• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.209-217
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• 2021

This paper investigates the effect of high strength hooked-end steel fiber content and aspect ratio on the compressive and flexural performance of concrete. A total of ten mixtures were prepared and tested. Concretes with specific compressive strength of 30 MPa were reinforced with three different aspect ratios (l/d) of steel fibers 64, 67, and 80 and three different percentages of steel fibers 0.25, 0.50, and 0.75% by volume of concrete. Tensile strengths of steel fibers with l/d of 64, 67, and 80 are 2,000, 2,400, and 2,100 MPa, respectively. The compressive and flexural properties of plain and steel fiber-reinforced concrete (SFRC) mixtures were evaluated and compared. The experimental results indicated that the incorporation of high-strength hooked-end steel fibers had significant effects on the compressive and flexural performance of concrete. With the increase of steel fiber content, compressive performances, such as Poisson's ratio and toughness, of concrete were improved. The steel fibers with the least l/d of 67 resulted in a larger enhancement of compressive performances. The residual flexural strength, that is, post-cracking flexural resistance and toughness, of concrete is mainly depended on the dosage and aspect ratio of steel fibers. The residual flexural strength at serviceability (SLS) and ultimate limit state (ULS) defined in fib Model Code 2010 (MC2010) is increased as the fiber content and aspect ratio increase.

• Advances in concrete construction
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• v.8 no.1
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• pp.1-7
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• 2019

The possibility of using recycled coarse glass aggregates as a substitute for natural crushed stone are relatively limited. In order to promote it for engineering application, this paper reports the effect of coarse glass aggregate on mechanical behavior of concrete. The coarse aggregates are substituted for coarse glass aggregate (CGA) as 0%,20%,40%,60%,80% and 100%.The results show that increasing the coarse glass aggregate content cause decrease in compressive strength, the elastic modulus, the splitting tensile strength, the flexural strength. An equation is presented to generate the relationship between cube compressive strength and prism compressive strength, the relationship between cube compressive strength and elastic modulus, the relationship between cube compressive strength and splitting tensile strength, the relationship between cube compressive strength and flexural strength of coarse glass concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.99-104
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• 2002

In this paper the influence or specimen length on flexural compressive strength and parameter or equivalent rectangular stress block of polymer concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to eccentric compression were tested using four different length-to-depth ratios(from 1.0, 2.0, 3.0 and 4.0) of specimens with compressive strength of 1,020kgf/cm$^2$. Results indicate that for the region of h/c$\leq$3.0 the reduction in equivalent rectangular stress block depth and flexural compressive strength with increase of length-to-depth ratios was apparent but for the region of h/c$\geq$3.0 they were nearly constant. It means that for the region of h/c$\geq$3.0 effect of specimen length on equivalent rectangular stress block depth and flexural compressive strength was negligible. It was also founded that the effect of specimen length on v, a coefficient of strength, that was from 0.84 to 0.86 regardless of h/c was petty. Finally, predictive equation is, suggested by using modified law of effect of specimen length and results.

• Computers and Concrete
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• v.17 no.3
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• pp.337-351
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• 2016

This paper presents the properties of pervious concrete containing high-calcium fly ash. The water to binder ratios of 0.19, 0.22, and 0.25, designed void ratios of 15, 20, and 25%, and fly ash replacements of 10, 20, and 30% were used. The results showed that the use of fly ash as partial replacement of Portland cement enhanced the mixing of paste resulting in a uniform mix and reduced amount of superplasticizer used in the mixture. The compressive strength and flexural strength of pervious concrete were slightly reduced with an increase in fly ash replacement level, while the abrasion resistance increased due mainly to the pozzolanic and filler effects. The compressive strength and flexural strengths at 28 days were still higher than 85% of the control concrete. The aggregate size also had a significant effect on the strength of pervious concrete. The compressive strength and flexural strength of pervious concrete with large aggregate were higher than that with small aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.307-312
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• 1999

The purpose of this study is to ascertain the strength properties of water-permeable concrete with redispersible polymer powder, silica fume and polypropylene fibers. The water-permeable concrete using rediapersibel polymer powder with a water-cement ratio of 25%, polymer-cement ratios of 0 to 10%, silica fume contents of 0 to 10% and fiber contents of 0 to 1.5% are prepared, and tested for flexural strength, compressive strength and water permeability. From the test results, improvements in the strength properties of the water-permeable concrete due to the addition of the redispersible polymer powder, silica fume and fibers are discussed. It is concluded from the test results that the superior flexural and compressive strengths of water-permeable concretes are obtained at a propylene fiber content of 1.0% with a void filling ratio of 50%. And, the water-permeable concrete having a flexural strength of 15.6~28.4kgf/$\textrm{cm}^2$, a compressive strength of 63.5~120.6kgf/$\textrm{cm}^2$, and a coefficient of permeability of 1.14~1.70cm/s at a void filling ratio of 30% can be prepared. Also water-permeable concrete having a flexural strength of 35.6~57.9kgf/$\textrm{cm}^2$, a compressive strength of 164.0~290.0kgf/$\textrm{cm}^2$, and a coefficient of permeability of 0.19~1.04cm/s at a void filling ratio of 50% can be prepared in the consideration of the mix proprotioning factors.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.4
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• pp.25-32
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• 2005

This study was performed to evaluate the strength properties of polymer concrete using recycled aggre-gate. The compressive strength, splitting tensile strength, flexural strength and pulse velocity of polymer concrete were decreased with increasing the content of recycled aggregate. At the curing age of 7days, the compressive strength was $80.5\~88.3$ MPa, the splitting tensile strength was $9.1\~10.6$ MPa, the flexural strength was $19.2\~21.5$ MPa and the pulse velocity was $3,931\~4,041$ m/s, respectively. Also, the compressive strength, splitting tensile strength, flexural strength and pulse velocity of concrete using recycled fine aggregate were higher than that of the silica sand. Therefore, these recycled aggregate polymer concretes were estimated for high strength concrete without major problem.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.8
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• pp.131-138
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• 2019

Since concrete has a low tensile strength compared to the compressive strength, reinforced concrete flexural members represent easy crack occurance under a small load. In order to overcome this problem, steel fiber reinforced concrete has been developed to compensate the tensile strength and brittleness of members. However, in the design formula of the domestic building code, it is not specified in the design formula reflecting the material characteristics. Therefore, the field application of the steel fiber reinforced concrete have had many restrictions. In this study, a flexural tensile strength model of steel fiber reinforced concrete is proposed by collecting and analyzing the material properties of material test results conducted by various researchers, and verified by the test results of cracking and stiffness evaluation of flexural members based on the proposed model. As a result of this study, the flexural tensile strength model of steel fiber reinforced concrete which can reflect the mixing ratio and aspect ratio of the steel fiber was proposed and the validity of the proposed material model equation was evaluated from the load-deflection relationship in the flexural test of the slab member.

• Advances in materials Research
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• v.8 no.2
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• pp.103-115
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• 2019

Polypropylene (PP) fibers for making fabric which is used for packing cement have a high strength and high tear resistance. Due to these excellent properties the present study investigates the effect of PP fibers on the mechanical strength of concrete. Mechanical strength parameters such as compressive strength, splitting tensile strength and flexural strength are evaluated. Structural integrity of concrete using Ultrasonic Pulse Velocity (UPV) was also studied. Concrete containing PP fibers in percentage of 0%, 0.15%, 0.25%, 0.5% and 0.75% was developed with a characteristic compressive strength of 25 MPa. Concrete cubes, cylinder and prismatic specimens were cast and tested. It was found that the UPV values recorded for all specimens were of the similar order. Test results indicated the used of PP fibers can significantly improve the flexural and splitting tensile strengths of concrete materials whereas it resulted a decreased in compressive strength. The relative increase in split tensile and flexural strength was optimum at a fiber dosage of 0.5% and a mild decreased were observed in 28 days compressive strength. The findings in this paper suggested that PP fibers deriving from these waste cement bags are a feasible fiber option for fiber-reinforced concrete productions.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.411-414
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• 2003

This study is performed to examine the physical and mechanical properties of recycled polymer concrete using recycled coarse aggregate and recycled fine aggregate. Tests for compressive strength, flexural strength and pulse velocity with replacement ratio of recycled coarse aggregate and recycled fine aggregate are performed. As a result, compressive strength, flexural strength and pulse velocity of polymer concrete containing recycled coarse aggregate are in the range of $826{\sim}849kgf/cm^2,\;192{\sim}200kgf/cm^2\;and\;3,932{\sim}4,000m/s$, respectively. Compressive strength, flexural strength and pulse velocity of polymer concrete containing crushed stone only are $805kgf/cm^2,\;197kgf/cm^2$ and 3,931 m/s, respectively. Accordingly, recycled aggregates is expected that can be utilizing as an aggregate of polymer concrete.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.415-418
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• 2003

This study is performed to examine properties of polymer permeability concrete using recycled coarse aggregate and blast furnace slag for application of structures needed permeability. Tests for compressive strength, flexural strength and pulse velocity with replacement ratio of recycled coarse aggregate are performed. As a result, compressive strength, flexural strength and coefficient of permeability of polymer permeability concrete containing recycled coarse aggregate are in the range of $180{\sim}200kgf/cm^2,\;58{\sim}64kgf/cm^2\;and\;4.6{\times}10^{-2}{\sim}6.9{\times}10^{-2}cm/s$, respectively. Compressive strength, flexural strength and pulse velocity of polymer concrete containing crushed stone only are $192kgf/cm^2,\;65kgf/cm^2\;and\;6.1{\times}10^{-2}cm/s$, respectively. Accordingly, recycled coarse aggregate is expected that can be utilizing as an aggregate of polymer permeability concrete.