Earticle

The purpose of this study is to enhance heat insulation effect and to decrease fire hazard by attaching aluminum foil to expanded polystyrene, which is mainly used for insulating materials, to have fire retardant. The result of the test confirmed that the insulating materials, expanded polystyrene of 10 kg/m3 and 14 kg/m3 of density attached aluminum foil on both sides, showed 12%, 14% of improved heat transfer coefficient respectively compared to existing expanded polystyrene of the same density. Besides, they met all the standards for the testing of heat release and gas hazard. On the other hand, the one made of general expanded polystyrene could not meet the standards of the heat release test and the gas hazard test.

The effects of packaging conditions on freshness extension of squash (Cucurbita moscata) were investigated during 7-day storage at 2$0^{\circ}C$. Weight loss of squash packed with corrugated paperboard box (control) was 5.5%, and those of LDPE (low density polyethylene, Ф0.02 mm), LDPE (Ф0.04mm) film and EPS (expanded polystyrene) box were 0.9%, 0.8%, and 1.1%, respectively. Firmness of EPS was 11% higher than that of control, chlorophill content of squash packed with EPS box was 18.9% higher, and total ascorbic acid content of squash packed with EPS box was 29.4% higher than that of control. Quality of packed squash was not different between EPS packages and LDPE packages. Decay of control was 1~2 pieces per box, but was not found in the LDPE, EPS box. Preferences in overall appearences of LDPE, EPS box was better than those of control.

개발한 EPS 포장상자가 사과의 신선도 유지효과 기능이 있는지의 여부를 조사코 자 사과를 포장하여 20 ℃에 저장하면서 골판지상자와 0.02와 0.04mm 두께의 LDPE필름, 기능성 MA필름과 50배로 발포시킨 EPS 상자에 사과를 15kg씩 포장하 여 포장재간의 신선도 유지효과를 비교하였다. 저장 40일 후 중량감소는 대조구는 5.7%, EPS 상자는 0.5%의 중량감소가 나타났고, 비타민C도 2.06과 2.31 mg%로 EPS 포장구가 높게 유지 되고 있었다. 당도와 산도는 포장구간에 큰 차이가 없었 으며 부패의 경우 대조구는 상자당 3- 5개과가 발생했으나 EPS포장구는 발생하지 않았으며 외관도 양호한 것으로 나타났다.

This study was measured weight loss, total ascorbic acid, titratable acidity , and soluble solids content to investigate the effect of EPS(expanded polystyrene foam) box , LDPE film pouches and double wall corrugat ed fiberboard box during storage at 20℃. Weight loss of apple packed with corrugat ed paperboard box after 40 day s storage was 5.7%, and those of LDPE, CE film and EPS box were 0.2- 0.5%. Ascorbic acid content of apple packed with LDPE, CE , EPS was higher than that of control. T itratable acidity and tot al soluble solid content of control were changed 40% and 10%, and the EPS were changed 27%and 4%, respectively . Overall appearances of 'Fuji ' apple packed with LDPE, CE and EPS were better than that of control.

The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. So, main purpose of this study was to establish the physical and mechanical properties of lightweight concrete using expanded polystyrene bead on fine aggregate and natural gravel, expanded clay and pumice stone on coarse aggregate. The test rusults of this study are summarized as follows; 1. The water-cement ratio of concrete using pumice stone was larger than that of the concrete using natural gravel and expanded clay. 2. The unit weights of concrete using pumice stone and expanded caly were shown less than 1,000g/$m^3$. 3. The compressive strengths of all types were shown less than 60kg/$cm^2$, tensile and bending strengths were shown less than l3kg/$cm^2$ and 3lkg/$cm^2$$^2$, respectively. 4. The pulse velocity of concrete was shown similar with using natural gravel and pumice stone, and shown the lowest using pumice stone. 5. The dynamic modulus of elasticity of concrete was shown considerably smaller, and shown the lowest using pumice stone. 6. The static modulus of elasticity of concrete using expanded clay and pumice stone were shown considerably smaller, and shown 22% ~29% as compared with the dynamic modulus of elasticity. 7. The stress-strain curves of concrete were shown similar, generally. And the curves were repeated at short intervals increase and decreased irregularly.

Use of soils with crushed expanded polystyrene(EPS) satisfied both recycling of industrial waste and development of new light-weight fill materials. Objectives of the study were to make the mixed the mixed soils with the crushed EPS and to suggest the most rational mixing ration as a fill material. A series of laboratory tests was performed to investigate the relationship between miximum dry density and optimum moisture contenr and to find the variation of CBR for mixtures with 3 soils and 2 sizes of the crushed EPS. Results of the test showed that the sizes fo the curshed EPS had a little effect on the properties of mixed soils. But gradatiion of soils and mixing ration with the crushed EPS were important factors to characterize compaction properties of the mixed soils.

개발한 EPS 포장상자가 사과의 신선도 유지효과 기능이 있는지의 여부를 조사코자 사과를 포장하여 $20^{\circ}C$ 저장하면서 골판지상자와 0.02와 0.04mm 두께의 LDPE 필름, 기능성 MA필름과 50배로 발포시킨 EPS상자에 사과를 15kg씩 포장하여 포장재간의 신선도 유지효과를 비교하였다. 저장 40일 후 중량감소는 대조구는 5.7%, EPS 상자는 0.5%의 중량감소가 나타났고, 비타민C도 2.06과 2.31 mg%로 EPS 포장구가 높게 유지되고 있었다. 당도와 산도는 포장구간에 큰 차이가 없었으며 부패의 경우 대조구는 상자당 3-5개과가 발생했으나 EPS포장구는 발생하지 않았으며 외관도 양호한 것으로 나타났다.

This study was measured weight loss, total ascorbic acid, titratable acidity, and soluble solids content to investigate the effect of EPS(expanded polystyrene foam) box, LDPE film pouches and double wall corrugated fiberboard box during storage at $20^{\circ}C$. Weight loss of apple packed with corrugated paperboard box after 40 days storage was 5.7%, and those of LDPE, CE film and EPS box were 0.2-0.5%. Ascorbic acid content of apple packed with LDPE, CE, EPS was higher than that of control. Titratable acidity and total soluble solid content of control were changed 40% and 10%, and the EPS were changed 27% and 4%, respectively. Overall appearances of 'Fuji' apple packed with LDFE, CE and EPS were better than that of control.

감용제 limonene을 이용하는 EPS 자원 재활용 공정에 있어서, limonene - EPS 혼합 액체의 저장$.$취급시의 화재위험성 평가에 대한 기초 자료로 제시하고자 혼합물의 농도 및 시료양의 변화에 따른 최저발화온도를 측정하였고, 발화와 비발화 영역을 비교하였다. 발화온도를 예측하는데 있어서 가장 과학적인 원리로서 이용되고 있는 발화 지연 시간, 활성화 에너지 및 발화온도의 관계식을 선형회귀분석을 이용하여 ln t = 0.704/T-5.819로서 제시하였다. 또, 가연성 혼합물의 농도 변화에 따른 발화위험성을 예측하기 위하여 혼합물의 농도와 발화온도의 관계식을 비선형회귀분석을 이용하여 $T_m=248.32+69.27X+172.60X^2$로서 제시하였다. 그 결과, 발화 지연 시간과 발화온도와의 관계식 및 혼합물의 농도와 발화온도와의 관계식에 의해서 limonene - EPS 혼합물의 발화온도의 추정이 가능하게 되었다.

In the reutilization process using limonene, the organic solvent to reduce volume of EPS, the AIT was measured with the variation of concentration and volume of mixture, in order to present the fund-mental data on the fire hazard assessment of limonene - EPS mixture at storage and handling. And ignition zone was compared with non-ignition zone. The equation related to AIT, activation energy and ignition delay time, used by the most scientific basis for predicting AIT values, was suggested using linear regression analysis as ln t = 0.704/T-5.819. And the equation related to concentration of mixture and AIT was also suggested to predict ignition hazard of combustible mixture using nonlinear regression analysis as $T_m/=248.32+69.27X+172.60X^2$. It enabled to predict ignition temperature according to variation of ignition delay time and concentration of mixture by the suggested equations.

To investigate the mechanical properties of Expanded Polystyrene (EPS) Beads Stabilized Lightweight Soil (EBSLS), Laboratory studies were conducted. Totally 20 sets of specimens according to the complete test design were prepared and tested with unconfined compressive test and consolidated drained triaxial test. Results showed that dry density of EBSLS ($0.67-1.62g/cm^3$) decreases dramatically with the increase of EPS beads volumetric content, while increase slightly with the increase of cement content. Unconfined compressive strength (10-2580 kPa) increases dramatically in parabolic relationship with the increase of cement content, while decreases with the increase of EPS beads volumetric content in hyperbolic relationship. Cohesion (31.1-257.5 kPa) increases with the increase of cement content because it is mainly caused by the bonding function of hydration products of cement. The more EPS beads volumetric content is, the less dramatically the increase is, which is a result of the cohesion between hydration products of cement and EPS beads is less than that between hydration products of cement and sand particles. Friction angle ($14.92-47.42^{\circ}$) decreases with the increase of EPS beads volumetric content, which is caused by the smoother surfaces of EPS beads than sand grains. The stress strain curves of EBSLS tend to be more softening with the increase of EPS beads content or the decrease of cement content. The shear contraction of EBSLS increases with the increase of $c_e$ or the decrease of $c_c$. The results provided quantitative relationships between physico-mechanical properties of EBSLS and material proportion, and design process for engineering application of EBSLS.

Many previous studies have focused on revealing the harmfulness of microplastic particles, whereas very few studies have focused on the effects of chemicals, particularly photooxidation product. In this study, products of photodegradation from expanded polystyrene (EPS), compounds produced by photolysis by ultraviolet (UV) light, were investigated. EPS was directly irradiated and photolyzed using a UV lamp, and then the extracted sample was analyzed using high-resolution mass spectrometry (HRMS). Multiple ionization techniques, including electrospray ionization, atmospheric pressure chemical ionization, and atmospheric pressure photoionization, were used. In total, >300 compounds were observed, among which polystyrene monomer, dimer, and oxidized products were observed. In this work, the data presented clearly demonstrate that it is necessary to identify and monitor oxidized plastic compounds and assess their effect on the environment.

본 연구의 연성포장설계의 해석적 연구를 위해 연성포장설계에 이용되는 EPS 지오폼 회복탄성계수 모델이 고안되어 노상층이 EPS 블럭인 연성포장의 수직방향 변형크기를 예측하기위한 프로그램인 RMEG 에 이용되었다. RMEG 프로그램은 EPS 지오폼의 노상층이 설계된 기한동안 얼마나 침하 하는지와 AASHTO 연성포장설계방정식에 의해 평가된 신뢰도 70%로 주어진 교통하중에 도로구조체가 얼마나 오랫동안 심각한 도로파손 없이 지탱하는지를 보여주었다. 그 결과, EPS 노상층의 예측 수직변형은 20.6년 동안 5mm 이하로 EPS 지오폼은 일반토사의 대체물로써 하자가 없음을 나타냈다.

The resilient modulus model of EPS geofoam to be used for a flexible pavement design was developed. In this study, the model was applied to design the flexible pavement and to predict the magnitude of the deformation of EPS geofoam blocks as a subgrade in the flexible pavement structure by using the resilient modulus model of EPS geofoam (RMEG) program. The RMEG program presented how much the EPS geofoam subgrade settled over the designed duration and the AASHTO flexible pavement design equation with the resilient modulus of EPS geofoam noted that how long the flexible pavement endured under traffic loads with 70% reliability for the estimated duration with less than 5mm vertical deformation during 20.6 years without the significant pavement distress as a substitute material for the natural soils.

본 논문에서는 발포폴리스티렌 비드 (EPB)와 폐 발포폴리스티렌 (WEP)의 대체율에 따른 경량 모르타르의 기초 특성을 평가였다. EPB 및 WEP를 이용한 경량 모르타르의 기초 특성으로서 단위용적중량, 압축 강도, 휨강도, 흡수율, 열전도율 및 폴리스티렌 (EPB 및 WEP) 분포를 분석하였다. 그 결과 경량 모르타르는 WEP의 대체율이 증가할수록 단위용적중량, 압축 강도, 휨강도, 흡수율 및 열전도율은 증가하고, 폴리스틸렌 면적 분포는 감소하였다.

This study presents an evaluation of basic properties of light weight mortar with expanded polystyrene bead(EPB) and waste expanded polystyrene(WEP) by varying replacement rations. In order to evaluate the basic properties of the light weight mortar with EPB and WEP, unit weight, compressive strength, flexural strength, water absorption ratio, thermal conductivity and distribution of polystyrene (EPB and WEP) in hardened mortar were performed. As a result, unit volume, compressive strength, bending strength, water absorption and thermal conductivity of light weight mortar were increased, but area distribution of polystyrene decreased with increasing the replacement ratio of WEP.

본 연구의 주된 목적은 반복적인 하중조건하에서 연성포장체의노반재료로써, EPS블럭의 시간의존적 변형을 연구하는데 있다. 반복하중 조건에서의 EPS블럭의 거동을 이해하기 위해서 본 연구에서는 실험적 방법 및 수치모형을 제시하였다. 이 수치모델링을 위해서 반복하중 조건하에서 관찰된 변형거동과 단위중량, 변형 그리고 적용된 하중과의 상관관계의 조사가 행해졌다. 실험결과는 핀들레이 이론과 반복하중 조건에서의 연구결과의 모델 분석등과 비교되었고, 보완된 핀들레이 모델과 본 연구에서 제시한 모델은 반복하중에서의 EPS블럭의 변형거동을 나타내는데 이용될 수 있는 것으로 기대된다.

The main objective of this study is to investigate the time-dependent deformation of EPS blocks under repeated loading conditions which is the one of the flexible pavement structure. The study comprised of both the experimental work and analytical modeling in order to understand the behavior of EPS blocks under repeated loading. The analytical modeling included the selection of a suitable model for describing the deformation behavior observed under repeated loading conditions, investigating the relationship among the unit weight, deformation and applied stress, analyzing the effect of repeated load on deformation. The test results were compared with the Findley's theory and model analysis with the results of this research under repeated loading conditions. Both Modified Findley's model and the proposed model can be adopted to illustrate the deformation behavior of EPS blocks under repeated loads.

본 연구에서는 발포 폴리스티렌과 폴리머가 혼입된 경량 복합체의 물리적 특성을 평가하였다. 발포 폴리스티렌(EPS) 비드는 경량성 및 높은 단열 특성을 가진다. 발포 폴리스티렌의 혼합 비율이 증가할수록 단위 용적 질량과 공기량은 감소한다. 휨 강도와 압축 강도는 크게 감소하지만, 열전도율은 크게 낮아져 단열 성능이 향상된다. 또한, 화재 및 열에 의한 중량 손실은 감소하는 경향을 보였다. 이러한 결과는 경량이며 다량의 공기를 포함하는 발포 폴리스티렌의 고유한 특성 때문인 것으로 판단된다. 폴리머의 혼합 비율이 증가할수록 단위 용적 질량은 감소하는 반면, 공기량, 압축 및 휨 강도는 증가한다. 열전도율은 약간 감소하는 경향을 보였으며, 폴리머는 화재 및 열에 의한 중량 손실 변화에 큰 영향을 미치지 않는 것으로 판단되었다.

In this study, the physical properties of a hardened body incorporated with expanded polystyrene and polymer were evaluated. Expanded polystyrene(EPS) beads are lightweight and possess high thermal insulation properties. As the mixing ratio of expanded polystyrene increases, the unit volume weight and air content decrease. The flexural and compressive strengths decrease significantly, while the thermal conductivity is greatly lowered, leading to an increase in thermal insulation performance. Furthermore, the weight loss due to fire and heat showed a decreasing trend. These results are considered to be due to the inherent characteristics of expanded polystyrene, which is lightweight and contains a large amount of air. When the mixing ratio of the polymer increases, the unit volume weight decreases, while the air content, compressive, and flexural strengths increase. The thermal conductivity showed a slight decreasing trend, and it was determined that the polymer does not have a significant effect on the change in weight loss due to fire and heat.

This study investigated the behavior and environmental impact of expanded polystyrene (EPS) in a simulated marine environment, focusing on the effects of UV exposure. Through a series of controlled experiments, it was found that UV-induced weathering increased the formation of smaller EPS degradation products, leading to higher concentrations of dissolved organic carbon (DOC) in the seawater. Additionally, it was suggested that the assembly behavior of dissolved organic matter (DOM) contributed to the reduction of DOC levels over time. The EPS layer exhibited slightly higher DOC concentrations compared to the seawater, likely due to hydrophobic interactions that retained degradation products near the EPS. Analysis of the soil layer revealed that EPS particles and degradation products settled or adsorbed more extensively under UV conditions, indicating a greater risk of sediment contamination. Soil layer elution experiments further confirmed that EPS particles and their degradation products could migrate through soil pores, posing a potential contamination risk to other environments. UV exposure resulted in a twentyfold increase in DOC release from EPS compared to dark conditions. These findings highlight the persistent pollution potential of EPS in marine environments, especially under UV exposure, and emphasize the need for effective EPS waste management and further research into its environmental impacts.

스치로폴은 발포폴리스티렌(EPS : Expanded Poly-Styrene)을 말하며, 이것은 스티렌모노머(Stone Monomer)를 중합하여 만든 플리스티렌과 여기에 첨가한 발포제가 주원료로 되어 있다. 폴리스티렌은 1930년대에 미국과 독일에서 공업화되었고 스치로폴은 1943년 초에 미국에서 공업화가 이루어져 건물의 단열재, 물품포장재 등으로 이용되어 왔다. 1972년에는 노르웨이에서 연약지반상 교량의 접속도로 보수공사에 처음 스치로폴 성토공법이 이용되어 교대의 측방유동 방지대책으로 성공을 거둠에 따라 연약지반상의 경량성 토재 및 토압을 받는 옹벽, 교대 등 구조물의 경량 뒷채움재로서 각광을 받게 되었다. 한편 우리나라에서는 1994. 6월에 한국지반 공학회 주최로 개최된 "발포폴리스티렌(EPS) 이용 성토공법 국제심포지엄"에서 양산-구포간 고속도로성토(L=70m) 및 서해안고속도로의 교대 뒷채움에 스치로폴 경량성토재가 이용된 문헌이 발표된 바 있으며, 시중에서 단열재용으로 판매되고 있는 스티로폴 평판의 규격은 표 1과 같다. 스치로폴은 그 가격이 비싼 편이지만 단위중량(20-40kgf/m$^3$)이 흑의 50/1-100/1 밖에 안되는 초경량재로서 강도, 내구성 및 시공성이 우수한 성토용 신재료이기 때문에 연약지반상에서 구조물 시공시 지반의 과대한 침하, 측방유동 및 사면활동 등이 생길 경우 도로성 토재 또는 교대, 옹벽 등 구조물의 뒷채움재로서 스치로폴을 사용하면 이를 방지할 수 있으므로 매우 효과적인 토목자재라 할 수 있다. 따라서 본고에서는 지금까지의 연구결과, 시험시공 및 시공실적 등을 토대로 발표된 참고문헌을 중심으로 연약지반상 스치로폴 성토공법의 설계방법에 대하여 간단히 소개하고자 한다. 소개하고자 한다.

The purpose of this study is to examine the influences of polystyrene content and St/UP on the setting shrinkage and strengths of polymer mortar with waste expanded polystyrene resin as a shrinkage-reducing agent, and to recommend the optimum binder formulations for product of low-shrinkage polymer mortar. In this paper, polymer mortar is prepared with waste expanded polystyrene content and St/UP, and tested for setting shrinkage, flexural and compressive strengths. From the test results, irrespective of increasing of waste expanded polystyrene resin, the strengths reduction of polymer mortar with waste expanded polystyrene(EPS) resin is not recognized. And the setting shrinkage is reduced with EPS resin content. The waste expanded polystyrene resin as a shrinkage-reducing agent can be used in the same manner as commercial polystyrene resin. In this study, we can obtain the optimum mix proportions of polymer mortar using EPS resin.

지하공간의 수요가 증가되면서 지중구조물의 기능을 저하시키는 상재하중 및 토피증가에 대한 구조물의 안정성 문제를 해결하기 위해 많은 연구자들이 고압축성 물질을 이용한 하중저감방법 연구를 진행해왔다. 본 논문은 하수관거에 작용하는 하중을 EPS Geofoam을 활용하여 경감시키는 하중저감공법을 아치구조물에 적용하고 그 효과를 증가시키기 위한 최적의 Soft Zone 적용방법에 대해 기술하고 있다. 지반구조 상호작용을 고려한 ABAQUS 유한요소해석을 통해 아치구조물의 거동 특성을 파악하고 4가지 EPS Geofoam 형식을 해석적으로 분석하여 최적의 적용형상을 확인하였다. 해석 결과를 토대로 선정된 최적 단면 형상에 대해 아치구조물의 라이즈비, 지간길이 변화를 해석변수로 고려하여 발생하는 토압감소율을 비교하여 적용성을 분석하였다. 수치해석에서 선정한 최적 Soft Zone를 적용한 아치구조물에 발생하는 토압이 평균 78% 감소되는 것을 확인하였다. 본 연구 결과에서 EPS Geofoam의 토압 경량화 효과와 이에 대한 지중아치구조물의 적용성 평가는 지중구조물 설계 시 경제적이고 합리적인 방법을 제공해 줄 것이며, 향후 심층 지하공간에 대한 활용성 증가에 도움이 될 것이다.

As the demand for underground space increases, many researchers have been studying the load reduction method using high compressible materials to solve for the stability problem of the overhead load and for the increase of the earth pressure which decreases the function of the underground structure. This paper determines the optimum soft zone and the effect of the using EPS Geofoam as a load reduction material to arch structures. A finite element analysis program, ABAQUS, is used to analyze the soil-structure interaction and the behavior of buried arch structures considering different four EPS Geofoam forms to confirm the most conservative shape. The optimum cross-sectional shape was determined by comparing the results of earth pressure reduction rate in accordance with the change of span-rise ratio and span length of the arch structure. It was confirmed that the earth pressure generated in the arch structure using the optimal soft zone selected by the numerical analysis was reduced by an average of 78%. In this study, the effect of EPS Geofoam on soil pressure reduction and its applicability to underground arch structures will provide an economical and conservative way to design underground structures and will help to increase the usability of deep underground space.