• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.377-378
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• 2009

The purpose of this study was to evaluate basic physical prorerties of color mortar using an industrial by-product called iron sulphate. First as the characteristic of fresh mortar, addition of iron sulphate reduced flow, air content and unit volume weight. Compressive strength was increased the most at substitution of 6% iron sulphate.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.231-234
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• 2005

Steel braced frames retrofit method has been broadly used due to their effectiveness in both light weight and construction periods. However, steel braced frames retrofit method has difficulties in application on the inner frames of buildings to be retrofitted consequently, there have been demands for the braced frames retrofit method that can be broadly and easily applicable to both inner and outer frames of the buildings. The objective of this study is to develop and evaluate the seismic retrofit method applicable to the inner frame also by dividing the reinforcing frames into three unit. From the cyclic test of specimens, the test results dearly showed that steel brace using HPFRCCs and steel bars ensure the better cyclic compressive performance than the normal braced members.

• Advances in concrete construction
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• v.14 no.5
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• pp.355-368
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• 2022

This paper investigates the impact of length and volume fractions (VFs) of banana fibres (BFs) on the mechanical and physical properties of concrete. The mechanical properties were compressive strength, splitting tensile, flexural strength, and bond stress, while the physical properties were unit weight and absorption. The slump test was used to determine workability. The concrete's behaviour with BFs was studied using scanning electron microscopy. Experimental work of concrete mixtures with BFs of various lengths (12 mm, 25 mm, and 35 mm) and VFs (0%, 0.5%, 1.0%, and 1.5%) were carried out. The samples did not indicate any agglomeration of fibres or heterogeneity during mixing. The addition of BFs to concrete with VFs of up to 1.50% for all fibre lengths have a significant impact on mechanical properties, also the longer fibres performed better than shorter ones at all volume fractions of BFs. The mix10, which contain BFs with VFs 1.5% and length 35 mm, demonstrated the highest mechanical properties. The compressive strength, splitting tensile, flexural strength, and bond stress of the mix10 were 37.71 MPa, 4.27 Mpa, 6.12 MPa, and 6.75 MPa, an increase of 7.37%, 20.96%, 24.13%, and 11.2% over the reference concrete, which was 35.12 MPa, 3.53 MPa, 4.93 MPa, and 6.07 MP, respectively. The absorption is increased for all lengths by increasing the VFs up to 1.5%. Longer fibres have lower absorption, while shorter fibres have higher absorption. The mix8 had the highest absorption of 4.52%, compared to 3.12% for the control mix. Furthermore, the microstructure of concrete was improved through improved bonding between the fibres and the matrix, which resulted in improved mechanical properties of the composite.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.419-426
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• 2016

This study examined the effect of transverse reinforcement and compressive stress on the shear friction performance at the shear interface intersecting two structural elements with various concrete types. From the prepared 12 push-off test specimens, various characteristics at the interface were measured as follows: crack propagation, shear load-relative slip relationship, initial shear cracking strength, ultimate shear friction strength, and shear transfer capacity of transverse reinforcement. The configuration of transverse reinforcement and compressive strength of concrete insignificantly influenced the amount of relative slippage at the shear friction plane. With the increase of applied compressive stress, the shear friction capacity of concrete tended to increase proportionally, whereas the shear transfer capacity of transverse reinforcement decreased, which was insignificantly affected by the configuration type of transverse reinforcement. The empirical equations of AASHTO-LRFD and Mattock underestimate the shear friction strength of concrete, whereas Hwang and Yang model provides better reliability, indicating that the mean and standard deviation of the ratios between measured shear strengths and predictions are 1.02 and 0.23, respectively.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.93-100
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• 2019

In this study, the mechanical properties of early-age concrete were evaluated by mixing the electric arc furnace oxidizing slag fine aggregate with 30% and 50% replacement ratio. Slump test, air content test and unit volume weight test were performed for fresh concrete, and compressive strength test and chloride penetration experiments were carried out in hardened concrete. The compressive strength increased up to 7 days of curing age with increasing replacement ratio of the electric furnace oxidizing slag, but the strength decreased to 90% level of OPC concrete at 28 days of age. Regarding the result of chloride penetration test, no significant differences from OPC concrete were evaluated, which shows a feasibility of application to concrete aggregate.

• Computers and Concrete
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• v.17 no.6
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• pp.787-799
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• 2016

Climate anomalies in recent years, numerous natural disasters caused by landslides and a large amount of entrained sands and stones in Taiwan have created significant disasters and greater difficulties in subsequent reconstruction. How to respond to these problems efficaciously is an important issue. In this study, the sands and stones were doped with recycled materials (waste LCD glass sand, slag powder), and material was mixed for recycled ready-mixed soil. The study is based on security and economic principles, using flowability test to determine the water-binder ratio (W/B=2.4, 2.6, and 2.8), a fixed soil: sand ratio of 6:4 and a soil: sand: glass ratio of 6:2:2 as fine aggregate. Slag (at concentrations of 0%, 20%, and 40%) replaced the cement. The following tests were conducted: flowability, initial setting time, unit weight, drop-weight and compressive strength. The results show that the slump values are 220 -290 mm, the slump flow values are 460 -1030 mm, and the tube flow values are 240-590 mm, all conforming to the objectives of the design. The initial setting times are 945-1695 min. The unit weight deviations are 0.1-0.6%. The three groups of mixtures conform to the specification, being below 7.6 cm in the drop-weight test. In the compressive strength test, the water-binder ratios for 2.4 are optimal ($13.78-17.84kgf/cm^2$). The results show that Recycled ready-mixed soil materials (RRMSM) possesses excellent flowability. The other properties, applied to backfill engineering, can effectively save costs and are conducive to environmental protection.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.60-67
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• 2018

As the lack of specific aggregation intensifies, the development of alternative resources is urgent. Construction waste is increasing every year, but recycled aggregate is used as a low value added material. Various studies are currently underway at the national level. In this paper, the mechanical performance of the concrete according to the concrete mixing method and the replacement amount of the circulating coarse aggregate was compared and evaluated. Concrete mixing method was normal mixing approach(NMA) method, two-stage mixing approach1 (TSMA1) method, two-stage mixing approach2 (TSMA2) method. Fresh concrete was tested for air content, slump test, and unit volume weight. Compressive strength and flexural strength were tested in hardened concrete. According to the TSMA method, the mechanical performance difference of concrete is shown, and the strength is decreased according to the circulating coarse aggregate replacement amount.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.35-42
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• 2003

To use ferro copper slag as aggregate in the construction, an evaluation upon the two kinds of ferro copper slag being produced was conducted to determine the basic physical, and mechanical properties, chemical component and environmental noxiousness. As a result of experiment, it was found that two kinds of ferro copper slag satisfies the physical and mechanical properties of aggregate, prescribed in KS F 2526, and that in the result of noxious heavy metal eruption test by single bach extraction, no eruption of noxious heavy metal was detected or the eruption was far below the reference value. And mortar test was conducted by replacing sand of 25, 50, 75, 100% and the performance level was presented upon reviewing the fluidity property and variable aspects of unit weight. The increase of strength in accordance with replacement rate of sand was found to be the below than the equivalent level compared to the testing specimens that did not use ferro copper slag, but those of 25% replacement rate was above than 0%. Thus, two kinds of ferro copper slag, produced in the domestic, were found to be possessing the enough physical properties to use as concrete aggregate assuming that used with sand and in particular, it was reviewed to be advantageous in manufacturing concrete or mortar that requires weight.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.278-284
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• 1998

This study was performed to evaluate the engineering properties of permeable polymer concrete with Fly Ash and $CaCo_3$. The following conclusions were drawn; 1. The unit weight was in the range of $1,830{\sim}1,932kgf/m^3$, the unit weights of those concrete were decreased 16~20% than that of the normal cement concrete. 2. The highest strength was achieved by fly ash 50% and $CaCo_3$ 50% filled permeable polymer concrete, it was increased 26% by compressive strength, 121% by tensile strength and 275% by bending strength than that of the normal cement concrete, respectively. 3. The ultrasonic pulse velocity was in the range of 2,805~2,904m/s, which was showed about the same compared to that of the normal cement concrete. Fly ash 50% and $CaCo_3$ 50% filled permeable polymer concrete was showed higher pulse velocity.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.79-87
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• 2004

The qualify of lightweight aggregate made from waste PET bottle(WPLA) and the workability, the unit weight and strength property of concrete with WPLA were investigated for the purpose of recycling the waste PET bottles as lightweight concrete fine aggregate. This study indicated a good result that WPLA should be replaced with less than $50\%$ of natural fine aggregate. When WPLA was replaced with $50\%$ of natural fine aggregate, the specific gravity and water absorption of mixed fine aggregate were greatly reduced about 23 and $75\%$ respectively in comparison with those of river sand. The quality of WPLA affected on the properties of lightweight aggregate concrete. The workability of fresh concrete with WPLA(WPLAC) was improved with increasing the replacement ratio of WPLA and water cement ratio. Slump increasing ratio of the former showed about $45 {\~} 120\%$ because that a specific gravity of fine aggregate was decreased from 2.6 to 1.7. The unit weight of concrete with $75\%$ WPLA was decreased about $17\%$ in comparison with that of control concrete. Furthermore, the compressive strength of concrete with 25 and $50 \%$ WPLA at the age of 28 days increased higher than 30 MPa regardless with water cement ratio (W/C=45, 49 and $53\%$) of this study. Specific strength of concrete with $25\%$ WPLA, $15.11{\times}10^3 MPa{\cdot}m^3/kg$, was higher than that of contro concrete in water cement ratio of $49\%$. The compressive strength-splitting tensile strength ratio and compressive strength-modulus of elasticity ratio of WPLAC were similar to that of nomal lightweight aggregate concrete. This results showed a good estimation that WPLA will be able to recycled as a fine aggregate for lightweight concrete.