scholarly journals Fiber-Reinforced Cemented Paste Backfill: The Effect of Fiber on Strength Properties and Estimation of Strength Using Nonlinear Models

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 718 ◽  
Author(s):  
Xin Chen ◽  
Xiuzhi Shi ◽  
Shu Zhang ◽  
Hui Chen ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Failure Modes ◽  
Nonlinear Models ◽  
Fiber Reinforcement ◽  
Strength Properties ◽  
Sem Analysis ◽  
Cemented Paste Backfill ◽  
Fiber Reinforced ◽  
Shear Cracks ◽  
Pull Out ◽  
Paste Backfill

This experimental investigation was conducted to research the properties of polypropylene (PP) fiber-reinforced cemented paste backfill (CPB). The unconfined compressive strength (UCS) of the fiber-reinforced CPB showed a significant improvement with average UCS increase ratios of 141.07%, 57.62% and 63.17% at 3, 7 and 28 days, respectively. The macroscopic failure mode and SEM analysis indicated that fibers prevented the formation of large tensile and shear cracks during the pull-out and pull-off failure modes. A linear fitting function for the UCS at a curing time of 3 days and two polynomial fitting functions for the UCS at curing times of 7 and 28 days were established to characterize the relationship between the UCS of the fiber-reinforced and unreinforced CPB. Moreover, based on composite mechanics, nonlinear models related to the UCS and fiber reinforcement index were obtained. The estimated functions containing the fiber reinforcement index λ, which consists of the fiber content and aspect ratio of fiber, could evaluate the UCS. Furthermore, the fiber reinforcement index λ quantifies the enhancement by the fibers. Both estimation results indicated that the UCS values were estimated accurately at curing times of 3, 7 and 28 days in this study. Additionally, the estimation models could be used to guide the strength design of fiber-reinforced CPB. Besides this, the results showed that fiber-reinforced CPB can be used more widely in mine backfills and meets the requirements of controlled low-strength material (CLSM) for broader applications.

scholarly journals Hybrid Failure of Cemented Paste Backfill

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1141
Author(s):  
Andrew Pan ◽  
Mohammadamin Jafari ◽  
Lijie Guo ◽  
Murray Grabinsky
Keyword(s):  
Strength Properties ◽  
Shear Stresses ◽  
Cemented Paste Backfill ◽  
Test Procedures ◽  
Element Analysis ◽  
Laboratory Equipment ◽  
Proposed Model ◽  
Dimensional Finite Element ◽  
Paste Backfill ◽  
Coupled Stress

The hybrid failure is a coupled failure mechanism under the action of tensile and shear stresses. The failure is critical in cemented paste backfill (CPB) since there are no visible signs prior to the failure. Few studies have been conducted on the coupled stress response of CPB. This is most likely due to a lack of suitable laboratory equipment and test procedures. This paper presents a new punching shear apparatus to evaluate the hybrid failure of CPB. We harness two-dimensional finite element analysis (FEA) for supplementing experimental study in providing stress transformation, deformation, and possible failure mechanisms. Our study suggests that the coupled stress is a combination of tensile and shear strength in function of the angle of the frustum. The strengths measured by the coupled stress are comparable to those measured by direct shear and tensile strength tests, in which the strength properties of CPB are curing time and binder content dependent. The FEA results substantiate the effectiveness of proposed model for predicting the hybrid failure of CPB.

Anchorage Capacity of Headed Bars in Steel Fiber Reinforced Concrete

2021 ◽  
Author(s):  
Payal Sachdeva ◽  
A.B. Danie Roy ◽  
Naveen Kwatra
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Failure Modes ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Concrete Compressive Strength ◽  
Pull Out

Headed bars (HB) with different head shapes (Square, Circular, and Rectangular) and bar diameters (db: 16, 20, and 25 mm) embedded in steel fiber reinforced concrete have been subjected to pull-out test. The influence of head shapes, concrete compressive strength (M20 and M40), db, and steel fibers (0, 0.5, 1, and 1.5%) on the anchorage capacity of HB have been evaluated. Numerical model for improving the anchorage capacity of HB has also been proposed. Results have revealed that the anchorage capacity of HB increases with the increase in concrete compressive strength, db, and steel fibers, which have been validated by non-linear regression analysis using dummy variables. Two failure modes namely, steel and concrete-blowout have been observed and the prevailing mode of failure is steel failure. Based on load-deflection curves and derived descriptive equations, it is observed that the circular HB has displayed the highest peak load.

Analysis of influence factors on interfacial bond between BFRP bars and seawater sea-sand concrete

2020 ◽  
pp. 073168442094160
Author(s):  
Yuntao Hua ◽  
Shiping Yin ◽  
Zihan Wang
Keyword(s):  
Bond Strength ◽  
Bond Length ◽  
Failure Modes ◽  
Influence Factors ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Pull Out ◽  
Reinforced Polymer

In this paper, the influences of parameters such as the bond length, surface textures of reinforcement, reinforcement type and stirrups restraint were considered. Pull-out failure, splitting failure and splitting-pullout failure modes were observed during the test. The slip at the free end always lagged behind the slip at the loading end and the bond-slip curve of ribbed basalt fiber reinforced polymer (BFRP) bars included the micro-slip stage, slip stage, descent stage, and residual stage. Reducing the bond length and using ribbed-sand coated bars were beneficial to improve the bond performance. Increasing the bond length from 2.5 d to 5 d reduced the bond strength by 49.2%. The application of ribbed-sand coated bars instead of plain bars increased the bond strength by 1202.3%. The difference in bond strength between steel bars, BFRP bars and glass fiber reinforced polymer (GFRP) bars was small and the bond strengths of the three were much greater than that of carbon fiber reinforced polymer (CFRP) bars. This was mainly attributed to the different rib forms of the bars. The application of stirrups increased the bond strength by 11.5%, which indicated that the stirrup restraints can improve the bond behavior to a certain extent. Besides, the analysis of the bond-slip curve based on the energy perspective was consistent with test results.

Effect of Fiber Content on Failure Modes of Glass Fiber Reinforced Injection Molded Polyamide 66 Composites

2015 ◽  
Vol 1119 ◽  
pp. 296-300
Author(s):  
Ikilem Gocek ◽  
Reyhan Keskin ◽  
Guralp Ozkoc
Keyword(s):  
Glass Fiber ◽  
Failure Modes ◽  
Morphological Structure ◽  
Sem Analysis ◽  
Fiber Reinforced ◽  
Polyamide 66 ◽  
Twin Screw Extrusion ◽  
Glass Fiber Reinforced ◽  
Twin Screw ◽  
Glass Fiber Reinforcement

In the present study, glass fiber reinforced Polyamide 66 composites were produced using laboratory type twin screw extrusion and injection molding processes. The glass fiber reinforcement was applied at 1, 10, 15, 20, 25 and 30 wt% loadings. The morphological structure of the samples and failure modes of glass fiber reinforced Polyamide 66 composites were investigated using scanning electron microscopy (SEM) analysis on fractured surfaces of tensile tested samples in this study.

scholarly journals Experimental Study on the Bond Performance between Fiber-Reinforced Polymer Bar and Unsaturated Polyester Resin Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Wenchao Li ◽  
Min Zhou ◽  
Fusheng Liu ◽  
Yuzhao Jiao ◽  
Qingfeng Wu
Keyword(s):  
Failure Modes ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Unsaturated Polyester Resin ◽  
Fiber Reinforced Polymer ◽  
Engineering Practice ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Frp Bar

Fiber-reinforced polymer (FRP) bar-reinforced unsaturated polyester resin concrete (UPC) can solve the problem of rebar corrosion in ordinary reinforced concrete members. However, it has not been widely used in engineering practice because there have been few studies conducted on the bond behaviors of FRP bar and UPC, and the interaction mechanisms between FRP bar and UPC have not been well understood. A series of pull-out tests are conducted on FRP bar-UPC specimens to study the bond behaviors between these two materials. Parametric studies are also carried out to investigate the effects of FRP bar diameter, fiber type, type of surface treatment, concrete cover thickness, and interfacial bond length between the two. Three failure modes of the specimens are observed from pull-out tests, i.e., FRP bar pull-out, tensile failure of FRP bar, and UPC split. A new constitutive model is, therefore, proposed to predict the bond stress of FRP bar and UPC in the residual stage, and the proposed model is finally verified by test data reported in this study.

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