Effect of curing temperature on time-dependent shear behavior and properties of polypropylene fiber-reinforced cemented paste backfill

Libos, Iarley Loan Sampaio; Cui, Liang; Liu, Xinrong

doi:10.1016/j.conbuildmat.2021.125302

Cited by 35 publications

(8 citation statements)

References 60 publications

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“…Depending on the desired function, either strength or ductility improvement, different types of fibers can be utilized to reinforce the cementitious materials. Besides the wide availability and low cost of polypropylene (PP) fibers, several experimental studies have confirmed that the usage of PP fibers can effectively improve the conventional geomechanical properties, including UCS, 15 tensile strength, 33 and shear strength parameters 12 of CPB materials. Herein, monofilament PP fibers (with a diameter of 80 μm and a tensile strength of 500 MPa) are used in the present study.…”

Section: Methodsmentioning

confidence: 99%

“…Correspondingly, the uniaxial compressive strength (UCS), 9 tensile strength, 10 and shear strength 11 are often utilized to evaluate the mechanical performance of CPB materials under field loadings. However, owing to the brittle behavior of long‐term CPB and poor tensile strength, failure still happens when CPB structures are subjected to mining disturbance even with sufficient UCS and shear strength 12 . The occurrence of rib falls and the majority of the stope collapse‐related accidents are because of CPB's low tensile strength and weak ductility.…”

Section: Introductionmentioning

confidence: 99%

“…However, owing to the brittle behavior of long-term CPB and poor tensile strength, failure still happens when CPB structures are subjected to mining disturbance even with sufficient UCS and shear strength. 12 The occurrence of rib falls and the majority of the stope collapse-related accidents are because of CPB's low tensile strength and weak ductility. These kinds of failures not only worsen the ore dilution but also increase the safety risk to miner workers.…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of fiber content and length on curing time‐dependent mode‐I fracture behavior and properties of cemented paste backfill and implication to engineering design

Fang

Cui

2022

Fatigue Fract Eng Mat Struct

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The inclusion of fiber in cemented paste backfill (CPB) can significantly alter the mechanical response of the CPB body. The intrinsic defects in CPB and the potential dynamic loading condition make it necessary to investigate the fracture properties of fiber-reinforced CPB (FR-CPB). The mode-I fracture behavior and properties are crucial to the successful engineering application of FR-CPB technology used in underground mines. The contribution of fiber length and content to the evolutive mode-I fracture behavior and properties of FR-CPB was examined in this study. The results show that the addition of fiber reduces the prepeak stiffness but improves the mode I fracture toughness (K Ic ), and the improvement in K Ic increases with fiber length. In contrast, the initial increase in fiber content (from 0% to 0.5%) benefits the K Ic acquisition, while a further increase in fiber content from 0.5% to 0.75% poses a negative influence on the K Ic development. Moreover, with the adoption of the cement hydration model, four predictive functions are proposed to describe the contribution of fiber length and content to the development of fracture properties. In addition, K Ic is identified as a more reliable fracture property for assessing the immediate ground support role played by the FR-CPB structure. The findings are helpful when it comes to the determination of the fiber length and content in FR-CPB design. K E Y W O R D Scemented paste backfill, fiber reinforcement, fracture toughness, tailings, underground mine List of abbreviations/symbols: CB, chevron bend; CCNBD, cracked chevron-notched Brazilian disc; FRCC, fiber-reinforced cementitious composites; FR-CPB, fiber-reinforced cemented paste backfill; K IC , mode I fracture toughness; LPD, load-point displacement; NT, natural tailings; PSD, particle size distribution; SCB, semicircular bending test; SR, short rod; ST, silicate tailings; TSF, tailings storage facilities; UCS, uniaxial compressive strength; w /c, water to cement ratio; T, thickness of sample; F l , fiber length; F c , fiber content; F lr , reference fiber length; a, notch length; D, diameter of sample; FM-ITZ, fiber-matrix interfacial transition zone; P, normal force; S, half of the distance between the two supporting rollers; R, radius of sample; k s , stiffness; E i , fracture initiation energy; E m , critical fracture energy; P m , peak force; Y I , stress intensity factor; u, displacement; i, stage number; E p , postpeak fracture energy; ξ f , final degree of cement hydration; ξ, degree of cement hydration; τ, curing time constant; β, shape constant; t e , curing time; T r , reference curing temperature; T c , actual curing temperature; E a , energy activating cement hydration; R', natural gas constant; a i , b i , c i , d i , fitting constants.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of fiber content and length on curing time‐dependent mode‐I fracture behavior and properties of cemented paste backfill and implication to engineering design

Fang

Cui

2022

Fatigue Fract Eng Mat Struct

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“…Ermolovich et al [57] used industrial waste of ores in place of particularly created inert ingredients to create backfill with improved strength properties. Some researchers [58][59][60] demonstrated the good ductility and toughness of CTB by adding 3D-printed polymers of diverse shapes or layer widths to CTB. Gao et al [61] found that the sum of layers and angles played a substantial role in the flexural strength of CTB by inspecting the flexural and damage behavior of laminated mine fills.…”

Section: Introductionmentioning

confidence: 99%

Polypropylene Fiber’s Effect on the Features of Combined Cement-Based Tailing Backfill: Micro- and Macroscopic Aspects

Li,

Cao,

Yilmaz

2024

Minerals

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In undercut-and-fill mining, backfills show weak tensile strength and poor ductility properties since they act as artificial pillars to support stope roofs. Hence, the enhancement of the stability of mining structures and backfills is a crucial requisite for underground mining backfill operations. This study addresses the reinforcing effect of polypropylene (PP) on the strength features of combined cement-based tailing backfill (CCTB) with varied cement/tail ratios (c/t: 1:8 to 1:4) at both macroscopic and microscopic levels. Fill specimens containing a fixed solid content of 70 wt% were reinforced with fiber (0.6 wt%) and with no fiber (classified as a reference sample). They were then cast in mold sizes of 160 × 40 × 40 mm3, and cured for 7 days. Following curing, some experiments covering three-point bending assisted by DIC and SEM were performed to inspect the microstructure and strength features of CCTB. The results illustrate that the flexural strength of fiber-oriented CCTB increases along with the c/t fraction, but it is not greater than that of specimens with a high c/t fraction without fiber. Adding PP fiber, the peak deflection of CCTB specimens was improved, and the increment of peak deflection increased linearly with rising c/t fraction, enhancing CCTB’s bending characteristics. CCTB damage starts from the bottom to the middle, and the main cause of the damage is the stress distribution at the lowest section. The addition of fiber to CCTBs increases the ability to dissipate energy, which helps to hinder crack extension and prevent brittle damage from occurring. The microstructure shows that AFt and CSH were key hydrate materials in CCTB. As a result, this study develops the security of mining with backfill and helps to determine its design properties for safe production inputs and sustainable filling operations.

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“…The research materials involved CTB [57,58], cementitious coal fly ash/coal gangue backfill materials [59,60], and others [61]. In terms of research tools, many scholars also considered using acoustic emission (AE) system [62], industrial computed tomography (CT) scan [63], mercury intrusion porosimetry [64], and nuclear magnetic resonance system [65]. Yang et al [66] examined the crack behavior of fiber-reinforced CTB by means of an AE system.…”

Section: Introductionmentioning

confidence: 99%

Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill

2023

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The mechanical strength properties of cemented tailings backfill are very important for the safe and environmentally friendly mining of mineral resources. To check the impact of polypropylene fiber on strength and microstructure of cementitious tailings waste rock fill (CTWRF), diverse fiber lengths (6 and 12 mm) and dosages (0-control specimen, 0.3, 0.6, and 0.9 wt.%) were considered to prepare fiber-reinforced CTWRF (FRCTWRF) matrices. Experiments such as UCS (uniaxial compressive strength), X-ray CT (computed tomography), and SEM (scanning electron microscopy) were implemented to better characterize the backfills studied. Results showed that UCS performance of FRCTWRF was the highest (0.93 MPa) value at 6 mm fiber long and 0.6 wt.% fiber content. The peak strain of FRCTWRF was the highest (2.88%) at 12 mm fiber long and 0.3 wt.% fiber content. Growing the length of fiber within FRCTWRF can reduce its fracture volume, enhancing the crack resistance of FRCTWRF. Fiber and FRCTWRF are closely linked to each other by the products of cement hydration. The findings of this work will offer the efficient use of FRCTWRF in mining practice, presenting diverse perspectives for mine operators and owners, since this newly formed cementitious fill quickens the strengths required for stope backfilling.

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Effect of curing temperature on time-dependent shear behavior and properties of polypropylene fiber-reinforced cemented paste backfill

Cited by 35 publications

References 60 publications

Experimental investigation of fiber content and length on curing time‐dependent mode‐I fracture behavior and properties of cemented paste backfill and implication to engineering design

Experimental investigation of fiber content and length on curing time‐dependent mode‐I fracture behavior and properties of cemented paste backfill and implication to engineering design

Polypropylene Fiber’s Effect on the Features of Combined Cement-Based Tailing Backfill: Micro- and Macroscopic Aspects

Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill

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