• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.89-94
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• 2003

Recently, the study to reduce and recycle industrial waste is underway vigorously in the various fields of industry according to the conservation of environment and resources. In construction work, the disposal problem of its waste and environmental disruption have already been serious all over the world. However the recycle of waste concrete is still at an early stage, recycled aggregate from waste concrete have only used those as subsidiary road fillers. The research institute and the company make the study that it is about the properties of recycled aggregate and those structural capacity since 1990. Through the experimentation last year, we know that strength and fluidity of recycle cement are inferior to normal cement, and admixing aggregate powder deteriorates its strength. The purpose of this study is to search for appropriate heating time and to improve performance of the recycle cement while heating hardened cement which is crushed, we investigate separating aggregate from hardened cement by preheating and improvement of strength and fluidity inrecycle cement which contains admixture.

• 한국건축시공학회지
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• 제5권3호
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• pp.109-116
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• 2005

Recently, there have been many studies seeking towards the utilization of cementitious powder from concrete waste as recycled cement. However, most of the studies actually have been researches about the reuse of mortar or paste, not concrete waste. In fact, either mortar or paste is quite different from a real concrete waste in terms of age and mixture. Thus the purpose of this study is to examine basic physical properties of recycled cement, manufactured with cementitious powder from concrete waste, and analyze differences in chemical and hydraulic properties of the cement and its tested model. As a result of the chemical analysis, recycle cement is composed mainly of CaO and $SiO_2$, and that it is even lower in the content of CaO than Portland cement, which is also supported by previous studies. But, Differently from previous studies, calcining temperature of 650 was found an optimal condition under which cementitious powder from concrete waste could restore its hydraulic properties.

• 한국세라믹학회지
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• 제42권11호
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• pp.737-742
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• 2005

Rheological properties of ordinary portland cement (OPC) containing metakaoline (MK), granulated blast furnace slag (GBS) and polycarboxylate type superplasticizer (PCA) were investigated using a mini-slump test, sedimentation test and viscometer. Fluidity of cement pastes containing MK (OPC-MK, OPC-MK-GBS systems) with PCA were higher than those of the cement pastes without MK(OPC, OPC-GBS systems). Colloid suspensions with $0.1\%$ PCA were changed from stable sedimentation behaviors to flocculation behaviors in the OPC-MK, OPC-GBS and OPC-MK-GBS systems. The colloid suspensions showed stable sedimentation behaviors with PCA greater than $0.2\%$. The OPC system showed shear thinning behavior. However, the other systems showed weak shear thinning behaviors with PCA. Rheological properties of cement pastes were improved when MK and GBS were contained together. The rheological properties of OPC-MK, OPC-GBS and OPC-MK-GBS systems were improved by PCA added greater than $0.2\%$.

• Geomechanics and Engineering
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• 제29권3호
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• pp.237-247
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• 2022

To investigate the curing temperature effect on the engineering properties of ground granulated blast furnace slag-cement bentonite (GGBS-CB) slurry for cutoff walls, the laboratory experiments including the setting time, unconfined compressive strength, and permeability tests were carried out. The mixing procedure for GGBS-CB slurry was as follows: (1) montmorillonite-based bentonite slurry was first fabricated and hydrated for four hours, and (2) cement or GGBS with cement was added to the bentonite slurry. The dosage range of GGBS was from 0 to 90 % of cement by mass fraction. The GGBS-CB slurry specimens were cured and stored in environmental chamber at temperature of 14±1, 21±1, 28±1℃ and humidity of 95±2% until target days. The highest average temperature of three seasons in South Korea was selected and used for the tests. The experimental results indicated that in early age (less than 28 days) of curing the engineering properties of GGBS-CB slurry were primarily affected by the curing temperature, whereas the replacement ratio of GGBS became a main factor to determine the properties of the slurry as the curing time increased.

• Computers and Concrete
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• 제33권6호
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• pp.707-724
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• 2024

This paper proposes a study of cement replacement with rice husk ash (RHA) and eggshell ash (ESA) for enhanced mechanical properties of geopolymer (GP) concrete with and without admixture. The main objective is to investigate the mechanical properties of GP with various replacement levels of Pozzolana Portland cement by RHA and ESA. The GP resistance to durability is examined and impact of ash materials on concrete's durability performance is determined. The environmental benefits of using agricultural waste materials in GP manufacturing minimize cement usage and CO2 emissions. The goal is to assess value of RHA-ESA of building material, paving stones for structures to lessen environmental impact. The novelty lies in use of ESA and RHA as partial replacements for cement and investigation of admixtures to enhance concrete properties, and reduce environmental impact. The research contributes by introducing a novel approach to reducing cement consumption by using ESA and RHA to address environmental concerns. It also explores the potential benefits of admixtures improving concrete performance and reducing environmental pollution. A study is carried with and without impacts of admixture to find compressive strength of GP cubes. The cement has been replaced by RHA and ESA in the range of (2.5%+7.5%, 5%+5%, 7.5%+2.5) by weight of cement for M20 mix. The compressive strength (CS) and split tensile strength (STS) at 7days, 14 days and 28 days is obtained as 21 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 24 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 28 N/mm2 at 7.5%RHA+2.5%ESA and 2.8 at 7.5%ESA respectively with normal curing condition.

• Advances in concrete construction
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• 제10권5호
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• pp.417-429
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• 2020

Waste glass is a global solid waste with huge reserves. The discarded waste glass has caused a series of problems such as resource waste and environmental pollution, so it is urgent to recycle waste glass with high replacement level. Glass powder (GP), as a supplementary cementitious material (SCM), used in cement-based materials has already become one of the important ways to recycle waste glass mainly attributed to its pozzolanic reaction and filling effect, especially to the suppressed ASR expansion. This paper demonstrates an overview of the properties of GP and its effect on the fresh and mechanical properties of cement-based materials. The study found that the influence of GP on the performance of cement-based materials mainly depends on its content, particle size, color and type, curing conditions, and other SCMs. Finally, based on the problems involved in the investigation of concrete containing GP, some corresponding suggestions and efforts are given to further guide the utilization of GP in cement-based materials.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.542-546
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• 2001

Converter slag has some compositional similarities to portland cement. But it has no hydration properties due to it's quite high concentrations of FeO(20-35%), MnO(4-6.5%). So it is needed to reduce the concentrations of iron and manganese of converter slag to use as cement additives by enhancing it's hydration properties. In this study, converter slag was modified it's composition by mixing of silica, alumina and quenched BF slag and reduced in induction furnace and quenched in running water. The hydraulic properties and structures of modified and quenched converter slag are significantly changed depend on the amount and kinds of additives. The addition of alumina up to 10% and BFQ slag up to 20% by weight on converter slag was effective to enhance the hydraulic properties of modified and quenched slag. The addition of reduced and quenched converter slag up to 20% by weight in replacement of portland cement in mixing of concrete mortar were shown higher compressive strength than 100% cement concrete mortar.

• 한국농공학회논문집
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• 제56권5호
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• pp.37-44
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• 2014

The physical, mechanical and freezing and thawing properties of non cement porous vegetation concrete using non-sintering inorganic binder have been evaluated in this study. Four types of porous vegetation concrete according to the binder type is evaluated. The pH value, void ratio, compressive strength, repeated freezing and thawing properties were tested. The test results indicate that the physical, mechanical and repeated freezing and thawing properties of porous vegetation concrete using the non-sintering inorganic binder is increased or equivalent compared to the porous vegetation concrete using the blast furnace slag + cement and hwang-toh + cement binders. Also, Vegetation monitoring test results indicate the porous vegetation concrete using the non-sintering inorganic binder have increasing effects of vegetation growth.

• 대한건축학회논문집:구조계
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• 제34권5호
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• pp.13-18
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• 2018

In this research, regarding the type three blast furnace slag (BS) regulated by KS F 2563 and supplied to actual ready mixed concrete plant, the fineness on specification and actually measured fineness by Blain test were compared, and by applying the hydrometer method used for early prediction of concrete strength, the feasibility of the hydrometer method for acquisition inspection of BS was analyzed. Additionally, the influence of various fineness of BS on properties of cement mortar was also assessed. According to the experimental results of this research, correlation of fineness values between specification and actually measured data were not matched. In the case of the rapid evaluation method using hydrometer, a good relation was shown between the fineness data obtained from hydrometer and Blain test. furthermore, from the cement mortar properties test, there was a good relation was obtained between fineness data from rapid evaluation method by hydrometer and cement mortar properties, while there was no clear relation between fineness data from specification and cement mortar properties. Hence, as a qulity controlling method of BS fineness, a rapid evaluation method using hydrometer is suggested as a new method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.528-535
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• 2000

Solid waste incinerator is expected to become widely used in Korea. The incineration of solid waste produces large quantities of bottom and fly ash, which has been disposed of primary by landfilling. However, as landfills become undesirable other disposal method are being sought. In this study, an experimental research is conducted to determine the geotechnical properties of municipal solid waste incinerator fly ash(MSWIF) in order to evaluate the feasibility of using the material for geotechnical applications. Basic pysicochemical characteristics, moisture-density relationship, strength, permeability, and leaching characteristics are examined. The results of MSWIF are compared to other MSWIF and coal fly ash which are used as construction material. In addition, the effectiveness of cement stabilization is investigated using various mix ratios. The result of stabilized mixes are compared to the unstabilized material. Cement stabilization is found to be very effective in reducing permeability, increasing strength, and immobilizing heavy metals. This results indicate that MSWIF with cement stabilization may be used effectively for geotechnical application.