scholarly journals Performance of Strain hardening cementitious composite as strengthening and protective overlay in flexural members

2018 ◽  
Vol 199 ◽  
pp. 09005 ◽  
Author(s):  
Sardar Umer Sial ◽  
M. Iqbal Khan
Keyword(s):  
Strain Hardening ◽  
Protective Layer ◽  
Bending Test ◽  
Rc Beams ◽  
Crack Control ◽  
Concrete Overlays ◽  
Flexural Response ◽  
Four Point Bending ◽  
Beam Height ◽  
Scale Control

Strain-hardening cementitious composites (SHCC) are advanced type of cement-based composite materials having superior crack control and tensile properties. Owing to such characteristics, SHCC can be used for strengthening and crack-width control of structural members. This paper presents a study on the flexural response of reinforced concrete (RC) beams with different overlays of SHCC. The work consists of RC-SHCC overlay beams, in which SHCC overlays of different thicknesses (15% and 30% of beam height, plus cover) and reinforcement ratios (0% and 0.4%) were cast at the bottom of the RC beams. The performance of the RC-SHCC overlay beams was compared with control RC beams having concrete overlays of similar parameters. A series of eight laboratory-scale control and composite beam specimens were tested under four-point bending test. From the experimental results, it was observed that RC-SHCC overlay beams showed improved flexural capacity and crack control as compared to that of control beams. The beams with unreinforced SHCC overlays showed significant improvement at service stage, while beams with reinforced SHCC overlays showed significant improvement at peak stage. The SHCC overlay beams without reinforcement have showed improved ductility as compared to control beams with concrete overlays. Additionally, the SHCC overlays performed as a protective layer for controlling the crack widths in the composite beams.

scholarly journals Study of Flexural Response in Strain Hardening Cementitious Composites Based on Proposed Parametric Model

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 113 ◽  
Author(s):  
Zhanfeng Qi ◽  
Zhiyi Huang ◽  
Hui Li ◽  
Wenhua Chen
Keyword(s):  
Strain Hardening ◽  
Absorption Capacity ◽  
Flexural Behavior ◽  
Bending Test ◽  
Cementitious Composites ◽  
Flexural Response ◽  
Modified Method ◽  
Four Point Bending ◽  
Transition Strain ◽  
The Moment

Strain hardening cementitious composites (SHCCs) are widely used in projects due to their excellent deformation resistance and large energy absorption capacity. However, determining tensile strain capacity is still a challenge for engineers. The current popular approach is to use inverse methods to predict the tensile behavior of SHCCs, such as the UM method (Qian and Li) and the JCI (Japan Concrete Institute) method. The key to these two approaches is to acquire the exact relationship between the bending and the uniaxial response. In this paper, a reasonable linear constitutive model of the SHCCs is modified. Initially, the moment-curvature diagrams are discussed by material parameters. The results reveal that the moment-curvature response is quite sensitive to the variations in the parameter of transition strain α, post-cracking tensile stiffness η, and strain softening stiffness μ, however, for the compressive parameters, the moment-curvature responses influence on flexural behavior is insignificant. Moreover, the load-deflection curve in the mid-span of SHCC, based on the consideration of shear effect, is simulated under a four-point bending test (FPBT). The results show a remarkable consistency with the experimental data when compared to the previous simulations. It is expected that this modified method can enhance an accurate program in order to obtain the tensile capacity.

Susceptibility of strain-hardening cementitious composite to curing conditions as a retrofitting material for RC beams

2021 ◽  
Vol 16 ◽  
pp. 155892502110203
Author(s):  
Mohammad Iqbal Khan ◽  
Galal Fares ◽  
Yassir Mohammed Abbas ◽  
Wasim Abbass ◽  
Sardar Umer Sial
Keyword(s):  
Strain Hardening ◽  
Environmental Conditions ◽  
Carrying Capacity ◽  
Flexural Behavior ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Curing Conditions ◽  
Flexural Members ◽  
Load Carrying ◽  
Curing Regime

Strain-hardening cement-based composites (SHCC) have recently been developed as repair materials for the improvement of crack control and strength of flexural members. This work focuses on strengthening and flexural enhancement using SHCC layer in tensile regions of flexural members under three different curing conditions. The curing conditions simulate the effect of different environmental conditions prevailing in the central and coastal regions of the Arabian Peninsula on the properties of SHCC as a retrofitting material. In this investigation, beams with SHCC layer were compared to control beams. The beams with SHCC layer of 50-mm thickness were cast. The results revealed that the flexural behavior and the load-carrying capacity of the normal concrete beam specimens under hot and dry environmental conditions were significantly reduced, lowering the ductility of the section. However, compressive strength is comparatively unaffected. Similarly, the hot curing conditions have also led to a notable reduction in the loading capacity of the beam with SHCC layer with a slight effect on its stiffness. On the other hand, steam-curing conditions have shown improvement in load-carrying capacity and a reduction in section ductility of the beam with SHCC layer. It was found that the structural unit retrofitted with SHCC layer was a curing-regime dependent as the tensile and strain-hardening properties of SHCC are highly sensitive to the alteration in the cement hydration process. A normal curing regime was found effective and satisfying the practical, cost, and performance requirements. Accordingly, a normal curing regime could be implemented to retrofit reinforced concrete (RC) beams with SHCC layers as recommended in the study.

scholarly journals Development of Highly Sensitive Strain Sensor Using Area-Arrayed Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura
Keyword(s):  
Graphene Nanoribbons ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Bending Test ◽  
Gauge Factor ◽  
Four Point Bending ◽  
Current Voltage ◽  
Highly Sensitive ◽  
Current Voltage Relationship

In this study, a basic design of area-arrayed graphene nanoribbon (GNR) strain sensors was proposed to realize the next generation of strain sensors. To fabricate the area-arrayed GNRs, a top-down approach was employed, in which GNRs were cut out from a large graphene sheet using an electron beam lithography technique. GNRs with widths of 400 nm, 300 nm, 200 nm, and 50 nm were fabricated, and their current-voltage characteristics were evaluated. The current values of GNRs with widths of 200 nm and above increased linearly with increasing applied voltage, indicating that these GNRs were metallic conductors and a good ohmic junction was formed between graphene and the electrode. There were two types of GNRs with a width of 50 nm, one with a linear current–voltage relationship and the other with a nonlinear one. We evaluated the strain sensitivity of the 50 nm GNR exhibiting metallic conduction by applying a four-point bending test, and found that the gauge factor of this GNR was about 50. Thus, GNRs with a width of about 50 nm can be used to realize a highly sensitive strain sensor.

scholarly journals Structural behaviour of PSCC slab panel under four-point bending test

2021 ◽  
Vol 1144 (1) ◽  
pp. 012039
Author(s):  
M A Iman ◽  
N Mohamad ◽  
A A A Samad ◽  
Steafenie George ◽  
M A Tambichik ◽  
...  
Keyword(s):  
Bending Test ◽  
Structural Behaviour ◽  
Four Point Bending ◽  
Four Point Bending Test

Manufacturing a carbon/epoxy NACA 23018 airfoil skin using a circular braiding machine: experimental and numerical study

2021 ◽  
pp. 152808372199377
Author(s):  
Jalil Hajrasouliha ◽  
Mohammad Sheikhzadeh
Keyword(s):  
Numerical Study ◽  
Filament Winding ◽  
Bending Test ◽  
Elastic Response ◽  
Manufacturing Processes ◽  
Fiber Reinforced Composite ◽  
Four Point Bending ◽  
Reinforced Composite ◽  
Four Point Bending Test ◽  
Meso Scale

In the interest of reducing the weight and also cost of blade skins, various automatic preform manufacturing processes were developed including tape laying, filament winding and braiding. Among them, the circular braiding process was found to be an efficient method in producing seamless preforms on mandrels with various geometries. In this regard, an attempt was made to produce a carbon fiber reinforced composite with the shape of NACA 23018 airfoil using a circular braiding machine. Thus, suitable wooden mandrels were manufactured using NACA 23018 airfoil coordinates, which were obtained by assuming the perimeter of 20 cm. Furthermore, both biaxially and triaxially braided preforms were produced and subsequently impregnated with epoxy resin through an appropriate fabrication method. To assess their performance, four-point bending test was carried out on samples. Ultimately, the elastic response of braided composite airfoils was predicted using a meso-scale finite element modeling and was validated with experimental results.

scholarly journals Use of Cement Suspension as an Alternative Matrix Material for Textile-Reinforced Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2127
Author(s):  
Richard Fürst ◽  
Eliška Fürst ◽  
Tomáš Vlach ◽  
Jakub Řepka ◽  
Marek Pokorný ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Epoxy Resin ◽  
High Performance Concrete ◽  
Bending Test ◽  
Resin Matrix ◽  
Cement Matrix ◽  
Sample Type ◽  
Textile Reinforced Concrete ◽  
Epoxy Resin Matrix ◽  
Four Point Bending

Textile-reinforced concrete (TRC) is a material consisting of high-performance concrete (HPC) and tensile reinforcement comprised of carbon roving with epoxy resin matrix. However, the problem of low epoxy resin resistance at higher temperatures persists. In this work, an alternative to the epoxy resin matrix, a non-combustible cement suspension (cement milk) which has proven stability at elevated temperatures, was evaluated. In the first part of the work, microscopic research was carried out to determine the distribution of particle sizes in the cement suspension. Subsequently, five series of plate samples differing in the type of cement and the method of textile reinforcement saturation were designed and prepared. Mechanical experiments (four-point bending tests) were carried out to verify the properties of each sample type. It was found that the highest efficiency of carbon roving saturation was achieved by using finer ground cement (CEM 52.5) and the pressure saturation method. Moreover, this solution also exhibited the best results in the four-point bending test. Finally, the use of CEM 52.5 in the cement matrix appears to be a feasible variant for TRC constructions that could overcome problems with its low temperature resistance.

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