• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1193-1198
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• 2008

Shaking table tests were performed to investigate the response of liquefaction mitigation of rammed aggregate piers(RAP) on soft ground. The displacements of the soft ground reinforced by RAP under area replacement ratio 7, 14, 28% during seismic loading were measured. The result of tests showed that effects of liquefaction mitigation were affected various area replacement ratios and ground acceleration on RAP systems.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.227-230
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• 1998

The void ratio, continuous void ratio, coefficient of permeability, compressive strength and tensile strength were considered according to the EAF(Electric Arc Furnace) slag replacement and sand percentage in permeable concrete used with EAF slag as aggregate. The sand percentage was directly proportional to the permeable coefficient, but inversely proportional to the compressive strength. When the compressive strength and coefficient of permeability were 230 kg/$\textrm{cm}^2$ and 1$\times$$10^{-1}$ cm/sec, the useful sand percentage was 8%. When the EAF slag replacement was 25%, the coefficient of permeability was the most low and compressive strength was the most high.

• Advances in concrete construction
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• v.3 no.1
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• pp.55-69
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• 2015

Tailing Material (TM) and Fly Ash (FA) are obtained as waste products from the mining and thermal industries. Studies were carried out to explore the possibility of utilizing TM as a part replacement to fine aggregate and FA as a part replacement to cement, in concrete mixes. The effect of replacing fine aggregate by TM and cement by FA on the standard sized specimen for compressive strength, split tensile strength, and flexural strengths are evaluated in this study. The concrete mix of M40 grade was adopted with water cement ratio equal to 0.40. Concrete mix with 35% TM and 65% natural sand (TM35/S65) has shown superior performance in strength as against (TM0/S100, TM30/S70, TM40/S60, TM50/S50, and TM60/S40). For this composition, studies were performed to propose the optimal replacement of Ordinary Portland Cement (OPC) by FA (Replacement levels studied were 20%, 30%, 40% and 50%). Replacement level of 20% OPC by FA, has shown about 0-5% more compressive strength as against the control mix, for both 28 day and 56 days of water curing. Interestingly results of split tensile and flexural strengths for 20% OPC replaced by FA, have shown strengths equal to that of no replacement (control mix).

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.641-646
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• 2001

Generally, when Fly-Ash was used as replacement material of cement in concrete, it might occur retardation of setting and hardening. So, it is unable to use a large amount of Fly-Ash as replacement for cement. However, if it is used as replacement material of fine aggregate in concrete, we can use a large amount of Fly-Ash and settle a problem of natural-aggregate exhaustion. Furthermore, engineering properties of High Volume Fly-Ash Concrete Is better than that of plain concrete But, the larger Fly-Ash is replaced, the more fluidity of High Volume Fly-Ash Concrete decrease, because porous organization of Fly-Ash adsorb water and Superplasticizer. In this study, after appending additional water to High Volume Fly-Ash Concrete in proportion to weight of Fly-Ash, we intend to find proper ratio which doesn't affect strength and satisfy fluidity As a result of this study, it was found that fluidity of mortar with 25~28 percentage of additional water was satisfied with fluidity of plain mortar, and compressive strength of that was similar to plain mortar's

• Land and Housing Review
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• v.2 no.4
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• pp.471-477
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• 2011

This paper will describe the experimental results on the shear behaviors of reinforced concrete (RC) beam with recycled coarse aggregate (RCA). The primary objective of this research is to evaluate the influences of different RCA replacement percentage (i.e, 0%, 30%, 60%, and 100%) on the shear performance of reinforced concrete beams without shear reinforcement. Eight large-scale RC beams without shear reinforcement were manufactured and tested to shear failure. All had a rectangular cross-section with 400mm width ${\times}$ 600mm depth and 6000mm length, and were tested with a shear span-to-depth of 5.1. The results showed that the deflection and shear strength were little affected by the different RCA replacement percentage. Actual shear strength of each RCA beam was compared with the shear strength predicted using the provisions of ACI 318 code and Zsutty'e equation for shear design of RC beams. ACI 318 code predicted the shear strength of RCA reinforced concrete beams well.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.409-415
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• 2012

To recycle the steel slag as manufactured composite materials of polymer concretes, we used the atomizing method to make round aggregates from steel slag, which is treated as industrial wastes. A round rapid-cooled steel slag was used to replace fine aggregate (river sand) or coarse aggregate (crushed aggregate), depending on the grain size. To examine general physical properties of polymer concrete composites manufactured from rapid-cooled steel slag, the polymer concrete specimen with various proportions depending on the addition ratio of polymer binder and replacement ratio of rapid-cooled steel slag were manufactured. In the result of the tests, the mechanical strength of the specimen made by replacing the optimum amount of rapid-cooled steel slag increased notably (maximum compressive strength 117.1 MPa), and the use of polymer binder, which had the most impact on the production cost of polymer concrete composites, could be remarkably reduced. However, the mechanical strength of the specimen was markedly reduced in hot water resistance test of polymer concrete composite.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.513-528
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• 2020

This paper presents the results of an experimental study on the residual behavior of reinforced recycled aggregate concrete (RRAC) beam-columns after exposure to elevated temperatures. Two parameters were considered in this test: (a) recycled coarse aggregate (RCA) replacement percentages (i.e. 0, 30, 50, 70 and 100%); (b) high temperatures (i.e. 20, 200, 400, 600, and 800℃). A total of 25 RRAC short columns and 32 RRAC beams were conducted and subjected to different high temperatures for 1 h. After cooling down to ambient temperature, the following basic physical and mechanical properties were then tested and discussed: (a) surface change and mass loss ratio; (b) strength of recycled aggregate concrete (RAC) and steel subjected to elevated temperatures; (c) bearing capacity of beam-columns; (d) load-deformation curve. According to the test results, the law of performance degradation of RRAC beam-columns after exposure to high temperatures is analyzed. Finally, introducing the influence coefficient of RCA replacement percentage and high temperatures, respectively, to correct the calculation formulas of bearing capacity of beam-columns in Chinese Standard, and then the residual bearing capacity of RRAC beam-columns subjected elevated temperatures is calculated according to the modified formulas, the calculated results are in good agreement with the experimental results.

• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.177-183
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• 2015

In this study, the thermal conductivity, physical and mechanical properties of lightweight aggregate concretes with hollow micro sphere(HMS) are experimentally examined as a basic research for the development of structural insulation concrete. As the results of this experiment, in the case of concrete mixed with HMS, the value of slump has been reduced, so it is found that the dosage of superplasticizer should be increased. As the replacement ratio of HMS increases, it has shown that the compressive strength is somewhat decreased due to the low interfacial adhesion strength of HMS. But the thermal conductivity is found to be greatly improved with the replacement ratio of HMS increases, the thermal conductivity of HMS shows the lower value of 68% at lightweight aggregate concrete and 32% of normal concrete. Also it is found that the compressive strength is decreased and thermal conductivity is increased as the water-cement ratio increases. The most outstanding for insulation performance is observed when using 20% of HMS and 50% of water-cement ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.437-440
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

• Computers and Concrete
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• v.29 no.5
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• pp.323-334
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• 2022

In order to study the axial compression performance of basalt-fiber reinforced recycled concrete (BFRRC) filled circular steel tubular short columns, the axial compression performance tests of seven short column specimens were conducted to observe the mechanical whole-process and failure mode of the specimens, the load-displacement curves and the load-strain curves of the specimens were obtained, the influence of design parameters on the axial compression performance of BFRRC filled circular steel tubular short columns was analyzed, and a practical mathematical model of stiffness degradation and a feasible stress-strain curve equation for the whole process were suggested. The results show that under the axial compression, the steel tube buckled and the core BFRRC was crushed. The load-axial deformation curves of all specimens show a longer deformation flow amplitude. Compared with the recycled coarse aggregate (RCA) replacement ratio and the basalt fiber dosage, the BFRRC strength has a great influence on the peak bearing capacity of the specimen. The RCA replacement ratio and the BFRRC strength are detrimental to ductility, whereas the basalt fiber dosage is beneficial to ductility.