마이크로 강섬유 보강 경량골재 콘크리트 특성 및 실용화

양근혁,이연정,권희용,Keun-Hyeok Yang,Yeon-Jeong Lee,Hee-Yong Kwon 한국건설순환자원학회 2023 한국건설순환자원학회지 Vol.18 No.4

콘크리트 배합설계를 고려한 구조물의 전과정 CO₂평가 모델

양근혁,서은아,Yang, Keun-Hyeok,Seo, Eun-A 한국콘크리트학회 2014 콘크리트학회논문집 Vol.26 No.2

이 연구는 콘크리트 구조물의 전과정 $CO_2$ 평가를 위한 단계적 모델을 제시하였다. 고려된 시스템 경계는 원료채취에서부터 재활용까지로서, 구성재료, 운송, 레미콘 공장에서의 계량 및 배합, 구조물의 사용 및 해체, 폐콘크리트의 파쇄 및 재활용까지를 포함한다. 구조물의 운영(40년) 및 재활용(20년) 단계에서 탄산화에 의한 $CO_2$ 포집양은 탄산화 깊이를 예측하기 위해 제시된 모델로부터 산정하였다. 제시된 $CO_2$ 평가모델에 기반하여 콘크리트 구조물의 전과정 $CO_2$양을 직접적으로 평가할 수 있는 성능평가표를 구체화하였다. 제시된 성능평가표를 이용한 사례분석 결과 보통포틀랜드 시멘트(OPC)가 콘크리트 구조물의 전과정 $CO_2$ 양에 미치는 기여비율은 약 85%이었다. 탄산화에 의한 $CO_2$ 포집양은 콘크리트 구조물의 전과정 $CO_2$ 양에 약 15~18%로 평가되었는데, 이는 OPC 생산으로부터 배출된 양의 약 19~22%에 해당된다. 결국, 제시된 $CO_2$ 성능평가표는 콘크리트 구조물의 각 단계에서 $CO_2$ 배출 또는 포집을 쉽게 결정할 수 있는 가이드라인으로서 설계 또는 시공 시 효율적으로 이용될 수 있다. The present study proposes a phased model to assess the lifecycle $CO_2$ amount of concrete structures. The considered system boundary is from cradle to recycling, which includes constituent material, transportation, batching and mixing in ready-mixed concrete plant, use and demolition of structure, and crushing and recycling of demolished concrete. The $CO_2$ uptake of concrete by carbonation during lifetime (40 years) of a structure and the recycling life (20 years) after demolition is estimated using a simple approach generalized to predict the carbonation depth from the surfaces of concrete element and recycled aggregates. Based on the proposed phased model, a performance evaluation table is realized to straightforwardly examine the lifecycle $CO_2$ amount of concrete structures. The proposed model demonstrates that the contribution of ordinary portland cement (OPC) to lifecycle $CO_2$ emission of the concrete structure occupies approximately 85%. Furthermore, the $CO_2$ uptake is estimated to be approximately 15~18% of the lifecycle $CO_2$ emissions of concrete structures, which corresponds to be 19~22% of the emissions from OPC production. Overall, the proposed $CO_2$ performance table is expected to be practically useful as a guideline to determine the $CO_2$ emission or uptake at each phase of concrete structures.

고로슬래그 기반 지오폴리머 콘크리트의 구조적 특성 및 실용화 사례

양근혁,송진규,Yang, G.H.,Song, J.K. 한국전산구조공학회 2011 전산구조공학 Vol.24 No.1

포스트텐션 경량콘크리트 일방향 슬래브의 휨 거동 및 비부착 긴장재의 응력

양근혁,문주현,변항용,오명호,Yang, Keun-Hyeok,Mun, Ju-Hyun,Byun, Hang-Yong,Oh, Myoung-Ho 대한건축학회 2011 대한건축학회논문집 Vol.27 No.6

Six post-tensioned lightweight concrete (LWC) one-way slabs were tested under a symmetrical one-point top loading system. According to tendon profile, the specimens were classified into two groups: S-group for slabs with straight tendons and V-groups for slabs with harped (counter-moment shaped) tendons. The span-to-tendon depth ratio($L/d_p$) varied to be 15, 35 and 55 in each group. The flexural cracking moment and ultimate moment of one-way slab tested and stress increase measured in unbonded tendons were compared with those of post-tensioned normal-weight concrete (NWC) beams compiled from the comprehensive database and predictions obtained from the design equations specified in the ACI 318-08 provision. Test results showed that the distribution and width of flexural cracks was significantly affected by the $L/d_p$, indicating that the larger the $L/d_p$, the smaller the crack width. On the other hand, tendon profile had a significant influence on deflection and flexural capacity of one-way slabs, showing a smaller deflection and a higher strength in slabs with harped tendons than in slabs with straight tendons. At the same value of reinforcing inde, the flexural cracking moment and ultimate moment of post-tensioned LWC one-way slabs were pretty comparable to those of post-tensioned NWC beams. In addition, flexural strengths and tendon stress increase of post-tensioned LWC one-way slabs could be conservatively predicted by the ACI 318-08 provision.

고성능 콘크리트의 실용화를 위한 시공특성에 관한 실험적 연구

양근혁,이영호,Yang, Keun-Hyeok,Lee, Young-Ho 한국건축시공학회 2003 한국건축시공학회지 Vol.3 No.1

The special requirements of high-performance concrete(HPC) could be enhanced property over others such as compressive strength, durability, and construction practices. In order to satisfy these requirements a series of laboratory trial mixes and following mock-up test of reinforced concrete wall at field were performed in this study. The objective of this study was to quantitatively evaluate the workability, compressive strength, and the increased heat of hydration caused by the increase of the specific weight of cement according to various variables. Six example series designed about a minimum compressive strength of 500kgf/$\textrm{cm}^2$ at 28 days, and an approximately slump and slump flow of 25cm and 60cm respectively were tested. The selection process of the specific weight of water and the percentage of fly-ash transposition determined to be most suitable for the production of HPC is presented in the following paper.

상계치 이론을 이용한 개구부를 갖는 철근콘크리트 단순·연속 깊은 보 내력의 수치해석 모델

양근혁,은희창,정헌수,Yang, Keun-Hyeok,Eun, Hee-Chang,Chung, Heon-Soo 한국콘크리트학회 2006 콘크리트학회논문집 Vol.18 No.4

상계치 이론을 이용하여 개구부를 갖는 단순 연속 깊은 보의 최대내력을 평가하기 위한 모델들이 제시되었다. 콘크리트는 인장강도를 무시한 수정 Coulomb 파괴기준을 따르는 완전 소성체로 가정하였으며, 철근은 기존 상계치 이론과는 달리 완전 탄 소성 재료로 고려하여 콘크리트의 한계 주 압축변형률을 사용하여 응력을 산정하였다. 파괴기구들은 실험 결과에 근거하여 포물선형의 항복선에 의해 분리되는 강체들로 이상화 하였다. 콘크리트의 유효압축 강도는 Vecchio & Collins의 모델에 의해 계산되었다. 본 연구에서 제시된 모델은 단순 연속 깊은 보의 실험 결과와 잘 일치하였으며, 특히 개구부 보강철근의 하중부담에 대한 과대평가를 감소시켰다. Models to predict the ultimate strength of simply supported or continuous deep beams with web openings are proposed. The derived equations are based on upper-bound theorem. The concrete is assumed as a perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cutoff. Reinforcing bar is considered as elastic-perfectly plastic material and its stress is calculated from the limiting principal compressive strain of concrete. The governing failure mechanisms based on test results are idealized as rigid moving blocks separated by a hyperbolic yield line. The effective compressive strength of concrete is calculated from the formula proposed by Vecchio and Collins. Comparisons with existing test results are performed, and they show good agreement.

원전용 중량콘크리트의 배합설계 및 구조적 특성

양근혁,Yang, Geun-Hyeok 한국건설관리학회 2013 한국건설관리학회 논문집 Vol.14 No.1

필름포장재 물질재활용 실증화 사례

양근혁,권성준,임희섭,Yang, Keun-Hyeok,Kwon, Seung-Jun,Lim, Hee-Seob 한국건설순환자원학회 2020 한국건설순환자원학회지 Vol.15 No.3

알카리활성 기포콘크리트의 품질특성 및 환경영향 평가

양근혁,유성원,이현호,김상철,Yang, Keun-Hyeok,Yoo, Sung-Won,Lee, Hyun-Ho,Kim, Sang-Chel 한국건설순환자원학회 2013 한국건설순환자원학회 논문집 Vol.1 No.2

본 연구에서는 공동주택의 난방시스템을 위한 단열재로서 지속가능한 알카리활성 기포콘크리트 배합설계를 제시하기 위한 5배합을 실험하였다. 알카리활성 결합재를 위해 73.5%의 고로슬래그와 15%의 고로슬래그가 5%의 수산화칼슘과 6.5%의 규산나트륨에 의해 활성화되었다. 주요 실험변수인 단위 결합재양은 $325kg/m^3$에서 $425kg/m^3$까지 $25kg/m^3$ 단위로 증가하였다. 실험결과 AA 기포콘크리트는 단위 결합재양이 $375kg/m^3$일 때 KS F 4039에서 제시하는 최소 강도조건 및 경제성을 만족시켰다. 또한 보통포틀랜드시멘트 기포콘크리트 대비 알카리활성 기포콘크리트의 환경영향 저감율은 광화학산화물의 경우 99%, 지구온난화의 경우 87~89%, 자원고갈의 경우 78~82%, 그리고 산성화와 인간독성의 경우 70~75% 수준으로서 매우 높았다. The present study tested 5 concrete mixes to develop reliable mixing proportions for the sustainable alkali-activated(AA) foamed concrete as a thermal insulation material for the floor heating system of buildings. The AA binder used was composed of 73.5% ground granulated blast-furnace slag, 15% fly ash, 5% calcium hydroxide, and 6.5% sodium silicate. As a main variable, the unit binder content varied from $325kg/m^3$ to $425kg/m^3$ at a space of $25kg/m^3$. The test results revealed that AA foamed concrete has considerable potential for practical applications when the unit binder content is close to $375kg/m^3$, which achieves the minimum quality requirements specified in KS F 4039 and ensures economic efficiency. In addition, lifecycle assessment demonstrated the reduction in the environmental impact profiles of all specimens relative to typical ordinary portland cement foamed concrete as follows: 99% for photochemical oxidation potential, 87~89% for global warming potential, 78~82% for abiotic depletion, and 70~75% for both acidification potential and human toxicity.

고로슬래그 기반 알카리활성 콘크리트 벽돌조의 재료특성

양근혁,심재일,송진규,이정한,Yang, Keun-Hyeok,Sim, Jea-Il,Song, Jin-Gyu,Lee, Jung-Han 대한건축학회 2011 대한건축학회논문집 Vol.27 No.1

The present study evaluated the various material properties of concrete brick-masonry using alkali-activated (AA) ground granulated blast-furnace slag (GGBS) binder in order to examine the limitation and significance of environmental-friendly cementless masonry. The reasonable mixing proportions for cementless bricks and masonry mortar using AA GGBS binder were determined from the laboratory and practical plant tests. The compressive strengths of brick and masonry mortar were measured for individual cementless materials. In addition, compressive strength, elastic modulus, diagonal shear strength and modulus of elasticity in shear of masonry prisms were recorded for cementless masonry wall. The measured properties of GGBS-based AA concrete brick-masonry were compared with those of ordinary portland cement (OPC) concrete brick-masonry and empirical equations proposed by different codes including UBC-97, EC 6, and KBC-2009 and existing researchers, wherever possible. The present study clearly showed that the developed GGBS-based AA concrete brick-masonry can be practically applicable as environmental-friendly masonry structures.