PURPOSES : This study aimed to develop a quantitative structure property relationships (QSPR) model to predict the density from the molecular structure information of the asphalt binder AAA1, a non-full connected structure mixed with a total of 12 molecules. METHODS : The partial least squares regression (PLSR) model, which models the relationship between predictions and responses and the structure of these variables, was applied to predict the density of a binder with molecule descriptors. The PLSR model could also analyze data with collinear, noisy, and multiple dimensional independent variables. The density and additive-free AAA1 binder’s molecule systems generated by an asphalt binder’s molecules-related study were used to fit the PLSR model with the molecular descriptors produced using alvaDesc software. In addition to developing the relationship, a systematic feature selection framework (i.e., the V-WSP- and PLSR-modelbased genetic algorithm (GA)) was applied to explore sets of predictors which contributed to predicting the physical property. RESULTS : The PLSR model accurately predicted the density for the AAA1 binder’s molecules using the condition of the temperature and aging level (R2 was 0.9537, RMSE was 0.00424, and MAP was 0.00323 for the test data) and provided a set of features which correlated well to the property. CONCLUSIONS : Through the establishment of the physical property prediction model, it was possible to evaluate the physical properties of construction materials without limited experiments or simulations, and it could be used to comprehensively design the modified material composition.

초고성능 콘크리트의 시멘트량 저감을 위해 시멘트와 치환하여 사용가능한 시멘트계 재료를 사용한 연구를 사전 조사하여 플라이애시와 고로슬래그를 선정하였다. 시멘트와 실리카흄 조합으로 120 MPa 이상의 압축강도를 보인 배합을 사용해 바인더조합의 변화에 따른 압축강도, 휨강도를 평가하였다. 플 라이애시와 고로슬래그를 사용한 배합은 유동성이 향상되었으며, 플라이애시는 압축강도가 실리카흄만 사용한 경우보다 다소 감소하였으나, 고로슬래그를 사용한 실험체는 실리카흄만 사용한 실험체와 유사 한 결과를 나타내었다.

내구연한이 도래한 아스팔트 혼합물은 사용자의 주행성 및 안전성 확보를 위해 주기적인 유지·보수를 실시한다. 과거에는 유지·보수 과정에서 발생된 폐아스팔트 혼합물을 각종 건설현장에서 단순 매립재로서 활용하였으나, 재활용 아스팔트 혼합물의 배합설계 기술이 확립된 이후에는 도로포장재료로서의 재활용되어왔다. 하지만 현재 시공된 재활용 아스팔트 혼합물 또한 내구연한이 다가옴에 따라 노화된 재활용 아스팔트 혼합물의 처리방안 수립이 필요한 시점이다. 본 연구에서는 한번 재활용된 아스팔트 혼합물이 기존의 재활용 배합설계법으로 반복적인 재활용이 가능한지 검증해보고자 하였다. 이를 위해 아스팔트 혼합물의 물성을 결정하는 가장 큰 요인 중 하나인 아스팔트의 물성이 노화 및 재생을 반복할때 어떻게 변하는지를 시험을 통해 분석하였다. 아스팔트 바인더의 노화를 모사하기 위해 공용성등급시험에 사용되는 단기노화 장비(Rolling Thin Film Oven, RTFO)와 장기노화 장비(Pressure Aging Vessel, PAV)을 활용하 였다. 노화된 아스팔트의 회생을 위한 재생첨가제 사용량은 국토부 시공지침의 배합설계법을 참고하였다. 실험결과, 노화된 바인더는 회생시 원바인더에 비해  sin는 감소하였으나, 회생된 바인더 간에는 유사한 결과값을 보였다. 반면 단기노화 시료는 회생이 반복 됨에 따라  sin이 감소한 경향을 보였으며, 장기노화시료는 회생이 반복되어도  sin가 유사한 것으로 확인되었다.

2022년 기준 국내 폐타이어 발생량은 약 37만톤으로 그 중 88.9%인 약 32만 9천톤이 재활용되는 것으로 조사되었다. 하지만 이 중 약 75%가 시멘트소성로용 등 열이용 분야에 사용되었다. 폐타이어는 대부분 고무와 플라스틱으로 이루어져 있기 때문에, 고온에서 분 해되면서 다양한 유해가스와 오염물질이 발생할 수 있고, 이러한 공해물질은 적극적으로 관리되지 않으면 대기오염, 수질 오염 등 다 양한 환경문제를 발생시킬 수 있다. 때문에 친환경적이고 지속적인 재활용에 대한 필요성이 대두되고 있다. 폐타이어 고무 분말을 아스팔트 혼합물의 골재 일부로 치환하여 재활용하는 접근 방식은 환경에 미치는 영향을 완화할 뿐만 아니라 천연 자원의 고갈 측면에서도 긍정적인 영향을 미치는 것으로 판단된다. 따라서 타이어분말을 아스팔트 혼합물에 적용하는 것은 환경 문제를 해결하고 자원 효율성을 높이는 두 가지 이점을 가지고 있다. 폐타이어 분말을 아스팔트 바인더와 아스팔트 혼합물에 적용할 경우 미치는 영향을 평가하기 위하여 DSR, BBR, MSCR 등의 시험 을 진행하였으며, 아스팔트 혼합물 내 폐타이어 분말의 분포를 조사하기 위해 SEM을 실시하였다. 또한 IDEAL-CT와 IDEAL-Rutting 시 험을 통해 아스팔트 혼합물의 성능을 평가하였다.

세라믹 분리막은 높은 열적, 화학적 안정성을 갖기 때문에 극한의 조건에서 운전되는 다양한 산업 공정에 적용할 수 있다. 그러나 투과도와 기계적 강도의 trade-off 현상에 의한 세라믹 분리막 활용에 제약이 있어, 고투과성-고강도 분리막 의 개발이 필요하다. 본 연구에서는 상전이-압출법으로 알루미나 중공사 분리막을 제조하고, 고분자 바인더의 종류와 그 혼합 비에 따른 분리막의 특성 변화를 관찰하였다. 용매인 DMAc (Dimethylacetamide)와 고분자 바인더의 한센 용해도 인자를 비 교하면, PSf (polysulfone)가 DMAc와 높은 용해도 특성을 갖기 때문에 도프 용액의 점도와 토출압력이 높게 나타나 분리막 내부가 치밀한 구조로 형성되기 때문에 높은 기계적 강도를 갖으나 수투과도가 감소하는 것으로 확인되었다. 그에 반해, PES (polyethersulfone)를 이용하여 분리막을 제조하면 기계적 강도가 다소 감소하고 수투과도가 증가하는 것으로 나타났다. 따라 서 분리막 성능과 물성을 최적화하기 위해 PSf와 PES를 혼합하여 분리막을 제조하였으며, 9:1로 혼합하여 제조된 분리막에 서 최적화된 수투과도와 기계적 강도를 얻을 수 있었다.

The lithium ion battery has applied to various fields of energy storage systems such as electric vehicle and potable electronic devices in terms of high energy density and long-life cycle. Despite of various research on the electrode and electrolyte materials, there is a lack of research for investigating of the binding materials to replace polymer based binder. In this study, we have investigated petroleum pitch/polymer composite with various ratios between petroleum pitch and polymer in order to optimize the electrochemical and physical performance of the lithium-ion battery based on petroleum pitch/polymer composite binder. The electrochemical and physical performances of the petroleum pitch/polymer composite binder based lithium-ion battery were evaluated by using a charge/discharge test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and universal testing machine (UTM). As a result, the petroleum pitch(MP-50)/polymer(PVDF) composite (5:5 wt % ratio) binder based lithium-ion battery showed 1.29 gf mm-1 of adhesion strength with 144 mAh g-1 of specific dis-charge capacity and 93.1 % of initial coulombic efficiency(ICE) value.

PURPOSES : This study aims to determine whether machine learning techniques based on the results of chemical analysis experiments can be rationally applied to evaluate the aging of various asphalt binders used throughout the country. METHODS : We conducted chemical experiments such as FT-IR, H-NMR, C- NMR, and GPC for the three-stage aging levels of eight types of asphalt binders used in the country and utilized two artificial neural network models to determine valid chemical experimentation and conditions for the use of neural modeling through predictions. RESULTS : The M-prop model, which combined the findings from each neural network model into a single artificial neural network model, demonstrated superior predictive performance compared with the M-base model, which assessed aging using two cluster layers. In addition, the minimum amount of data required to achieve 100% predictive accuracy for the target asphalt binders, regardless of the artificial neural network model, was 18, and the amount of training data decreased to less than 50%. CONCLUSIONS : The predictive accuracy of the aging of asphalt binders was significantly enhanced when GPC data was used, indicating that GPC should be prioritized in evaluating the aging of asphalt binders.

PURPOSES : In this study, we aimed to evaluate the transition temperature (Tt) of asphalt binders using molecular dynamics simulations, which can provide a more accurate assessment of the mechanical properties of a material at the molecular level and can be applied to material development and design. METHODS : Unlike conventional macro- or meso-level simulations, we utilized MD simulations to evaluate the Tg of asphalt binders based on material composition and aging degree as input variables. In this analysis, 11 temperatures ranging from 434 K to 233 K at 20 K intervals were utilized, and the bulk volume and density were calculated through MD simulations. RESULTS : The MD simulation successfully predicted the Tg of the asphalt binder, and the molecular-level properties and interactions determined in this study can be applied not only to material development but also to the determination of constitutive equations or contact models used in continuum mechanics or discrete element methods. The calculated Tg was slightly different depending on the aging of the asphalt binder; however, it was found to accurately reflect the transitional characteristics. CONCLUSIONS : This study demonstrated the potential of MD simulations as valuable tools for material development and design in the construction industry. The results indicate that the use of MD simulations can lead to more accurate and efficient material development and design by providing a more detailed understanding of material properties and interactions at the molecular level.

Porous ceramics are used in various industrial applications based on their physical properties, including isolation, storage, and thermal barrier properties. However, traditional manufacturing environments require additional steps to control artificial pores and limit deformities, because they rely on limited molding methods. To overcome this drawback, many studies have recently focused on fabricating porous structures using additive manufacturing techniques. In particular, the binder jet technology enables high porosity and various types of designs, and avoids the limitations of existing manufacturing processes. In this study, we investigated process optimization for manufacturing porous ceramic filters using the binder jet technology. In binder jet technology, the flowability of the powder used as the base material is an important factor, as well as compatibility with the binder in the process and for the final print. Flow agents and secondary binders were used to optimize the flowability and compatibility of the powders. In addition, the effects of the amount of added glass frit, and changes in sintering temperature on the microstructure, porosity and mechanical properties of the final printed product were investigated.

This research was conducted to reduce the defect rate caused by nozzle clogging of printing heads used in binder jet 3D printers. The binder jet 3D printing technology may adhere to the printing head nozzle by dispersing powder due to mechanical operation such as transferring the printing head and supplying powder, and may cause nozzle clogging by natural curing at the nozzle end depending on the type of binder used. To solve this problem, this study created a cleaning module exclusively for printing heads to check whether the durability of printing heads is improved through analysis of printing results before and after using the cleaning module. To this end, this research used a thermal bubble jet printing head, and the used powder was studied using gypsum powder.

PURPOSES : The process of extracting and recovering an asphalt binder from an asphalt mixture is harmful to the human body and can affect the properties of the asphalt binder owing to the presence of residual solvent quantities. This study was conducted to determine the properties of aged asphalt binders based on rejuvenator content without extracting and recovering the asphalt binders using RAP mortar. METHODS : After extracting and recovering aged binders from waste asphalt, a rejuvenator was added at a certain rate to evaluate the physical and rheological properties of the binder based on the added amount. RESULTS : When the rejuvenator content was greater than necessary, the absolute viscosity was not properly measured owing to the behavior of the rejuvenator. The phase angle was measured to be almost 90°, thus indicating that it acted as a liquid . In addition, the shear strain and nonrecovery compliance also increased significantly. CONCLUSIONS : If an excess rejuvenator quantity was added to the aged binder, the absolute viscosity was not properly measured, the phase angle was measured to be almost 90°, and the shear strain increased significantly. It is also necessary to conduct the same tests on different types of RAPs to ensure that the results of this study are reasonable.

PURPOSES : This study was conducted to compare and evaluate the compaction performance and physical properties of recycled asphalt mixtures by utilizing the characteristics of hot-mix asphalt mixtures and foamed asphalt. METHODS : A wearing-course mixture was used for performance evaluations. Subsequently, dynamic shear rheometry (DSR), compaction performance, general physical properties, tensile strength ratio, and Hamburg wheel tracking were tested. RESULTS : As a result of performance comparisons, compaction, and general physical properties satisfied the quality standards. In the Hamburg wheel tracking test, the mixture with the antistripping agent improved performance by approximately 40% compared with the general mixture. As the foamed asphalt binder was produced at a relatively low temperature compared with the general hot-mix asphalt binder, the penetration, viscosity, and DSR test results of the aged foamed asphalt binder showed that the aging of the asphalt binder was suppressed, and the flexibility increased. Therefore, the resistance to fatigue cracks is expected to be enhanced. CONCLUSIONS : Even though the foamed warm-mix recycled asphalt mixture was produced at a temperature that was 20~30°C lower than the hot-mix asphalt mixture, its physical properties were similar to those of the hot-mix asphalt mixture; its use is expected to reduce the production of fuel and air pollutants.

Among the Additive Manufacturing (AM) technologies, the Binder-Jetting printing technology is a method of spraying an adhesive on the surface of powder and laminate layer by layer. Recently, this technique has become a major issue in the production of large casting products such as ship-building, custom vehicles and so on. In this study, we performed research to make actual mold castings and increase mechanical property by using special sand and water-based binders. For use as a mold, it has a strength of more than 3MPa and permeability. Various experiments were carried out to obtain suitable them. The major process parameters were binder jetting volume, binder types, layer thickness and heat treatment condition. As a result of this study, the binder drop quantity was measured to be about 60 pico-liter, layer thickness was 100μm and the heat treatment condition was measured about 1,000℃ and compressive strength were measured to be more than 5MPa. The optimum condition of this experiment was established through actual casting of aluminum. The equipment used in this study was a Freeforms T400 model (SFS Co., Ltd.), and the printing area of 420 * 300 * 250mm and resolution of 600dpi can be realized.

In existing ceramic mold manufacturing processes, inorganic binder systems (Si-Na, two-component system) are applied to ensure the effective firing strength of the ceramic mold and core. These inorganic binder systems makes it possible to manufacture a ceramic mold and core with high dimensional stability and effective strength. However, as in general sand casting processes, when molten metal is injected at room temperature, there is a limit to the production of thin or complex castings due to reduced fluidity caused by the rapid cooling of the molten metal. In addition, because sodium silicate generated through the vitrification reaction of the inorganic binder is converted into a liquid phase at a temperature of 1,000 °C. or higher, it is somewhat difficult to manufacture parts through high-temperature casting. Therefore, in this study, a high-strength ceramic mold and core test piece with effective strength at high temperature was produced by applying a Si-Na-Ti three-component inorganic binder. The starting particles were coated with binary and ternary inorganic binders and mixed with an organic binder to prepare a molded body, and then heat-treated at 1,000/1,350/1,500 °C to prepare a fired body. In the sample where the two-component inorganic binder was applied, the glass was liquefied at a temperature of 1,000 °C or higher, and the strength decreased. However, the firing strength of the ceramic mold sample containing the three-component inorganic binder was improved, and it was confirmed that it was possible to manufacture a ceramic mold and core via high temperature casting.