Micro-Reinforced Cementitious Materials

1990 ◽  
Vol 211 ◽  
Author(s):  
Nemkumar Banthia ◽  
Jiakang Sheng
Keyword(s):  
Energy Absorption ◽  
Carbon Fibers ◽  
Cementitious Materials ◽  
Steel Fibers ◽  
Hybrid Fiber ◽  
Cement Matrices ◽  
Hybrid Forms ◽  
Strength And Toughness

AbstractReinforcement of cements with very fine fibers of carbon and steel in mono- and hybrid-forms has been investigated. While both carbon and steel fibers led to considerable improvements in strength and toughness, on a comparative basis, carbon fibers bring about a better improvement in the toughness or energy absorption, and the steel fibers impart higher tensile strengths to the base cement matrices. In the hybrid-fiber systems, the improvements lie somewhere in between those of the equivalent mono-fiber systems.

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

scholarly journals Shrinkage and Mechanical Properties of Self-Compacting SFRC With Calcium-Sulfoaluminate Expansive Agent

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 588 ◽  
Author(s):  
Changyong Li ◽  
Pengran Shang ◽  
Fenglan Li ◽  
Meng Feng ◽  
Shunbo Zhao
Keyword(s):  
Mechanical Properties ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Volume Stability ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of steel fiber. By using the expansive agent to reduce the shrinkage deformation of self-compacting SFRC, the strength reduction of hardened self-compacting SFRC is another issue. To solve these issues, this paper performed an experimental investigation on the workability, shrinkage, and mechanical properties of self-compacting SFRC compared to the self-compacting concrete (SCC) with or without an expansive agent. The calcium-sulfoaluminate expansive agent with content optimized to be 10% mass of binders and the steel fiber with a varying volume fraction from 0.4% to 1.2% were selected as the main parameters. The mix proportion of self-compacting SFRC with expansive agent was designed by the direct absolute volume method, of which the steel fibers are considered to be the distributed coarse aggregates. Results showed that rational high filling and passing ability of fresh self-compacting SFRC was ensured by increasing the binder to coarse-aggregate ratio and the sand ratio in the mix proportions; the autogenous and drying shrinkages of hardened self-compacting SFRC reduced by 22.2% to 3.2% and by 18.5% to 7.3% compared to those of the SCC without expansive agent at a curing age of 180 d, although the expansion effect of expansive agent decreased with the increasing volume fraction of steel fiber; the mechanical properties, including the compressive strength, the splitting tensile strength, and the modulus of elasticity increased with the incorporation of an expansive agent and steel fibers, which met the design requirements.

Repair of Severely Damaged Reinforced Concrete Beams with High-Strength Cementitious Grout

2020 ◽  
Vol 2674 (6) ◽  
pp. 372-384
Author(s):  
Antoine N. Gergess ◽  
Mahfoud Shaikh Al Shabab ◽  
Razane Massouh
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Rc Structures

High-strength cementitious materials such as high-performance concrete are extensively used for retrofit of reinforced concrete (RC) structures. The effectiveness of these materials is increased when mixed with steel fibers. A commonly used technique for strengthening and repair of RC beams consists of applying high-performance fiber-reinforced concrete jackets around the beam perimeter. This paper investigates the jacketing method for repairing severely damaged RC beams. Four 2 m (6 ft 63/4 in.) long rectangular RC beams, 200 × 300 mm (8 ×12 in.) were initially cast and loaded until failure based on three-point bending tests. The four beams were then repaired by thickening the sides of the damaged RC beams using a commercially available high-strength shrinkage grout with and without steel fibers. Strain and deformation were recorded in the damaged and repaired beams to compare structural performance. It is shown that the flexural strength of the repaired beams is increased and the crack pattern under loading is improved, proving that the proposed repair method can restore the resistance capacity of RC beams despite the degree of damage. A method for repair is proposed and an analytical investigation is also performed to understand the structural behavior of the repaired beams based on different thickening configurations.

Study on the Mechanical Properties of High Performance Hybrid Fiber Reinforced Cementitious Composite (HFRCC) under Impact Loading

2014 ◽  
Vol 629-630 ◽  
pp. 79-84 ◽  
Author(s):  
Hui Xian Yang ◽  
Jing Li ◽  
Yan Sheng Huang
Keyword(s):  
Impact Loading ◽  
Material Properties ◽  
High Performance ◽  
Steel Fibers ◽  
Cementitious Composites ◽  
Peak Strain ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Dynamic Material Properties ◽  
Fiber Reinforced Cementitious Composites

The dynamic material properties of high performance hybrid fiber reinforced cementitious composites (HFRCC) with various volumetric fractions of steel and polyvinyl alcohol (PVA) fibers were studied by the Split Hopkinson Press Bar (SHPB) test. The results show that HFRCC with higher volumetric fraction of steel fibers are more sensitive to stain rate and the dynamic compressive strength increase more prominently with the strain rate increasing, but peak strain shows the opposite trend. The PVA fibers increase the ductility of HFRCC more effectively than steel fibers. Compared to PVA fiber reinforced cementitious composites (FRCC), HFRCC present better dynamic material properties under impact loading.

scholarly journals Paper 1: “Cement as a Thermoelectric Material,” [J. Mater. Res. 15, 2844-2848 (2000)] And Paper 2: “Rectifying and Thermocouple Junctions Based on Portland Cement,” J. Mater. Res. 16, 1989-1993 (2001)]

2004 ◽  
Vol 19 (4) ◽  
pp. 1294-1294 ◽  
Author(s):  
Sihai Wen ◽  
D.D.L. Chung
Keyword(s):  
Portland Cement ◽  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Carbon Fibers ◽  
Thermoelectric Material ◽  
Steel Fibers ◽  
Cement Pastes ◽  
The Absolute ◽  
P Type ◽  
Wrong Sign

In the two papers listed above, the conversion of the Seebeck coefficient (relative to copper) to the absolute thermoelectric power was done by using the wrong sign of the absolute thermoelectric power of copper (2.34 μV/°C). The corrected tables are shown below for both papers. The correction means that plain cement paste is slightly p-type rather than slightly n-type. In addition, it means that cement pastes with carbon fibers are more p-type and those with steel fibers are less n-type than reported. Note in Table III of Paper 2 that all cement pastes are p-type except for paste (ii). Note in Table IV of Paper 2 that all cement junctions are pn-junctions (rather than some being nn+-junctions).

scholarly journals Flexural strengthening of reinforced concrete beams with carbon fibers reinforced polymer (CFRP) sheet bonded to a transition layer of high performance cement-based composite

2012 ◽  
Vol 5 (5) ◽  
pp. 596-626 ◽  
Author(s):  
V. J. Ferrari ◽  
J. B. de Hanai
Keyword(s):  
Carbon Fibers ◽  
Transition Layer ◽  
High Performance ◽  
High Strength ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Layer Transition ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Strengthening Technique

Resistance to corrosion, high tensile strength, low weight, easiness and rapidity of application, are characteristics that have contributed to the spread of the strengthening technique characterized by bonding of carbon fibers reinforced polymer (CFRP). This research aimed to develop an innovate strengthening method for RC beams, based on a high performance cement-based composite of steel fibers (macro + microfibers) to be applied as a transition layer. The purpose of this transition layer is better control the cracking of concrete and detain or even avoid premature debonding of strengthening. A preliminary study in short beams molded with steel fibers and strengthened with CFRP sheet, was carried out where was verified that the conception of the transition layer is valid. Tests were developed to get a cement-based composite with adequate characteristics to constitute the layer transition. Results showed the possibility to develop a high performance material with a pseudo strain-hardening behavior, high strength and fracture toughness. The application of the strengthening on the transition layer surface had significantly to improve the performance levels of the strengthened beam. It summary, it was proven the efficiency of the new strengthening technique, and much information can be used as criteria of projects for repaired and strengthened structures.

scholarly journals Carbon fibers coated with graphene reinforced TiAl alloy composite with high strength and toughness

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Sen Cui ◽  
Chunxiang Cui ◽  
Jiaqi Xie ◽  
Shuangjin Liu ◽  
Jiejie Shi
Keyword(s):  
Carbon Fibers ◽  
Tial Alloy ◽  
High Strength ◽  
Alloy Composite ◽  
Strength And Toughness

scholarly journals Properties of Lightweight Aggregate Concrete Reinforced with Carbon and/or Polypropylene Fibers

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 640 ◽  
Author(s):  
Hui Wei ◽  
Tao Wu ◽  
Xue Yang
Keyword(s):  
Tensile Strength ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Polypropylene Fibers ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Ductility Index ◽  
Hybrid Forms

The impact of carbon and polypropylene fibers in both single and hybrid forms on the properties of lightweight aggregate concrete (LWAC), including the slump, density, segregation resistance, compressive strength, splitting tensile strength, flexural strength, and compressive stress–strain behavior, were experimentally investigated. The toughness ratio and ductility index were introduced for quantitatively evaluating the energy-absorbing capacity and post-peak ductility. A positive synergistic effect of hybrid carbon and polypropylene fibers was obtained in terms of higher tensile strength, toughness, and ductility. The toughness ratio and ductility index of hybrid fiber-reinforced LWAC were increased by 26%–37% and 12%–27% compared with plain LWAC, respectively. The fiber in both single and hybrid forms had a smaller effect on the linearity ascending branch of the stress–strain curves, whereas the post-peak patterns in terms of the toughness and ductility for the hybrid fiber-reinforced LWAC were significantly improved when the fiber in hybrid form.

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