• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.2
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• pp.135-142
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• 2009

This study investigates the characteristic properties of strength, flowability, durability and drying shrinkage to control strength and to reduce heat of hydration of high performance concrete using crushed stone fines. According to the experimental results, when crushed stone fines are increased every 10%, $10{\sim}15%$ of compressive strength is decreased and flowability of high performance concrete is effectively improved due to the decrease of modulus of deformation and confined water ratio. When crushed stone fines are replaced every 10%, $4^{\circ}C$ of the highest adiabatic temperature rise is decreased by reducing the unit cement. However, 5% of drying shrinkage is increased in the same condition In the meantime, durability of high performance concrete is excellent, having over 100% of good relative dynamic modulus of elasticity due to fineness of formation mused by the increase of the unit powder content and the improvement of flowability, without regard to the replacement of crushed stone fines. Therefore, It can be said that the usage of crushed stone fines can control the strength of high performance concrete by replacement and reduce heat of hydration.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.283-290
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• 2009

Differently from fly ash, the bottom ash produced from thermoelectric power plant has been treated as an industrial waste matter, and almost reclaimed a tract from the sea. If this waste material is applicable to foam concrete as an aggregate owing to its light-weight, however, it may be worthy of environmental preservation by recycling of waste material as well as reducing self-weight of high-rising structure and horizontal forces and deformations of retaining wall subject to soil pressure. This study has an objective of evaluating the effects of application of bottom ash on the mechanical properties of foam concrete. Thus, the ratio of bottom ash to cement was selected as a variable for experiment and the effect was measured in terms of unit weight of concrete, air content, water-cement ratio and compressive strength. It can be observed from experiments that the application ratios have different effects on the material parameters considered in this experiment, thus major relationships between application ratio and each material parameter were finally introduced. The result of this study can be applied to decide a mix design proportion of foam concrete while bottom ash is used as an aggregate of the concrete.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.652-660
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• 2008

For the recycling of rapid-chilled steel slag, the mechanical strengths and physical properties of EVA-polymer modified mortars with the various replacement ratios of rapid-chilled steel slag were investigated. Twenty five specimens of polymer modified mortars were prepared with the five different amounts of EVA-polymer modifier (0, 5, 10, 15, 20 wt%) and rapid-chilled steel slag (0, 25, 50, 75, 100 wt%). For the investigation of the characteristics of polymer modified mortars, the measurements such as water-cement ratio, unit volume weight, air content for fresh mortar and compressive strength, flexural strength, water absorption, hot water resistance, porosity and SEM investigation for curing specimens were conducted. As a results, with an increase in the replacement ratio of rapid-chilled steel slag, water-cement ratios decreased but unit volume weight increased remarkably. With increasing EVA-polymer modifier and the replacement ratio of rapid-chilled steel slag, percent of water absorption decreased but compressive and flexural strengths increased remarkably. By the hot water resistance test, mechanical strengths decreased but total pore volume and porosity increased remarkably. In the SEM observation, the components of specimen were shown to stick to each other in the form of co-matrix phase before hot water resistance test, but polymer modifier of co-matrix phase was decomposed or deteriorated after hot water resistance test.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.207-217
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• 1997

This study was performed to evaluate the engineering properties of rice-husk ash concrete using normal portland cement, natural aggregates and rice-husk ash. The following conclusions were drawn; 1. The unit weight was in the range of $2,216{\sim}2,325kgf/m^3$, the weights of those concrete were decreased 1~6% than that of the normal cement concrete, respectively. 2. The highest strength was achieved by 10% rice-husk ash filled rice-husk ash concrete, it was increased 8% by compressive strength, 17% by tensile strength and 18% by bending strength than that of the normal cement concrete, respectively. 3. The ultrasonic pulse velocity was in the range of 3,252~4,016 m/s, which was showed about the same compared to that of the normal cement concrete. The highest ultrasonic pulse velocity was showed by 10% rice-husk ash filled rice-husk ash concrete. 4. The dynamic modulus of elasticity was in the range of $242{\times}10^3{\sim}306{\times}10^3kgf/cm^2$, which was showed about the same compared to that of the normal cement concrete. The highest dynamic modulus was showed by 10% rice-husk ash filled rice-husk ash concrete. 5. The static modulus of elasticity was in the range of $185{\times}10^3{\sim}275{\times}10^3kgf/cm^2$, which was showed about the same compared to that of the normal cement concrete. The poisson's number of rice-husk ash concrete was less than that of the normal cement concrete. The dynamic modulus was increased approximately 11~30% than that of the static modulus. 6. The durability was increased with increase of the content of rice-husk ash. The durability was increased 1.3 times by 10% rice-husk ash, 1.6times by 20% rice-husk ash filled concrete than that of the normal cement concrete. respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.96-102
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• 2019

When GGBFS(Ground Granulated Blast Furnace Slag) with high blaine is incorporated in concrete, compressive strength in the initial period is improved, but several engineering problems arise such as heat of hydration and quality control. In this paper, compressive strength and durability performance of concrete with 3,000 Grade-low fineness slag are evaluated. Three conditions of concrete mixtures are considered considering workability, and the related durability tests are performed. Although the strength of concrete with 3,000 Grade slag is slightly lower than the OPC(Ordinary Portland Cement) concrete at the age of 28 days, but insignificant difference is observed in long-term compressive strength due to latent hydration activity. The durability performances in concrete with low fineness slag show that the resistances to carbonation and freezing/thawing action are slightly higher than those of concrete with high fineness slag, since reduced unit water content is considered in 3,000 Grade slag mixture. For the long-term age, the chloride diffusion coefficient of the 3000-grade slag mixture is reduced to 20% compared to the OPC mixture, and the excellent chloride resistance are evaluated. Compared with concrete with OPC and high fineness GGBFS, concrete with lower fineness GGBFS can keep reasonable workability and durability performance with reduced water content.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.73-82
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• 2011

Coal ash of industial by-products was not recycled about 30% in total emissions. Moreover, it caused environmental pollution as well as wasted unnecessary expenses and time. Currently, fly ash(FA) is recycled as construction material however ponded ash(PA) is mostly buried. Lightweight foamed Controlled Low-Strength Materials(CLSM) evaluated in this study reduces unit weight by mixing foam in the traditional Controlled Low-Strength Material and has lightweight and flowability to be available for backfill materials in construction. Flow test, unconfined compressive strength test, and foamed-slurry unit weight test were performed in this study and the applicability of lightweight foamed CLSM for construction materials was evaluated. The results indicate that the mixture ratio(PA:FA) ranging from 70:30 to 50:50, cement of 7%, foam of 2~3%, and water content of 26.5~29.5% were required to satisfy the following standards such as flow value(i.e., 20cm), unconfined compressive strength(i.e., 0.8~1.2MPa), and foamed-slurry unit weight(i.e., $12{\sim}15kN/m^3$).

• Journal of the Korean GEO-environmental Society
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• v.18 no.5
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• pp.27-33
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• 2017

In this research, laboratory tests were carried out to investigate the engineering properties of Light-Weight Air Foamed Soil (LWAS) based on silty clays with the animal foaming agent and cement. LWAS has been used as an embankment material over soft ground for road and side extension of the existing road. In field, unit weight and flow value is measured right after producing in mixing plant in order to control the quality of LWAS, and laboratory tests are carried out to confirm the quality through compressive strength of LWAS as well. In this research, direct estimation of the specification requirement of strength using flow values in field is the main purpose of the study together with other characteristics. From the test results, it can be seen that flow values increase with the initial water content and unit weight increases with the depth due to material segregation. Compared to the upper specimen, lower end of 60 cm specimen shows about 2 times higher compressive strength. Relationship between flow values and normalized factor presented by Yoon & Kim (2004) was presented. With that relationship, compressive strength can be predicted from flow values in field. From the relationship, the normalized factor was calculated. Thereafter calculated compressive strengths according to the flow values were compared to measured strengths in the laboratory. The higher the initial water content of the dredged soil has, the better relationship between predicted and measured shows. Therefore it is necessary to predict the compressive strength in advance through the relationship between the flow value and the normalized factor to reflect it in the design stage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.54-59
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• 2017

GGBFS (Ground Granulated Blast Furnace Slag) is a byproduct with engineering advantages and HVSC (High Volume Slag Concrete) is widely attempted due to active utilization and reduction of eco-load. In the present work, characteristics of drying shrinkage and early-aged behavior are evaluated for the concrete with 65% replacement ratio of GGBFS and 50MPa of design strength. For the work, 3 different mix conditions are considered and several tests including slump flow, compressive strength, drying and autogeneous shrinkage are performed. From the test, OPC 100 mixture without replacement shows higher strength development before 7 days, however the strength reduction in concrete replaced with GGBFS is not significant due to sufficient free water for cement hydration. OPC 100 mixture also shows significant drying shrinkage due to a great autogeneous shrinkage before 3 days. In the concrete with GGBFS replacement, the drying shrinkage behavior is improved due to relatively small deformation by autogeneous shrinkage. The mixture (OPT BS 65) with lower w/b ratio (0.27) and unit content of water ($160kg/m^3$) shows more improved shrinkage behavior than BS 65 mixture which has simple replacement of GGBFS with 0.30 of w/b and $165kg/m^3$ of water unit content.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.540-548
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• 2002

The purpose of this study is to analyze the application of oyster shells (OS) as aggregates for concrete. For this purpose, five reference mixes with W/C ratios of 0.4 ∼0.6 at intervals of 0.05 were used. The replacement proportion of OS was varied with ratios of 0, 10, 30, 50 and 100％ by volume of fine or coarse aggregate in the reference mixes. OS was washed and crushed for using as aggregates. New chemical reaction between crushed OS aggregate and cement paste was tested through XRD and SEM analysis. Two strength properties (compressive and flexural) were considered. Strength tests were carried out at the ages of 1, 3, 7, 14 and 28 days. The variations of workability, air content and density, drying shrinkage of the specimens with different proportions of OS were also studied. Finally, the hollow concrete block using OS as a substitute material for fine aggregate was made for testing the application of OS. Experimental results showed that my new chemical reaction did not occur due to mixing OS in concrete. The workability and strengths decreased with increase in proportion of OS. The same trend was observed in density and unit weight, but air content increased due to the inherent pores in OS, which showed a possibility to produce light weight concrete with low strength by using OS as coarse aggregates for concrete. Tests on hollow concrete block showed that the compressive strength and absorption ratio were satisfied with quality requirements when the fine aggregate was substituted with OS up to 50％ in volume.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.77-85
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• 2007

This paper investigates the mechanical characteristics of composite geo-material which was developed to reuse both dredged soils and bottom ash. The composite geo-material used in this experiment consists of dredged soil taken from the construction site of Busan New Port, cement, air foam and bottom ash. Bottom ash is a by-product generated at the Samcheonpo thermal power plant. Several series of laboratory tests were performed to investigate behavior characteristics of composite gee-material, in particular the reinforcing effect by mixing bottom ash. The experimental results of composite geo-material indicated that the stress-strain relationship and the unconfined compressive strength are strongly influenced by mixing conditions. Especially it was observed that the compressive strength of composite geo-material increased with an increase in bottom ash content due to reinforcing effect by the bottom ash. Compressive strength of composite geo-material increased with the increase in curing time. The 28-day strength of composite geo-material is $1.7{\sim}1.8$ times higher than the 7-day strength. The moist unit weight strongly depended on air-foam content as well as bottom ash content added to the composite goo-material. In composite geo-material, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of bottom ash.