scholarly journals Effect of steel fiber on impact resistance and durability of concrete containing nano-SiO2

2021 ◽  
Vol 10 (1) ◽  
pp. 504-517
Author(s):  
Peng Zhang ◽  
Hongsen Zhang ◽  
Guo Cui ◽  
Xiaodong Yue ◽  
Jinjun Guo ◽  
...  
Keyword(s):  
Impact Energy ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Chloride Ion ◽  
Penetration Resistance ◽  
Freeze Thaw ◽  
Chloride Ion Penetration ◽  
The Impact ◽  
Durability Of Concrete ◽  
Ion Penetration

Abstract Impact drop weight tests, rapid chloride migration coefficient tests, single-sided freeze–thaw tests, and mechanical property tests were performed to investigate the effect of the steel fiber (SF) content on the impact resistance and durability of concrete containing nano-SiO2 (NS). A fixed NS content of 3% and six SF contents in a range of 0–2.5% by volume were used. The impact resistance was measured based on the number of blows (N1, N2) and the impact energy. The durability of concrete includes its freeze–thaw resistance and chloride ion penetration resistance, which were appraised by the chloride ion diffusion coefficient (CDC) and relative dynamic elastic modulus (RDM), respectively. The ductility ratio was used to predict the impact resistance of concrete containing NS with different SF contents, and a linear relation between this ratio and the impact energy (R 2 = 0.853) was found. The experimental results indicated that SF could greatly improve the impact resistance of concrete. The addition of 2.0% SF increased N1 and N2 by 106 and 169%, respectively. In addition, an appropriate SF content significantly improved the durability of the concrete, including its frost resistance (especially in the middle and late freezing–thawing cycles) and chloride ion penetration resistance. An SF content of 1.5% was the optimum, decreasing the CDC of nano-concrete by 17.1% and minimizing the RDM loss. Moreover, the 1.5% SF content increased the compressive strength of concrete containing NS by 18.5%, whereas an SF content of 2.0% increased the splitting tensile strength and flexural strength by 77 and 20%, respectively. Furthermore, when the SF content exceeded a certain value, the improvement effect on these properties began to decrease and even became negative.

The Durability Failure of Pre-Damaged Concrete Induced by Mechanical Load

2012 ◽  
Vol 594-597 ◽  
pp. 1061-1065
Author(s):  
Fang Zhi Zhu ◽  
Fu Xiang Jiang ◽  
Jun Shang ◽  
Zhong Hua Bi
Keyword(s):  
Chloride Ion ◽  
Load Level ◽  
Uniaxial Tensile ◽  
Chloride Diffusion Coefficient ◽  
Freezing And Thawing ◽  
Chloride Ion Penetration ◽  
Negative Effect ◽  
The Impact ◽  
Durability Of Concrete ◽  
Ion Penetration

Chloride ion penetration and freezing and thawing damage are the two main factors that affect the durability of concrete structures. Through the chloride ion penetration test and freezing and thawing test of concrete specimens after tensile and compressive loading, the influence of load-induced damage on the long-term durability of concrete was studied. The results showed that the apparent chloride diffusion coefficient of concrete increased by 6.4% and 34%, and the surface chloride concentration increased 10% and 40%, respectively, both of which showed the "negative effect" when the uniaxial tensile load level reached the 65% and 75% of the ultimate capacity. However, with the increasing uniaxial compressive load level, the impact on the frost resistance of concrete experienced a transformation from the "positive effect" to the "negative effect".

scholarly journals Mechanical and Durability Characteristics of Latex-Modified Fiber-Reinforced Segment Concrete as a Function of Microsilica Content

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Woong Kim ◽  
Ri-On Oh ◽  
Joo-Ha Lee ◽  
Mi-Sol Kim ◽  
Sang-Min Jeon ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Impact Resistance ◽  
Chloride Ion ◽  
Penetration Resistance ◽  
Synthetic Fiber ◽  
Fiber Reinforced ◽  
Synthetic Fibers ◽  
Chloride Ion Penetration ◽  
Ion Penetration

This study evaluated the performance of latex-modified fiber-reinforced concrete (RC) segments as a function of the substitution level of microsilica and type of reinforced fiber, to address the problem of corrosion of steel segments and steel-reinforced fiber segments, which are commonly used to shield tunnel-boring machine (TBM) tunnels in urban spaces. Our study compared macro synthetic, steel, and hybrid (macro synthetic fiber + polypropylene fiber) reinforcing fibers. The substitution levels of microsilica used were 0, 2, 4, and 6%. The target strengths were set at 40 and 60 MPa to test compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance. Testing of latex-modified and fiber-reinforced segment concrete showed that the compressive strength, flexural strength, and chloride ion penetration resistance increased with an increasing substitution level of microsilica. These improvements were attributed to the densification of the concrete due to filling micropores with microsilica. Micro synthetic fiber was more effective in terms of improved compressive strength, flexural strength, and chloride ion penetration resistance than steel fiber. These results were due to the higher number of micro synthetic fibers per unit volume compared with steel fiber, which reduced the void volume and suppressed the development of internal cracks. The optimal microsilica content and fiber volume fraction of micro synthetic fiber were 6% and 1%, respectively. To evaluate the effects of the selected mixtures and hybrid fibers simultaneously, other mixing variables were fixed and a hybrid fiber mixture (combination of macro synthetic fibers and polypropylene fibers) was used. The hybrid fiber mixture produced better compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance than the micro synthetic fibers.

scholarly journals The Influence of the Hybridization of Steel and Polyolefin Fiber on the Mechanical Properties of Base Concrete Designed for Marine Shotcreting Purposes

2021 ◽  
Vol 11 (20) ◽  
pp. 9456
Author(s):  
Changjoon Lee ◽  
Andres Salas Montoya ◽  
Hoon Moon ◽  
Hyunwook Kim ◽  
Chulwoo Chung
Keyword(s):  
Steel Fiber ◽  
Mechanical Performance ◽  
Synergetic Effect ◽  
Chloride Ion ◽  
Concrete Specimen ◽  
Hybrid Fiber ◽  
Electrically Conductive ◽  
Chloride Ion Penetration ◽  
Binder Ratio ◽  
Ion Penetration

The present study investigated the influence of the hybridization of steel and polyolefin fiber on the mechanical performance and chloride ion penetration of base concrete designed for marine shotcreting purposes. The purpose of fiber hybridization is to reduce the risk of corrosion that might occur during service life. Sets of hybrid fiber reinforced base concrete, whose water to binder ratio was 0.338, were prepared. The fiber contents in the base concrete were 0.54 and 1.08 vol%, and the volume proportion of polyolefin fiber in the hybrid fiber varied from 0 to 100%. Although the effect of fiber hybridization was not clearly observed from the compressive strength, a synergetic effect which increased both the flexural strength and toughness occurred at a fiber content of 1.08 vol%. The optimum ratio of steel and polyolefin fiber was 50:50. With respect to chloride ion penetration, an increasing amount of steel fiber increased the amount of current passing through the base concrete specimen due to the presence of electrically conductive steel fiber. However, chloride ion diffusivity was not greatly affected by the presence of steel fiber.

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