خيارات البحث
النتائج 1 - 10 من 40
Thermal, hygric, and environmental performance evaluation of thermal insulation materials for their sustainable utilization in buildings
2021
Wi, Seunghwan | Park, Ji Hun | Kim, Young Uk | Yang, Sungwoong | Kim, Sumin
As energy use in the building sector is increasing worldwide, building materials with characteristics that save energy are becoming increasingly important; in addition, there is an emerging need for high-performance insulation materials with low thermal conductivity. However, thermal insulation should consider thermal conductivity, which is the main performance parameter, in addition to the water adsorption rate, acidity, and deformation and expansion due to drying conditions. This study evaluated the main performance of 21 insulation materials used at construction sites to objectively and clearly evaluate their overall performance, including their thermal conductivity. Thermal conductivity was measured by the heat flow meter method according to ASTM C518 and ISO 8301 standards; it was also evaluated according to the drying conditions. The water absorption rate was evaluated by ISO 2896 to ensure the sustainability and long-term thermal conductivity performance of the material. Acidity was evaluated with ASTM E861 to reduce the environmental load of the buildings and soil. The results of this study reviewed an appropriate method to measure the main performance according to the type of insulation.
اظهر المزيد [+] اقل [-]Fire retardant performance, toxicity and combustion characteristics, and numerical evaluation of core materials for sandwich panels
2022
Wi, Seunghwan | Yang, Sungwoong | Yun, Beom Yeol | Kang, Yujin | Kim, Sumin
According to fire accident statistics, fires in buildings are increasing. The flame-retardant performance of insulation materials is considered an important factor for preventing the spread of fire and ensuring evacuation. This study evaluated the flame-retardant performance and combustion characteristics of four types of organic thermal insulation used as core materials in sandwich panels. The flame-retardant performance evaluation based on total heat release and heat release rate revealed that phenolic foam (PF) satisfied the criteria for non-combustible grade insulation. An analysis of the hazardous gases released while combustion of the four insulation materials indicated that a significant amount of CO was released—an average of 19,000 ppm or higher—in the rigid urethan foam (PIR) and spray-type polyurethane foam (SPU). The fractional effective dose (FED) value was derived from the gas analysis results according to ISO 13344. PIR and SPU had an average FED value of 2.0 or higher and were identified as very dangerous in the case of fire accidents. Moreover, the evacuation time in the case of a fire in a warehouse-type building was comprehensively analyzed considering the material, size, and height for the four types of insulation. PIR was the most vulnerable to fire, and for PF, the danger limit was not reached until the end of the simulation.
اظهر المزيد [+] اقل [-]Hazard evaluation of indoor environment based on long-term pollutant emission characteristics of building insulation materials: An empirical study
2021
Wi, Seunghwan | Kang, Yujin | Yang, Sungwoong | Kim, Young Uk | Kim, Sumin
Insulation materials are essential components in construction, and their main objective is to increase the efficiency of thermal energy by minimizing internal and external thermal exchange. Accordingly, research and development studies are being actively conducted to increase the thermal resistance of insulation materials, and high-performance insulation materials that use organic chemicals have been developed after industrialization. However, thermal insulation comprising chemicals poses a potential risk of pollutant emissions and can cause health problems. In this study, five types of insulation materials and the contaminants generated from the building materials used in insulation construction were quantitatively analyzed. In addition, an empirical study on the discharge of pollutants was conducted using a test bed, and the effects of the pollutants discharged from the insulation material on the indoor environment were examined by analyzing the pollutant concentration for 90 days. In addition, we analyzed the effect of an insulation material on an indoor environment through the standard specifications. Moreover, the necessity of legal management of the emission of contaminants from insulation materials was proposed based on the empirical research results.
اظهر المزيد [+] اقل [-]Numerical analysis and modeling of two-loop experimental setup for measurements of radon diffusion rate through building and insulation materials
2020
Szajerski, Piotr | Zimny, Arkadiusz
Radon is a natural radioactive gas present in the environment, which is considered as the second most important lung cancer cause worldwide. Currently, radon gas is under focus and was classified as contaminant of emerging concern, which is responsible for serious biological/health effects in human. In presented work we propose the numerical model and analysis method for radon diffusion rate measurements and radon transport parameters determination. The experimental setup for radon diffusion was built in a classical, two chamber configuration, in which the radon source and outlet reservoirs are separated by the sample being tested. The main difference with previously known systems is utilization of only one radon detector, what was achieved by a careful characterization of the Rn-222 source and development of a numerical model, which allows for exact determination of radon transport parameters by fitting simulated radon concentration profile in the outlet reservoir to experimental data. For verification of the developed system, several insulation materials commonly used in building industry and civil engineering, as well as, common building materials (gypsum, hardened cement paste, concrete) were tested for radon diffusion rate through these barriers. The results of radon transmittance, permeability and diffusion coefficients for investigated materials are in compliance with values known previously from the literature. The analysis method is fast and efficient, and requires measurement period varying from a dozen or so hours up to 2–3 days depending on material properties. The described method is entirely based on a numerical analysis of the proposed differential equation model using freely available SCILAB software and experimental data obtained during sample measurements.
اظهر المزيد [+] اقل [-]Response of stable carbon isotope in epilithic mosses to atmospheric nitrogen deposition
2010
Liu, Xue-Yan | Xiao, Hua-Yun | Liu, Cong-Qiang | Li, You-Yi | Xiao, Hong-Wei | Wang, Yan-Li
Epilithic mosses are characterized by insulation from substratum N and hence meet their N demand only by deposited N. This study investigated tissue C, total Chl and δ13C of epilithic mosses along 2 transects across Guiyang urban (SW China), aiming at testing their responses to N deposition. Tissue C and total Chl decreased from the urban to rural, but δ13Cmoss became less negative. With measurements of atmospheric CO2 and δ13CO2, elevated N deposition was inferred as a primary factor for changes in moss C and isotopic signatures. Correlations between total Chl, tissue C and N signals indicated a nutritional effect on C fixation of epilithic mosses, but the response of δ13Cmoss to N deposition could not be clearly differentiated from effects of other factors. Collective evidences suggest that C signals of epilithic mosses are useful proxies for N deposition but further works on physiological mechanisms are still needed.
اظهر المزيد [+] اقل [-]Effects of oil and oil burn residues on seabird feathers
2016
Fritt-Rasmussen, Janne | Linnebjerg, Jannie Fries | Sørensen, Martin X. | Brogaard, Nicholas L. | Rigét, Frank F. | Kristensen, Paneeraq | Jomaas, Grunde | Boertmann, David M. | Wegeberg, Susse | Gustavson, Kim
It is well known, that in case of oil spill, seabirds are among the groups of animals most vulnerable. Even small amounts of oil can have lethal effects by destroying the waterproofing of their plumage, leading to loss of insulation and buoyancy. In the Arctic these impacts are intensified. To protect seabirds, a rapid removal of oil is crucial and in situ burning could be an efficient method. In the present work exposure effects of oil and burn residue in different doses was studied on seabird feathers from legally hunted Common eider (Somateria mollissima) by examining changes in total weight of the feather and damages on the microstructure (Amalgamation Index) of the feathers before and after exposure. The results of the experiments indicate that burn residues from in situ burning of an oil spill have similar or larger fouling and damaging effects on seabird feathers, as compared to fresh oil.
اظهر المزيد [+] اقل [-]Lignocellulosic materials as soil–cement brick reinforcement
2022
Sabino, Ticyane Pereira Freire | Coelho, Nayane Pereira Freire | Andrade, Nayhara Camila | Metzker, Stefânia Lima Oliveira | Viana, Queilla Santos | Mendes, Juliana Farinassi | Mendes, Rafael Farinassi
The need for environmental preservation requires civil engineering to reach new concepts and technical solutions aiming at the sustainability of its activities and products. In this context, this study aimed to evaluate the effect of using different types and percentages of vegetable particles on the physical, mechanical, and thermal properties of soil–cement bricks. Bamboo, rice husk, and coffee husk particles at 1.5 and 3% percentages and a control treatment not using the particle were evaluated. The chemical properties, shrinkage, compaction, consistency limits, and grain size were characterized for the soil; and the anatomical, chemical, and physical properties for the lignocellulosic particles. The bricks were produced using an automatic press and characterized after the curing process for density, water absorption, porosity, loss of mass by immersion, compressive strength, durability, and thermal conductivity. The increase in the lignocellulosic waste percentage caused a mechanical strength decrease and bricks’ porosity and water absorption increase. However, it caused a decrease in density and an enhancement in loss of mass and thermal insulation properties. The bricks produced with rice husk obtained the best results in terms of mechanical and thermal properties, and were still among the best treatments for physical properties, standing out among the lignocellulosic waste as an alternative raw material source for soil–cement brick production.
اظهر المزيد [+] اقل [-]Characterisation of magnesite mine tailings as a construction material
2021
Shanmugasundaram, Vinodhkumar | Shanmugam, Balaji
Magnesite Mine Tailings (MMT) is a kind of waste produced during the mining of magnesite ore. Due to open cast mining process, huge amount of tailings are generated and dumped as open landfill that leads to numerous environmental hazards in the vicinity. MMT from Salem mine dump site, India, is collected, and a series of laboratory tests related to physical, chemical, mineralogical, mechanical, electrical and thermal properties have been conducted to characterise the MMT as construction material. Further, the results are compared with river sand and conventional coarse aggregates. The results indicate that the MMT can be used as aggregates in concrete for non-wearing surfaces, manufacturing of bricks, low thermal insulation panels, embankment and thermal insulation fills.
اظهر المزيد [+] اقل [-]Using water-based drilling cuttings from shale gas development to manufacture sintered bricks: a case study in the southern Sichuan Basin, China
2021
Liu, Wenshi | Yuan, Hui | Fan, Zhenzhen | Li, Jing | Sun, Lingru
Large amounts of water-based drilling cuttings (WDC) would be generated during the drilling of shale gas wells, which would occupy land resources and pose significant threat to soil and groundwater environment. The aim of this study was to assess the feasibility of using WDC as a replacement of natural clay to prepare sintered bricks. To determine the optimum preparation condition, the weight loss on ignition, bulk density, water absorption, and compressive strength of the samples were tested. Meanwhile, the environmental performance of the final products was evaluated and micro-analysis was conducted via X-ray diffraction and scanning electron microscopy. The results showed that using WDC to manufacture sintered bricks was technically feasible, but the physical mechanical performance would significantly decrease with the increase of the replacement ratio because of the presence of less silica and excessive calcium. The addition of waste glass and fly ash could promote the generation of molten glassy phase and form the crystal particle bonding structure, which would contribute to the physical-mechanical performance of WDC sintered bricks. Some mineral components in raw materials decomposed and formed minerals with better thermal stability during the sintering process. Under the optimum preparation conditions (mass ratio of WDC: waste glass: fly ash at 40:20:40, sintering temperature at 900 °C, and insulation time at 2 h), the physical-mechanical and environmental performance of WDC sintered bricks could meet the requirements of corresponding Chinese standards and ASTM standards. Thus, in this study, an effective solution to recycle WDC from shale gas development is provided.
اظهر المزيد [+] اقل [-]Water quality assessment and phosphorus budget of a lake (Mariut, Egypt) after diversion of wastewaters effluents
2020
Shreadah, Mohamed A. | El-Rayis, Osman A. | Shaaban, Nashwa A. | Hamdan, Amira M.
The water quality of Lake Mariut has been deteriorated for about 5 decades due to continuous discharge of agricultural, municipal, and industrial wastes from Alexandria City and the adjacent land. During the past two decades, some steps were taken for rehabilitation of the lake through primary treatment of the discharged wastes and insulation of the polluted wastewater of QD from the water body in the main basin of the lake. Several parameters of water quality at the surface and near bottom were measured at twelve locations during winter (January) and summer (August) of 2013 and 2014. The present study revealed that the lake water appeared to be well aerated but still containing high concentrations of N and P and suffering hyper-eutrophic conditions. The water quality index (WQI) reflected medium condition in the lake and bad condition in the diverted drains. The P-budget calculation displayed that TP input into the LMMB from UDᵤₛ and resuspension process from sediments exceeded the output by out flowing at UDdₛ and settling.
اظهر المزيد [+] اقل [-]