기존 포장에서 고내구성과 조기강도 발현을 위하여 쓰이고 있는 바인더의 경우, 고가의 폴리머를 다량 으로 사용하고 속경성 시멘트를 적용한다. 또한 단위시멘트 360 kg/㎥이상의 부배합 시멘트를 적용하고, 양질의 골재를 사용하고 있다. 이로 인하여 재료비가 증가하게 되고 시공을 위한 고가의 특수 장비를 운 영해야 하기 때문에 공사비가 증가된다. 이러한 문제점을 해결하기 위하여 콘크리트의 내구성을 증진시켜 주는 산업폐기물로 시멘트를 치환하고, 현장 레미콘을 사용하여 재료 단가를 낮춰 줌으로써 경제성을 확 보 할 수 있다. 레미콘에 현장에서 직접 혼화재료를 투입하기 때문에, 혼화재료 투입의 효율을 증대시키 기 위한 장비개발을 위한 연구가 필요시 된다. 따라서 기존에 인력으로 투입되던 혼화재료를 현장생산 system(기포발생장치)를 이용하여 레미콘에 투입하고, 인력투입대비 공정효율을 증가시키는 것이 본 연 구의 목적이다. 현장생산system(기포발생장치)를 이용하여 개선된 방안을 토대로 공정 효율을 비교한 결과 인력투입대 비 약 140% 이상 효율이 증대되는 것을 확인하였다.

PURPOSES : In this study, an image analysis method is used to evaluate the pore structure characteristics and permeability of hybrid concrete. METHODS: The binder weight of hybrid concrete is set to 400 kg/m3, 370kg/m3, and 350 kg/m3, and for each value of binder weight, the pore structure and permeability of concrete mixture is evaluated. The permeability of hybrid concrete is evaluated using a rapid chloride penetration test(RCPT). RESULTS : The concrete pore structure characteristics of hybrid concrete reveals that as the binder weight is reduced, the entrained air is reduced and the entrapped air is increased. The permeability of the hybrid concrete for all values was measured to be below 1000 C, which indicates a "Very Low" level of permeability relative to the evaluation standard of KS F 2711. Additionally, as the binder weight is decreased, there is a significant increase in the permeability of chloride ions. CONCLUSIONS : In this study, the pore structure characteristics of hybrid concrete at different binder weights shows that as the binder weight is reduced, the entrained air is reduced and the entrapped air is increased. Consequently, chloride ion penetration resistance of the hybrid concrete is diminished. As a result, it is expected that this will reduce the concrete’s durability.

PURPOSES : In this study blast furnace slag, an industrial byproduct, was used with an activating chemicals, Ca(OH)2 and Na2SiO3 for carbon capture and sequestration as well as strength development. METHODS: This paper presents the optimized mixing design of Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar. Design of experiments in order to the optimized mixing design was applied and commercial program (MINITAB) was used. Statistical analysis was used to Box-Behnken (B-B) method in response surface analysis. RESULTS : The influencing factors of experimental are water ratio, Chemical admixture ratio and Curing temperature. In the results of response surface analysis, to obtain goal performance, the optimized mixing design for Carbon-Capturing and Sequestering Activated Blast- Furnace Slag Mortar were water ratio 40%, Chemical admixture ratio 58.78% and Curing temperature of 60℃. CONCLUSIONS: Compared with previous studies of this experiment is to some extent the optimal combination is expected to be reliable.

본 연구에서는 활성 산업부산물을 활용한 탄소흡수용 도로재료 개발 연구의 일환으로 산업부산물인 고로슬래그와 탄소포집 활성화제로 수산화칼슘과 규산나트륨을 사용한 콘크리트의 압축강도 실험을 수행하여 얻어진 결과에 대하여 고찰하였다. 본 실험에서는 탄소포집 활성 고로슬래그 콘크리트의 예비배합으로 다음 표 1과 같은 배합표에 따라 콘크리트 시험체 제작 후 압축강도를 측정하였다. 탄소포집 활성 고로슬래그 콘크리트의 양생온도에 따른 압축강도 실험결과, 양생온도 50℃에서의 28일 압축강도가 최대 약 30MPa 정도의 수준을 나타내었으며, 전반적으로 양생온도가 더 높은 50℃에서 양생 한 시험체의 압축강도가 다소 높은 것으로 나타났다. 또한 탄소포집 활성화제의 첨가량 증가에 따른 압축 강도의 변화폭이 미미한 수준으로 나타났으며, 따라서 추후 실험에서는 배합비, 양생방법 등을 고려한 추가적인 실험이 진행되어져야 할 것으로 판단된다.

PURPOSES : As a research to develop a cement treated base course for an airport pavement which can enhance its drainage, this paper investigated the strength, infiltration performance and durability of the pervious concrete with respect to maximum coarse aggregate sizes and compaction methods. METHODS : This study measured compressive strength, infiltration rate, continuous porosity and freeze-thaw resistance of pervious concrete specimens, which were fabricated with five different compaction methods and different maximum aggregate sizes. In addition, in order to reduce the usage of Portland cement content and to enhance environment-friendliness, a portion of the cement was replaced with Ground Granulated Blast Furnace Slag (GGBS). RESULTS: Compressive strength requirement, 5 MPa at 7 days, was met for all applied compaction methods and aggregate sizes, except for the case of self-compaction. Infiltration rate became increased as the size of aggregate increased. The measured continuous porosities varied with the different compaction methods but the variation was not significant. When GGBS was incorporated, the strength requirement was successfully satisfied and the resistance to freezing-thawing was also superior to the required limit. CONCLUSIONS: The infiltration rate increased as the maximum size of aggregate increased but considering construct ability and supply of course aggregate, its size is recommended to be 25mm. With the suggested mix proportions, the developed pervious concrete is expected to successfully meet requirements for strength, drainage and durability for cement treated base or subbase course of an airport pavement.

PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the Ca(OH)2 keeps absorbing CO2 in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.

The amount of newly-built bridges has been gradually reduced so that the importance of maintenance for existing bridges which has a long services period is issued. Therefore, the maintenance budget for existing bridges is going to be consistently increased. It is needed that a reasonable decision-making methodology for existing bridge maintenance is required to effectively use the limited maintenance budget. In this study, a method of the structural vulnerability evaluation is newly suggested as the one of the evaluation stage for developing a reasonable decision-making methodology.

As the service period of bridges become increased, more effective maintenance strategy is needed. The decision making strategy should be able to prioritize bridges for maintenance. This study, as preliminary study for the development of prioritization decision making tool, reviews bridge maintenance strategies abroad and domestic.

Limestone powder can be used for concrete as a partial replacement of Portland cement so that concrete becomes more environment-friendly construction material. One of the great applications of limestone powder added cement concrete might be a cement concrete pavement since the concrete pavement consumes massive quantity of Portland cement. However, it has been reported recently that Alkali-Silica Reaction (ASR) occurs on the cement concrete pavement causing a serious damage. This study investigates the resistance of limestone powder added cement mortar to ASR. The mortar used very high reactive silicious aggregate for accelerated ASR. Experimental procedures followed ASTM C 1260 and variables included different replacement levels of limestone powder in the mortar mix.