A mesomechanics-based analysis on the flexural behavior of ultra-high-performance concrete (UHPC) with different steel fiber lengths

Niu, Yanfei; Wei, Jiangxiong; Jiao, Chujie; Qiang-qiang, Miao

doi:10.1016/j.jmrt.2022.02.018

Cited by 10 publications

(5 citation statements)

References 28 publications

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“…When the compressive strain value reached zero, the fracture process zone appeared and the maximum crack width was 0.036 mm. The localization zone ended, and the maximum strain at the crack tip could be obtained when the crack width was 0.06 mm [ 19 , 23 ].…”

Section: Resultsmentioning

confidence: 99%

“…The BCSFs begin to de-bond from the matrix when the pullout load is between critical and maximum loads. It was seen that the debonding zone extends to the end of the embedded BCSFs [ 23 ]. In Figure 15 c,d, the BCSFs have a smooth surface and a small number of hydration products on the surface, which meant that the interfacial bonding strength between the matrix and the BCSFs was weak [ 17 ].…”

Section: Resultsmentioning

confidence: 99%

“…The brass film promoted a physical–chemical bond and frictional resistance between the BCSFs and the UHPC matrix owing to the increase in surface roughness, as shown in Figure 16 b by EDS analyze. Fe element ( Figure 16 d), element O ( Figure 16 e), and Na element ( Figure 16 f) were also found by EDS analysis, suggesting that the O and Na elements in the matrix diffused to the surface of the BCSFs through the BCSFs–matrix interface because the coated brass film favors adhesion with the HPC matrix [ 23 ]. The increased additional adhesion indicated a significant BCSFs–matrix adhesion, which contributes to increasing the flexural and compressive strength of the UHPC mixture.…”

Section: Resultsmentioning

confidence: 99%

“…Less unhydrated cement particles and smaller porous areas were observed around the embedded BCSFs, which leads to a denser microstructure. The BCSFs–matrix interface is favored by densification of the UHPC matrix and surface alteration of the BCSFs [ 23 ]. Fe ( Figure 17 c), Al ( Figure 17 d), Si ( Figure 17 e), Ca ( Figure 17 f), Cl ( Figure 17 g), O ( Figure 17 h), and Cu ( Figure 17 i) were also found by EDS analysis, suggesting that these elements in the matrix diffused to the surface of the BCSFs through the BCSFs–matrix interface because the specimen has better bonding properties and less micro-cracking of the BCSFs–matrix interface.…”

Section: Resultsmentioning

confidence: 99%

“…Jang studied the effects of nano-SiO2 coating and induced corrosion of steel fiber on the interfacial bond and tensile properties of UHPC [ 22 ]. Niu studied the flexural behavior of UHPC with different steel fiber lengths [ 23 ]. Yu studied the effect of steel and polyoxymethylene fibers on the characteristics of UHPC [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the Mechanical Properties and Crack Expansion Mechanism of Different Content and Shapes of Brass-Coated Steel Fiber-Reinforced Ultra-High-Performance Concrete

Jiang

et al. 2023

Materials

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Steel fiber-reinforced ultra-high-performance concrete (UHPC) is becoming an important type of concrete reinforcement. After mixing with the reinforced steel fibers, the UHPC has perfect flex resistance, shear strength, crack resistance, shock resistance, and anti-seepage. In this study, the influence of straight, corrugated, and hooked brass-coated steel fibers (BCSFs) on the microstructure, mechanical properties, and crack expansion mechanism of ultra-high-performance concrete (UHPC) with varying content of 1–6 wt.% under different curing times were investigated. Field emission scanning electron microscopy and energy dispersive X-ray spectrometry were employed to characterize the microstructure of the BCSF-reinforced UHPC mix specimens. X-ray computed tomography was employed to determine the porosity of the BCSF-reinforced UHPC mix specimens. The obtained results indicate the flexural strength and compressive strength of BCSF-reinforced UHPC mix specimens are enhanced, along with increasing the content of BCSFs reinforcement with different shapes (straight, corrugated, and hooked). The embedded BCSFs play a major role in the adhesive property and stress transfer of the BCSFs–UHPC matrix interface. Different from many studies, the flexural strength of mix UHPC with straight BCSFs is higher than those with corrugated and hooked BCSFs. However, the compressive strength of UHPC with corrugated BCSFs is higher than those with straight and hooked BCSFs. The flexural strength of mix UHPC with 6 wt.% straight BCSFs at 28 days reaches the maximum value of 26.2 MPa, and the compressive strength of UHPC with 6 wt.% corrugated BCSFs at 28 days reaches the maximum value of 142.3 MPa. With the increase in straight BCSF content from 1 wt.% to 6 wt.%, the porosity in mix UHPC reduces gradually from 18.4% to 8.3%. The length of average crack spacing is dependent on the straight BCSF content. With the increase in straight BCSF content from 1 wt.% to 6 wt.%, the average crack length reduces gradually from 34.2 mm to 12.1 mm, and the average crack width reduces gradually from 0.78 mm to less than 0.1 mm. During crack extension, part of the energy in the UHPC mixture specimen with the 6 wt.% BCSF content flows into the crack tip region converted into the work dissipated during the bridging process. The crack propagation resistance of the UHPC mixture with straight BCSFs was improved compared with those with corrugated and hooked BCSFs. The bond strength between the BCSFs and UHPC matrix was enhanced by using vibrational mixing, and the brass film coated on the BCSFs contributes to increase the flexural and compressive strength of the UHPC mixture.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%