• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.4
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• pp.48-55
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• 1994

This study was performed to evaluate the engineering properties of the lightweight concrete using surlightweight aggregate foaming agent and high performance agent. The following conclusions were drawn. 1. The unit weight of type A, B and C concrete was 0.912t/m$^3$, 1.592t/m$^3$ and 1.070t/m$^3$, respectively. Specially, the unit weight of type A concrete was decreased 42% than that of the type B concrete. 2. The highest engineering property was measured in the lightweight concrete using high performance agent Also, the ratio of tensile and bending strength to compresive streng-th of the lightweight concrete was higher than that of the normal cement concrete. 3. The dynamic modulus of elasticity of the lightweight concrete was in the range of 2.86 x 10 5~9.86 x 10 5 kg/cm$^2$ which was approximately 300% than that of the normal cement concrete. 4. The ultrasonic pulse velocity of the lightweight concrete was in the range 2047~3394 n/sec, which was smaller than that of the normal cement concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.132-133
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• 2014

In this study, high volume of industrial by-products including blast furnace slag, recycled aggregate powder and incineration ash have been utilized on the slurry of the foamed lightweight concrete. As to decrease the price of the lightweight foam concrete, mortar based slurry and concrete based slurry has been fixed. As the variation of the foam conduction ratio and aggregates, the foam ratio and compressive strength has been tested. Results showed that using recycled aggregates in the slurry showed better effect than using natural aggregates due to the alkali properties of the recycled aggregates could activate the potential hydraulic properties of the blast furnace slag. Consider about the low price of the recycled aggregates, it could be identified that using recycled aggregates in high volume blast furnace slag blended lightweight concrete showed better compressive strength than natural aggregates.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.127-131
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• 2009

The purpose of this study is to provide fundamental data on chloride diffusion from lightweight aggregate concrete by utilizing crushed stone-powder. Accordingly, the study performed experiments using concrete aggregates of Crushed Aggregate (CG), Single-sized Lightweight Aggregate (SLG), Continuous Graded Lightweight Aggregate (CLG), and using water-binder ratio of 0.4, 0.5, 0.6, and using binder of FA and BFS. The chloride diffusion coefficient is calculated after experiment based on NT BUILD 492. Diffusion coefficient of SLG and CLG were little bit higher than CG Concrete, but the difference is meaningless. Also, chloride diffusion coefficient indicates that it is highly affected by water-binder ratio, and it decreases with the decrease in water-binder ratio. The admixture substitution indicates decrease only with water-binder ratio of 0.4 for FA15% case, but admixture substitution indicates decrease with all levels of ratio for FA10 + BFS20% which means more appropriate. According to the analysis result of chloride diffusion from lightweight aggregate concrete, crushed stone-powder utilized lightweight aggregate concrete indicates higher chloride diffusion coefficient than CG concrete, which is not a significant difference, and can improve resistance through water-binder ratio and admixture substitution.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.7
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• pp.19-26
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• 2018

This study tested 25 lightweight aggregate concrete (LWAC) mixtures using the expanded bottom ash and dredged soil granules to examine the compressive strength gain of such concrete with different ages. The test parameters investigated were water-to-cement ratios and the natural sand content for the replacement of lightweight fine aggregate. The compressive strength gain rate in the basic equation specified in fib model code was experimentally determined in each mixture and then empirically formulated as a function of the water-to-cement ratio and oven-dried density of concrete. When compared with 28-day compressive strength, the tested LWAC mixtures exhibited relatively low gain ratios (0.49~0.82) at an age of 3 days whereas the gain ratios (1.16~1.41) at 91 days were higher than that (1.05~1.15) of the conventional normal-weight concrete. Thus, the fib model equations tend to overestimate the early strength gain of LWAC but underestimate the long-term strength gain. The proposed equations are in good agreement with the measured compressive strength development of LWAC at different ages, indicating that the mean and standard deviation of the normalized root mean square errors determined in each mixture are 0.101 and 0.053, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.91-96
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• 2002

This study is to investigate the insulation performance of lightweight concrete using recycled lightweight aggregate, to develop lightweight concrete products which have an excellence on the insulation performance are satisfied with properties of building materials. As a result of this study, recycled EPS aggregate is considered to have an independent pores which is closed by dense partitions. So, it is showed that the insulation performance of lightweight concrete using recycled EPS aggregate are excellent. Especially, in the case of lightweight concrete under conditions of replacement ratio over 100%, it is considered that insulation performance is very excellent as thermal conductivity is showed about 0.2kcal/mh$^{\circ}C$. According to considering the relation between ultrasonic pulse velocity, unit weight and thermal conductivity through the graph, the result of relation between ultrasonic pulse velocity, unit weight and thermal conductivity on the graph expressed their high interaction shown as direct proportion on the graph. So that it is possible to extract the insulation performance of lightweight concrete using recycled EPS aggregate by ultrasonic pulse velocity and unit weight.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.851-858
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• 2010

In this study, waste glass and bottom ash were used as basic materials in order to secure a recycling technology of by-products which was mostly discarded and reclaimed. In addition, because softening point of waste glass is less than $700^{\circ}C$ and bottom ash includes combustible material, it was possible to manufacture low-temperature sintering lightweight aggregates for energy saving at $800{\sim}900^{\circ}C$ that it is as much as 20~30% lower than sintering temperature of existing lightweight aggregates. Thermal conductivity of newly-developed lightweight aggregates was 0.056~0.105W/m. K and its porosity was 40.36~84.89%. A coefficient of correlation between thermal conductivity and porosity was -0.97, it showed very high negative correlationship. With this, we were able to verify that porosity is key factor to affect thermal conductivity. Microstructure of lightweight aggregates by $CaCO_3$ content and replacement ratio of bottom ash in the variation of temperature were that $CaCO_3$ content increased along with pore size while replacement ratio of bottom ash increased as pore size decreased. Specially, most pores were open pore instead of closed pore of globular shape when replacement ratio of bottom ash was 30%, and pore size was small about 1/10~1/5 as compared with case in bottom ash 0~20%. In addition, open pore shapes were remarkably more irregular form of open pore in $900^{\circ}C$ than $700^{\circ}C$ or $800^{\circ}C$ when replacement ratio of bottom ash was 30%. We reasoned hereby that these results will influence on absorption increase, strength and thermal conductivity decrease of lightweight aggregates.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.625-632
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• 2021

In this paper, the applicability of bottom ash to insulation concrete was investigated to increase the utilization of bottom ash. Bottom ash was used as the aggregates in porous concrete and extensive experiments were conducted to investigate the characteristics of porous concrete using two types of bottom ash aggregates. The water-binder ratios of 0.25 and 0.35 were chosen and concrete specimens was produced with the compaction of 0.5, 1.5, and 3.0MPa to analyze the material properties at different compaction conditions. After concrete specimens were cured for 28 days at water tanks, unit weight, total void ratio, and thermal conductivity were measured. Based on the measured experimental results, the relationships between the unit weight, total void ratio, and thermal conductivity of porous concrete containing bottom ash was presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.131-136
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• 2002

In recent year, it has been investigated on the reduction of mass of structures for the purpose of the larger space and the economy with the industry developing very fast and qualitatively. So the purpose of this study is to investigate the manufacture of light weight concrete panel using the artificial light-weight aggregate as a part of the substitution of foamed styrene and polyurethane because of narrow allocable temperature zone in use. The compressive strength, flexural strength, unit weight, absorption test and thermal conductivity were practised at 3, 7 and 28 days after manufacturing the light-weight concrete lot the panel core: the filling ratio of continuous void was defied as 40%, 50%, and 60% and water-cement rate was 35, 40 and 45%. As a result of this, it was revealed that the mixture derived from filling ration of void of 50% and water-cement ratio 40% were developing the best properties of the others.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.175-176
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• 2011

Applying previous studies performed in the moisture transportation characteristics and shrinkage of lightweight concrete application of shrinkage reduction is to discuss. Applicability of shrinkage reduction effect of lightweight concrete applies for the analysis of PSC girder bridge beam placed on the construction site. Stress of the concrete bridge deck, rebar quantity is calculated by effective elastic modulus method and crack risk is assessed by moisture transport and differential shrinkage analysis. After approximately 10 days maximum tensile stress occurs 6MPa, similar to the case of normal concrete, a maximum tensile stress occurs 3MPa in lightweight concrete and comparing to normal concrete stress was reduced to approximately 50%. Normal and lightweight concrete crack index, respectively, is reduced 1.6 to 1.2, 1.2 to 0.9 in surface and boundary region. Therefore, reduction in shrinkage of concrete were able to confirm reduction of crack risk.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.106-112
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• 2001

Recent advance in material technology has accelerated the development of high strength concrete using lightweight artificial aggregates. The lightweight concrete has many advantages that the reduction of dead loads and the increase in load capacity can offer. In this study the lightweight polymer concrete using unsaturated polyester resin and lightweight aggregate were prepared and tested for testing the physical and the mechanical properties. The compressive strengths of lightweight polymer concretes with apparent specific gravity for 1.32 to 1.78 were 250 to 470 kfg/cm$^2$ and flexural strengths were measured to be in the range of 1/3-1/4 of compressive strength.