Improving steel fiber reinforced concrete pull-out strength with nanoscale iron oxide coating

2015 ◽  
Vol 79 ◽  
pp. 311-317 ◽  
Author(s):  
Qinyue He ◽  
Chuangwei Liu ◽  
Xun Yu
1990 ◽  
Vol 17 (4) ◽  
pp. 610-620 ◽  
Author(s):  
Nemkumar Banthia

With the objective of understanding the reinforcing mechanisms of fibers in steel fiber reinforced concrete, the bond between the fibers and the surrounding matrix is studied by conducting single fiber pull-out tests on fibers bonded in cementitious matrices. Various matrix compositions and fiber geometries have been investigated and the effects of various other factors on the pull-out behavior of the fibers have been quantified through pull-out load–extension plots. Finally, the various modes of fiber–matrix load transfer have been discussed and the favorable and unfavorable conditions for such a transfer have been recognized. Key words: steel fiber reinforced concrete, toughness, fiber–matrix bond, deformed fiber, pull-out tests, load–extension plots.


Author(s):  
Payal Sachdeva ◽  
A.B. Danie Roy ◽  
Naveen Kwatra

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.


2021 ◽  
Author(s):  
Xiliang Liu ◽  
Feiyue Sun ◽  
Fuli Kong ◽  
Jiaqi GUO

Abstract Based on axial pull-out performance tests of anchor and shotcrete support system with three types of plates and two kinds of shotcretes (plain and steel fiber reinforced concrete) conducted by use of the multi-functional testing system. The mechanical behavior of the anchor and shotcrete support system with the different plate and shotcrete such as the pull-out performance of support system, deformation and failure properties of shotcrete was studied and analyzed. Experimental results showed that the relationship curves between elongation and drawing force has three stages, which are elastic, yielding and strengthening. Different plate types have obvious influence on the tensile stiffness during the elastic stage. The steel fiber reinforced concrete spray layer can improve the yield strength of rockbolt under the coupling effect by the support system. The strain at the interface between the initial shotcrete layer and surrounding rock mass is greater than that of the external surface of the resprayed shotcrete layer, though they are equal far away from the rockbolt hole. The shotcrete strain values of steel fiber reinforced concrete is lower than that of plain concrete, and the shotcrete strain values decreases with the improvement of steel fiber content. For shotcrete strain values on the same position, the higher they are the steel fiber content, the lower their strain will be. The failure of plain shotcrete usually begins around of rockbolt hole, when the interfacial stress between the initial shotcrete layer and surround rock is higher than that in the initial shotcrete layer and resprayed shotcrete layer. The steel fiber can effectively improves the toughness, anti-cracking performance and prevent fracture of shotcrete from failure properties.


1987 ◽  
Vol 114 ◽  
Author(s):  
Parviz Soroushian ◽  
Ziadz Bayasi

ABSTRACTSilica fume is known to improve the pore system of cementitious pastes and their adhesion capacity to fibers and other mix inclusions. This study has been mainly concerned with the effect of silica fume on the pull-out strength of randomly oriented steel fibers from concrete. Silica fume effects on the fresh mix workability and the overall flexural and compressive behavior of steel fiber reinforced and plain concretes were also assessed. The only variable in different fibrous and plain mixes was the fraction of portland cement substituted with silica fume. This fraction ranged from 0% to 20%.The workability of plain and fibrous mixes were obtained by slump and inverted slump cone tests, respectively. In both the flexure and compression tests on fiber concrete, the complete load-deformation relationship was obtained. The pull-out strength of randomly oriented fibers was assessed through analysis of the flexural test data.All aspects of the fresh and hardened steel fiber reinforced concrete performance considered in this study, especially the pull-out strength of randomly oriented fibers from concrete, were observed to improve with the increase in silica fume-cementitious ratio up to a certain limit, after which the trends in silica fume effects were reversed.


2017 ◽  
Vol 59 (7-8) ◽  
pp. 653-660 ◽  
Author(s):  
Wang Yan ◽  
Ge Lu ◽  
Chen Shi Jie ◽  
Zhou Li ◽  
Zhang Ting Ting

2021 ◽  
pp. 136943322098165
Author(s):  
Hossein Saberi ◽  
Farzad Hatami ◽  
Alireza Rahai

In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.


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