• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.5-13
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• 2010

Low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground, and has advantage which construction is possible in insufficient space. However it has been not yet studied sufficiently to estimate the effect of ground improvement in design step and to prove the estimating method. So the method must be developed in order to use the low slump mortar grouting method in various cases. In this study, the field tests were performed in the reclaimed soils to measure the effect of ground improvement. Then it was compared with what was calculated by the existing formula that was formerly suggested. The results show that the value from the formula was similar with the value from the field tests. Also it was proved that the formula was available to estimate the effect of ground improvement in the loose granular soils.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.123-128
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• 2013

This study was performed to evaluate the slump flow, air content, setting time, compressive strength, adiabatic temperature rise and diffusion coefficient of chloride used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furnace slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performances of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for low carbon green concrete material.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.480-488
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• 2010

The CGS method is non-discharge replacement method improving ground stiffness by the effect of static compaction with injecting very low slump mortar into ground, and is applied for increasing bearing capacity and filling ground cavity by lifting or restoring differential settled structures and preventing differential settlement. This paper suggests design of ground improvement and construction case history for civil engineering structures by CGS method. This method can be used for reinforcing soft ground and liquefaction of loose sandy soil. This method was used in SongDo area in Incheon Economic Free Zone due to its low vibration of ground while it can improve the soft soil where underground structures(subway and box culvert) are already existed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.129-130
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• 2021

For the development of high-fluidity concrete using low-binder, The effect of the use of the developed acrylic viscosity agent on the physical properties of concrete evaluated. The amount acrylic viscosity agent used was 0.28%, 0.29% and 0.30% based on the binder amount of 350kg/m³, and slump flow test, air volume measurement, U-Box passing test and strength compressive were conducted to determine the effect of the physical properties of concrete. it was judged that 0.29% of the cellulose type viscosity agent used in high-fluidity concrete using low-binder was most suitable.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.02a
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• pp.1-13
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• 1999

The use of Compaction Grouting evolved in the 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major uses of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other application include preventing liquefaction, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. The technique replaced slurry injection, or 'pressure grouting', as the preferred method of densification grouting. There are several reasons for the increased use of Compaction Grouting which can be summarized in one word: CONTROL. The low slump grout and injection processes are usually designed to keep the grout in a homogeneous mass at the point of injection, while acceptable in some limited applications, tends to quickly get out of control. Hydraulic soil fracturing can cause extensive grout travel, often well beyond the desired treatment zone. So, on the basis of the two case history constructed in recent year, a study has been peformed to analyze the basic mechanism of the Compaction Grouting and verify the effectiveness of the ground improvement using some test methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.373-376
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• 2008

The objective of this study is to investigate the properties of fresh concrete with recycled fine aggregates. Three different kinds of fine aggregate with natural, high and low quality recycled aggregates were prepared. The concrete mixtures were produced with test parameters of replacement ratio of recycled fine aggregate. The properties of the fresh concrete were measured by means of slump and air content according to elapsed time. Quality control method to maintain the constant total mixing water for recycled aggregate concrete was suggested. The all concrete mixtures were produced with approximately the same slump on the job site after an hour. Test results indicated that compressive strength of the concrete mixtures with constant slump is not affected by the replacement ratio of recycled fine aggregate. Therefore, the practical way for the quality control of recycled aggregate concrete is to maintain the constant total mixing water.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.671-674
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• 2005

In this study, it is examined the properties of early strength of concrete mixed with polycarboxylate superplasticizer. For this experiment, it is analyzed that the slump and strength properties according to the mixture factors, compared with cements and superplasticizers of each company and curing temperature($15,\;20^{\circ}C$). (1) The slump loss of concrete used polycarboxylate superplasticizer(rapid strength type) showed $0.5\~1.5cm$, it is judged that slump loss according to the time lapse can be minimized. (2) The performance of polycarboxylate superplasticizer kept up consistency and accelerated strength development. it is possible to reveal 12MPa within $18\~20$hours at $20^{\circ}C$ curing, but impossible within 24hours at $15^{\circ}C$. (3) It is necessary to studies about rapid strength development in the low temperature.

• Physical Therapy Korea
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• v.16 no.2
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• pp.31-39
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• 2009

This study is performed to investigate the difference of the spinal stability system with and without low back pain. There were 9 participants with low back pain and 9 asymptomatic subjects to be recruited, they were measured thoracic and lumbar curvature, trunk muscle activation in upright sitting postures and slump sitting, back muscle endurance, and lumbar proprioception. Spinal curvature and surface electromyography of 4 trunk muscles were measured in an upright sitting postures and slump sitting in 18 subjects. The result of the study was that there were significant differences between the groups in spinal curvature (p<.05), significantly higher external oblique activity and less internal oblique in the low back pain group than the healthy subjects (p<.05), and significantly less proprioception in the low back pain group (p<.05). But there was not a significant difference between the trunk muscle endurance groups. According to the result, the low back pain group had greater thoracic extension and higher global muscle activity in the upright sitting posture and less proprioception. This study was useful to suggest postural training for normal muscle activation, selective muscle strengthening to prevent chronic deterioration, and helpful in making a treatment plan to indicate a synthetic care method that includes increasing proprioception.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.555-558
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• 2000

It has been increasingly proving in interest of environment pollution around the world. so, recycling of waste resources are seriously taken into consideration. Great deal of coolant for the car have been wasted for along time. due to the end of life time of them. Therefore, validities of wasted coolant as an agent for concrete are described in this paper. Mechanical properties of concrete using coolant wastes is investigated. As contents of coolant wastes increase, slump and slump flow decrease, while air content show reverse tendency. setting time shows to be accelerated with increase of waste contents. As for the effect of low curing temperature, low curing temperature increase compressive strength with increase of coolant waste. Application of coolant waste to cold weather concrete is considered to achieve favorable effects.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.15-18
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• 2003

Development of the construction industry generally exhausts natural aggregate. Hence it is problem to the lack of supply and quality deterioration, so the resource saving and protection of environment is made an effort through recycling by-product. This study presents that fundamental properties of concrete which used cooper slag as alternate sand of low fineness modulus and plan of cooper slag as concrete aggregate. Testing factors are concrete's slump, air contents, unit weight and compressive strength. The results of this study are as follows; (1) Concrete slump is generally satisfied with the condition but is inferior to the others in substitution rates 30%. Also air contents are 3.1-4.1% and go up according to increase substitution rate. (2) Unit weight increase in 1.1% as the mixing ratio of cooper slag argument 10%. (3) compressive strength of cooper slag concrete is similar to plain and especially higher 11-15% in W/C 45%, 50%. So it seems that aggregate mixed cooper slag is suitable to low water-cement ratio mixture.