• International Journal of Highway Engineering
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• v.9 no.4
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• pp.93-104
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• 2007

This study evaluates the mechanical properties of steel fiber reinforced porous concrete for pavement according to content of slag aggregate and fly ash to elicit the presentation of data and the way to enhance its function for the practical field application of porous concrete as a material of pavement. As a result, void ratio and permeability coefficient of porous concrete for pavement increased a little as mixing rate of slag aggregates increased. Void ratio and permeability coefficient increased a lot as mixing rate of fly ash decreased. As fly ash was mixed, national regulation of permeable concrete for pavement(8% and 0.1 cm/sec) was met. Compressive strength and flexural strength decreased as mixing rate of slag aggregates increased, but they increased a lot as mixing rate of fly ash increased. Even when slag aggregates were mixed 50% with 5% fly ash mixed, national regulation of pavement concrete(18MPa and 4.5MPa) was met. In addition, compared to non-mixture, flexural strength increased about 22.8% when 0.75vol.% of steel fiber was added. Regarding sliding resistance, BPN increased as mixing rate of slag aggregates increased. But BPN decreased as fly ash was mixed. Compared to crushed stone aggregates, abrasion resistance and fleers-thaw resistance decreased as mixing rate of slag aggregates increased. When fly ash was mixed, abrasion resistance and freeze-thaw resistance improved remarkably. Compared to non-mixture, 10% mixture of fly ash improved abrasion resistance and freeze-thaw resistance about 5.6% and 14.3 respectively.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.194-201
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• 2019

This study analyzed the properties of concrete depending on the coal gasification slag(CGS) contents in order to examine the applicability of CGS as the fine aggregate for concrete. Experimental results, trended that the slump and slump flow increased with increasing CGS contents, and air contents has decreased. Evaluation index for segregation of normal strength concrete(EISN) is showed was good from CGS 25% when using crushed sand A(CSa) and CGS 50% when using mixed sand(MS). The compressive strength decreased with increasing CGS contents when CSa was used. However, when MS was used, the maximum value was CGS 50% due to parabolic tendency. Depending on fine aggregates type, compared with compressive strength of CSa was about 8% higher than that of MS, and depending on the use or unuse of CGS, more advantageous at higher strength than low strength. As a result of relative performance study on the quality of concrete according to the CGS contents, it is considered that CGS can be positively contributed to enhancement of workability and strength development when mixed with fine aggregate around 25~50%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.452-459
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• 2017

In recent years, to reduce self-weight of structural elements, the use of SCP (Steel Concrete Plate) instead of prestressed concrete is increasing. Because SCP has a complicated sectional shape and includes a large number of studs, the use of high-fluidity concrete is required. Therefore, in this study, to prevent the restrained shrinkage behavior by the stud, the effects of using an expansive agent (EA) and shrinkage reducing agent (SRA) were investigated, and the optimal mixture proportions to maximize the filling capacity were determined based on the fine aggregate ratio. The test results indicated that the combined use of EA and SRA exhibited the smallest shrinkage. The ratio of the crushed sand and washed sea sand was determined to be 5:5, and the proper fine aggregate ratio was found to be 55.6%, because when the ratio was too high, a decrease in strength and an increase in shrinkage strain were expected. The high-fluidity concrete effectively filled the large-sized SCP module.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.83-91
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• 2015

Porous concrete consists of cement, water and coarse aggregate and has been used for the purpose of decreasing the earth environmental load such as air and water permeability, sound absorption, etc. However, the physical and mechanical properties of porous concrete changes due to compaction load during construction. For such a reason, the purpose of this study is to investigate the physical and mechanical properties of porous concrete according to the kinds of binder, the ratio of water to binder and target void ratio. In particular, this study has been carried out to investigate the influence of compaction load on the void ratio, strength and coefficient of permeability. Aggregate used in this study are by-products generated during production of crushed gravel with a maximum size of 13mm. The results of this study showed that the target void ratio, the coefficient of permeability and compressive strength of porous concrete had a close relationship with the void ratio, and it will be possible that the void ratio is suggested by the mix design of porous concrete. The compressive strength of porous concrete was the highest at the content of the expansive admixture of 5% and compared to non-mixture, 10% mixture of silica fume improved compressive strength about 32%. And in the result of the study to change the compaction load, the compressive strength increased from the load of 15kN, the void ratio decreased from the load of 0.8kN, the coefficient of permeability decreased from the load 35kN, respectively.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.595-602
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• 2005

The purpose of this study is to utilize recycled concrete aggregates as permeable pavement materials. This study evaluates mechanical properties and durability of porous concrete depending on mixing rates of recycled aggregates and polyme. As a result, void ratio and permeability coefficient of porous concrete for pavement increased a little as mixing rate of recycled aggregates increased. Void ratio and permeability coefficient increased a lot as mixing rate of polymer increased. As polymer was mixed $20\%$, national regulation of permeable concrete for pavement($8\%$ and 0.01cm/sec) was met. Compressive strength and flexural strength decreased as mixing rate of recycled aggregates increased but they increased a lot as mixing rate of polymer increased. Even when recycled aggregates were mixed $75\%\;with\;10\%$ polymer mixed, national regulation of pavement concrete(18MPa and 4.5MPa) was met. In addition, regarding sliding resistance, BPN increased as mixing rate of recycled aggregates increased. But BPN decreased as polymer was mixed. Compared to crushed stone aggregates, abrasion resistance and freeze-thaw resistance decreased as mixing rate of recycled aggregates Increased. When polymer was mixed, abrasion resistance and freeze-thaw resistance improved remarkably. Compared to non-mixture, $10\%$ mixture of polymer improved abrasion resistance and freeze-thaw resistance about $8.6\%$ and 3.8times respectively.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.5-14
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• 2012

In the current design codes for anti-freezing layer, the thickness of anti-freezing layer is calculated by freezing depth against the temperature condition. Therefore, they have a tendency of over-design and uniform thickness without the considerations of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential for studying the appropriateness and bearing capacity of road foundation materials as well as their seasonal and mechanical properties to take an appropriate and reasonable design of the road structure system. In this paper, the freezing and bearing capacity characteristics of typical road foundation materials were evaluated in the large scale laboratory test. LFWD (light falling weight deflectometer) was used to determine the change of elastic modulus ($E_{LFWD}$) caused by to the frost heave and thaw. Furthermore, the influence of crushed natural aggregate on the freezing of the subgrade soil was studied to verify the function and effectiveness of the anti-freezing layer.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.465-472
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• 2012

This research aims to find an effective mixing method for controlled low strength material (CLSM) using diverse recycled industrial byproducts. This study is a fundamental research to develop and commercialize a resource-recycling CLMS that can greatly contribute to cost reduction and environmental stress relief. In the past, few studies have been performed on CLSM in Korea. This research is expected to provide fundamental data not only for development and commercialization of the resource-recycling CLSM satisfying required material performances but also serve as a ground breaking study on utilization of recycled material in construction industry and ultimately leading to advanced resource-recycling practices at national level. From the comprehensive analysis of minimum unit quantity for maximum strength and material segregation prevention, it was found that the optimal mixing condition for mixing FSD, RSID and SD material to filler-aggregate ratio (f/a) was approximately 50.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.82-88
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• 2013

In this project a preliminary experimental research work was done to apply mortars containing magnetite as fine aggregates unto floor finishing materials in order to make indoor environment eco-friendly and to have noiseproof control between floors. Crushed magnetites were substituted as sands in the mix design with a range of 0, 20, 40, 60, 100%. First far-infrared radiation tests to determine emissivity and emission power were done in accordance with the KICM test standard and an outstanding result was obtained. Density and compressive strength test results also showed that as the substitution increases, test values increase in a linear trend. However dry shrinkage test results revealed that as the substitution increases, shrinkage strain also increases. To clearly seek a solution about this problem, more experimental works should be done on oncoming experimental program.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.35-43
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• 2010

This study was carried out to find reliable relations between various concrete strength properties which are used as input data in concrete pavement design program. Concretes were made from different sources of coarse grained(granite, limestone and sandstone) and fine grained aggregates such as natural sand, washed sand and crushed sand. From strength test results, model equations were obtained based on the relation between strengths. For each coarse grained aggregate, models for compression-flexural strengths, compression-split tensile strengths, compressive strength-modulus and flexural-split tensile strengths with age were obtained. For concrete mixed with gneiss granite aggregates, concrete strengths were obtained from numerical mean values of concrete strengths mixed with fine grained aggregates. In addition models for concrete split tensile strengths and modulus values were provide by averaging numerically the estimated values obtained from the derived relationship and the experimental values. This is due to more scattered values of split tensile strengths and modulus values than other strength properties. Finally criteria for drying shrinkage strain as well as Poisson's ratio for concrete used in pavement were presented for all mixes with differed coarse grained aggregates.

• Journal of computational fluids engineering
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• v.20 no.4
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• pp.81-92
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• 2015

Construction waste mainly consists of concrete aggregates of various size. Improper handling of concrete waste would be a major environmental problem whereas its recycling would be both economically useful and environmentally friendly. Bigger concrete aggregates are crushed and converted to medium and fine particles to make them recyclable. An apparatus to separate the concrete aggregates by their size is thus needed for their effective recycling. In this work, segregation of concrete particles in air flows from a newly designed rotary separator having three stages of blades is simulated using a commercial software, ANSYS-CFX. Both 2-D and 3-D models with 360, 240 and 180 blades in each stage are considered. Fundamental mechanism of separation of particles(pase) and the effect of design parameters such as particle size, rotor speed, air flow rate etc. on the performance of the separator are investigated. Critical size of particles that can be separated by the developed separator is also presented in this work. Simulation results are overall in good agreement with data predicted from the theoretical model previously reported in the companion paper.