An experimental study on strength and toughness of steel fiber reinforced expanded-shale lightweight concrete

For the popularized structural application, steel fiber-reinforced expanded-shale lightweight concrete (SFRELC) with high freeze-thaw resistance was developed. The experimental study of this paper figured out the effects of air-entraining content, volume fraction of steel fibers, and fine aggregate type. Results showed that while the less change of mass loss rate was taken place for SFRELC after 300 freeze-thaw cycles, the relative dynamic modulus of elasticity and the relative flexural strength presented clear trends of freeze-thaw resistance of SFRELC. The compound effect of the air-entraining agent and the steel fibers was found to support the SFRELC with high freeze-thaw resistance, and the mechanisms were explored with the aid of the test results of water penetration of SFRELC. The beneficial effect was appeared from the replacement of lightweight sand with manufactured sand. Based on the test results, suggestions are given out for the optimal mix proportion of SFRELC to satisfy the durability requirement of freeze-thaw resistance.

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Elasto-plastic Bending Behaviors of Steel Fiber Reinforced Expanded-shale Lightweight Concrete Beams Analyzed by Nonlinear Finite-element Method

Case Studies in Construction Materials ◽

10.1016/j.cscm.2020.e00372 ◽

2020 ◽

Vol 13 ◽

pp. e00372

Author(s):

Changyong Li ◽

Qi Li ◽

Xiaoke Li ◽

Xiaoyan Zhang ◽

Shunbo Zhao

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Steel Fiber ◽

Lightweight Concrete ◽

Concrete Beams ◽

Nonlinear Finite Element ◽

Nonlinear Finite Element Method ◽

Fiber Reinforced ◽

Plastic Bending ◽

Expanded Shale

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Complete Stress–Strain Curves of Self-Compacting Steel Fiber Reinforced Expanded-Shale Lightweight Concrete under Uniaxial Compression

Materials ◽

10.3390/ma12182979 ◽

2019 ◽

Vol 12 (18) ◽

pp. 2979 ◽

Cited By ~ 6

Author(s):

Zhao ◽

Zhang ◽

Shang ◽

Fu ◽

Zhang ◽

...

Keyword(s):

Uniaxial Compression ◽

Steel Fiber ◽

Lightweight Concrete ◽

Volume Fraction ◽

Compressive Strain ◽

Strain Curve ◽

Lightweight Aggregate Concrete ◽

Fiber Reinforced ◽

Stress Strain ◽

Expanded Shale

To expand the structural application of steel fiber reinforced expanded-shale lightweight concrete (SFRELC), a self-compacting SFRELC with high-workability was developed based on previous research. As part of the investigation, the present study focuses on the adaptability of formulas used for the complete stress–strain curves of steel fiber reinforced lightweight-aggregate concrete and conventional concrete under uniaxial compression. On the basis of mix proportion of SFRELC, self-compacting SFRELC was designed with the volume fraction of steel fiber as 0%, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0%. Eighteen cylindrical specimens with dimensions of Φ150 mm × 300 mm were tested to measure the uniaxial compressive stress–strain curves of self-compacting SFRELC. Results indicated that, with the increasing volume fraction of steel fiber, the compressive strain at the peak-stress of the stress–strain curve increased, while the slope of the descending portion decreased. This increased the energy absorption of self-compacting SFRELC with a higher compression toughness. With a comparison of test results between four groups of calculation models, a group of formulas is selected to express the complete stress–strain curves of self-compacting SFRELC under uniaxial compression.

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Bond of Ribbed Steel Bar in High-Performance Steel Fiber Reinforced Expanded-Shale Lightweight Concrete

Buildings ◽

10.3390/buildings11120582 ◽

2021 ◽

Vol 11 (12) ◽

pp. 582

Author(s):

Mingshuang Zhao ◽

Guirong Liu ◽

Lingli Liu ◽

Yanyan Zhang ◽

Kang Shi ◽

...

Keyword(s):

Bond Strength ◽

High Performance ◽

Steel Fiber ◽

Lightweight Concrete ◽

Volume Fraction ◽

Bond Stress ◽

Fiber Reinforced ◽

Bond Slip ◽

Steel Bar ◽

Expanded Shale

For the structural application of high-performance Steel Fiber Reinforced Expanded-shale Lightweight Concrete (SFRELC), a reliable bond of ribbed steel bar should be ensured. In this paper, an experimental study was carried out on the bond properties of ribbed steel bar embedded in SFRELC by the direct pull-out test. The SFRELC was produced with a strength grade of 35 MPa and a volume fraction of steel fiber as 0%, 0.8%, 1.2%, 1.6% and 2.0%, respectively. Fifteen groups of specimens were made with a central placed steel bar with diameter of 14 mm, 20 mm and 28 mm, respectively. Complete bond stress-slip curves were determined for each group of specimens, and the characteristic values of bond-stress and slip at key points of the curves were ascertained. Results show that the bond strength, peak-slip and residual bond strength increased with the increase of the volume fraction of steel fiber. With the increase of steel bar diameter, bond strength decreased while the peak-slip increased, and the descending curves became sharp with a decreased residual bond strength. Formulas for calculating the bond strength and peak-slip were proposed. The relationships were determined for the splitting bond strength, residual bond strength with the bond strength, the splitting bond slip and residual bond slip with the peak-slip. Combined with rational fitting analyses of bond strength and slip, a constitutive model was selected for predicting the bond stress-slip of ribbed steel bar in SFRELC.

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Testing and Prediction of Shear Performance for Steel Fiber Reinforced Expanded-Shale Lightweight Concrete Beams without Web Reinforcements

Materials ◽

10.3390/ma12101594 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1594 ◽

Cited By ~ 7

Author(s):

Xiaoke Li ◽

Changyong Li ◽

Minglei Zhao ◽

Hui Yang ◽

Siyi Zhou

Keyword(s):

Steel Fiber ◽

Lightweight Concrete ◽

Shear Capacity ◽

Fiber Reinforced Concrete ◽

Bending Test ◽

Fiber Reinforced ◽

Cracking Resistance ◽

Shear Performance ◽

Shear Cracking ◽

Expanded Shale

In this paper, for a wide application of high-performance steel fiber reinforced expanded-shale lightweight concrete (SFRELC) in structures, the shear behavior of reinforced SFRELC beams without web reinforcements was experimentally investigated under a four-point bending test. Twenty-six beams were fabricated considering the influencing parameters of SFRELC strength, shear-span to depth ratio, longitudinal reinforcement ratio and the volume fraction of the steel fiber. The statistical analyses based on the foundational design principles and the experimental results are made based on the shear cracking resistance, the shear crack distribution and width, the mid-span deflection, the patterns of shear failure, and the shear capacity of the specimens. This confirms the effective strengthening of steel fibers on the shear performance of reinforced SFRELC beams without web reinforcements. Based on the modifications to the formulas of reinforced conventional concrete, lightweight-aggregate concrete or steel fiber reinforced concrete (SFRC) beams, and the validation against the experimental findings, formulas are proposed for the prediction of shear cracking resistance and shear capacity of reinforced SFRELC beams without web reinforcements. Finally, formulas are discussed for the reliable design of the shear capacity of reinforced SFRELC beams without web reinforcements.

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