Effective mixing of different-sized aggregates in mobile asphalt plant dryers is crucial for ensuring high-quality, consistent asphalt production. This study explores the application of spatial analysis techniques, particularly the Discrete Element Method (DEM), to understand and optimize the mixing process of aggregates in drum dryers. The research emphasizes the importance of proper mixing to achieve uniform moisture removal and heating across various aggregate sizes. Larger aggregates heat more slowly, while finer particles risk overheating or being carried away by air currents, necessitating careful management of the mixing process. Using LIGGGHTS, an open-source simulation framework, we conducted DEM simulations to analyze the spatial distribution and behavior of aggregates within a 3D model of a drum dryer. The study considered multiple factors affecting mixing efficiency, including drum inclination, rotational speed, and aggregate feeding frequency. Results indicate that the rotational speed of the drum dryer has the most significant impact on mixing effectiveness. The DEM simulations provided valuable insights into particle movement, heat transfer, and potential segregation issues within the dryer. Further investigations into additional factors that may influence aggregate mixing in drum dryers is recommended, paving the way for improved efficiency and quality in asphalt manufacturing.

PURPOSES : In this study, the resources and energy consumed to produce hot mix asphalt mixtures and hot mix reclaimed asphalt mixtures in asphalt concrete plants were estimated and the emissions from the detailed processes of the production process were evaluated based on TRACI(the tool for the reduction and assessment of chemical and other environmental impacts). METHODS : To estimate the energy consumption of the aggregate drying process, which consumes a significant amount of energy in the production process, an energy consumption calculation model based on the thermal equilibrium equation was used, and the energy consumed for material transportation, storage, and operation of other facilities was cited from the literature. RESULTS : For the system boundary conditions established and the inventory considered, the emissions to produce one ton of hot mix reclaimed asphalt mix are greater than the emissions to produce one ton of hot mix asphalt mix for a number of key impact categories. The process of producing hot mix reclaimed asphalt mixtures was evaluated to consume more resources and energy in the production of recycled aggregates and heating for drying than in the production of hot mix asphalt mixtures, but less resources and energy in the production of binders and natural virgin aggregates and the heating to heat these materials. CONCLUSIONS : The results of the emissions assessment using the life cycle inventory for the production of hot mix asphalt mixtures were generally similar to the results understood in the field and in much of the literatures, confirming the reliability of the methodology. However, in order to evaluate the dominance of specific processes or mixtures, it is believed that the construction of a wide range of inventory databases after inventory redesign is necessary for a specific and rigorous assessment.

PURPOSES : Water content causes a big problem in terms of the quality and economy of the asphalt plant. However, the current guidelines do not suggest specific rules other than roof installation. Therefore, this study proposes a water content management index, QM, and management flow chart by analyzing the water content variability of the stockpile and cold bin aggregates and suggests a guideline rule for improving water content management, including stockpile floor inclination via analysis of slope stability. METHODS : To analyze the variability of water content in the asphalt plant, stockpile and cold bin aggregate samples were collected from the asphalt plant over two years and a water content lab test was conducted via sieve analysis. In addition, domestic and foreign water content management guidelines were compared and the economic effect was analyzed according to water content DB analysis for the importance of water content management. The influence factors of water content variability were also analyzed. To apply the 3σ quality management technique for the development of the water content management index, QM, a water content management limit and procedure was proposed through the asphalt mix design. RESULTS : As a result of analyzing the water content variability, it was found that the water content of the stockpile fine aggregates should be intensively managed immediately after the rainy season and the QM index developed in this study should be 1 or more. In addition, as a result of the stability analysis according to the change in the stockpile floor inclination, it was found that the safety factor was lowered according to the slope angle and floor inclination. CONCLUSIONS : In the past, a passive method of preventing rainwater with a roof was used for water content management and ambiguous qualitative rules were suggested in the guidelines. In this study, a procedure for managing the water content of asphalt plant aggregates using the QM index, a quantitative stock floor inclination chart, and rules for improving water content management were presented for the quality control of asphalt plant aggregates.

Recently, in an asphalt mixture manufacturing plant, "environment" "safety" "energy saving and resource saving" is an important issue. Many plants already make efforts to save energy, that is, to reduce CO2 emissions by using low fuel consumption burners and devising to change the shape of the blades to improve the thermal efficiency in the drier. In addition, the heating and classification of stone materials and dust generated during mixing are handled by dust collectors. Furthermore, with regard to various materials used in plants, we are working on environmental conservation by emphasizing environmental pollution prevention and safety of working environment. However, recently, the location conditions of plants have diversified, such as the presence of residential areas in the vicinity of plants, and these measures are not enough. In this report, we report a part of the actual situation of "environment", "safety", "energy conservation and resource saving" adopted in plants in Japan. 1, Introduction to odor control In an asphalt mixture production plant, a special odor is generated by the trace amounts of hydrocarbon oxides and sulfur compounds when loading an exhaust stack or an asphalt mixture. In an asphalt mixture production plant, a special odor is generated by a very small amount of hydrocarbon oxides and sulfur compounds when the gas from the exhaust pipe and the transporting asphalt mixture. As a countermeasure against the odor of the exhaust pipe, a method of burning trace substances is adopted by using a deodorizing furnace, but since it consumes a large amount of energy, there is a problem of suppressing CO2 emission. In this report, we identify odor-causing substances from plant and propose odor reduction by deodorant suitable for these substances. 2,　Introduction to anti-adhesion agents for asphalt Conventionally, mineral oil such as heavy oil and diesel oil was applied to deal with the adhesion of asphalt mixture to the equipment of asphalt mixture production plant, dump for delivery, finisher at construction, road roller and so on. However, by using a large amount of these mineral oils, a part of the asphalt composite material is cut back, causing problems such as pot holes after construction. In addition, problems such as water pollution due to leakage of mineral oil are also raised. In this report, we propose a water - soluble and biodegradable anti - adhesion agent. 3, Introduction to Recycling Additives More than 70% of the asphalt mixture used in Japan is a recycled mixture. Effective utilization of recycled mixture is the most important question to be considered from the perspective of resource protection, energy conservation, cost reduction. In Japan, initially, blends with asphalt with high needle penetration and low softening point and amethod of adding crude by-products of lubricating oil production has been adopted. However, in the former, the ratio of the recycled asphalt mixture is limited to about 10 to 20%, and in the latter case, since it is high viscosity, it is necessary to heat at the time of use, that the recycling effect is not sufficient. In addition, there is a problem in that it contains a large amount of aromatic moieties, especially polycyclic aromatic moieties, which are likely to be carcinogenic. In order to solve these problems, in this report, the combination of several kinds of special mineral oils and the use of special additives are used to achieve low viscosity, high flash point, low aromaticity, And high recycle additives are proposed. Asphalt mixture manufacturing plants in Japan are located in urban areas near the demand of large cities, so the environment is well considered. Recently, regulations such as the Air Pollution Prevention Ordinance, the Anti-Odor Prevention Ordinance and the Noise Prevention Ordinance have been strengthened. Furthermore, the safety training for workers using SDS for hazardous substances has been complicated is in fact. In order to solve these problems, we are not limited to this report, but we fully understand the needs of the plant and develop products that meet the environmental, safety, energy and resource conservation key words. I would like to propose.

PURPOSES:The objective of this study is to ascertain the curing period of cementless cold central plant recycled asphalt base-layer, using mechanical analyses and specimen quality tests on the field.METHODS :Cold central plant recycled asphalt base-layer mixture was produced in the plant from reclaimed asphalt, natural aggregate, filler for the cold mix, and the modified emulsion AP using asphalt mix design and plant mix design. In order to examine the applicability of the curing period during the field test, the international standards for the possibility of core extraction and the degree of compaction and LFWD deflection were analyzed. Moreover, Marshall stability test, porosity test, and indirect tensile strength test were performed on the specimens of asphalt mix and plant mix design.RESULTS :The plant production process and compaction method of cementless cold central plant recycled asphalt base-layer were established, and the applicability of the optical moisture content for producing the mixture was verified through the field test. In addition, it was determined that the core extraction method of the conventional international curing standard was insufficient to ensure performance, and the LFWD test demonstrated that the deflection converges after a two-day curing. However, the back-calculation analysis reveals that a three-day curing is satisfactory, resulting in a general level of performance of dense asphalt base-layer. Moreover, from the result of the specimen quality test of the asphalt mix design and plant mix design according to the curing period, it was determined that the qualities satisfied both domestic and international standards, after a two-day curing. However, it was determined that the strength and stiffness after three-day curing are higher than those after a two-day curing by approximately 3.5 % and 20 %, respectively.CONCLUSIONS:A three-day curing period is proposed for the cementless cold central plant recycled asphalt base-layer; this curing period can be demonstrated to retain the modulus of asphalt-base layer in the field and ensure stable quality characteristics.

최근 인공지반녹화가 주변 생활공간의 쾌적화, 에너지 절약효과, 도시 미관의 환경개선 등의 장점을 갖고 있어 콘크리트 위에 녹화 공간 조성이 증가하고 있다. 이에 따라 건축공사 표준 시방서, 건축물 녹화 설계기준 등에서는 방수층의 수밀안정성 확보를 위해 일정 품질 이 상의 방근층 설치를 규정하고 있으나, 실제 우리나라의 많은 현장은 방수층 위에 누름콘크리트 타설 후 인공녹화를 시행하고 있는 실정이다. 이에 본 연구에서는 방근층을 시공하지 않은 현장을 대상으로 지표를 설정하였으며, 누름콘크리트의 균열에 따른 식물의 뿌리가 균열부로 침 입 및 관통하여 누름콘크리트 하단부의 아스팔트 방수시트에 미치는 영향을 평가하였다.