The Experts below are selected from a list of 4146 Experts worldwide ranked by ideXlab platform
Seon-keun Hwang - One of the best experts on this subject based on the ideXlab platform.
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structural performances of an eco friendly prestressed concrete sleeper
2016Co-Authors: Taehoon Koh, Younghoon Bae, Moochul Shin, Seon-keun HwangAbstract:Abstract This study focuses on investigating structural performances of a newly developed eco-friendly prestressed concrete sleeper for railway tracks in South Korea. An eco-friendly concrete has been developed by authors at the Korea Railroad Research Institute (KRRI) with the aims of reducing carbon dioxide (CO 2 ) emissions and finding a replacement of Natural sand for Fine Aggregate. Direct and indirect CO 2 emissions are one of the main environmental issues in the concrete industry. Reducing the amount of cement usage is beneficial to address the issue of CO 2 emissions in the concrete industry. Another environmental issue in the concrete industry in South Korea is the shortage of Natural sand as a Fine Aggregate. So there is a need for finding a replacement of Natural sand. The authors utilized two types of recycled industrial byproducts (slags) to handle the environmental issues of railway prestressed concrete sleepers: (1) ground granulated blast furnace (GGBF) slag, which replaces 30% of Portland Type III cement and (2) electric arc furnace (EAF) oxidizing slag, which entirely replaces Natural Fine Aggregate. With the recycled industry slags, an eco-friendly concrete was developed with a high initial compressive strength at prestressing release (
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field evaluation and durability analysis of an eco friendly prestressed concrete sleeper
2015Co-Authors: Taehoon Koh, Seon-keun HwangAbstract:AbstractWhile there have been various research activities to develop the green vehicles which reduce the energy consumption such as high-speed train, tilting train, light rail transit, wireless tram, and so on, researches on the eco-friendly railway infrastructure have been very limited to deal with the important social issue of reducing CO2 emissions. In this background, eco-friendly prestressed concrete (PSC) sleeper, using ground granulated blast furnace slag and rapid-cooling electric arc furnace oxidizing slag, has been recently developed to reduce the usage of cement and Natural Fine Aggregate as main ingredients of the concrete. It was already found that eco-friendly PSC sleeper satisfied its static and dynamic performances required by international standards. In this paper, the field performance of eco-friendly PSC sleeper was evaluated in the operating line of conventional railway and its durability against extreme environmental conditions was performed in the laboratory as well. Steel slags (gro...
Alaa M Rashad - One of the best experts on this subject based on the ideXlab platform.
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cementitious materials and agricultural wastes as Natural Fine Aggregate replacement in conventional mortar and concrete
2016Co-Authors: Alaa M RashadAbstract:Abstract In the last 15 years, the worldwide consumption of Natural sand as Fine Aggregate in mortar/concrete production is very high and many developing countries have encountered some problems in the supply of Natural sand in order to meet the increasing demands of construction development. In many countries there is a shortage of Natural sand that is suitable for construction. On the other hand, disposal of wastes such as fly ash (FA), bottom ash (BA) and agricultural wastes can be considered as the major environmental challenges. This challenge continues to increase with the increase of these wastes. Therefore, studies have been carried out to find suitable solutions of the shortage of Natural sand and the huge increasing in the wastes disposal. One logical option to solve this problem is employing these materials as a part of Fine Aggregate instead of Natural one in mortar/concrete. This paper presents an overview of the previous studies carried out on the use of the previous wastes as a partial or full of Natural Fine Aggregate replacement in traditional mortar/concrete mixtures based on Portland cement (PC). Other cementitious material such as ground basaltic pumice and metakaolin (MK), which can replace part or full of Natural Fine Aggregate was also included. Fresh properties, hardened properties and durability of mortar/concrete containing these waste/cementitious materials as Natural Fine Aggregate replacement have been reviewed.
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A comprehensive overview about recycling rubber as Fine Aggregate replacement in traditional cementitious materials
2016Co-Authors: Alaa M RashadAbstract:Currently, the need to incorporate recycled materials such as rubber in building products is becoming more important than ever before. The use of waste rubber in mortar/concrete mixtures creates landfill avoidance and decreases the depletion of virgin raw materials. Waste rubber can be used as a part of Fine Aggregate, coarse Aggregate or both Aggregates. It can be used as an additive to Portland cement (PC). This paper presents an overview of the previous researches carried out on the use of waste rubber as partially or fully Natural Fine Aggregate replacement in traditional mortar/concrete mixtures based on PC. The effects of rubber sand on workability, setting time, bleeding, density, strength, impact energy, impact load, toughness, ductility, shrinkage, abrasion resistance, freeze/thaw resistance, fire resistance, thermal insulation, carbonation resistance, corrosion resistance, water absorption, porosity, chloride ion penetration, resistance to aggressive environmental, energy absorption, sound absorption, electrical resistance and cracking resistance of rubberised mortar/concrete were reviewed.
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Recycled cathode ray tube and liquid crystal display glass as Fine Aggregate replacement in cementitious materials
2015Co-Authors: Alaa M RashadAbstract:With the rapid advances in the electronic industry, the disposal of cathode ray tube (CRT) glass and liquid crystal display (LCD) glass has become a major environmental problem. One option for safe environmental and economic disposal of these wastes is to reuse them in building materials. Many past studies have reported that the use of CRT glass and LCD glass waste as a part of Fine Aggregate and few others reported the possible use as a part of binder material. This paper presents an overview for the previous literature which was carried out on the use of CRT and LCD recycled glass as a partial or a complete replacement of the Natural Fine Aggregate in traditional mortars and concretes based on Portland cement (PC). Fresh properties, hardened properties and durability of these mortars and concretes have been reviewed in this paper. This review showed that using CRT and LCD glass sand in the matrix led to some advantages and some disadvantages. The main disadvantages of using these systems are decreasing compressive strength and increasing the expansion of alkali-silica reaction (ASR).
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recycled waste glass as Fine Aggregate replacement in cementitious materials based on portland cement
2014Co-Authors: Alaa M RashadAbstract:Abstract Disposal of waste glass derived from container or packaging glass, flat glass, domestic or tableware glass and continuous filament glass fibres is one of the major environmental challenges. This challenge continues to increase with increasing the amount of waste glass and decreasing the capacity of landfill space. Therefore, studies have been carried out to find practical ways to recycle waste glass in building materials such as cement, mortars, concretes and blocks. This paper presents an overview of the previous studies carried out on the use of waste glass as partial or full Natural Fine Aggregate replacement in traditional mortar/concrete mixtures based on Portland cement (PC). Fresh properties, mechanical properties, abrasion resistance, water absorption, chloride ion penetration, permeability, chemical resistance, carbonation resistance, drying shrinkage and alkali-silica reaction (ASR) expansion of mortar/concrete mixtures containing waste glass as Fine Aggregate replacement have been reviewed.
Taehoon Koh - One of the best experts on this subject based on the ideXlab platform.
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structural performances of an eco friendly prestressed concrete sleeper
2016Co-Authors: Taehoon Koh, Younghoon Bae, Moochul Shin, Seon-keun HwangAbstract:Abstract This study focuses on investigating structural performances of a newly developed eco-friendly prestressed concrete sleeper for railway tracks in South Korea. An eco-friendly concrete has been developed by authors at the Korea Railroad Research Institute (KRRI) with the aims of reducing carbon dioxide (CO 2 ) emissions and finding a replacement of Natural sand for Fine Aggregate. Direct and indirect CO 2 emissions are one of the main environmental issues in the concrete industry. Reducing the amount of cement usage is beneficial to address the issue of CO 2 emissions in the concrete industry. Another environmental issue in the concrete industry in South Korea is the shortage of Natural sand as a Fine Aggregate. So there is a need for finding a replacement of Natural sand. The authors utilized two types of recycled industrial byproducts (slags) to handle the environmental issues of railway prestressed concrete sleepers: (1) ground granulated blast furnace (GGBF) slag, which replaces 30% of Portland Type III cement and (2) electric arc furnace (EAF) oxidizing slag, which entirely replaces Natural Fine Aggregate. With the recycled industry slags, an eco-friendly concrete was developed with a high initial compressive strength at prestressing release (
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field evaluation and durability analysis of an eco friendly prestressed concrete sleeper
2015Co-Authors: Taehoon Koh, Seon-keun HwangAbstract:AbstractWhile there have been various research activities to develop the green vehicles which reduce the energy consumption such as high-speed train, tilting train, light rail transit, wireless tram, and so on, researches on the eco-friendly railway infrastructure have been very limited to deal with the important social issue of reducing CO2 emissions. In this background, eco-friendly prestressed concrete (PSC) sleeper, using ground granulated blast furnace slag and rapid-cooling electric arc furnace oxidizing slag, has been recently developed to reduce the usage of cement and Natural Fine Aggregate as main ingredients of the concrete. It was already found that eco-friendly PSC sleeper satisfied its static and dynamic performances required by international standards. In this paper, the field performance of eco-friendly PSC sleeper was evaluated in the operating line of conventional railway and its durability against extreme environmental conditions was performed in the laboratory as well. Steel slags (gro...
Rafa Siddique - One of the best experts on this subject based on the ideXlab platform.
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microstructure and properties of concrete using bottom ash and waste foundry sand as partial replacement of Fine Aggregates
2014Co-Authors: Yogesh Aggarwal, Rafa SiddiqueAbstract:Abstract The possibility of substituting Natural Fine Aggregate with industrial by-products such as waste foundry sand and bottom ash offers technical, economic and environmental advantages which are of great importance in the present context of sustainability in the construction sector. The study investigated the effect of waste foundry sand and bottom ash in equal quantities as partial replacement of Fine Aggregates in various percentages (0–60%), on concrete properties such as mechanical (compressive strength, splitting tensile strength and flexural strength) and durability characteristics (rapid chloride penetration and deicing salt surface scaling) of the concrete along with microstructural analysis with XRD and SEM. The results showed that the water content increased gradually from 175 kg/m 3 in control mix (CM) to 238.63 kg/m 3 in FB60 mix to maintain the workability and the mechanical behavior of the concrete with Fine Aggregate replacements was comparable to that of conventional concrete except for FB60 mix. The compressive strength was observed to be in the range of 29–32 MPa, splitting tensile strength in the range of 1.8–2.46 MPa, and flexural strength in the range of 3.95–4.10 MPa on the replacement of Fine Aggregates from 10% to 50% at the interval of 10%. Furthermore, it was observed that the greatest increase in compressive, splitting tensile strength, and flexural strength compared to that of the conventional concrete was achieved by substituting 30% of the Natural Fine Aggregates with industrial by-product Aggregates. The inclusion of waste foundry sand and bottom ash as Fine Aggregate does not affect the strength properties negatively as the strength remains within limits except for 60% replacement. The morphology of the formations arising as a result of the hydration process was not observed to change in the concrete with varying percentages of waste foundry sand and bottom ash.
Chi Sun Poon - One of the best experts on this subject based on the ideXlab platform.
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use of furnace bottom ash for producing lightweight Aggregate concrete with thermal insulation properties
2015Co-Authors: Binyu Zhang, Chi Sun PoonAbstract:Abstract The influence brought by Furnace Bottom Ash (FBA) incorporation on the properties of lightweight Aggregate concrete was studied systematically. In total, six mixtures of concrete targeted at a 28 d compressive strength of 30 MPa were designed, including one control mix made with all normal weight Aggregates and at a water/cement ratio (w/c) of 0.6, and another five lightweight Aggregate concrete mixes at a w/c of 0.39 by using 0, 25%, 50%, 75% and 100% FBA replacing Natural Fine Aggregate (crushed Fine stone). The testing results of the hardened concrete properties showed that, for the lightweight Aggregate concrete using 100% FBA to replace crushed Fine stone, a 28 d oven-dried density of about 1500 kg/m 3 was obtained. The test results showed the lightweight Aggregate concrete had lower strength and stiffness compared to the normal Aggregate concrete. But in terms of the effectiveness of strength provided by unit weight of concrete indicated by compressive strength in MPa divided by saturated-surface dried (SSD) density in g/cm 3 , f c /D, a satisfactory ratio can be obtained when not more than 50% FBA was used to replace the crushed Fine stone. The durability property indicated by the chloride ion penetration test shows the lightweight Aggregate concrete with FBA had high chloride ion penetrability. The heat insulation property (thermal conductivity K-value) test demonstrated that by using the porous lightweight Aggregate, the thermal conductivity could be lowered to around 70% of the control. When more FBA was used to replace crushed Fine stone, the thermal conductivity value could be further reduced. The results of this study demonstrated it is feasible to produce lightweight Aggregate concrete with high volume of FBA incorporation for building insulation uses.
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feasible use of recycled crt funnel glass as heavyweight Fine Aggregate in barite concrete
2012Co-Authors: Tungchai Ling, Chi Sun PoonAbstract:Abstract The challenge of managing discarded cathode ray tube (CRT) waste has become a major environmental concern in Hong Kong and other cities. Recycled CRT funnel glass with a relatively high density (∼3000 kg m −3 ) can be used as a potential material for the production of heavyweight concrete. This paper presents the results of an investigation on the feasibility of using recycled CRT funnel glass, both treated (lead has been removed from the glass surface) and untreated (without removal of lead) as partial and full replacements of Fine Aggregates in heavyweight barite concrete. The inclusion of barite Aggregate and recycled funnel glass increased the hardened density but reduced the compressive and splitting tensile strengths. The replacement of Natural Fine Aggregate with recycled CRT glass had no significant effect on the elastic modulus but considerably improved the drying shrinkage of the concrete. In conclusion, the overall properties of heavyweight barite concrete made with the treated and untreated recycled CRT funnel glass are comparable, except for lead leaching results. The results show that it is feasible to use the treated CRT glass as 100% substitution of Fine Aggregate in making heavyweight concrete. However, the substitution of untreated glass should be limited to below 25% due to its potential lead leaching.