scholarly journals Recent Advances in Strain-Hardening UHPC with Synthetic Fibers

2021 ◽  
Vol 5 (10) ◽  
pp. 283
Author(s):  
Jian-Guo Dai ◽  
Bo-Tao Huang ◽  
Surendra P. Shah
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Strain Hardening ◽  
Crack Width ◽  
Tensile Strain ◽  
Cumulative Probability ◽  
Strain Capacity ◽  
Synthetic Fibers ◽  
Recent Advances ◽  
Tensile Strain Capacity

This paper summarizes recent advances in strain-hardening ultra-high-performance concretes (UHPC) with synthetic fibers, with emphasis on their tensile properties. The composites described here usually contain about 2.0% high-density polyethylene (PE) fibers. Compared to UHPC with steel fibers, strain-hardening UHPC with synthetic fibers generally show a higher tensile ductility, lower modulus in the cracked state, and relatively lower compressive strength. The tensile strain capacity of strain-hardening UHPC with synthetic fibers increases with increasing tensile strength. The f’cftεt/w index (compressive strength × tensile strength × tensile strain capacity/tensile crack width) is used to compare the overall performance of strain-hardening UHPC. Moreover, a probabilistic approach is applied to model the crack width distributions of strain-hardening UHPC, and estimate the critical tensile strain in practical applications, given a specific crack width limit and cumulative probability. Recent development on strain-hardening UHPC with the use of seawater, sea-sand and PE fibers are also presented.

scholarly journals Strain-Hardening and High-Ductile Behavior of Alkali-Activated Slag-Based Composites with Added Zirconia Silica Fume

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3523 ◽  
Author(s):  
Jeong-Il Choi ◽  
Se-Eon Park ◽  
Huy Hoàng Nguyễn ◽  
Sang Lyul Cha ◽  
Bang Yeon Lee
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Silica Fume ◽  
Tensile Strain ◽  
Alkali Activated Slag ◽  
Strain Capacity ◽  
Activated Slag ◽  
Ductile Behavior ◽  
Tensile Strain Capacity ◽  
Alkali Activated

This paper presents an experimental study on the effects of zirconia silica fume on the composite properties and cracking patterns of fiber-reinforced alkali-activated slag-based composites. Four mixtures were prepared with added zirconia silica fume and varying water-to-binder ratio. Polyethylene fiber was used as a reinforcing fiber for all the mixtures at a volumetric ratio of 2.0% cubic specimens and uniaxial tensile specimens were prepared to evaluate their density, compressive strength, and tensile behavior. The test results demonstrated that the compressive strength, tensile strength, and tensile strain capacity of the composite can be simultaneously improved by incorporating zirconia silica fume. A mixture incorporating zirconia silica fume showed high-ductile behavior of 26.5% higher tensile strength, and 13.7% higher tensile strain capacity than the mixture without zirconia silica fume. The composite with added zirconia silica fume also showed excellent cracking patterns, i.e., narrow crack spacing and crack width.

scholarly journals Development of Engineered Cementitious Composites Using Sea Sand and Metakaolin

2021 ◽  
Vol 8 ◽  
Author(s):  
Qiyao Yao ◽  
Zuo Li ◽  
Chenyu Lu ◽  
Linxin Peng ◽  
Yuejing Luo ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fracture Energy ◽  
Tensile Strain ◽  
Chloride Ions ◽  
Silica Sand ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Strain Capacity ◽  
Sea Sand ◽  
Tensile Strain Capacity

The present study investigates the possibility of using sea sand, instead of silica sand, in producing engineered cementitious composites (ECCs) and the optimal mix proportion, mechanical behavior, and erosive effect of chloride ions on sea sand ECCs (SECCs). Nine groups of SECC specimens were prepared based on the orthogonal test design, and these cured for the uniaxial tensile, uniaxial compression, and fracture energy tests. The roundness and sphericity of sea sand and silica sand were quantified by digital microscopy. The microstructure and composition of SECCs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mix proportions of SECCs with a tensile strain capacity more than 2% and a compressive strength more than 60 MPa were obtained. The factor analysis of these serial tests revealed that the contents of both fly ash and sea sand have a significant effect on the compressive strength and tensile strain capacity of SECCs. The fracture energy test revealed that the matrix fracture toughness of SECCs significantly increases with the increase in sea sand content. The XRD analysis revealed that the addition of metakaolin can enhance the ability of SECCs to bind chloride ions, and with the increase in chloride ion content, the ability of SECCs to bind chloride ions would improve. The results of the present study provide further evidence of the feasibility of using sea sand in the production of ECCs, in order to meet the requirements of diverse concrete components on ductility and durability.

A Study on Flexural Performance of RC Beam Strengthened with UHTCC for Improved Durability

2008 ◽  
Vol 400-402 ◽  
pp. 43-54
Author(s):  
Shi Lang Xu ◽  
Xiu Fang Zhang ◽  
Christopher K.Y. Leung
Keyword(s):  
Composite Beam ◽  
Crack Width ◽  
Tensile Strain ◽  
Experimental Results ◽  
Rc Beam ◽  
Rc Beams ◽  
Strain Capacity ◽  
Flexural Performance ◽  
High Toughness ◽  
Tensile Strain Capacity

Ultra-high toughness cementitious composite (UHTCC) exhibits the pseudo-hardening feature when subjected to tensile load and has high tensile strain capacity of normally up to 3%. Also, UHTCC has a unique cracking behavior. From cracking up to ultimate tensile strain capacity, the crack width in UHTCC could be still kept below 100m. This paper presents the utilization of UHTCC to replace a layer of concrete surrounding the main flexural reinforcement in ordinary RC beam to improve flexural performance especially beam durability as UHTCC displays high toughness and shows multiple fine cracks. Analytical closed-form formulae for flexural capacity, curvature and deformation of UHTCC/RC composite beam derived based on the elastic beam theory is presented first. Subsequently, experimental results of two groups of different reinforcement ratios of UHTCC/RC beams and control RC beams tested under flexural loading to verify the feasibility of analytical formulae as well as to examine the performance improvement of UHTCC/RC composite beam over the control beam is presented. Moment-curvature curves and load-mid span displacement curves for the tested beams are compared with the theoretical analysis. A good agreement between experimental and analytical results is found. The experimental results show that the use of a layer of UHTCC in RC beams can enhance both flexural capacity and ductility. The improvement is not significant with the increase in reinforcement ratio; however, the maximum crack width under service load even in the case of lightly reinforced beams can be limited within 0.1mm.

scholarly journals Effects of Supplementary Cementitious Materials and Curing Condition on Mechanical Properties of Ultra-High-Performance, Strain-Hardening Cementitious Composites

2021 ◽  
Vol 11 (5) ◽  
pp. 2394
Author(s):  
Min-Jae Kim ◽  
Booki Chun ◽  
Hong-Joon Choi ◽  
Wonsik Shin ◽  
Doo-Yeol Yoo
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Strain Hardening ◽  
High Performance ◽  
Tensile Behavior ◽  
Supplementary Cementitious Materials ◽  
Cementitious Composites ◽  
Cement Kiln ◽  
Strain Capacity ◽  
Test Result

This study investigated the influence of ordinary Portland cement (OPC) and reactive and non-reactive mineral additives on the characteristic microstructure and mechanical performance of ultra-high-performance, strain-hardening cementitious composites (UHP–SHCCs). Nine mixes of cementitious composites were considered composed of reactive and non-reactive materials, such as ground granulated blast furnace slag (GGBS), silica fume (SF), cement kiln dust (CKD), and silica flour. Compressive strength and direct tensile tests were performed on the nine mixes cured for 7 d and 28 d. The test result was analyzed based on microstructural inspections, including thermogravimetry and scanning electron microscopy. The test result and analysis showed that the microstructural property of the UHP–SHCC impacted the compressive strength and the tensile behavior and also influenced the fiber-matrix interaction. Although most of the 7 d cured specimens did not exhibit notable strain-hardening behaviors, the specimen containing the CKD exhibited a tensile strength of 11.6 MPa and a very high strain capacity of 7.5%. All the specimens with OPC, silica flour, GGBS, or SF exhibited considerably improved tensile behavior at 28 d. The specimen with only OPC as a binder could achieve the tensile strength of 11.6 MPa and strain capacity of 6.2%.

Durability of Mechanically Loaded Strain-Hardening Cement-Based Composites (SHCC)

2011 ◽  
Vol 306-307 ◽  
pp. 577-581
Author(s):  
Wei Qun Cao ◽  
Li Tian ◽  
Tie Jun Zhao
Keyword(s):  
Composite Material ◽  
Tensile Stress ◽  
Strain Hardening ◽  
Crack Width ◽  
Tensile Strain ◽  
Crack Formation ◽  
Multiple Cracks ◽  
Crack Bridging ◽  
Strain Capacity ◽  
Increased Strength

Strain-hardening cement-based composites (SHCC) resist increased tensile stress after first crack formation, over a significant range of tensile strain. This increased strength and strain capacity is achieved by effective crack bridging by fibres, across multiple cracks of widths in the micro-range. Whether the crack width limitation translates into increased durability through retardation of ingress of moisture, gas and other deleterious matter, is scrutinised in this paper. The potential of the comparatively new composite material becomes obvious, yet it is clearly outlined that further research is necessary before we fully understand the basic mechanisms underlying durability of SHCC.

Multi-Tier Tensile Strain Models for Strain-Based Design: Part 2 — Development and Formulation of Tensile Strain Capacity Models

2012 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang ◽  
Yaxin Song ◽  
David Horsley ◽  
Steve Nanney
Keyword(s):  
Driving Force ◽  
Tensile Strain ◽  
Weld Strength ◽  
Experiment Data ◽  
Pipe Wall Thickness ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Welding Processes ◽  
Tensile Strain Capacity

This is the second paper in a three-paper series related to the development of tensile strain models. The fundamental basis of the models [1] and evaluation of the models against experiment data [2] are presented in two companion papers. This paper presents the structure and formulation of the models. The philosophy and development of the multi-tier tensile strain models are described. The tensile strain models are applicable for linepipe grades from X65 to X100 and two welding processes, i.e., mechanized GMAW and FCAW/SMAW. The tensile strain capacity (TSC) is given as a function of key material properties and weld and flaw geometric parameters, including pipe wall thickness, girth weld high-low misalignment, pipe strain hardening (Y/T ratio), weld strength mismatch, girth weld flaw size, toughness, and internal pressure. Two essential parts of the tensile strain models are the crack driving force and material’s toughness. This paper covers principally the crack driving force. The significance and determination of material’s toughness are covered in the companion papers [1,2].

Estimation of Tensile Strain Capacity of Vintage Girth Welds

2021 ◽  
Author(s):  
Banglin Liu ◽  
Bo Wang ◽  
Yong-Yi Wang ◽  
Otto Jan Huising
Keyword(s):  
Tensile Strain ◽  
Strain Capacity ◽  
Girth Welds ◽  
Tensile Strain Capacity
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