In order to solve the problem of low strength and easy cracking of shotcrete in permanent support of tunnel single shell lining, theeffects of steel fiber-reinforced siliceous on mechanical properties of wet shotcrete were investigated by the tests of compressivestrength, splitting tensile strength, flexural strength, shear strength, and bending toughness. )e strength and the crackingresistance mechanism of steel fiber-reinforced siliceous wet shotcrete were analyzed by the bending toughness evaluation method.)e results show that (1) the steel fiber-reinforced siliceous can improve splitting tensile, flexural, and shear capacity of theshotcrete, and the maximum growth rates were 77.42%, 72.73%, and 98.31%. )e steel fiber plays a major role, and silica fumeplays a subsidiarity role. (2) )e effect of different types and contents of steel fibers on the compressive strength of wet shotcreteare not obvious. (3) )e strengthening effect of shear undaform steel fiber on concrete is obviously better than that of shear flatsteel fiber. (4))e flexural toughness of wet shotcrete with the silica content of 10% and the shear steel fiber of 60 kg/m3 is the best.
1. Introduction
With the rapid reduction of traditional resources, thescarcity of resources has become a key factor in restrictingeconomic development. At present, as a raw material widelyused in the field of engineering infrastructure, concrete hasa huge demand and consumption. So the research on high-efficient and environmental-friendly concrete to replacetraditional consumption resources is the key to the devel-opment of modern concrete. Steel fiber-reinforced siliceouswet shotcrete is a kind of new composite material, which ismixed with steel fiber, silica fume, and high-performanceadmixtures in common concrete, and the wet method is usedin the spray technology. In recent years, shotcrete and cast-in-situ concrete have been widely used in tunnel supportfield. Cast-in-situ concrete needs three processes includingsupporting-formwork, pouring, and demoulding, so theoperation is complicated and the cost is high. But shotcretecan be used in high pressure to carry out long-distancetransportation, and the supporting efficiency is high. Inaddition, shotcrete technology can be divided into spraydrying and wet spurt. )e wet spurt technology has been
widely used in the process of tunnel construction, because ofits low spring rate and less dust.
)e permanent support technique of tunnel single shelllining is mainly divided into three steps. )e first step is thatwaterproof concrete is sprayed in time, after the roadway isexcavated. )e second step is that cable anchor and steelframe support are carried out according to the surroundingrock classification. )e third step is that one or more layersof reference concrete are sprayed. )e reference concretebelongs to brittle material, which has many problems such asinsufficient mechanical strength index, high hydration heat,and serious self shrinkage. Moreover, the complex force ofthe shotcrete lining structure in the permanent support ofsingle lining of tunnel, which causes the shotcrete prone tocracking, water inrush, and mud sudden accident [1–3].)erefore, studying on the mix design method [4] and themechanical properties of shotcrete [5, 6] has become a key inpermanent support of tunnel single shell lining. In the pastyears, schol1ars had done a lot of research on shotcrete athome and abroad. For example, Zhang et al. [7] had studiedthe effect of silica fume and fly ash on the performance ofshotcrete through laboratory tests. )e result of the tests
HindawiAdvances in Materials Science and EngineeringVolume 2018, Article ID 1637261, 8 pageshttps://doi.org/10.1155/2018/1637261
concluded that the optimum ratio of new shotcrete caneffectively reduce the amount of cement, the cracking, therebound, and dust. Liu et al. [8] analyzed the shrinkageperformance of silica fume concrete through the orthogonaltest. )e research result indicated that the ratio of water tocement, sand rate, and silica fume addition significantlyaffected the shrinkage performance of silica fume concrete.Ardalan et al. [9] and Fallah andNematzadeh [10] found thatthe strength and durability of shotcrete can be improved bymixing silica fume. Wang et al. [11] and Su et al. [12] foundthat the mixing of steel fiber can effectively improve themechanical properties of shotcrete. Naqvi et al. [13] explainedthe seismic behavior principle of steel fiber shotcrete. Nguyenet al. [14] studied on the impact resistance of steel fibershotcrete. Nehdi et al. [15] and Hoang and Fehling [16]studied on the effect of steel fiber with different lengths andcontents on mechanical properties of shotcrete. Marar et al.[17] discussed the effect of steel fiber with different aspectratios and contents on shear strength of shotcrete. Yoo et al.[18] analyzed the effect of deformed steel fiber on strength andbending toughness of shotcrete. Nattaj and Nematzadeh [19]obtained the effect of steel fiber with different contents onmechanical properties of silica fume shotcrete. Ghavidel et al.[20] tested on the stability of shotcrete during the steel fiberwas pulled out of the shotcrete matrix. Abbass et al. [21]obtained the evaluation method of steel fiber-reinforcedconcrete with different strength. Zhang et al. [22] hadstudied the flexural toughness of steel fiber-reinforced wetconcrete.
)e above scholars had studied the mechanical prop-erties of steel fiber or silica fume shotcrete, but little researchhad been done on the mechanical properties of steel fiber-reinforced siliceous wet shotcrete. )erefore, 10 groups ofcontrast tests were designed in this paper. )e effects of steelfiber-reinforced siliceous on mechanical properties of wetshotcrete were investigated by the test of compressivestrength, splitting tensile strength, flexural strength, shearstrength, and bending toughness. Finally, the optimum mixratio of wet shotcrete was obtained. )e new steel fiber-reinforced siliceous wet shotcrete makes full use of industrialwaste to replace nonrenewable raw materials, which hasgreen environmental properties. It also significantly en-hances the mechanical strength index, antiseepage, andanticracking ability. Moreover, it not only improves thesupporting effect of tunnel engineering, but also avoids theoccurrence of water bursting and mud outburst.
2. Experimental
2.1. Raw Material. )e shotcrete of this test adopted No.42.5 Portland cement. )e fine aggregate was sand, and thefineness modulus was 2.64. )e well-graded coarse ag-gregate was crushed stone, and the particle size was 5–10mm. Silica fume was produced by Ark New Materials(Shandong) Co., Ltd. )e performance parameters of silicafume are shown in Table 1. Steel fiber was produced byHuaxing(Yueyang)Co., Ltd. It was divided into two types:shear undaform and shear flat. Its specific parameters areshown in Table 2. )e admixture adopted a low alkaline
liquid setting accelerator of FZ-100C. Photographs of steelfiber and silica fume are shown in Figure 1.
2.2. Mix Proportion Design of Wet Shotcrete. )e specifica-tion GB 50086-2015 of bolt shotcrete support technologywas used to carry out the mix proportion design of wetshotcrete.)e dust, resilience, and pumping capacity of wetshotcrete were also considered. )e apparent density ofshotcrete was 2400 kg/m3. )e ratio of cement to sand was1 : 2.4. )e water-cement ratio was 0.55. )e content ofgravel was 598 kg/m3. )e silica fume was 10% cementquality. )e content of accelerator was 1.2 kg/m3, andaccelerator was 5% cement quality. )e maximum contentof steel fiber was 60 kg/m3.)ere were 10 groups of contrasttests, and the specific mix proportion of each group isshown in Table 3.
2.3. Experimental Method. )e experiment was divided intoten groups, with 15 specimens in each group. )e 6 cubespecimens of 100mm× 100mm× 100mm were used tocarry out the tests of compressive and splitting tensilestrength. )e 3 cube specimens of 100mm× 100mm× 300mm were used to carry out the test of shear strength.)e 6 rectangular specimens of 100mm× 100mm× 400mmwere used to carry out the tests of flexural and bendingtoughness strength. )is test adapted forced action mixer of60 L. )e time of entry template was 4 minutes later, and thetime of dismantling template was 24 h later. )e vibratingtime was 60 s. )e specimens shall be carried out for 28 daysat standard curing condition.)e electronic universal testingmachine CSS44100 of 300 kN was used by this test, and themethod of steel fiber concrete JG/T 472–2015 was used tocarry out the continuous loading on shotcrete specimens.)e test of bending toughness adopted the loading methodof four-point bending, and the loading rate was 0.2mm/min.When the discreteness was lower, the wet shotcrete intensityof this group was defined as the average value of the in-tensities of three specimens. When it was higher, the wetshotcrete intensity of a group was defined as the medianvalue of the intensities of three specimens if the differencebetween the maximum or minimum value and the medianvalue was larger than 15 percent of the median value, if not,this experiment was invalid. )e electronic universal testingmachine is shown in Figure 2.
3. Results and Discussion
3.1. Combined Effect of Silica Fume and Steel Fiber.Table 4 shows the test results of compression, splittingtensile, flexural, shear, and first-crack strength.
Comparison of group 2 and group 1 shows that whensilica fume was mixed only, the compressive strength,splitting tensile strength, flexural strength, shear strength,and initial splitting strengths of silica fume concrete wereimproved by 15.94%, 7.53%, 37.97%, 50.56%, and 18.92%,respectively, compared with the reference concrete. )isshowed that silica fume had a good enhancement effect. )esilica fume of high pozzolanic activity and water did not
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involve in the hydration reaction but silica fume and hy-dration product Ca(OH)2 of cement involved in the sec-ondary hydration reaction to produce C-S-H gel, thusimproving viscosity of the mixture. In addition, the mi-croscopic pore structure of hardened cement paste can befilled with silica fume with microaggregate effect and sec-ondary hydration products. Not only it can improve themicroscopic pore structure but also increase the density andstrength of silica fume concrete.
Comparison of group 3 and group 1 shows that whenshear undaform steel fiber was mixed only, the compressivestrength, splitting tensile strength, flexural strength, shearstrength, and initial splitting strength of steel fiber concretewere improved by 18.12%, 33.33%, 39.57%, 78.09%, and28.38%, respectively, compared with the reference concrete.It concluded that the crack resistance of steel fiber was better
than that of silica fume. Moreover, the splitting tensilestrength, flexural strength, and shear strength of the steelfiber concrete were obviously improved. Due to gravity, steelfibers and solid particulate matter took place subsidenceduring the hardening process of steel fiber-reinforcedconcrete, but the distributed steel fiber hindered the sub-sidence of the solid particles, and it played a reinforcing role,which increased the density of the steel fiber concrete andreduced the occurrence of the original microcracks. Inaddition, the bridging action of the steel fiber across thecracks prevented the coalescence of microcracks, and itreduced the depth and number of cracks, thus played a rolein crack resistance.
Comparison of group 5 and group 1 shows that whenshear undaform steel fiber of 50 kg/m3 and silica fume weremixed together, the compressive strength, splitting tensile
Table 2: Steel fiber performance parameter.
Steel fiber type Length (mm) Equivalent diameter (mm) Aspect ratio Tensile strengthShear undaform 30 0.3 100 Greater than 1150MPaShear flat 25 0.3 83 Greater than 1150MPa
Average particle size (μm) Specific surface area (m2·kg−1) Fineness (%) Density (g/cm3)0.1 15000 0.05 2.3
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strength, flexural strength, shear strength, and initial splittingstrength of steel fiber-reinforced siliceous shotcrete wereimproved by 23.91%, 74.19%, 60.43%, 85.39%, and 33.11%,respectively, compared with the reference concrete. It foundthat the edge of the reference concrete was broken anddropped seriously, and there was an explosive spalling phe-nomenon during the test. Finally, brittle failure took place.)e steel fiber-reinforced siliceous shotcrete was relativelycomplete during the test, and there was no shedding dregsphenomenon. Finally, ductile failure took place. )e C-S-Hgel produced by secondary hydration can increase the co-hesion force between the matrix and the steel fiber. So, it notonly decreased segregation and bleeding of aggregate but alsoreduced the shrinkage of hardening cement paste.
By comparing the data, it is concluded that the com-pressive strength of steel fiber-reinforced siliceous shotcretewas not very different from the former two kinds of concrete.When shotcrete was subjected to axial pressure, the lateralexpansion deformation of the shotcrete was restrained. Be-cause of the cohesive force between the steel fiber and the
matrix, the compressive strength can only be indirectly im-proved. )erefore, the effect of compression was not obvious.
But the splitting tensile strength, flexural strength, shearresistance, and initial crack strength of steel fiber-reinforcedsiliceous shotcrete had obvious effect on enhancement andcrack resistance. However, the steel fiber and the matrixbeared the load together, which hindered the extension andexpansion of crack in the initial loading process. When theultimate limit load of the matrix was reached, the steel fibersof across or near the crack tip played a bridging action,which forced the crack to change the direction of devel-opment or destroy the steel fiber. When the ultimate limitload was reached, pulling-out and shearing phenomena tookplace during the test. )e pulling out, debonding, and de-struction of steel fibers with high modulus of elasticityconsumed most of the fracture energy, so it can greatlyincrease the splitting tensile strength, flexural strength, andshear strength of steel fiber-reinforced siliceous shotcrete.
Finally, the macrocracks of steel fiber-reinforced sili-ceous shotcrete were expanding and coalescence. Ductile
Table 4: Test results of compression, splitting tensile, flexural, shear, and first-crack strength.
failure took place because of the short bearing capacity ofsteel fiber andmatrix together. A comparison of compressiveand shear failure of steel fiber-reinforced siliceous shotcreteis shown in Figures 3 and 4.
3.2. Influence of Steel Fiber Content and Type.Comparison of groups 1 and 5–10 in Table 4 shows thatwhen the content of shear undaform steel fiber was increasedfrom 40 kg/m3 to 50 kg/m3 and 60 kg/m3, the growth rate ofcompressive strength and initial crack strength of steel fiber-reinforced siliceous shotcrete was little changed. For com-pressive strength, the content of steel fiber can not changethe lateral expansion limited deformation and then in-directly increased the compressive strength. For the initialcrack strength, the steel fiber and the matrix beared the loadtogether before the initial crack. )e matrix was unloadedbut the load was carried by the steel fiber after the initialcrack. Finally, it reached the limit load. )e initial crackstrength of steel fiber-reinforced siliceous shotcrete wasmainly controlled by the matrix, while the limited strengthwas mainly controlled by steel fiber. )erefore, the contentof steel fiber had little influence on the initial crack strengthof steel fiber-reinforced siliceous shotcrete.
When the content of steel fiber was increased from40 kg/m3 to 50 kg/m3, the growth rate of splitting tensilestrength, flexural strength, and shear strength of steel fiber-reinforced siliceous shotcrete was very greatly changed; butfrom 50 kg/m3 to 60 kg/m3, the growth rate was graduallydecreased. With the increasing content of steel fiber andnonmixing uniformity of shotcrete, which reduced theslump and workability of shotcrete. So it gradually increasedporosity and microcracks. Some steel fibers appeared to theagglomerates by observing the cross section of steel fiber-reinforced siliceous shotcrete.
Comparison of group 5 and group 6, group 7 and group8, and group 9 and group 10 shows that the shape of the steelfiber had little effect on the compressive strength, but thesplitting tensile strength, flexural strength, shear strength,and initial crack strength of mixing the shear undaform steelfiber were about 10% higher than that of mixing the shearflat steel fiber. Because the special section of shear undaformsteel fiber had anchoring effect, and the bonding area waslarge between shear undaform steel fiber and matrix, whichincreased the cohesion force. So pulling out, tensile failure,and shearing of undaform steel fiber required higher energy.)e steel fiber-reinforced siliceous shotcrete section isshown in Figure 5.
3.3. Analysis and Evaluation of Bending Toughness of WetShotcrete. According to the JG/T 472-2015 test method ofsteel fiber concrete, the bending toughness index and thevariation coefficients of load-carrying capability were cal-culated. )e bending toughness of wet shotcrete was eval-uated by comparing two parameters with two parameters ofthe ideal elastoplastic material. )e bending toughness indexwas expressed by I5, I10, and I30, and the variation co-efficients of load-carrying capability was expressed by ξm,n,5,ξm,n,10, and ξm,n,30. )e bending toughness test results are
shown in Table 5, and the load deflection curves of differenttypes of wet shotcrete are shown in Figure 6.
As is shown in Table 5, when silica fume was mixed only,wet shotcrete took place brittle failure rapidly after reachingthe initial crack strength. So silica fume can not improve thebending toughness of wet shotcrete. When shear undaformsteel fiber of 50 kg/m3 was mixed only, the I5, I10, and I30 ofwet shotcrete was 4.86, 9.26, and 24.91, which was signifi-cantly higher than that of reference concrete. When shearundaform steel fiber of 50 kg/m3 and silica fume were addedtogether, the I5, I10, and I30 of wet shotcrete were increasedby 0.35, 0.47, and 1.96, respectively, compared with steelfiber concrete. Although the bending toughness index hadbeen improved to some extent, it had not changed greatly.When the content of shear undaform steel fiber was in-creased from 40 kg/m3 to 50 kg/m3, the bending toughnessindex had changed greatly. But from 50 kg/m3 to 60 kg/m3,its growth rate was decreased obviously.
As is shown in Figure 6, the peak load of the seventhgroup of shotcrete was maximum. At first, the bendingdeformation ability was not as good as that of the ninthgroup, and the ninth group was declined faster. But thebending deformation ability of the seventh group was morethan the ninth group beyond a certain deflection. When thecontent of steel fiber exceeded a certain limit, the im-provement effect of bending toughness was weakened. )ebending toughness index of mixing the shear undaformsteel fiber was slightly larger than that of mixing the shearflat steel fiber. )e change trend of the variation coefficientsof load-carrying capability was similar to the bendingtoughness index, and the change mechanism of bendingtoughness was similar to splitting tensile strength. )econtent of silicon fume was cement quality of 10% andshear undaform steel fiber was 60 kg/m3, and the bendingtoughness of wet shotcrete was the best by comprehensiveanalysis.
4. Conclusions
(1) )e mixing of steel fiber and silica fume can sig-nificantly improve the splitting tensile strength,flexural strength, shear strength, and bendingtoughness of wet shotcrete. )e steel fiber playeda major role, and silica fume played a subsidiarityrole. When the content of shear undaform steel fiberwas 60 kg/m3, the maximum growth rate of the shearstrength was 98.31%.
(2) )e effect of different types and contents of steelfibers on the compressive strength of wet shotcretewas not obvious. When shear undaform steel fiberand silica fume were mixed together, the maximumgrowth rate of the compressive strength was 28.99%.
(3) When steel fiber and silica fume were mixed to-gether, the splitting tensile strength, flexuralstrength, shear strength, and initial crack strength ofmixing the shear undaform steel fiber were about10% higher than that of mixing the shear flat steelfiber.
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(4) When silica fume was mixed only, it can not improvethe bending toughness of wet shotcrete. When steelfiber and silica fume were mixed together, the
bending toughness index had a little improved. )eseventh group of wet shotcrete was the optimummixture ratio; moreover, the bending toughness
(a) (b)
Figure 5: Section of steel fiber-reinforced silica fume concrete.
index and the variation coe�cients of load-carryingcapability were closest to the corresponding pa-rameters of ideal elastic-plastic material.
(5) �e ordinary steel �ber-reinforced wet shotcrete hasbeen initially applied in the tunnel of Brunel �amesin Britain and the Riva tunnel in Turkey, but the steel�ber-reinforced siliceous wet shotcrete could moree�ectively enhance the antiseepage and anticrackingability of tunnels, underground stations, and mineconstruction. Moreover, it could also avoid the waterinrush and mud outburst disaster.
Data Availability
�e data used to support the �ndings of this study areavailable from the corresponding author upon request.
Conflicts of Interest
�e authors declare that they have no conicts of interest.
Acknowledgments
�is work was fully supported by the Key Research andDevelopment Plan of Shandong Province of China(2018GSF116006).
References
[1] M. Rostami and K. Behfarnia, “�e e�ect of silica fume ondurability of alkali activated slag concrete,” Construction andBuilding Materials, vol. 134, pp. 262–268, 2017.
[2] A. J. Daniel, S. Sivakamasundari, and A. Nishanth, “Study onpartial replacement of silica fume based geopolymer concretebeam behavior under torsion,” Procedia Engineering, vol. 173,pp. 732–739, 2017.
[3] K. Alireza, M. R. Elias, H. Payam, and T. Hamidreza, “Me-chanical performance of self-compacting concrete reinforcedwith steel �bers,” Construction and Building Materials, vol. 51,pp. 179–186, 2014.
[4] J. Yu, S. M. Lei, X. W. Liang et al., “A design method of mixproportion for a new type of hybrid steel �ber reinforced self
Figure 6: Shotcrete load-deection curve. (a) Comparison of shear undaform steel �ber concrete and reference concrete. (b) Comparison ofshear undaform steel �ber concrete and silica fume concrete.
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compacting concrete,” Journal of Building Materials, vol. 20,no. 4, pp. 611–615, 2017.
[5] W. F. Cheng, X. P. Lin, Y. N. Ding et al., “Study on engi-neering application of silica fume additives and steel fibershotcrete,” Journal of Rock Mechanics and Engineering,vol. 30, no. 11, pp. 2311–2329, 2011.
[6] X. R. Liu, Y. H. Zhu, X. H. Li et al., “Experimental research onsingle-layer tunnel lining of steel fiber shotcrete,”GeotechnicalMechanics, vol. 30, no. 8, pp. 2319–2323, 2009, in Chinese.
[7] L. C. Zhang, S. C. Li, S. Li et al., “Influence of silica fume andfly ash on Shotcrete performance,” Journal of ShandongUniversity, vol. 46, no. 5, pp. 103–109, 2016, in Chinese.
[8] Y. Liu, R. Ma, J. Yang et al., “Shrinkage properties of silicafume concrete,” Journal of Guangxi University, vol. 40, no. 4,pp. 909–914, 2015, in Chinese.
[9] R. B. Ardalan, A. Joshaghani, and R. D. Hooton, “Workabilityretention and compressive strength of self-compacting con-crete incorporating pumice powder and silica fume,” Con-struction and Building Materials, vol. 134, pp. 116–122, 2017.
[10] S. Fallah and M. Nematzadeh, “Mechanical properties anddurability of high-strength concrete containing macro-polymeric and polypropylene fibers with nano-silica andsilica fume,” Construction and Building Materials, vol. 132,pp. 170–187, 2017.
[11] L. C.Wang, P. Q. Jiang, Y. Q. Liang et al., “Experimental studyon dynamic mechanical properties of steel fiber concreteunder biaxial compression,” Journal of Building Materials,vol. 20, no. 1, pp. 106–111, 2017.
[12] C. D. Su, Y. Li, Z. Q. Xiong et al., “Splitting strength anddeformation characteristics of steel fiber reinforced highperformance concrete,” Journal of Building Materials, vol. 17,no. 4, pp. 587–591, 2014.
[13] S. Naqvi, K. Mahmoud, and E. El-Salakawy, “Effect of axialload and steel fibers on the seismic behavior of lap-splicedglass fiber reinforced polymer-reinforced concrete rectan-gular columns,” Engineering Structures, vol. 134, pp. 376–389,2017.
[14] T. Nguyen, T. T. Nguyen, and W. Pansuk, “Experimentalstudy of the punching shear behavior of high performancesteel fiber reinforced concrete slabs considering casting di-rections,” Engineering Structures, vol. 131, pp. 564–573, 2017.
[15] M. L. Nehdi, S. Abbas, and A. M. Soliman, “Exploratory studyof ultra-high performance fiber reinforced concrete tunnellining segments with varying steel fiber lengths and dosages,”Engineering Structures, vol. 101, pp. 733–742, 2015.
[16] A. L. Hoang and E. Fehling, “Influence of steel fiber contentand aspect ratio on the uniaxial tensile and compressivebehavior of ultra high performance concrete,” Constructionand Building Materials, vol. 153, pp. 790–2806, 2017.
[17] K. Marar, O. Eren, and H. Roughani, “)e influence ofamount and aspect ratio of fibers on shear behaviourof steelfiber reinforced concrete,” Journal of Civil Engineering, vol. 21,no. 4, pp. 1393–1399, 2017.
[18] D. Y. Yoo, S. W. Kim, and J. J. Park, “Comparative flexuralbehavior of ultra-high-performance concrete reinforced withhybrid straight steel fibers,” Construction and Building Ma-terials, vol. 132, pp. 219–2229, 2017.
[19] F. H. Nattaj andM. Nematzadeh, “)e effect of forta-ferro andsteel fibers on mechanical properties of high-strength con-crete with and without silica fume and nano-silica,” Con-struction and Building Materials, vol. 137, pp. 557–572, 2017.
[20] R. Ghavidel, R. Madandoust, and M. M. Ranjbar, “Reliabilityof pull-off test for steel fiber reinforcedself -compactingconcrete,” Measurement, vol. 73, pp. 628–639, 2015.
[21] W. Abbass, M. I. Khan, and S. Mourad, “Evaluation of me-chanical properties of steel fiber reinforced concrete withdifferent strengths of concrete,” Construction and BuildingMaterials, vol. 168, pp. 556–569, 2018.
[22] J. P. Zhang, L. M. Liu, Z. D. Zhu, and J. Z. Cao, “Flexuralfracture toughness and first-crack strength tests of steel fiber-silica fume concrete and its engineering applications,”Strength of Materials, vol. 50, no. 1, pp. 166–175, 2018.
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