• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.78-79
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• 2013

A policy for recycling waste concrete has been extensively studied, but it is still lacking to recycle and reuse as a cementitious powder, and the property has big different depending on the aggregate rates. In this study, the amount of cement powder according to the internal properties of the aggregate were mixed. From as a result, Concrete Powder to play inside the aggregate composition of the cement composition CaO rigs that causes loss of power and strength reduction due to rising real water cement ratio will affect large.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.139-140
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• 2016

In this research, the possibility of wasted refractory aggregate pulverized from refractory block as an expansive admixture and additional alkaline stimulant for class two and three blast furnace slag cements (BSC) was assessed with its high content of free CaO or free MgO. As the replacement ratios of wasted refractory powder and blast furnace slag were increased, flow and air content were decreased, while unit volume weight was increased under same conditions. Compressive strength of mortar was increased with increased replacement ratio of wasted refractory powder, especially, in the case of class three BSC, the highest compressive strength was obtained when wasted refractory aggregate was replaced 2%.

• 한국건축시공학회지
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• 제14권1호
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• pp.11-20
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• 2014

This research examined the effect of the quality of aggregate on concrete workability and compressive strength through an investigation into regional aggregate used in domestic ready mixed concrete plants. Through the research, it was found that aggregate for ready mixed concrete shows poor quality overall. The main factor of deterioration in the quality of the concrete is the particle size of fine aggregate and fine particle content in coarse aggregate. The quality of aggregate significantly influences concrete's workability, which is defined based on 0.08mm passage related with powder and absorption. In addition, poor aggregate quality leads to increased water content in concrete to secure workability, which is related with a decline in the compressive strength and durability of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.172-179
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• 1996

Recently, the broken concrete lumps resulting from the demolition of concrete structures are creshed for reuse as aggregates(i.e. recycled fine and gravel). And also, in the processing of crusing, the recycled powder of an equivalent of between 20% to 30% by wt.% of the broken concrete lumps is generated. The extensive research of recycled concrete aggregates has been carried out in various parts of the world. But less reseatch on the reuse of recycled concrete powder has been carried out. It is the purpose of this report that the study on the quality evaluation of recycled aggregates for recycled concrete. In specially, this report deals with the properties such as flow, compressive strength, bending strength, drying shrinkage and wight loss rate of mortars replaced standard fine aggregate with recycled powders at the rate of 3, 7, 15, 20 and 30 wt.%. Since the characteristics of recycled mortars with the recycled powders were comparable to those of the normal mortar without the recycled powders as described above, its concretes could be found extensive application in such field as concrete products.

• Computers and Concrete
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• 제27권3호
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• pp.241-252
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• 2021

An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

• 한국구조물진단유지관리공학회 논문집
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• 제15권4호
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• pp.193-203
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• 2011

본 연구에서는 폐콘크리트에서 발생하는 순환잔골재가 구조용 재료로서 많은 문제점이 있음을 인지하고 순환잔골재가 포함하고 있는 미분말이 강도증진 효과와 유동성을 증가 시킬 수 있다는 특성을 이용하여 자기충전 콘크리트(Self-Compacting Concrete, 이하 SCC로 표기)에 활용하게 되었다. 즉 순환잔골재가 갖는 미분말이 자기충전 콘크리트 특성인 고강도(40 MPa 이상)와 높은 유동성(JSCE 2등급)을 발현하기에 적당하여 폐콘크리트에서 발생하는 순환잔골재를 일반잔골재 대비 순환잔골재의 혼입률을 25%씩 증가시켜, 총 5수준으로 달리하여 자기충전 콘크리트에 적용하였으며, 이에 따라 굳지 않은 콘크리트의 물리적 특성, 경화한 콘크리트의 역학적 및 내구 특성을 검토하여 순환잔골재를 자기충전 콘크리트 재료로서 활용 가능성을 검토하고자 한다. 그 결과 물리적, 역학적 및 내구특성의 5수준 배합비율 중 일반잔골재 대비 순환잔골재는 50% 혼입률까지 적용가능하다는 결론을 얻었으며, 그 이상의 혼입률에서는 오히려 성능저하가 발생한다는 것을 알 수 있었다. 또한 실생활에서의 적용 가능성을 알아보기 위한 실구조물의 적용성이 차후 검토 되어야 할 것으로 판단된다.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.367-375
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• 2022

순환 잔골재 혼합비율에 따른 압축강도는 설계기준강도별 보통콘크리트 대비 순환 잔골재 혼합비율에 따라 유사하거나 다소 낮은 강도 발현을 보였으며, 순환 잔골재 혼합비율이 증가할수록 압축강도는 감소하는 경향을 보였다. 재령일이 증가할수록 강도저하는 발생하지 않았으며, 설계기준강도 대비 강도 발현이 가능할 것으로 판단된다. 순환 잔골재 15 %, 20 %, 25 %로 혼합비율에 따른 순환골재 콘크리트의 길이변화 및 동결융해에 대한 내구특성은 보통콘크리트와 유사한 경향으로 나타났다. 콘크리트용 순환 잔골재의 비율은 총 골재량의 25 %(총잔골재의 50 %)까지 적용하면 슬럼프 및 공기량에 문제가 없을 것으로 판단되며, 설계기준강도에 따른 분체량과 단위수량 및 공기연행제량에 대한 관리가 필요할 것으로 판단된다.

• 한국건설순환자원학회논문집
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• 제4권2호
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• pp.157-164
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• 2016

본 연구에서는 고로슬래그 미분말 다량 치환한 시멘트 모르타르의 자극재로 탈황석고(FGD)를 사용한 경우, FGD에 포함되어 있는 활성탄의 제거로 체가름방법과 고온가열 조건을 원분과 비교하고, 또한 골재로서 순환골재(RFA)와 천연골재(NFA)를 사용하는 골재종류 변화 조건에서 각종 품질특성을 검토하였다. 실험결과 FGD의 활성탄 제거방법은 $500^{\circ}C$ 고온가열보다 0.3mm 체가름법이 우수하였고, FGD 치환율은 5~10%일 때, 잔골재는 NFA보다 RFA에서 비교적 양호한 결과를 얻을 수 있었다. 그러나 RFA를 이용한 모르타르의 경우는 실무 활용시 건조수축 길이변화율 및 흡수율 측면에서는 용도제한 및 별도의 품질향상 대책이 요구되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.93-95
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• 2011

This study is to investigate experimentally the engineering characteristics of cement mortar incorporating both recycled aggregate powder (RP) below 0.08 mm and cement kiln dust(CKD). RP is substituted for fine aggregate ranged from 5~15% and CKD is also substituted for RP from 10~30%. The use of RP resulted in a decrease in flow value at fresh mortar, while an increase in CKD did not affect the flow value significantly. The combination of RP and CKD provided slight increase in compressive strength at early and 28 days and in the high curing temperature at early age showed an increasing Strength value.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.676-679
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• 2004

In this study, we considered the characteristic of drying shrinkage from age of high strength concrete with garnet minute powder to be industry by-product. The factors of experiment are unit water content$(160kg/m^3)$, water-binder ratio(30, $35\%$), fine aggregate ratio(40, 42, $44\%$), admixture replacement ratio(0, 10, $20\%$), admixture type(garnet minute powder, fly ash, blast-furnace slag). We make a comparative study of shrinkage about concrete with a passage of age(1, 3, 7, 14, 28, 56, 91 days). As a result of experiment, we reach a conclusion as follow. In the same mix condition, as unit water content and fine aggregate ratio go up, the drying shrinkage ratio increase. In the drying shrinkage ratio according to admixture replacement ratio, it goes up when admixture replacement Ratio increase in case of fly ash and blast-furnace slag. But, drying shrinkage ratio decrease when admixture replacement ratio increase in case of garnet minute powder.