behavior ◽  
Cyclic Tension ◽  
Reinforced Cement

This study investigates the tensile response of reinforced ultra high strength strain- hardening cement composite (UHS-SHCC) ties in directly monotonic and cyclic tension. The UHS-SHCC exhibits valuable material properties such as high compressive strength, tensile strain-hardening and ductility. However, UHS-SHCC requires high volume of cement, which leads to more shrinkage than conventional concrete. Authors have considered replacing a part of cement by the expansive admixture (EXA) for compensating the shrinkage of UHS-SHCC. Specifically, this paper explores the structural application of a shrinkage-compensating UHS-SHCC to improve tension stiffening in structural members. The cement composite type and EXA replacement were taken as experimental parameters. All specimens had a square cross-section dimension of 100 x 100mm and length of 1,500mm. The test results indicate that the shrinkage compensating UHS-SHCC is very effective to improve tension stiffening behavior and initial crack load of reinforced cement composite ties.

scholarly journals DESIGN OF CEMENT COMPOSITES WITH INCREASED IMPERMEABILITY

Vestnik MGSU ◽  
2016 ◽  
pp. 72-81
Author(s):  
Roman Sergeevich Fedyuk
Keyword(s):  
Composite Materials ◽  
Cement Composite ◽  
Vapor Permeability ◽  
Cement Stone ◽  
Cement Composites ◽  
Hydrated Cement ◽  
Body Density ◽  
Scale Levels ◽  
Positive Effect ◽  
Improved Characteristics

The paper deals with the development of composite binders for producing concrete with improved characteristics of gas, water and vapor permeability. The authors investigate the processes of composite materials formation in order of decreasing scale levels from macro to nanostructures. The criteria for optimization of the volume of dispersed additives in concrete are offered. The authors theoretically studied the technological features of the formation of hydrated cement stone structure. A positive effect of nanodispersed additives on the structure and physico-mechanical properties of cement composite materials are predicted. Thanks to its improved features, such as good ratio of strength and body density, high density and lifetime, the modified concrete may be used when solving various practical tasks of the construction branch.

scholarly journals Using scanned images to estimate salt formation on the surface of cement composites

Vestnik MGSU ◽  
2020 ◽  
pp. 1523-1533
Author(s):  
Vladimir T. Erofeev ◽  
Victor V. Afonin ◽  
Tatiana F. Elchishcheva ◽  
Marina M. Zotkina ◽  
Irina V. Erofeeva
Keyword(s):  
Building Materials ◽  
Control Sample ◽  
Cement Composite ◽  
Operating Conditions ◽  
Cement Composites ◽  
High Humidity ◽  
Grayscale Image ◽  
Salt Formation ◽  
Scanned Images ◽  
Composite Samples

Introduction. An engineering method is proposed for assessing salt formation on the surface of cement composites exposed to adverse operating conditions. The technique is based on the histogram method used to determine the dominant brightness of the half-tone image of scanned cement composites. The criterion for ranking composites is a relative dimensionless value –– a metric obtained by comparing the brightness of a grayscale image with the brightness level of white. Materials and methods. We selected three types of compositions of composites in the amount of 21 items; each of them contains three samples –– a control sample and samples exposed to high humidity and positive temperatures for 15 and 45 days. Each composition is represented by a scanned raster image of the sample surface. The images are further subjected to digital processing using a software program written in the C++ programming language and the OpenCV technical vision library. This allows you to use the available methods and classes to develop algorithms to solve the problem in question and to convert a full-color RGB image to a grayscale image. Such images are used to analyze histograms, which determine the dominant level of brightness to determine the numerical metric for quantifying the salt formation on the surface of cement composite samples on the basis of their scanned images. Results. A description of the software algorithm, used to detect salt formation on the surface of cement composite specimens that have passed performance tests under high humidity conditions at positive temperatures, is presented. The method of ranking cement composite samples using the values of their dominant brightness relative to the brightness of control samples is shown. The comparative analysis of the study is presented in the form of numerical data and explanatory diagrams. Conclusions. Software modeling is employed to demonstrate the expediency of the methodology for the assessment of salt formation on the surface of cement composites and other building materials prone to salt formation.

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